Professor Annette Sterr


Professor of Cognitive Neuroscience and Neuropsychology
PhD, Dipl Psych, CPsychol, HPCP
+44 (0)1483 68
02 AC 04
Tuesday 2pm - 4pm or by appointment

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Publications

MALCOLM VON SCHANTZ, SIMON EVANS, Mario Miguel, Tamara P. Taporoski, Luz Marina Gomez, Andréa Horimoto, ERKAN ALKAN, Felipe Beijamini, Mario Pedrazzoli, Kristen L. Knutson, Jose Eduardo Krieger, Homero Vallada, ANNETTE MARIE STERR, Alexandre Pereira, André Negrão Evening preference correlates with regional brain volumes in the anterior occipital lobe, In: Chronobiology International Taylor and Francis
Chronotype or diurnal preference is a questionnaire-based measure influenced both by circadian period and by the sleep homeostat. In order to further characterize the biological determinants of these measures, we used a hypothesis-free approach to investigate the association between the score of the morningness-eveningness questionnaire (MEQ) and the Munich chronotype questionnaire (MCTQ), as continuous variables, and volumetric measures of brain regions acquired by magnetic resonance imaging (MRI). Data were collected from the Baependi Heart Study cohort, based in a rural town in South-Eastern Brazil. MEQ and anatomical 1.5-T MRI scan data were available from 410 individuals, and MCTQ scores were available from a subset of 198 of them. The average MEQ (62.2±10.6) and MCTQ (average MSFsc 201±85 min) scores were suggestive of a previously reported strong general tendency towards morningness in this community. Setting the significance threshold at P>0.002 to account for multiple comparisons, we observed a significant association between lower MEQ score (eveningness) and greater volume of the left anterior occipital sulcus (β=-0.163, p=0.001) of the occipital lobe. No significant associations were observed for MCTQ. This may reflect the smaller dataset for MCTQ, and/or the fact that MEQ, which asks questions about preferred timings, is more trait-like than the MCTQ, which asks questions about actual timings. The association between MEQ and a brain region dedicated to visual information processing is suggestive of the increasingly recognized fluidity in the interaction between visual and non-visual photoreception and the circadian system, and the possibility that chronotype includes an element of masking.

The brain is a very delicate, but sophisticated and complex organ of the body. During life, the brain grows and develops, matures, and then ages like all other organs of the body. This maturation and ageing comes with various physiological and anatomical changes which have an impact on the background activity of the brain. Brain activity can be recorded using various techniques including magnetoencephalography and magnetic resonance imaging, and these recordings combined with signal processing can be useful to characterise the changes in the brain that can be a result of the ageing process. By analysing various aspects of the brain, such as functional and effective connectivity, entropy and complexity, the state of the resting brain at different ages can be understood with greater detail. Furthermore, these analyses can be used to investigate the resting state brain networks that are present in the brain, as well as their topology. This information can be combined with network analysis techniques such as graph theory and used to understand the manner in which the brain both matures and ages.

This research made use of two magnetoencephalogram (MEG) databases recorded from both males and females. The first, containing resting state MEGs (rMEGs) from 220 healthy volunteers (aged 7-84), was used as the main database in this thesis to investigate the effects of age on rMEG signals throughout life. The aim of this research was to make use of rMEG signals and signal processing techniques to determine the effects of healthy ageing on the brain throughout life. It was hypothesised that the effects of age are identifiable using advanced signal processing techniques. Thus, the effects of age on linear interactions, causality, synchronisation, information flow, entropy and complexity, were investigated in the 148 MEG channels lying over 5 brain regions (anterior, central, left lateral, posterior, and, right lateral) using multiple linear and non-linear analysis techniques (namely: Pearson’s correlation, coherence, Granger causality, phase slope index, rho index, transfer entropy, synchronisation likelihood, Lempel-Ziv complexity, permutation Lempel-Ziv complexity, permutation entropy, and, modified permutation entropy). Additionally, graph theory principles were used to evaluate different network components such as integration (global efficiency), segregation (clustering coefficient and modularity), centrality (betweenness), and resilience (strength and assortativity) so as to obtain an understanding of the construct of the resting brain network. Moreover, complex network analysis was also used to determine the overall network topology of the brain network and how this changed at different stages in life. Gender effects were also studied so as to identify if there were any significant differences between males and females at different stages of life. Results from these analyses showed that the healthy resting brain has low effective and functional connectivity, relatively low complexity and entropy, as well as no significant detectable direction of information flow. Therefore this showed that there is very little synchronous or simultaneously occurring information in the rMEG time series. Thus, during rest, the brain resembles a system in limbo/phase transition, with low effective and functional connectivity, relatively low complexity and entropy, and no significant detectable direction of information flow.

The second database used in this research project was obtained during a collaboration visit to the Cognitive and Computational Neuroscience laboratory at the Centre for Biomedical Technology- Universidad Politécnica de Madrid (CTB-UPM). This database was made up of rMEGs recorded from 199 healthy volunteers (aged 60-80), and the focus of this additional set of analyses was to identify differences between the rMEG signals recorded from healthy individuals, those with subjective cognitive decline as well as those with mild cognitive impairment, with the hypothesis that the effects of cognitive decline (namely MCI) are identifiable using advanced signal processing techniques. The objective of this study was to use MEG data and non-linear complexity measures to identify the regions of the brain associated with cognitive decline. Similar to analyses performed using database 1, graph theory and complex network analyses were used to investigate the network structure of the resting brain for controls, and subjects with subjective cognitive decline and mild cognitive impairment. Results from these analyses showed that subjects with mild cognitive impairment had lower complexity scores than those with subjective cognitive decline in broadband analyses. Moreover, in the beta frequency band, controls and subjective cognitive decline subjects had significantly higher MEG complexity than subjects with mild cognitive impairment. A dual effect of hypo- and hyper-connectivity associated with cognitive decline during analyses using Pearson’s correlation and Granger causality was identified, with synchronisation likelihood showing only a decrease associated with mild cognitive impairment. Gender effects were also investigated using this database, and it was found that significant differences were present between males and females with subjective cognitive decline.

All in all, taking the novel findings from this thesis into account, this research project managed to highlight the effects of age, gender and cognitive decline on rMEG signals, and thus an extension to the description of what can be termed an ‘illustration of a physiological rhythm’ showing the evolution of different attributes of the healthy brain activity throughout life was presented. Moreover, in the long term, these results can be used to form a benchmark for healthy ageing which could be used to generate a fingerprint for healthy ageing. This fingerprint can then be used as part of the process of diagnosing pathology, or as a step towards pre-diagnosis of brain pathology.

Annette Sterr, K Herron, Derk-Jan Dijk, J Ellis (2009)Time to wake-up: Sleep problems and daytime sleepiness in long-term stroke survivors, In: Brain Injury22(7-8)pp. 575-579 Taylor & Francis
Background and purpose: In work with chronic stroke patients the authors observed that patients frequently appear sleepy and often comment on their poor sleep. Sleep difficulties are frequently reported and indeed clinically recognized in the acute phase post-stroke, but little is known about the sleep and daytime sleepiness of chronic stroke patients with sustained disabilities. The latter, however, deserves clarification because sleep is a critical modulator of health, daytime performance and wellbeing. The present study therefore explored the sleep and sleepiness in a chronic stroke population with sustained physical deficits. Methods: An opportunity sample of 20 patients with chronic low-functioning hemiplegia (12 months) completed the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, Medical Outcome Study Short Form 36 and Hospital Anxiety and Depression Scale. Results: Compared to a normative healthy population, long-term stroke survivors reported poorer sleep and greater daytime sleepiness. Increased levels of sleepiness were associated with longer chronicity, whereas nocturnal sleep parameters were not. Conclusions: In line with clinical observations, stroke survivors with sustained physical disabilities report poorer sleep and experience greater levels of sleepiness. Further research in a larger cohort and including objective sleep measures is necessary to investigate the nature and scale of sleep difficulties and daytime sleepiness in more detail so that care and treatment strategies can be developed in due course.
Advances in the understanding of the neural plasticity occurring with motor learning and hemiparetic stroke have contributed to the development of motor rehabilitation strategies for treating poststroke upper limb hemiparesis. However, a relative drawback has been that, in general, these strategies are most compatible with the recovery profiles of relatively high-functioning stroke survivors and therefore do not easily translate into benefit to those individuals sustaining low-functioning upper limb hemiparesis, who otherwise have poorer residual motor function. For these individuals, alternative motor rehabilitation strategies are currently needed (Chapter 1). Chapter 2 reviews several upper limb immobilisation (ULI) studies that have been conducted with humans and animals. Then, it discusses how their findings could inspire the creation of a neural plasticity model that is likely to be of great relevance to the contexts of motor rehabilitation after stroke and motor learning. For instance, such model could contribute to the development of alternative motor rehabilitation strategies for treating poststroke upper limb hemiparesis and to enhancing motor learning in humans. Chapter 3 outlines the research questions addressed in this Thesis. Chapter 4 describes the methods and results of two studies (Studies 1 and 2) which, respectively, assessed the test-retest reliability and characterised the learning of a computer-based motor task designed to be used in futures studies in combination with an immobilisation protocol. Chapter 5 describes the method of transcranial magnetic stimulation (TMS), which was used in another study (Study 3) that makes up this Thesis. Chapter 6 briefly outlines the outcomes of a pilot study performed to optimise the methods for Study 3. In the latter, TMS was used to assess changes in motor cortex/corticospinal excitability during a protocol of 9 hours of ULI (Chapter 7). Chapter 8 discusses the results from Studies 1, 2 and 3, and Chapter 9 provides a conclusion with the implications of the present findings. Chapter 10 summarises the novelties from this Thesis.
People with obsessive-compulsive disorder (OCD) commonly report doubt and uncertainty and feel driven to perform repetitive behaviours and rituals. Neuropsychological accounts of obsessive-compulsive (OC) behaviours suggest that dysfunction in cognitive processing may underpin such symptomology. Selective attention and long-term memory have been proposed as areas of cognition in which processing may be altered in OCD. However, although the weight of evidence points to possible dysfunction in these areas, the results of previous research examining both have been mixed. This thesis argues that inconsistencies in such research might be attributable to the use of the unsuitable methodological approaches, an inconsistent use of symptom-salient stimuli in experiments and a lack of acknowledgement of the heterogeneity of OCD or the impact of comorbidities. The studies presented here adopted methodological approaches which are novel in OCD research, with the aim of providing more nuanced accounts of OC cognition. Four studies are reported which examined how far altered OC selective attention and long-term memory, and particularly that of Checkers, may be rooted in the operation the same mechanism – bias towards distracting and symptom-salient stimuli. Studies 1, 2 and 3 used selective attention visual search paradigms with inter-trial components, based on the priming of pop-out (PoP) design. Study 4 was a comprehensive examination of verbal long-term memory, including remember/know memory, using the CID-R paradigm. All four used non-clinical OC populations, in line with arguments that clinical OCD only accounts for a minority of individuals who display OC symptomology. Study 1 (N=28) looked to establish initial evidence of possible selective attention and attentional bias differences between a homogenous OC group and Controls. Study 2 (N=43) and Study 3 (N=46) then built on these findings, examining possible differences between Checker and Non-Checker groups with the presentation of symptom-salient and emotional stimuli. Finally, Study 4 (N=59) looked to assess how far possible altered attention and bias among Checkers would also be apparent in dysfunction and bias in Checker verbal long-term memory. This study also used symptom-salient stimuli, and recruited Washer and generalised OC participants for comparison with Checkers. Key findings were as follows. In Study 1, OC participants demonstrated, firstly, a deficit in selective attention in the PoP task and, secondly, attentional bias towards distractor stimuli in particular inter-trial sequences. However, when the first of these findings was followed-up in Study 2 using Checker and Non-Checker populations and emotional pictures added to the PoP paradigm, group differences evident in Study 1 were eliminated. But in Study 3, which further examined the second finding of Study 1, evidence of attentional bias in Checkers towards emotional and symptom-salient picture stimuli when inter-trial sequences were examined. Finally, in Study 4, Checkers demonstrated bias towards checking-salient word targets when compared with Controls, and accurate hit rate performance for checking words even though they were significantly more reliant on familiarity with stimuli ('know' memory) than firm recollection ('remember' memory). Effect sizes for group difference findings across the studies were large. The findings provide novel and nuanced evidence of the key roles of bias and emotion in the operation of OC cognition and the make-up of Checker symptomology, and further highlight the value of using non-clinical participants in OC research.
The neurological basis of learning an artificial language ‘BROCANTO’, and how this is influenced by sleep wake cycle position, was investigated using fMRI. BROCANTO requires both declarative (vocabulary) and procedural (grammar) processes. Behavioural results show equivalent performance can be reached with different declarative and procedural trajectories, with peak learning at 3pm and 24 hours consolidation. Right IFG, and left BA6 are key regions responding independently of performance, at this time. Left BA6 and right thalamus respond to the interaction between consolidation and morning/evening training. During rest, the connection between the hippocampus and IFG that is stronger in the morning and negative post task, especially on the right, indicating a BROCANTO learning related disconnection. IFG connectivity is particularly responsive to the experimental conditions during rest. In a PPI task analysis, the hippocampus input to the thalamus strengthens at the second session in the morning, and its connections to right IFG and BA6 decline, when its input to IFG is negative. Connections between IFG and BA6 and thalamus and BA6 are key. The connection between left BA6 and left IFG, responds to the interaction between consolidation and sleep/wake cycle, during task and rest. Together, the results suggest a hub role for BA6, modulated by the thalamus. This could represent an essential core BROCANTO processing system, mediating between declarative and procedural learning to be investigated further. The combined results do indicate that consolidation facilitates a shift towards procedural processing, and that its functional neural pathway is influenced by the sleep wake cycle. Analysis with further temporal information, and to identify strength and direction of connections would be needed to further clarify the mechanism. These findings can inform network models of language such as the ‘dorsal and ventral’ stream, with a view to developing optimal training schedules to benefit flexible study and work patterns.
Amanda Wallace, Alexandra Pietrusz, Elizabeth Dewar, Magdalena Dudziec, Katherine Jones, Philip Hennis, Annette Sterr, Gianluca Baio, Pedro Machado, Laurá Matilde, Iwona Skorupinska, Mariola Skorupinska, Karen Butcher, Michael Trenell, Mary M Reilly, Michae Hanna, Gita M Ramdharry (2018)Community exercise is feasible for neuromuscular diseases and can improve aerobic capacity, In: Neurology92(15)pp. e1773-e1785 American Academy of Neurology
Objective: The aim of this phase 2 trial was to ascertain the feasibility and effect of community based aerobic exercise training for people with two of the more common neuromuscular diseases: Charcot-Marie-Tooth disease type 1A (CMT) and Inclusion Body Myositis (IBM). Methods: A randomised single blinded cross over trial design was used to compare a 12-week aerobic training programme using recombinant exercise bicycles compared to a control period. The training occurred three times per week in community gyms local to the participants. Support was available from trained gym staff and a research physiotherapist. The two disease groups were analysed separately. The primary outcome measure was peak oxygen uptake (VO2 peak) during a maximal exercise test, with secondary measures of muscle strength, function and patient reported measures. Results: Data from 23 people with CMT and 17 people with IBM was included in the analysis. Both disease groups had high levels of participation and demonstrated improvements in VO2 peak, with a moderate effect size in the CMT participants (Cohen’s d = 0.53) and a strong effect size in the IBM group (Cohen’s d = 1.72). No major changes were observed in the secondary outcome measures. Qualitative interviews revealed that participants valued the support of gym instructors and the research physiotherapists in overcoming challenges to participation. Conclusion: Twelve weeks of aerobic training in community gyms was feasible, safe and improved aerobic capacity in people with CMT and IBM. Classification of Evidence: This study provides Class II evidence that for patients with CMT type 1A and IBM, an aerobic training program increases aerobic capacity.
Annette Sterr, Susanna Freivogel (2004)Intensive training in chronic upper limb hemiparesis does not increase spasticity or synergies, In: Neurology63pp. 2176-2177
The authors assessed whether intensive training increases spasticity and leads to the development of “pathologic movement patterns,” a concern often raised by Bobath-trained therapists. The authors used a baseline-control repeated-measures test to study 29 patients with chronic upper limb hemiparesis who received daily shaping training. Their results suggest that training has no adverse effects on muscle tone and movement quality.
J Conti, A Sterr, SM Brucki, AB Conforto (2015)Diversity of approaches in assessment of executive functions in stroke: limited evidence?, In: eNeurologicalSci1(1)pp. 12-20
Stroke is a leading cause of disability worldwide. Cognitive functions and, in particular, executive function, are commonly affected after stroke, leading to impairments in performance of daily activities, decrease in social participation and in quality of life. Appropriate assessment and understanding of executive dysfunction are important, firstly to develop better rehabilitation strategies for executive functions per se and secondly to consider executive function abilities on rehabilitation strategies in general. The purpose of this review was to identify the most widely used assessment tools of executive dysfunction for patients with stroke, and their psychometric properties. We systematically reviewed manuscripts published in English in databases from 1999 to 2015. We identified 35 publications. The most frequently used instruments were the Stroop, Digit Span and Trail making tests. Psychometric properties were described for the Executive Function Performance Test, Executive Clock Drawing Task, Chinese Frontal Assessment Battery and Virtual Action Planning - Supermarket, and two subtests of the Cambridge Cognitive Examination - Revised. There is a paucity of tools to reliably measure executive dysfunction after stroke, despite the fact that executive dysfunction is frequent. Identification of the best tools for executive dysfunction assessment is necessary to address important gaps in research and in clinical practice.
C Kranczioch, S Athanassiou, S Shen, G Gao, Annette Sterr (2008)Short-term learning of a visually guided power-grip task is associated with dynamic changes in EEG oscillatory activity, In: Clinical Neurophysiology119(6)pp. 1419-1430 Elsevier
Objective: Performing a motor task after a period of training has been associated with reduced cortical activity and changes in oscillatory brain activity. Little is known about whether learning also affects the neural network associated with motor preparation and post movement processes. Here we investigate how short-term motor learning affects oscillatory brain activity during the preparation, execution, and post-movement stage of a force-feedback task. Methods: Participants performed a visually guided power-grip tracking task. EEG was recorded from 64 scalp electrodes. Power and coherence data for the early and late stages of the task were compared. Results: Performance improved with practice. During the preparation for the task alpha power was reduced for late experimental blocks. A movement execution-related decrease in beta power was attenuated with increasing task practice. A post-movement increase in alpha and lower beta activity was observed that decreased with learning. Coherence analysis revealed changes in cortico-cortical coupling with regard to the stage of the visuomotor task and with regard to learning. Learning was variably associated with increased coherence between contralateral and/or ipsilateral frontal and parietal, fronto-central, and occipital brain regions. Conclusions: Practice of a visuomotor power-grip task is associated with various changes in the activity of a widespread cortical network. These changes might promote visuomotor learning. Significance: This study provides important new evidence for and sheds new light on the complex nature of the brain processes underlying visuomotor integration and short-term learning. (c) 2008 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
C Hope, E Seiss, PJA Dean, K Williams, A Guinn, A Sterr (2011)Response time slowing by glucose dependent on strength of stimulus response association: investigations with the flanker task, In: Frontiers in Human Neuroscience: ICON XI, Conference Abstracts
Previous studies showed that performance in difficult tasks, such as memory tasks, can be improved by glucose administration (Riby, 2004). Whether glucose has similar effects on sensorimotor conflicts is unclear. Here we present 2 behavioural experiments with a double-blind placebo-controlled design to investigate glucose effects on response conflicts in a flanker task. In both experiments, blood glucose levels (BCG) levels were kept around 6.5 Mmol/litre in the glucose and 5 Mmol/l in the placebo condition. In experiment 1, 12 participants (age: 25.1 years) performed an arrow version of the flanker task. Results showed that reaction times (RTs) of block 1 were 24 ms slower in the glucose (436 ms) than the placebo condition (412 ms) but not for subsequent blocks. The absence of the glucose effect in blocks 2-8 can be explained by the strong stimulus-response association (SRA) in the arrow-version of the flanker task. Experiment 2 tested this explanation by using a flanker-task version with weaker letter-key associations whereby new SRAs had to be learned after every block. Data from 12 participants (age: 20.1 years) confirmed the previous finding of slower reaction times in the glucose condition (437 ms) with an increase of 40 ms compared to the placebo condition (397 ms). Critically this effect was maintained throughout the experiment. However, the response conflict, indexed by the difference between congruent and incongruent trials, was not affected by glucose. Our data suggest that sensorimotor processes can be slowed by glucose, a finding which contrasts reports of facilitatory effects of glucose on cognition (Riby, 2004). In addition the critical variable for glucose-induced RT effects appears to be the strength of SRA rather than the actual response conflict.
Annette Sterr, James Ebajemito, Kaare B. Mikkelsen, Maria Bonmati-Carrion, Nayantara Santhi, Ciro della Monica, Lucinda Grainger, Giuseppe Atzori, Victoria Revell, Stefan Debener, Derk-Jan Dijk, Maarten DeVos (2018)Sleep EEG Derived From Behind-the-Ear Electrodes (cEEGrid) Compared to Standard Polysomnography: A Proof of Concept Study, In: Frontiers in Human Neuroscience12452 Frontiers Research Foundation
Electroencephalography (EEG) recordings represent a vital component of the assessment of sleep physiology, but the methodology presently used is costly, intrusive to participants, and laborious in application. There is a recognized need to develop more easily applicable yet reliable EEG systems that allow unobtrusive long-term recording of sleep-wake EEG ideally away from the laboratory setting. cEEGrid is a recently developed flex-printed around-the-ear electrode array, which holds great potential for sleep-wake monitoring research. It is comfortable to wear, simple to apply, and minimally intrusive during sleep. Moreover, it can be combined with a smartphone-controlled miniaturized amplifier and is fully portable. Evaluation of cEEGrid as a motion-tolerant device is ongoing, but initial findings clearly indicate that it is very well suited for cognitive research. The present study aimed to explore the suitability of cEEGrid for sleep research, by testing whether cEEGrid data affords the signal quality and characteristics necessary for sleep stage scoring. In an accredited sleep laboratory, sleep data from cEEGrid and a standard PSG system were acquired simultaneously. Twenty participants were recorded for one extended nocturnal sleep opportunity. Fifteen data sets were scored manually. Sleep parameters relating to sleep maintenance and sleep architecture were then extracted and statistically assessed for signal quality and concordance. The findings suggest that the cEEGrid system is a viable and robust recording tool to capture sleep and wake EEG. Further research is needed to fully determine the suitability of cEEGrid for basic and applied research as well as sleep medicine.
Behavioural studies have indicated that response times on complex reaction time tasks are faster if blood glucose concentrations are slightly elevated above normal (Donohoe & Benton, 2000). Such tasks involve several cognitive processing stages but it is not clear which of these stages are speeded after glucose administration. In order to investigate this problem we have used a double blind repeated measures design for the administration of glucose and placebo drinks. Participants performed a Flanker task while EEG was recorded as a physiological measure. More specifically, we used a Flanker task that required participants to respond to either left or right pointing central arrows by pressing a left or a right button, respectively. In addition on each trial there are extra arrows surrounding the central arrow which all either pointed in the same (congruent condition) or opposite (incongruent condition) direction as the central arrow or they were lines without an arrow head (neutral condition) All condition were presented equiprobably. No significant differences between the glucose and placebo condition were observed in mean reaction times and errors rates. However the ERP data showed that the N1 amplitude was significantly increased after glucose administration. This could indicate that stimulus identification is influenced by glucose administration, as previous researchers have found an increased N1 amplitude during discriminative feature processing compared to simple detection tasks (Hopf et al., 2002). In addition, mean reaction times and error rates were analysed separately for each of the 8 blocks. Differences between drink types were only found for the reaction times of the first block. Participants who had received glucose during their 1st session and placebo during the 2nd session, had longer reaction times after glucose administration compared to placebo. However this effect was not found for participants who received placebo before glucose drinks. These findings might be linked to task difficulty effects. Previous research has shown that high task difficulty is necessary to find glucose enhancement effects on the Hick task (sensorimotor function; Donohoe & Benton, 2000), working memory (Kennedy & Scholey, 2001) and episodic memory (Sünram-Lea et al., 2002). Our results conflict directly with Donohoe and Benton’s (2000), potentially caused by methodological or task differences. It might be also possible that separate cognitive processes might be differently affected by glucose; which should be explored in future studies.
C Hope, E Seiss, P Dean, A Sterr (2009)An electrophysiological investigation of glucose administration effects on movement preparation and execution, In: Psychophysiology. Special Issue: Society for Psychophysiological Research Abstracts for the Forty-Ninth Annual Meeting46(Supple)pp. S97-?
Behavioural studies suggest that elevated blood glucose concentrations accelerate response times in complex tasks (Owens and Benton, 2004, Neuropsychobiology). With the present study we aimed to explore the mechanisms subserving elevated blood glucose effects (7 mmol/litre versus fasting levels of 5 mmol/litre) by studying EEG-derived indices of sensorimotor processing. More specifically, the Eriksen flanker task was used to examine glucose-dependent modulations of the P300, the stimulus lateralized readiness potentials (LRPs), and response-locked LRP, to see whether enhanced blood glucose levels affect stimulus evaluation, response planning, and response selection respectively. 10 participants took part in a within-participant double-blind 2-session experiment where either glucose (25 g) or placebo drinks were administered. Initial data suggests slower reaction times, higher error rates and delayed stimulus-locked LRP onset in incongruent compared to congruent and neutral trials. With placebo administration error rates were increased for the non-dominant hand but not the dominant hand; no effects were found for the EEG parameters. This suggests that hyperglycaemia does not affect senorimotor processing in the flanker task. However, the placebo-related increase in error rates together with the findings of (Donohoe and Benton, 2000) support the proposition that beneficial effects of increased blood glucose levels on cognition might only occur when cognitive demands are high.
A Sterr, C Nissen, S Funk, D Ettine, T Unbehaun, D Kuemmerer, D Riemann (2013)CHANGES OF POLYSOMNOGRAPHIC SLEEP CHARACTERISTICS IN CHRONIC POST-STROKE HEMIPLEGIA, In: PSYCHOPHYSIOLOGY50pp. S40-S40
A Sterr, PJA Dean, AJ Szameitat, AB Conforto, S Shen (2013)Corticospinal Tract Integrity and Lesion Volume Play Different Roles in Chronic Hemiparesis and Its Improvement Through Motor Practice, In: Neurorehabil Neural Repair28(4)pp. 335-343 Sage
Background. Initial evidence suggests that the integrity of the ipsilesional corticospinal tract (CST) after stroke is strongly related to motor function in the chronic state but not the treatment gain induced by motor rehabilitation. Objective. We examined the association of motor status and treatment benefit by testing patients with a wide range of severity of hemiparesis of the left and right upper extremity. Method. Diffusion tensor imaging was performed in 22 patients beyond 12 months after onset of stroke with severe to moderate hemiparesis. Motor function was tested before and after 2 weeks of modified constraint-induced movement therapy. Results. CST integrity, but not lesion volume, correlated with the motor ability measures of the Wolf Motor Function Test and the Motor Activity Log. No differences were found between left and right hemiparesis. Motor performance improved significantly with the treatment regime, and did so equally for patients with left and right arm paresis. However, treatment benefit was not associated with either CST integrity or lesion volume. Conclusion. CST integrity correlated best in this small trial with chronic long-term status but not treatment-induced improvements. The CST may play a different role in the mechanisms mediating long-term outcome compared to those underlying practice-induced gains after a chronic plateau in motor function.
B. Berger, B. Griesmayr, T. Minarik, A. L. Biel, D. Pinal, A. Sterr, P. Sauseng (2019)Dynamic regulation of interregional cortical communication by slow brain oscillations during working memory, In: NATURE COMMUNICATIONS10(1)4242 NATURE PUBLISHING GROUP
Transiently storing information and mentally manipulating it is known as working memory. These operations are implemented by a distributed, fronto-parietal cognitive control network in the brain. The neural mechanisms controlling interactions within this network are yet to be determined. Here, we show that during a working memory task the brain uses an oscillatory mechanism for regulating access to prefrontal cognitive resources, dynamically controlling interactions between prefrontal cortex and remote neocortical areas. Combining EEG with non-invasive brain stimulation we show that fast rhythmical brain activity at posterior sites are nested into prefrontal slow brain waves. Depending on cognitive demand this high frequency activity is nested into different phases of the slow wave enabling dynamic coupling or de-coupling of the fronto-parietal control network adjusted to cognitive effort. This mechanism constitutes a basic principle of coordinating higher cognitive functions in the human brain.
Kaare Mikkelsen, James K. Ebajemito, Mari Bonmati‐Carrion, Nayantara Santhi, Victoria Revell, Giuseppe Atzori, Ciro della Monica, Stefan Debener, Derk-Jan Dijk, Annette Sterr, Maarte Vos (2019)Machine‐learning‐derived sleep–wake staging from around‐the‐ear electroencephalogram outperforms manual scoring and actigraphy, In: Journal of Sleep Research28(2)e12786 Wiley-Blackwell Publishing
Quantification of sleep is important for the diagnosis of sleep disorders and sleep research. However, the only widely accepted method to obtain sleep staging is by visual analysis of polysomnography (PSG), which is expensive and time consuming. Here, we investigate automated sleep scoring based on a low‐cost, mobile electroencephalogram (EEG) platform consisting of a lightweight EEG amplifier combined with flex‐printed cEEGrid electrodes placed around the ear, which can be implemented as a fully self‐applicable sleep system. However, cEEGrid signals have different amplitude characteristics to normal scalp PSG signals, which might be challenging for visual scoring. Therefore, this study evaluates the potential of automatic scoring of cEEGrid signals using a machine learning classifier (“random forests”) and compares its performance with manual scoring of standard PSG. In addition, the automatic scoring of cEEGrid signals is compared with manual annotation of the cEEGrid recording and with simultaneous actigraphy. Acceptable recordings were obtained in 15 healthy volunteers (aged 35 ± 14.3 years) during an extended nocturnal sleep opportunity, which induced disrupted sleep with a large inter‐individual variation in sleep parameters. The results demonstrate that machine‐learning‐based scoring of around‐the‐ear EEG outperforms actigraphy with respect to sleep onset and total sleep time assessments. The automated scoring outperforms human scoring of cEEGrid by standard criteria. The accuracy of machine‐learning‐based automated scoring of cEEGrid sleep recordings compared with manual scoring of standard PSG was satisfactory. The findings show that cEEGrid recordings combined with machine‐learning‐based scoring holds promise for large‐scale sleep studies.
L Frase, H Piosczyk, S Zittel, F Jahn, P Selhausen, L Krone, B Feige, F Mainberger, JG Maier, M Kuhn, S Kloppel, C Normann, Annette Sterr, K Spiegelhalder, D Riemann, MA Nitsche, C Nissen (2016)Modulation of total sleep time by transcranial direct current stimulation (tDCS), In: Neuropsychopharmacology.41(10)pp. 2577-2586 Nature Publishing Group
Arousal and sleep are fundamental physiological processes, and their modulation is of high clinical significance. This study tested the hypothesis that total sleep time in humans can be modulated by the non-invasive brain stimulation technique transcranial direct current stimulation (tDCS) targeting a ‘top-down’ cortico-thalamic pathway of sleep-wake regulation. Nineteen healthy participants underwent a within-subject, repeated-measures protocol across five nights in the sleep laboratory with polysomnographic monitoring (adaptation, baseline, three experimental nights). tDCS was delivered via bi-frontal target electrodes and bi-parietal return electrodes prior to sleep (anodal ‘activation’, cathodal ‘deactivation’ and sham stimulation). Bi-frontal anodal stimulation significantly decreased total sleep time, compared to cathodal and sham stimulation. This effect was location specific. Bi-frontal cathodal stimulation did not significantly increase total sleep time, potentially due to ceiling effects in good sleepers. Exploratory resting-state EEG analyses prior to and after the tDCS protocols were consistent with the notion of increased cortical arousal after anodal stimulation and decreased cortical arousal after cathodal stimulation. The study provides proof-of-concept that total sleep time can be decreased by non-invasive bi-frontal anodal tDCS in healthy humans. Further elucidating the ‘top-down’ pathway of sleep-wake regulation is expected to increase knowledge on the fundamentals of sleep-wake regulation and to contribute to the development of novel treatments for clinical conditions of disturbed arousal and sleep.
A Wallace, L Dewar, A Pietrusz, M Dudziec, A Sterr, M Laura, I Skorupinska, M Skorupinska, M Hanna, M Trenell, G Baio, M Reilly, G Ramdharry (2015)Evaluating the benefits of community based aerobic training on the physical health and well-being of people with neuromuscular diseases: A pilot study, In: NEUROMUSCULAR DISORDERS25pp. S273-S274
D.P. Szameitat, C.J. Darwin, A.J. Szameitat, D. Wildgruber, A. Sterr, S. Dietrich, K. Alter FORMANT CHARACTERISTICS OF HUMAN LAUGHTER, In: Proceedings of the Interdisciplinary Workshop on The Phonetics of Laughter
Although laughter is an important aspect of nonverbal vocalization, its acoustic properties are still not fully understood. Here we provide new data on the spectral properties of laughter. We measured fundamental frequency and formant frequencies of the vowels produced in laughter syllables. In accordance with theoretical predictions and prior observations laughter was mainly based on central vowels. Furthermore, laughter syllables showed higher formant frequencies than normal speech vowels; in particular F1 values could be as high as 1300 Hz for male speakers and 1500 Hz for female speakers. These exceptionally high F1 values might be based on the extreme positions adopted by the vocal tract during laughter in combination with physiological constraints accompanying production of a “pressed” voice. Keywords: laughter, formant, vowel, nonverbal, F1.
Basic neuroscience research on brain plasticity, motor learning and recovery has stimulated new concepts in neurological rehabilitation. Combined with the development of set methodological standards in clinical outcome research, these findings have led to a double-paradigm shift in motor rehabilitation: (a) the move towards evidence-based procedures for the assessment of clinical outcome & the employment of disablement models to anchor outcome parameters, and (b) the introduction of practice-based concepts that are derived from testable models that specify treatment mechanisms. In this context, constraint-induced movement therapy (CIT) has played a catalytic role in taking motor rehabilitation forward into the scientific arena. As a theoretically founded and hypothesis-driven intervention, CIT research focuses on two main issues. The first issue is the assessment of long-term clinical benefits in an increasing range of patient groups, and the second issue is the investigation of neuronal and behavioural treatment mechanisms and their interactive contribution to treatment success. These studies are mainly conducted in the research environment and will eventually lead to increased treatment benefits for patients in standard health care. However, gradual but presumably more immediate benefits for patients may be achieved by introducing and testing derivates of the CIT concept that are more compatible with current clinical practice. Here, we summarize the theoretical and empirical issues related to the translation of research-based CIT work into the clinical context of standard health care.
DM Noone, TA Willis, J Cox, F Harkness, J Ogilvie, E Forbes, A Sterr, AM Gregory (2014)Catastrophizing and Poor Sleep Quality in Early Adolescent Females, In: BEHAVIORAL SLEEP MEDICINE12(1)pp. 41-52 ROUTLEDGE JOURNALS, TAYLOR & FRANCIS LTD
Simon Mathews, Phil John Ainsley Dean, Annette Sterr (2006)EEG dipole analysis of motor-priming foreperiod activity reveals separate sources for motor and spatial attention components., In: Clinical Neurophysiology117(12)pp. 2675-2683 Elsevier
Objective: This study employed EEG source localisation procedures to study the contribution of motor preparatory and attentional 10 processing to foreperiod activity in an S1–S2 motor priming task. Methods: Behavioural and high-density event-related potential (ERP) data were recorded in an S1–S2 priming task where participants 12 responded to S2 with a left or right-hand button press. S1 either provided information about response hand (informative) or ambiguous information (uninformative). Results: Responses were significantly faster in informative trials compared with uninformative trials. Dipole source analysis of fore-period lateralized ERPs revealed sources of motor preparatory activity in the dorsolateral premotor cortex (PMd) in line with previous work. In addition, two spatial attention components (ADAN, LDAP) were identified with generators in the PMd and occipitotemporal visual areas in the middle temporal (MT) region, respectively. Separation of motor-related and attentional PMd source locations was reliable along the rostral–caudal axis. Conclusions: The presence of attentional components in a motor priming paradigm supports the premotor theory of attention which suggests a close link between attention and motor preparatory processes. Separation of components in the premotor cortex is in accord with a functional division of PMd into rostral (higher-order processing) and caudal (motor-related processing) areas as suggested by imaging work. Significance: A prime for response preparation is a trigger for separate, but closely linked, attention-related activity in premotor areas. copyright: Mathews2006 Published by Elsevier Ireland Ltd. on behalf of International Federation of Clinical Neurophysiology.
A Sterr, L Furlan (2015)A case to be made: theoretical and empirical arguments for the need to consider fatigue in post-stroke motor rehabilitation, In: NEURAL REGENERATION RESEARCH10(8)pp. 1195-1197 MEDKNOW PUBLICATIONS & MEDIA PVT LTD
A Wallace, L Dewar, A Sterr, M Hanna, M Trenell, A Pietrusz, M Dudziec, P Hennis, R Stokes, M Reilly, G Ramdharry (2015)Normative aerobic exercise values in CMT, In: NEUROMUSCULAR DISORDERS25pp. S285-S286
Philip Dean, JR Sato, G Vieira, A McNamara, Annette Sterr (2014)Multimodal imaging of mild traumatic brain injury and persistent postconcussion syndrome, In: Brain and Behavior
Background: Persistent postconcussion syndrome (PCS) occurs in around 5– 10% of individuals after mild traumatic brain injury (mTBI), but research into the underlying biology of these ongoing symptoms is limited and inconsistent. One reason for this could be the heterogeneity inherent to mTBI, with individualized injury mechanisms and psychological factors. A multimodal imaging study may be able to characterize the injury better. Aim: To look at the relationship between functional (fMRI), structural (diffusion tensor imaging), and metabolic (magnetic resonance spectroscopy) data in the same participants in the long term (>1 year) after injury. It was hypothesized that only those mTBI participants with persistent PCS would show functional changes, and that these changes would be related to reduced structural integrity and altered metabolite concentrations. Methods: Functional changes associated with persistent PCS after mTBI (>1 year postinjury) were investigated in participants with and without PCS (both n = 8) and non-head injured participants (n = 9) during performance of working memory and attention/processing speed tasks. Correlation analyses were performed to look at the relationship between the functional data and structural and metabolic alterations in the same participants. Results: There were no behavioral differences between the groups, but participants with greater PCS symptoms exhibited greater activation in attention-related areas (anterior cingulate), along with reduced activation in temporal, default mode network, and working memory areas (left prefrontal) as cognitive load was increased from the easiest to the most difficult task. Functional changes in these areas correlated with reduced structural integrity in corpus callosum and anterior white matter, and reduced creatine concentration in right dorsolateral prefrontal cortex. Conclusion: These data suggest that the top-down attentional regulation and deactivation of task-irrelevant areas may be compensating for the reduction in working memory capacity and variation in white matter transmission caused by the structural and metabolic changes after injury. This may in turn be contributing to secondary PCS symptoms such as fatigue and headache. Further research is required using multimodal data to investigate the mechanisms of injury after mTBI, but also to aid individualized diagnosis and prognosis.
SC Magalhaes, A Kaelin-Lang, A Sterr, GF do Prado, AL Eckeli, AB Conforto (2015)Transcranial magnetic stimulation for evaluation of motor cortical excitability in restless legs syndrome/Willis-Ekbom disease, In: SLEEP MEDICINE16(10)pp. 1265-1273 ELSEVIER SCIENCE BV
B Berger, S Omer, T Minarik, A Sterr, P Sauseng (2014)Interacting memory systems-does EEG alpha activity respond to semantic long-term memory access in a working memory task?, In: Biology (Basel)4(1)pp. 1-16
Memory consists of various individual processes which form a dynamic system co-ordinated by central (executive) functions. The episodic buffer as direct interface between episodic long-term memory (LTM) and working memory (WM) is fairly well studied but such direct interaction is less clear in semantic LTM. Here, we designed a verbal delayed-match-to-sample task specifically to differentiate between pure information maintenance and mental manipulation of memory traces with and without involvement of access to semantic LTM. Task-related amplitude differences of electroencephalographic (EEG) oscillatory brain activity showed a linear increase in frontal-midline theta and linear suppression of parietal beta amplitudes relative to memory operation complexity. Amplitude suppression at upper alpha frequency, which was previously found to indicate access to semantic LTM, was only sensitive to mental manipulation in general, irrespective of LTM involvement. This suggests that suppression of upper EEG alpha activity might rather reflect unspecific distributed cortical activation during complex mental processes than accessing semantic LTM.
C Kranczioch, S Mathews, PJA Dean, A Sterr (2010)Task complexity differentially affects executed and imagined movement preparation: evidence from movement-related potentials., In: PLoS ONE5(2)pp. e9284-? Public Library of Science
Background The neural simulation theory predicts similarity for the neural mechanisms subserving overt (motor execution) and covert (movement imagination) actions. Here we tested this prediction for movement preparation, a key characteristic of motor cognition. Methodology/Principal Findings High-density electroencephalogram (EEG) was recorded during covert and overt actions. Movement preparation was studied with a motor priming paradigm, which varied task complexity and amount of advance information. Participants performed simple or complex sequential finger movements either overtly or covertly. Advance information was either fully predictive or partially predictive. Stimulus-locked event-related potential (ERP) data showed the typical pattern of foreperiod activation for overt and covert movements. The foreperiod contingent negative variation (CNV) differed between simple and complex movements only in the execution task. ERP topographies differed between execution and imagination only when advance information was fully predictive. Conclusions/Significance Results suggest a differential contribution of the movement preparation network to action imagination and execution. Overt and covert actions seem to involve similar though not identical mechanisms, where overt actions engage a more fine-grained modulation of covert preparatory states.
A Sterr, A Saunders (2006)CI therapy distribution: Theory, evidence and practice, In: Neurorehabilitation21(2)pp. 97-105
Traditional rehabilitation for hemiplegia is not necessarily based on a supported theoretical foundation and some evidence questiones the efficacy of current practice. The uncertainty relating to underlying theories is a serious issue, henceforth there has been a move to base treatment strategies on scientific foundations which incorporate knowledge of human learning mechanisms and accompanying neurobiological processes. In this paper we argue that constraint induced movement therapy is a potentially very effective intervention that benefits from a strong theoretical grounding. It is demonstrated that the treatment mechanisms are supported by established behavioural learning theory and evidence of brain plasticity. As empirical support for the therapy is gradually mounting, the integration into mainstream practice lends itself as a natural course. In this paper, a series of issues surrounding the distribution of CIT such as constraint use, dose response relationships and accessibility to a wider group of patients are discussed. Further research in these areas is considered important for CIT integration into mainstream practice.
A Sterr, A Szameitat, S Shen, S Freivogel (2006)Application of the CIT concept in the clinical environment - Hurdles, practicalities, and clinical benefits, In: Cognitive and Behavioral Neurology19(1)pp. 48-54
Basic neuroscience research on brain plasticity, motor learning, and recovery has stimulated new concepts in motor rehabilitation. Combined with the development of methodological goal standards in clinical outcome research, these findings have effectuated the introduction of a double-paradigm shift in physical rehabilitation: (a) the move toward evidence-based procedures and disablement models for the assessment of clinical outcome and (b) the introduction of training-based concepts that are theoretically founded in learning theory. A major drive for new interventions has further come from recent findings on the adaptive capacities of neural networks and their linkage to perception, performance, and long-term recovery. In this context, constraint-induced movement therapy, an intervention initially designed for upper-limb hemiparesis, represents the theoretically and empirically most thoroughly founded training concept. Several clinical trials on constraint-induced therapy (CIT) have shown its efficacy in higher functioning patients; however, the transfer of the treatment into standard health care seems slow. Survey research further suggests a rather poor acceptance of CIT among clinical staff and it seems that the implementation of CIT is hindered by barriers constructed of beliefs and assumptions that demand a critical and evidence-based discussion. Within this context, we have conducted a series of experiments on amended CIT protocols and their application in the clinical environment which addressed the following issues: (1) massed practice: are 6 hours of daily training inevitable to achieve clinical benefits? (2) practicality: what is feasible in the standard care setting and what are the clinical benefits achieved by "feasible compromise CIT protocols?" (3) apprehensions: are concerns on increased muscular tone and pathologic movement patterns justified, and (4) learned nonuse: is the assumption of "hidden" residual present paper, the key findings of these studies will be summarized and critically discussed.
RL dos Santos-Fontes, KN Ferreiro de Andrade, A Sterr, AB Conforto (2013)Home-Based Nerve Stimulation to Enhance Effects of Motor Training in Patients in the Chronic Phase After Stroke: A Proof-of-Principle Study, In: NEUROREHABILITATION AND NEURAL REPAIR27(6)pp. 483-490 SAGE PUBLICATIONS INC
Aim: Fatigue is a common, but vaguely defined symptom in MS. The aim of our study was to assess fatigue in the sense of performance at rest and fatigability after cognitive load objectively (Kluger, Krupp, & Enoka, 2013)(Kluger et al. 2013). Method: Alertness was measured in fifteen controls and thirty patients with Multiple Sclerosis and cognitive fatigue according to the Fatigue Scale for Motor and Cognition (FSMC) at rest (t1), after a 2.5 hours lasting test battery (t2) and one hour later (t3). The test battery was used as standardized cognitive load. Epworth Sleepiness Scale and Beck Depression Inventory were used for exclusion of common causes of secondary fatigue. Results: Reaction times at rest were 401 msec in patients, compared to 208 msec in controls. Reaction times increased in patients significantly and dramatically after the cognitive load (t2) and recovered slowly in most of the patients at t3. Normal volunteers did not show any increase in reaction times. Patients showed a significant correlation between self-estimation of fatigue (FSMC) and reaction times. Conclusion: Alertness at rest appears to be a surrogate marker for fatigue. Alertness after cognitive load represents change of performance or fatigability. Knowledge of recovery of alertness offers further opportunities for management of fatigue.
T Elbert, A Sterr, B Rockstroh, D Charbonnier, H Flor, C Pantev, C Wienbruch, S Knecht, E Taub (2000)Cortical reorganization in arm amputees: Alterations of the somatosensory representation of the intact arm, In: BIOMAG 96: PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON BIOMAGNETISM, VOLS I & IIpp. 999-1002
André J. Szameitat, Shan Shen, Annette Sterr (2007)Motor imagery of complex everyday movements. An fMRI study, In: NeuroImage34pp. 702-713 Elsevier
The present study aimed to investigate the functional neuroanatomical correlates of motor imagery (MI) of complex everyday movements (also called everyday tasks or functional tasks). 15 participants imagined two different types of everyday movements, movements confined to the upper extremities (UE; e.g., eating a meal) and movements involving the whole body (WB; e.g., swimming), during fMRI scanning. Results showed that both movement types activated the lateral and medial premotor cortices bilaterally, the left parietal cortex, and the right basal ganglia. Direct comparison of WB and UEmovements further revealed a homuncular organization in the primary sensorimotor cortices (SMC), with UE movements represented in inferior parts of the SMC and WB movements in superior and medial parts. These results demonstrate that MI of everyday movements drives a cortical network comparable to the one described for more simple movements such as finger opposition. The findings further are in accordance with the suggestion that motor imagery-based mental practice is effective because it activates a comparable cortical network as overt training. Since most people are familiar with everyday movements and therefore a practice of the movement prior to scanning is not necessarily required, the current paradigm seems particularly appealing for clinical research and application focusing on patients with low or no residual motor abilities.
Diana, P. Szameitat, Kai Alter, André J. Szameitat, Chris J. Darwin, Dirk Wildgruber, Susanne Dietrich, Annette Sterr (2009)Differentiation of Emotions in Laughter at the Behavioral Level, In: Emotion9(3)pp. 397-405 American Psychological Association
Although laughter is important in human social interaction, its role as a communicative signal is poorly understood. Because laughter is expressed in various emotional contexts, the question arises as to whether different emotions are communicated. In the present study, participants had to appraise 4 types of laughter sounds (joy, tickling, taunting, schadenfreude) either by classifying them according to the underlying emotion or by rating them according to different emotional dimensions. The authors found= that emotions in laughter (a) can be classified into different emotional categories, and (b) can have distinctive profiles on W. Wundt’s (1905) emotional dimensions. This shows that laughter is a multifaceted social behavior that can adopt various emotional connotations. The findings support the postulated function of laughter in establishing group structure, whereby laughter is used either to include or to exclude individuals from group coherence. Keywords: nonverbal communication, social interaction, emotion, laughter, tickling
S. Shen, A. Szameitat, A Sterr (2008)Detection of infarct lesions from brain MRI images using inconsistency between voxel intensity and spatial location. A 3D automatic approach., In: IEEE Transactions on Information Technology in Biomedicine12(4)pp. 532-540 Institute of Electrical and Electronics Engineers

Abstract—Detection of infarct lesions using traditional segmentation methods is always problematic due to intensity similarity between lesions and normal tissues, so that multi-spectral magnetic resonance imaging (MRI) modalities were often employed for this purpose. However, the high costs of MRI scan and the severity of patient conditions restrict the collection of multiple images. Therefore, in this paper, a new 3D automatic lesion detection approach was proposed, which required only a single type of anatomical MRI scan. It was developed on a theory that when lesions were present, the voxel intensity based segmentation and the spatial location based tissue distribution should be inconsistent in the regions of lesions. The degree of this inconsistency was calculated which indicated the likelihood of tissue abnormality. Lesions were identified when the inconsistency exceeded a defined threshold. In this approach, the intensity based segmentation was implemented by the conventional fuzzy c-mean (FCM) algorithm, while the spatial location of tissues was provided by prior tissue probability maps. The use of simulated MRI lesions allowed us to quantitatively evaluate the performance of the proposed method, as the size and location of lesions were pre-specified. The results showed that our method effectively detected lesions with 40-80% signal reduction compared to normal tissues (Similarity Index>0.7). The capability of the proposed method in practice was also demonstrated on real infarct lesions from 15 stroke patients, where the lesions detected were in broad agreement with true lesions. Furthermore, a comparison to a statistical segmentation approach presented in the literature suggested that our 3D lesion detection approach was more reliable. Future work will focus on adapting the current method to multiple sclerosis (MS) lesion detection.

H Grunze, B Amann, M Schafer, A Sterr, L Schaerer, E Wild, J Walden (2000)Efficacy, safety and practicability of valproate delayed release minitablets in bipolar affective disorders, In: Fortschritte der Neurologie Psychiatrie68(11)pp. 496-502
Valproate has recently emerged as a drug of first choice in treating acute mania because of its efficacy and relative safety. It can be administered as an intravenous, oral non-sustained release or oral sustained release loading therapy. A new sustained release formulation of valproate consists of 'mini-tablets' with the possible advantage of a less problematic and more reliable administration of the drug. We report on eleven patients with an acute manic exacerbation who were investigated for sufficient control of manic symptoms and the duration of building up and maintaining sufficient blood levels of valproate in once/d versus twice/d administration of valproate delayed release minitablets (VPA mrt.). Acute and prophylactic effectiveness in mania were rated with the Young-Mania Rating Scale (YMRS), respectively the Global Clinical Impression Scale for Bipolar Disorder (CGI-BP). Results: Within a short period of time sufficient blood levels in both groups (once/d versus twice/d administration) were built up. Seven of eleven patients were responders according to a reduction of 50% of the YMRS. In respect of prophylactic treatment all of the ten patients showed satisfactory results and no re-exacerbation of manic symptoms or depression.
Annette Sterr, Philip Dean, S Mathews (2008)Preparing the unlikely event - when no-response priming activates the motor system, In: Progress in Biological Psychology Research(Expert)pp. 13-10 Nova Science Publishers
Driven by considerations arising from studies in hemiplegic patients, we examined how the insertion of rare n-response trials affects motor preparation studied in S1-S2 paradigms. Results for the motor priming task (experiment 1) showed that for response-requiring conditions the 'validity effect' was conserved for behavioural and ERP indices. For the no-response condition, foreperiod activities were similar to neutral trials suggesting motor preparation in both conditions and hence preparation for the unlikely event. A second experiment with fully predictive primes showed no evidence for movement preparation processes in no-response trials. These findings suggest different strategies for the anticipation of likely responses compared to likely events that don't require a response.
Kai Alter, André J. Szameitat, Dirk Wildgruber, Annette Sterr, Chris J. Darwin (2009)Acoustic profiles of distinct emotional expressions in laughter, In: The Journal of the Acoustical Society of America (JASA)126(1)pp. 354-366 Acoustical Society of America
Although listeners are able to decode the underlying emotions embedded in acoustical laughter sounds, little is known about the acoustical cues that differentiate between the emotions. This study investigated the acoustical correlates of laughter expressing four different emotions: joy, tickling, taunting, and schadenfreude. Analysis of 43 acoustic parameters showed that the four emotions could be accurately discriminated on the basis of a small parameter set. Vowel quality contributed only minimally to emotional differentiation whereas prosodic parameters were more effective. Emotions are expressed by similar prosodic parameters in both laughter and speech.
Objectives According to ICD-10 or DSM-IV criteria Post-Concussion Syndrome (PCS) requires a prior mild traumatic brain injury (mTBI). However, PCS symptoms are non-specific and can also affect non-mTBI populations. Symptoms further overlap with other diagnoses, such as depression. Consequently, the degree to which PCS is specific to or caused by mTBI is still debated. With the present study we aim to investigate the nature of PCS in greater detail by looking whether PCS is specific to mTBI, and the extent to which these symptoms and related factors (depression, anxiety, daytime sleepiness and cognitive failures) exist in the non-mTBI population. Method An online survey was sent to University staff and students. Included in this survey were the Rivermead Post Concussion Questionnaire (RPQ), Cognitive Failures Questionnaire (CFQ), Hospital Anxiety and Depression Scale (HADS), Epworth Sleepiness Scale (ESS), along with demographic questions and those related to the mTBI sustained. PCS was diagnosed as 3 or more symptoms within DSM-IV criteria. Results The survey created a database of 375 entries, 127 for mTBI and 248 controls (no history of mTBI). Within these groups the proportion of individuals experiencing PCS symptoms was not statistically different (39% for mTBI, 32% for control; Chi squared p=0.2), and there was no group difference for the RPQ, HADS or ESS. However, respondents with a history of mTBI showed significantly higher CFQ scores (p<0.001) than controls. In contrast, when split by PCS diagnosis, those with PCS revealed significantly greater scores for all questionnaires (p<0.001). When split into subgroups (mTBI+PCS, mTBI-PCS, Control+PCS, Control-PCS), a similar pattern was observed. The two groups with PCS both had greater scores for the RPQ, CFQ and HADS than both groups without PCS (p<0.005). There was only one difference when comparing the two groups with mTBI to those without (CFQ: mTBI+PCS greater than Control+PCS (p<0.05)). The ESS score for Control+PCS was greater when compared to both groups without PCS (mTBI-PCS (p<0.01); Control-PCS (p<0.005)). Conclusions The study suggests that PCS is equally common in a self-selected sample of persons with and without brain injury. Data on depression, anxiety, cognitive failures and daytime sleepiness scores show no increase in those with mTBI, but are significantly higher in those with PCS. Analysis of the four subgroups revealed no interaction between mTBI and PCS. This suggests that PCS is associated with but not specific to mTBI, as it is observed in the general population in similar proportions. It is worth considering how the presence of PCS in the control group may affect the data when designing prospective experiments. In addition to depression, anxiety and cognitive failures, this study suggests that those with PCS experience greater daytime sleepiness, a possible direction for future research. Available online at: https://ibia.conference-services.net/programme.asp?conferenceID=1677&action=prog_list&session=6397
S Kolbel, T Elbert, B Rockstroh, A Sterr, T Jahn, E Taub (1998)Constraint-induced (CI) movement therapy in patients treated according to German rehabilitation programs, In: JOURNAL OF PSYCHOPHYSIOLOGY12(2)pp. 206-206
A Sterr, MM Muller, T Elbert, B Rockstroh, C Pantev, E Taub (1998)Changed perceptions in Braille readers, In: NATURE391(6663)pp. 134-135
Andre J Szameitat, Adam McNamara, Shan Shen, Annette Sterr Functional connectivity during motor imagery of complex bimanual everyday actions, In: Neurophysiology
The present study investigated the functional neuroanatomical correlates of motor imagery (MI) of complex bimanual everyday actions (also called functional tasks). For this, 17 participants underwent functional magnetic resonance imaging (fMRI) and performed MI of bimanual actions (e.g., tying shoelaces) and of unimanual actions (e.g. writing) performed with the right and left hand. While a standard univariate fMRI analysis showed no reliable cortical activations specific to bimanual MI, a subsequent functional connectivity analysis (psychophysiological interactions) showed increased connectivity during bimanual MI, as compared to unimanual MI, mainly between inter- and intrahemispheric somatosensory and premotor cortices. These results demonstrate that MI of ecologically valid everyday tasks shows a comparable pattern of functional connectivity as has been reported for MI of more simple, standardized laboratory tasks such as finger-opposition. Furthermore, the present results show for the first time that MI of bimanual actions shows a comparable pattern of functional connectivity as has been reported for overt bimanual performance, thus strongly supporting the assumed equivalence of MI and motor execution. Potential benefits of MI of bimanual everyday actions over MI of unimanual simple laboratory tasks for clinical application such as motor rehabilitation and for training of athletes and musicians are discussed. Keywords Motor imagery, bimanual, functional magnetic resonance imaging (fMRI), functional connectivity (psychophysiological interactions), functional tasks
Philip Dean, Annette Sterr (2013)Long-term effects of mild traumatic brain injury on cognitive performance, In: Frontiers in Human Neuroscience730pp. 1-11 Frontiers Research Foundation
Although a proportion of individuals report chronic cognitive difficulties after mild traumatic brain injury (mTBI), results from behavioral testing have been inconsistent. In fact, the variability inherent to the mTBI population may be masking subtle cognitive deficits. We hypothesized that this variability could be reduced by accounting for post-concussion syndrome (PCS) in the sample. Thirty-six participants with mTBI (>1 year post-injury) and 36 non-head injured controls performed information processing speed (Paced Visual Serial Addition Task, PVSAT) and working memory (n-Back) tasks. Both groups were split by PCS diagnosis (4 groups, all n = 18), with categorization of controls based on symptom report. Participants with mTBI and persistent PCS had significantly greater error rates on both the n-Back and PVSAT, at every difficulty level except 0-Back (used as a test of performance validity). There was no difference between any of the other groups. Therefore, a cognitive deficit can be observed in mTBI participants, even 1 year after injury. Correlations between cognitive performance and symptoms were only observed for mTBI participants, with worse performance correlating with lower sleep quality, in addition to a medium effect size association (falling short of statistical significance) with higher PCS symptoms, post-traumatic stress disorder (PTSD), and anxiety. These results suggest that the reduction in cognitive performance is not due to greater symptom report itself, but is associated to some extent with the initial injury. Furthermore, the results validate the utility of our participant grouping, and demonstrate its potential to reduce the variability observed in previous studies.
K Herron, DJ Dijk, P Dean, E Seiss, A Sterr (2009)EEG-Derived biomarkers for daytime sleepiness in patients with chronic stroke, In: Special Issue: Society for Psychophysiological Research Abstracts for the Forty-Ninth Annual Meeting46(Supple)pp. S108-?
Stroke patients with motor deficits often report daytime sleepiness. While slowing of the EEG during wakefulness has been shown after stroke, it is unknown if and how this is linked to their perception of sleepiness. Using waking EEG and a motor task (associated with mild sleepiness), we examined: 1) differences in the frequency composition and lateralisation of the EEG between stroke patients and controls, and 2) the relationship between the EEG and subjective sleepiness ratings. EEG and Karolinska Sleepiness Scale (KSS) data were collected from 15 right hemispheric stroke patients and 15 matched controls before and after a motor priming task. Frequency analysis was performed on C3 and C4 channels. Prior to the task, the stroke group revealed increased power density below 10 Hz compared to controls for both hemispheres, with more pronounced effects within the lesioned hemisphere. The motor task significantly increased KSS scores in both groups. Increased beta and alpha activity was observed after the task in the control group. The stroke group showed post task increases in beta activity for the non-affected hemisphere and bilateral increases in alpha and theta activity. An association between KSS and the EEG was observed post task in the stroke patients within the theta and alpha bands. Therefore, slowing of the EEG is related to perception of daytime sleepiness in stroke patients. This effect may not have been observed in the controls due to the way in which the motor task manipulates sleepiness within each group, as it is more challenging for those with motor deficits.
B Roder, W Teder-Salejarvi, A Sterr, F Rosler, SA Hillyard, HJ Neville (1999)Improved auditory spatial tuning in blind humans, In: NATURE400(6740)pp. 162-166
Poster presented at the Seventh World Congress On Brain Injury, 9-12 April, 2008.Lisbon, Portugal. Organised by The International Brain Injury Association. www.internationalbrain.org
E Seiss, C Hope, A Guinn, PJA Dean, A Sterr (2013)The effect of elevated blood sugar levels on encoding and retrieval in averbal memory task, In: Psychophysiology50(S1)pp. S92-S93
Previous studies suggest that oral glucose administration directly facilitates declarative memory encoding and retrieval (Sünram-Lea et al., 2002; Manning et al., 1992). However, glucose could indirectly facilitate memory encoding by already enhancing pre-mnemonic sensory or lexical/semantic processes, which produce important substrates for memory encoding. In the present study we used ERP measures combined with a robust placebo-controlled double-blind glucose elevation protocol to (1) replicate the glucose facilitation effect on declarative memory performance, and (2) determine whether glucose modulates pre-mnemonic or mnemonic processes at the encoding and retrieval stage. EEG was collected from 32 electrodes while participants performed a word recognition task under conditions of elevated (6.5 ± 0.12 mmol) and normal (4.57 ± 0.12 mmol) blood glucose levels. In line with the literature, recall rates were better in the glucose condition. Glucose also enlarged the LPC component, which is functionally linked to memory encoding and consolidation processes. Glucose also modulated VEPs (P1, N1), the P300, and the N400, a marker of pre-mnemonic lexical/semantic processing. The N400 amplitude positively correlated with memory performance. At the recognition stage similar effects on VEPs and the P300 were observed, and glucose numerically enhanced the FN400, while reducing the LP. In summary the glucose facilitation of declarative memory may be enacted through effects on earlier information processing stages as well as later memory-specific processes.
B Rockstroh, BA Clement, C Pantev, LD Blumenfeld, A Sterr, T Elbert (1998)Failure of dominant left-hemispheric activation to right-ear stimulation in schizophrenia, In: NEUROREPORT9(17)pp. 3819-3822
S. Shen, A.J. Szameitat, A Sterr (2008)Detection of Infarct Lesions From Single MRI Modality Using Inconsistency Between Voxel Intensity and Spatial Location—A 3-D Automatic Approach, In: IEEE Transactions on Information Technology in Biomedicine12(4)pp. 532-540 Institute of Electrical and Electronics Engineers

Detection of infarct lesions using traditional segmentation methods is always problematic due to intensity similarity between lesions and normal tissues, so that multispectral MRI modalities were often employed for this purpose. However, the high costs of MRI scan and the severity of patient conditions restrict the collection of multiple images. Therefore, in this paper, a new 3-D automatic lesion detection approach was proposed, which required only a single type of anatomical MRI scan. It was developed on a theory that, when lesions were present, the voxel-intensity-based segmentation and the spatial-location-based tissue distribution should be inconsistent in the regions of lesions. The degree of this inconsistency was calculated, which indicated the likelihood of tissue abnormality. Lesions were identified when the inconsistency exceeded a defined threshold. In this approach, the intensity-based segmentation was implemented by the conventional fuzzy c-mean (FCM) algorithm, while the spatial location of tissues was provided by prior tissue probability maps. The use of simulated MRI lesions allowed us to quantitatively evaluate the performance of the proposed method, as the size and location of lesions were prespecified. The results showed that our method effectively detected lesions with 40–80% signal reduction compared to normal tissues (similarity index $>$0.7). The capability of the proposed method in practice was also demonstrated on real infarct lesions from 15 stroke patients, where the lesions detected were in broad agreement with true lesions. Furthermore, a comparison to a statistical segmentation approach presented in the literature suggested that our 3-D lesion detection approach was more reliable. Future work will focus on adapting the current method to multiple sclerosis lesion detection.

B Rockstroh, H Watzl, ZJ Kowalik, R Cohen, A Sterr, M Muler, T Elbert (1997)Dynamical aspects of the EEG in different psychopathological states in an interview situation: a pilot study, In: SCHIZOPHRENIA RESEARCH28(1)pp. 77-85
EB Plow, V Sankarasubramanian, DA Cunningham, K Potter-Baker, N Varnerin, LG Cohen, A Sterr, AB Conforto, AG Machado (2016)Models to Tailor Brain Stimulation Therapies in Stroke, In: NEURAL PLASTICITYARTN 40716 HINDAWI PUBLISHING CORP
Shan Shen, William A. Sandham, Malcolm H. Granat, Annette Sterr (2005)Intensity Non-uniformity Correction of Magnetic Resonance Images Using a Fuzzy Segmentation Algorithm, In: 2005 IEEE Engineering in Medicine and Biology 27th Annual Conferencepp. 1-4

Artifacts in magnetic resonance images can make conventional intensity-based segmentation methods very difficult, especially for the spatial intensity non-uniformity induced by the radio frequency (RF) coil. The non-uniformity introduces a slow-varying shading artifact across the images. Many advanced techniques, such as nonparametric, multi-channel methods, cannot solve the problem. In this paper, the extension of an improved fuzzy segmentation method, based on the traditional fuzzy c-means (FCM) algorithm and neighborhood attraction, is proposed to correct the intensity non-uniformity. Experimental results on both synthetic non-MR and MR images are given demonstrate the superiority of the algorithm.

E Wolf, M Kuhn, C Norman, F Mainberger, JG Maier, S Maywald, A Bredl, S Klöppel, K Biber, D van Calker, D Riemann, A Sterr, C Nissen (2015)Synaptic plasticity model of therapeutic sleep deprivation in major depression., In: Sleep Med Rev30pp. 53-62
Therapeutic sleep deprivation (SD) is a rapid acting treatment for major depressive disorder (MDD). Within hours, SD leads to a dramatic decrease in depressive symptoms in 50-60% of patients with MDD. Scientifically, therapeutic SD presents a unique paradigm to study the neurobiology of MDD. Yet, up to now, the neurobiological basis of the antidepressant effect, which is most likely different from today's first-line treatments, is not sufficiently understood. This article puts the idea forward that sleep/wake-dependent shifts in synaptic plasticity, i.e., the neural basis of adaptive network function and behavior, represent a critical mechanism of therapeutic SD in MDD. Particularly, this article centers on two major hypotheses of MDD and sleep, the synaptic plasticity hypothesis of MDD and the synaptic homeostasis hypothesis of sleep-wake regulation, and on how they can be integrated into a novel synaptic plasticity model of therapeutic SD in MDD. As a major component, the model proposes that therapeutic SD, by homeostatically enhancing cortical synaptic strength, shifts the initially deficient inducibility of associative synaptic long-term potentiation (LTP) in patients with MDD in a more favorable window of associative plasticity. Research on the molecular effects of SD in animals and humans, including observations in the neurotrophic, adenosinergic, monoaminergic, and glutamatergic system, provides some support for the hypothesis of associative synaptic plasticity facilitation after therapeutic SD in MDD. The model proposes a novel framework for a mechanism of action of therapeutic SD that can be further tested in humans based on non-invasive indices and in animals based on direct studies of synaptic plasticity. Further determining the mechanisms of action of SD might contribute to the development of novel fast acting treatments for MDD, one of the major health problems worldwide.
C Baglioni, C Nissen, A Schweinoch, D Riemann, K Spiegelhalder, M Berger, C Weiller, A Sterr (2016)Polysomnographic Characteristics of Sleep in Stroke: A Systematic Review and Meta-Analysis, In: PLOS ONE11(3)ARTN e0148 PUBLIC LIBRARY SCIENCE
C Pieridi, D Brown, A Sterr (2012)The experience of returning to work following a traumatic brain injury, In: Brain Injury26(4-5)pp. 625-625
Objectives: Returning to work after having experienced a brain injury poses difficulties for people who have undergone this traumatic experience. Research in general and into brain injury in particular has neglected to address the social aspects of experiencing a brain injury and returning to work. This research aimed to offer a qualitative perspective into the area of research into brain injury and returning to work. The objective was to acknowledge the voices of people who have experienced a brain injury and their experiences of returning to work. Methods: Four participants took part in the research and encouraged to narrate their experiences. A narrative approach to data analysis was employed to examine the data. Results: Results indicate that there is variability in the psychological process that each individual goes through after their brain injury; all participants experienced their trauma and the consequent symptoms differently. However, some commonalities arose when participants referred to their return to work: a number of external and internal factors, which include social environment, self perceptions, support and nature of the job, were described as influencing their decision of returning to work and the experience of work itself. Conclusions: Returning to work after experiencing a brain injury is a process that engages the self with its social environment and the work environment. Society and science need to pay attention to the voices of the individuals and the stories they share about themselves and their experiences. It is hoped that by identifying the elements that influence the return to employment, vocational rehabilitation services and organisations can become more person-tailored and flexible to each person’s situation.
WS Hou, XY Wu, XL Zheng, S Shen, AM Sterr (2006)A behavior study on the effect of visual feedback gain to force production, In: Chinese Journal of Biomedical Engineering25(5)pp. 542-546
Visual feedback is a crucial factor to motor function, and a few parameters, such as gain, delay and frequency, can influence the motor output. Here presented a behavioral study on the effect of visual feedback gain to movement by measuring the grasp force output under different visual feedback gain. Two force track tasks with different increasing/decreasing force rate have been designed, and 12 participants have been recruited in this experiment. Force deviation and error rate produced by participants have been detected under different gains. The statistical analysis revealed that gain of visual stimuli can influence force output significantly. For the same force track task, visual feedback with high gain can enhance the regulation of force production. The results suggested that different visual feedback gains may recruit different cortex function area to execute different motor tasks.
T Elbert, V Candia, E Altenmuller, H Rau, A Sterr, B Rockstroh, C Pantev, E Taub (1998)Alteration of digital representations in somatosensory cortex in focal hand dystonia, In: NEUROREPORT9(16)pp. 3571-3575
IJ Billows, S Khan, A Sterr (2013)Exploring sleep, sleepiness and fatigue in chronic stroke: A mixed methods study, In: INTERNATIONAL JOURNAL OF STROKE8pp. 73-73 WILEY-BLACKWELL
A Sterr, M Muller, T Elbert, B Rockstroh, E Taub (1999)Development of cortical reorganization in the somatosensory cortex of adult Braille students, In: FUNCTIONAL NEUROSCIENCE: EVOKED POTENTIALS AND MAGNETIC FIELDS(49)pp. 292-298
P Halder, A Sterr, S Brem, K Bucher, S Kollias, D Brandeis (2005)Electrophysiological evidence for cortical plasticity with movement repetition, In: European Journal of Neuroscience21(8)pp. 2271-2277
The role of movement repetition and practice has been extensively studied as an aspect of motor skill learning but has rarely been investigated in its own right. As practice is considered a prerequisite for motor learning we expected that even the repetitive execution of a simple movement would rapidly induce changes in neural activations without changing performance. We used 64-channel event-related potential mapping to investigate these effects of movement repetition on corresponding brain activity in humans. Ten healthy right-handed young adults performed a power grip task under visual force control to ensure constant behaviour during the experimental session. The session consisted of two parts intersected by a break. For analysis each part was subdivided into two runs to control for potential attention or fatigue effects, which would be expected to disappear during the break. Microstate analysis revealed that distinct topographies and source configurations during movement preparation, movement execution and feedback integration are responsive to repetition. The observed patterns of changes differed for the three microstates, suggesting that different, repetition-sensitive neural mechanisms are involved. Moreover, this study clearly confirms that movement repetition, in the absence of skill learning, is capable of inducing changes in neural networks.
C Lukoschek, A Sterr, D Claros-Salinas, R Guetler, C Dettmers (2015)Fatigue in multiple sclerosis compared to stroke, In: FRONTIERS IN NEUROLOGY6UNSP 116 FRONTIERS MEDIA SA
J Ellis, A Thomsom, AM Gregory, AM Sterr (2012)Biased Processing of Sleep-Related Stimuli in Children of Parents With Insomnia, In: Behavioral Sleep Medicine10 Routledge, Taylor & Francis Group
Disorder-specific cognitive biases have been observed in children whose parents suffer from psychological disorders. Despite those same biases being observed in individuals with insomnia, they have yet to be explored as an index of vulnerability in children of parents with insomnia. It was hypothesized that potentially vulnerable children would demonstrate cognitive biases to sleep- related cues, relative to controls. Following a “tired-state induction,” a sleep-related Emotional Stroop was completed by 2 groups: 38 children of parents with insomnia and 51 controls. Children also reported their observations about the content of the Stroop words. Results showed an attention bias in children whose parents have insomnia, but no interpretive bias. The results are discussed in terms of a predispositional vulnerability to insomnia.
André J. Szameitat, Shan Shen, Annette Sterr (2007)Effector-dependent activity in the left dorsal premotor cortex in motor imagery, In: The European Journal of Neuroscience26pp. 3303-3308 Blackwell Publishing Ltd
Although right- and left-hand motor imagery (MI) typically results in lateralized cortical activation patterns in various areas, such an effect has never been observed in the left premotor cortex (PMC). Using functional magnetic resonance imaging we tested whether the left PMC, which is supposed to be effector independent, i.e. it is activated irrespective of the hand used for MI, shows differential activation during right- and left-hand MI of ecologically valid everyday actions. Results showed that the left dorsal PMC was activated more strongly during right- than left-hand MI, and that the co-varying quality of imagination could not explain the observed effects. We conclude that the left dorsal PMC incorporates effector-dependent functionality and therefore is not fully generic for MI, as has been suggested before. Implications for clinical research are discussed. Keywords: ecologically valid task, functional magnetic resonance imaging, motor planning, motor preparation, premotor cortex
T Elbert, A Sterr, H Flor, B Rockstroh, S Knecht, C Pantev, C Wienbruch, E Taub (1997)Input-increase and input-decrease types of cortical reorganization after upper extremity amputation in humans, In: EXPERIMENTAL BRAIN RESEARCH117(1)pp. 161-164
PJ Dean, MC Otaduy, LM Harris, A McNamara, E Seiss, A Sterr (2013)Monitoring long-term effects of mild traumatic brain injury with magnetic resonance spectroscopy: a pilot study., In: Neuroreport24(12)pp. 677-681 Lippincott, Williams & Wilkins
This pilot study explores the metabolic changes associated with persistent postconcussion syndrome (PCS) after mild traumatic brain injury (mTBI; >12 months after injury) using magnetic resonance spectroscopy. We hypothesized that those mTBI participants with PCS will have larger metabolic differences than those without. Data were collected from mTBI participants with PCS, mTBI participants without PCS and non-head-injured participants (all groups: n=8). Magnetic resonance spectroscopy metabolite profiles within the dorsolateral prefrontal cortex showed a reduced creatine/choline ratio in mTBI patients compared with control participants. This data provides initial evidence for residual metabolic changes in chronic mTBI patients, but there was no conclusive relationship between these metabolic changes and PCS symptom report. Creatine is involved in maintaining energy levels in cells with high or fluctuating energy demand, suggesting that there may be some residual energy impairment in chronic mTBI.
A Sterr, MM Muller, T Elbert, B Rockstroh, E Taub (1998)Expansion of cortical hand representation and tactile sensory thresholds in blind Braille readers: A link between cortical organization and perception, In: JOURNAL OF PSYCHOPHYSIOLOGY12(2)pp. 193-194
M Encke, PJA Dean, E Seiss, A Sterr (2013)Effects of aging on motor preparation processes, In: Psychophysiology50(S1)pp. S87-S87
The last-in first-out theory suggests that late-maturing brain regions are affected earlier in the life span than those maturing early. Maturation of the motor system and the frontal executive control system continues into early adulthood. Evidence further suggests that motor preparation, index by the contingent negative variation (CNV), matures relatively late in adolescence and is compromised in persons aged 68–83 years. With the present study we explored the progression of age-related changes in motor preparation control by contrasting behavioral and CNV effects in young (18–23), middle-aged (33–44) and older (61–72) persons using a modified response priming paradigm. All three groups showed the typical motor priming effect pattern with faster RTs in valid trials compared to invalid trials. RTs were significantly slower in the older than the middle-aged and young groups, with no significant difference in error rates. A significantly larger CNV validity effect was found for the young group compared to the older group. CNV topography shifted from parietal to more frontal regions with age. These data provide initial evidence for early changes in motor preparation control mechanisms and lend support for the last-in first-out hypothesis.
C Nissen, L Frase, H Piosczyk, B Feige, A Sterr, D Riemann (2014)The modulation of sleep continuity through transcranial direct current stimulation (TDCS), In: JOURNAL OF SLEEP RESEARCH23pp. 39-39
A Sterr, MM Müller, T Elbert, B Rockstroh, C Pantev, E Taub (1998)Perceptual Correlates of Changes in Cortical Representation of Fingers in Blind Multifinger Braille Readers, In: The Journal of Neuroscience18pp. 4417-4423

The mature mammalian nervous system alters its functional organization in a use-dependent manner. Enhanced stimulation of a body part enlarges its cortical representational zones and may change its topographic order. Little is known about the perceptual and behavioral relevance of these plastic alterations in cortical organization. We used blind Braille readers who use several fingers on each hand and who do so for many hours each day as a model to investigate this issue. Magnetic source imaging indicated that the cortical somatosensory representation of the fingers was frequently topographically disordered in these subjects; in addition, they frequently misperceived which of these fingers was being touched by a light tactile stimulus. In contrast, neither the disordered representation nor mislocalizations were observed in sighted controls. Blind non-teacher Braille readers who used only one finger for reading were not significantly different from the sighted controls. Thus, use-dependent cortical reorganization can be associated with functionally relevant changes in the perceptual and behavioral capacities of the individual.

Cornelia Kranczioch, Simon Mathews, Phil J.A. Dean, Annette Sterr (2009)On the Equivalence of Executed and Imagined Movements: Evidence From Lateralized Motor and Nonmotor Potentials, In: Human Brain Mapping John Wiley & Sons
The neural simulation theory assumes that motor imagery and motor execution draw on a shared set of mechanisms underlying motor cognition. Evidence is accumulating that motor imagery and motor execution have many common features. The extent of the similarity and whether it spreads into the preparation phase is however unclear. This study used electroencephalographic recordings to compare the effects of providing advance information about upcoming movements on preparatory processing in a motor imagery and execution paradigm. Event-related potential data were recorded in a priming task where participants were cued to perform simple or complex finger movements. We hypothesized that a high degree of functional similarity of motor imagery and motor execution should be reflected in similar alterations of lateralized preparatory activity. Lateralized preparatory activity was indeed very similar, showing both motor-related (lateralized readiness potential, LRP) and cognitive components (anterior directing-attention negativity or ADAN, late directing-attention positivity or LDAP). Dipole analysis revealed that LRP, ADAN, and LDAP sources were very comparable for motor imagination and execution. Results generally support the idea of common underlying functional networks subserving both the preparation for execution and imagery of movements. They also provide a broader context for this notion by revealing similarities in cognitive components associated with the movement tasks. Hum Brain Mapp 00:000–000, 2009. VVC 2009 Wiley-Liss, Inc. Key words: electroencephalography; fingers; movement preparation; motor imagery; lateralized readiness potential; ADAN; LDAP; LRP; dipole source localisation
T Elbert, Annette Sterr, B Rockstroh, C Pantev, MM Muller, E Taub (2002)Expansion of the tonotopic area in the auditory cortex of the blind, In: Journal of Neuroscience22(22)pp. 9941-9944
A part of the core area of the auditory cortex was examined in nine blind and10 sighted individuals by magnetic source imaging and was found to be enlarged by a factor of 1.8 in the blind compared with the sighted humans. Moreover, the latency of the N1m component of the auditory-evoked magnetic response was significantly decreased in the blind. The development of use-dependent cortical reorganization may be a consequence of the absence of visual input in combination with enhanced auditory activity generated by the long-term concentration by blind individuals on nonvisual cues to interact appropriately with the environment. It is consistent with and well suited to mediate the demonstrated increased ability of the blind to accurately localize acoustic sources in peripheral auditory fields and to decode speech.
A Sterr, PJA Dean, JR Sato, G Vieira, AB Conforto, S Shen (2013)Cortical thickness changes in the non-lesioned hemisphere associated with non-paretic arm immobilization in modified CI therapy, In: NeuroImage: Clinical2(1)pp. 797-803
Recent evidence suggests that immobilization of the upper limb for 2-3 weeks induces changes in cortical thickness as well as motor performance. In constraint induced (CI) therapy, one of the most effective interventions for hemiplegia, the non-paretic arm is constrained to enforce the use of the paretic arm in the home setting. With the present study we aimed to explore whether non-paretic arm immobilization in CI therapy induces structural changes in the non-lesioned hemisphere, and how these changes are related to treatment benefit. 31 patients with chronic hemiparesis participated in CI therapy with (N = 14) and without (N = 17) constraint. Motor ability scores were acquired before and after treatment. Diffusion tensor imaging (DTI) data was obtained prior to treatment. Cortical thickness was measured with the Freesurfer software. In both groups cortical thickness in the contralesional primary somatosensory cortex increased and motor function improved with the intervention. However the cortical thickness change was not associated with the magnitude of motor function improvement. Moreover, the treatment effect and the cortical thickness change were not significantly different between the constraint and the non-constraint groups. There was no correlation between fractional anisotropy changes in the non-lesioned hemisphere and treatment outcome. CI therapy induced cortical thickness changes in contralesional sensorimotor regions, but this effect does not appear to be driven by the immobilization of the non-paretic arm, as indicated by the absence of differences between the constraint and the non-constraint groups. Our data does not suggest that the arm immobilization used in CI therapy is associated with noticeable cortical thinning. © 2013 The Authors. Published by Elsevier Inc. All rights reserved.
C Hope, E Seiss, PJA Dean, K Williams, A Sterr (2013)Consumption of glucose drinks slows sensorimotor processing: Double-blind placebo-controlled studies with the Eriksen flanker task, In: Frontiers in Human Neuroscience7651pp. ?-? Frontiers
Modulations of blood glucose concentration (BGC) in the normal range are known to facilitate performance in memory and other cognitive tasks but few studies have investigated the effects of BGC variations on complex sensorimotor task so far. The present study aimed to examine glucose effects with the Eriksen flanker task. This task was chosen because it can dissociate between the effects of BGC on sensorimotor processing and cognitive control by assessing congruency effects. In two linked double-blind placebo controlled experiments BGC was elevated within the normal BGC range (4-7 mmol/litre) by approx. 1.5 mmol/litre with glucose drinks and compared to a placebo drink condition while a flanker task with either strong or weak stimulus-response (SR) mapping was performed. Modulation of the performance in the flanker task by glucose was linked to the strength of the SR mapping but not congruency effects. Under weak SR mapping, reaction times (RT) were slowed in the glucose condition compared to placebo while error rates remained unchanged, whereas cognitive control was not affected by glucose. When SR mapping was strong, no differences were found between glucose and placebo. Enhanced glucose levels differentially affect behaviour. Whereas the literature mainly reports facilitating characteristics of enhanced glucose levels in the normal range, the present study shows that higher glucose levels can slow RTs. This suggests that glucose does not have a uniform effect on cognition and that it might be differential depending on the cognitive domain.
A. Sterr, M. Kuhn, C. Nissen, D. Ettine, S. Funk, B. Feige, R. Umarova, H. Urbach, C. Weiller, D. Riemann (2018)Post-stroke insomnia in community-dwelling patients with chronic motor stroke: Physiological evidence and implications for stroke care, In: Scientific Reports8(1)8409pp. 1-9 Nature Research
Questionnaire studies suggest that stroke patients experience sustained problems with sleep and daytime sleepiness, but physiological sleep studies focussing specifically on the chronic phase of stroke are lacking. Here we report for the first time physiological data of sleep and daytime sleepiness obtained through the two gold-standard methods, nocturnal polysomnography and the Multiple Sleep Latency Test. Data from community-dwelling patients with chronic right-hemispheric stroke (>12 months) were compared to sex- and age-matched controls. Behavioural and physiological measures suggested that stroke patients had poorer sleep with longer sleep latencies and lower sleep efficiency. Patients further spent more time awake during the night, and showed greater high-frequency power during nonREM sleep than controls. At the same time the Multiple Sleep Latency Test revealed greater wake efficiency in patients than controls. Importantly these findings were not due to group differences in sleep disordered breathing or periodic limb movements. Post-stroke insomnia is presently not adequately addressed within the care pathway for stroke. A holistic approach to rehabilitation and care provision, that includes targeted sleep interventions, is likely to enhance long-term outcome and quality of live in those living with chronic deficits after stroke.
N Grossheinrich, M Reinl, C Mulert, O Pogarell, K Fast, S Karch, A Sterr, F Padberg (2007)Modulation of event-related potentials by repetitive transcranial magnetic stimulation of the prefrontal cortexpp. 372-?
K Herron, D Dijk, PJA Dean, E Seiss, A Sterr (2014)Quantitative Electroencephalography and Behavioural Correlates of Daytime Sleepiness in Chronic Stroke, In: BioMed Research Internationl2014794086pp. ?-?
Sleepiness is common after stroke, but in contrast to its importance for rehabilitation, existing studies focus primarily on the acute state and often use subjective sleepiness measures only. We used quantitative electroencephalography (qEEG) to extract physiological sleepiness, as well as subjective reports, in response to motor-cognitive demand in stroke patients and controls. We hypothesised that (a) slowing of the EEG is chronically sustained after stroke; (b) increased power in lower frequencies and increased sleepiness are associated; and (c) sleepiness is modulated by motor-cognitive demand. QEEGs were recorded in 32 chronic stroke patients and 20 controls using a Karolinska Drowsiness Test protocol administered before and after a motor priming task. Subjective sleepiness was measured using the Karolinska Sleepiness Scale.The findings showed that power density was significantly increased in delta and theta frequency bands over both hemispheres in patients which were not associated with subjective sleepiness ratings. This effect was not observed in controls.The motor priming task induced differential hemispheric effects with greater increase in low-frequency bands and presumably compensatory increases in higher frequency bands. The results indicate sustained slowing in the qEEG in chronic stroke, but in contrast to healthy controls, these changes are not related to perceived sleepiness.
SM Anjos, LG Cohen, A Sterr, KNF de Andrade, AB Conforto (2014)Translational Neurorehabilitation Research in the Third World What Barriers to Trial Participation Can Teach Us, In: STROKE45(5)pp. 1495-1497 LIPPINCOTT WILLIAMS & WILKINS
Tara Kidd, Nicola Carey, Freda Elizabeth Mold, Susan Westwood, Maria Miklaucich, Emmanouela Konstantara, Annette Sterr, Deborah Cooke (2017)A Systematic Review of the Effectiveness of Self-Management Interventions in People with Multiple Sclerosis at Improving Depression, Anxiety and Quality of Life., In: PLoS ONE12(10)e0185931 Public Library of Science
Background

Self-management interventions have become increasingly popular in the management of long term health conditions; however, little is known about their impact on psychological well-being in people with Multiple Sclerosis (MS).

Purpose

To examine the effectiveness of self-management interventions on improving depression, anxiety and health related quality of life in people with MS.

Method

A structured literature search was conducted for the years 2000 to 2016. The review process followed the PRISMA guidelines, and is registered with PROSPERO (no. CRD42016033925).

Results

The review identified 10 RCT trials that fulfilled selection criteria and quality appraisal. Self-management interventions improved health-related quality of life in 6 out of 7 studies, with some evidence of improvement in depression and anxiety symptoms.

Conclusion

Although the results are promising more robust evaluation is required in order to determine the effectiveness of self-management interventions on depression, anxiety and quality of life in people with MS. Evaluation of the data was impeded by a number of methodological issues including incomplete content and delivery information for the intervention and the exclusion of participants representing the disease spectrum. Recommendations are made for service development and research quality improvement.

The response-priming paradigmis frequentlyemployed to studymotor control bymeans of behavioural aswell as psychophysiological methods. In this paradigm, response performance is studied under various preparation conditions, but in all cases participants are generally primed for action. This setting neglects an essential ability of the motor system in everyday situations, i.e. the efficient execution of a movement with and without warning. In this context the present experiment assessed the behavioural effects of a modified response-priming paradigm, in which participants were asked to execute movements when primed for action, and when the prime predicted that no response would be required. Thirty volunteersparticipated the experiment, which tested whether the insertion of no-response trials would affect the validity effect, and assessed the differences between invalid trials and reactions performed subsequent to no-response primes. The data showed that the validity effect is not modulated by the added no-response condition, which suggests that movement preparation mechanisms can be studied with this particular task. In addition, responses in invalid trials were substantially different from responses executed after no-response primes. These results are interpreted in relation to psychophysiological evidence on advance movement preparation. It is proposed that the performance differences between response- and no-response priming conditions may be due to different preactivations of motor regions evoked by the prime stimuli, a hypothesis to be addressed with psychophysiological measures in the future. Keywords: Validity effects; Motor control; Advance movement preparation
P Dean, L Perkins, A McNamara, P Sauseng, A Sterr (2014)A novel method for acquiring cognitive data after brain injury and during follow-up: The use of mobile technology in a visuo-spatial working memory task, In: BRAIN INJURY28(5-6)pp. 656-656 INFORMA HEALTHCARE
Annette Sterr, Shan Shen, Andre J Szameitat, Katherine A Herron (2010)The Role of Corticospinal Tract Damage in Chronic Motor Recovery and Neurorehabilitation: A Pilot Study, In: Neurorehabilitation and Neural Repair24(5)pp. 413-419 SAGE
Background. With diffusion-tensor imaging (DTi) it is possible to estimate the structural characteristics of fiber bundles in vivo. This study used DTi to infer damage to the corticospinal tract (CST) and relates this parameter to (a) the level of residual motor ability at least 1 year poststroke and (b) the outcome of intensive motor rehabilitation with constraintinduced movement therapy (CIMT). Objective. To explore the role of CST damage in recovery and CIMT efficacy. Methods. Ten patients with low-functioning hemiparesis were scanned and tested at baseline, before and after CIMT. Lesion overlap with the CST was indexed as reduced anisotropy compared with a CST variability map derived from 26 controls. Residual motor ability was measured through the Wolf Motor Function Test (WMFT) and the Motor Activity Log (MAL) acquired at baseline. CIMT benefit was assessed through the pre–post treatment comparison of WMFT and MAL performance. Results. Lesion overlap with the CST correlated with residual motor ability at baseline, with greater deficits observed in patients with more extended CST damage. Infarct volume showed no systematic association with residual motor ability. CIMT led to significant improvements in motor function but outcome was not associated with the extent of CST damage or infarct volume. Conclusion. The study gives in vivo support for the proposition that structural CST damage, not infarct volume, is a major predictor for residual functional ability in the chronic state. The results provide initial evidence for positive effects of CIMT in patients with varying, including more severe, CST damage. Keywords constraint-induced movement therapy, diffusion tensor imaging, chronic hemiplegia, upper limb, stroke rehabilitation, fractional anisotropy
PJ Dean, D O'Neill, A Sterr (2012)Post-concussion syndrome: Prevalence after mild traumatic brain injury in comparison with a sample without head injury., In: Brain Injury26(1)pp. 14-26 Informa Health Care
Primary objective: To compare the prevalence of persistent post-concussion syndrome (PCS; >1 year post-injury) in participants with mild traumatic brain injury (mTBI) and those without head injury. Research design: A cross-sectional sample of 119 participants with mTBI and 246 without previous head injury. Methods: Online questionnaires collected data about post-concussion symptoms, cognitive failures, anxiety, depression, sleep behaviour and post-traumatic stress disorder. Variability within the sample was addressed by splitting by PCS diagnosis to create four groups: mTBI + PCS, mTBI-PCS, Control + PCS and Control-PCS. PCS was diagnosed using ICD-10 criteria in all groups, with controls not requiring previous head injury. Main outcomes and results: PCS was present to a similar extent in participants with no head injury (34%) compared to those with mTBI (31%). Only report of headaches, which could be caused by expectation bias, distinguished between mTBI + PCS and Control + PCS groups. In addition, significantly higher cognitive problems were observed in participants with mTBI compared with the control group. Conclusions: Persistent PCS, as currently defined, is not specific to mTBI. These data suggest that somatic and cognitive symptoms are most likely to be able to distinguish PCS after mTBI from that present in the general population. Further research is necessary into these factors in order to create more specific PCS diagnostic criteria.
Annette Sterr, Susanna Freivogel, Dieter Schmalohr (2002)Neurobehavioral Aspects of Recovery: Assessment of the Learned Nonuse Phenomenon in Hemiparetic Adolescents, In: Archives of Pysical Medicine and Rehabilitation83pp. 1726-1731
Objective: To test the learned nonuse assumption of constraint-induced movement therapy (CIMT), through behavioral assessment, that residual movement abilities are not used to their fullest extent in persons with chronic hemiparesis. Design: Repeated-measures cohort design. Participants: Twenty-one persons with upper-limb hemiparesis after brain injury and 21 age-matched healthy controls. Participants were hospitalized when tested. Interventions: Not applicable. Main Outcome Measures: Spontaneous affected hand use for the items of the Motor Activity Log and the Actual Amount of Use Test were compared with the subjects’ actual ability to perform these items with the affected hand. Results: A significant difference between the residual movement capability and the spontaneous use was found in both tests. Most movements could be performed with moderate to good movement quality with the affected hand, but were still performed with the unaffected “good” hand in the spontaneous use condition. This effect was equally strong in right- and left-side affected persons. Conclusion: Hemiparetic persons do not use their residual movement capabilities to the fullest extent. According to the learned nonuse model, this behavior reflects a learned suppression of affected arm movements, which may be overcome by CIMT. Key Words: Arm; Motor skills; Rehabilitation, Treatment outcome.
A Szameitat, A McNamara, S Shen, Annette Sterr (2012)Neural Activation and Functional Connectivity during Motor Imagery of Bimanual Everyday Actions, In: PLoS One7(6) Public Library of Science
Bimanual actions impose intermanual coordination demands not present during unimanual actions. We investigated the functional neuroanatomical correlates of these coordination demands in motor imagery (MI) of everyday actions using functional magnetic resonance imaging (fMRI). For this, 17 participants imagined unimanual actions with the left and right hand as well as bimanual actions while undergoing fMRI. A univariate fMRI analysis showed no reliable cortical activations specific to bimanual MI, indicating that intermanual coordination demands in MI are not associated with increased neural processing. A functional connectivity analysis based on psychophysiological interactions (PPI), however, revealed marked increases in connectivity between parietal and premotor areas within and between hemispheres. We conclude that in MI of everyday actions intermanual coordination demands are primarily met by changes in connectivity between areas and only moderately, if at all, by changes in the amount of neural activity. These results are the first characterization of the neuroanatomical correlates of bimanual coordination demands in MI. Our findings support the assumed equivalence of overt and imagined actions and highlight the differences between uni- and bimanual actions. The findings extent our understanding of the motor system and may aid the development of clinical neurorehabilitation approaches based on mental practice.
Shan Shen, Annette Sterr, Andre J. Szameitat (2005)A Template Effect Study on Voxel-Based Morphometry in Statistic Parametric Mapping, In: 2005 IEEE Engineering in Medicine and Biology 27th Annual Conferencepp. 1-4

Voxel-based morphometry (VBM) is an automated method allowing identification of anatomical differences in the whole brain without the pre-specification of a region of interests. Spatial normalization is one of the major processes in VBM, which transforms all images to a standard template. A variety of templates were employed in VBM researches in the literature, including the MNI template and study-specific templates. Few studies were presented to test the effect of templates on the detection accuracy of VBM, although it is claimed in many papers that the study-specific template performs better. However, the creation of the study-specific template differs on the subjects included. In this paper, the gray matter (GM) difference of two groups (female vs male) was analyzed to evaluate the effects of templates on the VBM results. The statistic parametric mapping (SPM) package, as the standard software for VBM implementation, was used for analyses.

PJ Dean, E Seiss, A Sterr (2012)Motor Planning in Chronic Upper-Limb Hemiparesis: Evidence from Movement-Related Potentials., In: PLoS One7(10)pp. e44558-? Public Library of Science
Background Chronic hemiplegia is a common long-term consequence of stroke, and subsequent motor recovery is often incomplete. Neurophysiological studies have focused on motor execution deficits in relatively high functioning patients. Much less is known about the influence exerted by processes related to motor preparation, particularly in patients with poor motor recovery. Methodology/Principal Findings The current study investigates motor preparation using a modified response-priming experiment in a large sample of patients (n = 50) with moderate-to-severe chronic hemiparesis. The behavioural results revealed that hemiparetic patients had an increased response-priming effect compared to controls, but that their response times were markedly slower for both hands. Patients also demonstrated significantly enhanced midline late contingent negative variation (CNV) during paretic hand preparation, despite the absence of overall group differences when compared to controls. Furthermore, increased amplitude of the midline CNV correlated with a greater response-priming effect. We propose that these changes might reflect greater anticipated effort to respond in patients, and consequently that advance cueing of motor responses may be of benefit in these individuals. We further observed significantly reduced CNV amplitudes over the lesioned hemisphere in hemiparetic patients compared to controls during non-paretic hand preparation, preparation of both hands and no hand preparation. Two potential explanations for these CNV reductions are discussed: alterations in anticipatory attention or state changes in motor processing, for example an imbalance in inter-hemispheric inhibition. Conclusions/Significance Overall, this study provides evidence that movement preparation could play a crucial role in hemiparetic motor deficits, and that advance motor cueing may be of benefit in future therapeutic interventions. In addition, it demonstrates the importance of monitoring both the non-paretic and paretic hand after stroke and during therapeutic intervention.
Background: An important aspect in functional imaging research employing magnetic resonance imaging (MRI) is how participants perceive the MRI scanning itself. For instance, the knowledge of how (un)comfortable MRI scanning is perceived may help institutional review boards (IRBs) or ethics committees to decide on the approval of a study, or researchers to design their experiments. Methods: We provide empirical data from our lab gained from 70 neurologically healthy mainly student subjects and from 22 mainly elderly patients suffering from motor deficits after brain damage. All participants took part in various basic research fMRI studies using a 3T MRI scanner. Directly after the scanning, all participants completed a questionnaire assessing their experience with the fMRI procedure. Results: 87.2% of the healthy subjects and 77.3% of the patients rated the MRI procedure as acceptable to comfortable. In healthy subjects, males found the procedure more comfortable, while the opposite was true for patients. 12.1% of healthy subjects considered scanning durations between 30 and 60 min as too long, while no patient considered their 30 min scanning interval as too long. 93.4% of the healthy subjects would like to participate in an fMRI study again, with a significantly lower rate for the subjects who considered the scanning as too long. Further factors, such as inclusion of a diffusion tensor imaging (DTI) scan, age, and study duration had no effect on the questionnaire responses. Of the few negative comments, the main issues were noise, the restriction to keep still for the whole time, and occasional feelings of dizziness. Conclusion: MRI scanning in the basic research setting is an acceptable procedure for elderly and patient participants as well as young healthy subjects.
Wendy Parker, Heather Gage, Annette Sterr, Peter Williams (2017)Holiday play for disabled children in England: access, choice and parents’ views about integration, In: International Journal of Disability, Development and Education64(6)pp. 573-595 Taylor & Francis
Families with children with disabilities can feel isolated during school holidays and concerns exist that they face greater difficulties than families of children without disabilities in finding enriching activities for their child. In the context of national policies that encourage integrated play, local service commissioners in England require evidence on what sort of short breaks parents and children prefer. The parents of 99 children with disabilities and 43 children without disabilities attending various holiday play schemes in summer 2010 completed mailed questionnaires. Parents of children with disabilities reported more difficulty getting information, less choice of schemes and further distances to travel than parents of children without disabilities. Although 72% of parents of children without disabilities and 55.5% of parents of children with disabilities stated integrated schemes would be suitable for their child, open text comments provided weaker support. Variety of provision is required to meet all needs and preferences.
Z-X Mou, W-S Hou, X-L Zheng, X-Y Wu, S Shen, AM Sterr, C-L Peng (2009)fMRI observation of the effect of visual feedback gain on force production, In: Chinese Journal of Medical Imaging Technology25(5)pp. 749-752
Objective: To study the effect of visual feedback gain on movement with the whole-brain functional magnetic resonance imaging (fMRI). Methods: Fifteen healthy volunteers were recruited to execute a grasping task with right hand, and two force track tasks with different increasing/decreasing force rate were performed. The activated areas were evaluated with BOLD fMRI, and functional responses were established by students group t test analysis. Results: All four different grasping tasks could activate the primary somatosensory cortex (SMC), bilateral pre-motor area (PMC), supplementary motor area (SMA), cerebellum, basal ganglia (BG), the contralateral posterior parietal cortex (PPC), etc. With the increase of feedback-dependent BOLD signal, both the size and the intensity decreased in S1, PPC, PMC and cerebellum, while the activation of BG was opposite. The intensity of the active area in SMA swelled while the extent decreased, and no significant difference was found in the M1. Conclusion: Visual stimuli can influence force output significantly and different visual feedback gains may recruit different cortex function areas to execute different motor tasks. PPC, PMC, cerebellum and BG participate in regulating the power of the hand grasp with different gains.
T. P. Taporoski, N.E. Duarte, S. Pompéia, A. Sterr, L.M. Gómez, R.O. Alvim, A.R.V.R. Horimoto, J.E. Krieger, H. Vallada, A.C. Pereira, M. von Schantz, A.B. Negrão (2019)Heritability of semantic verbal fluency task using time-interval analysis, In: PLOS ONE14(6)e0217814pp. 1-13 Public Library of Science
Individual variability in word generation is a product of genetic and environmental influences. The genetic effects on semantic verbal fluency were estimated in 1,735 participants from the Brazilian Baependi Heart Study. The numbers of exemplars produced in 60 s were broken down into time quartiles because of the involvement of different cognitive processes — predominantly automatic at the beginning, controlled/executive at the end. Heritability in the unadjusted model for the 60-s measure was 0.32. The best-fit model contained age, sex, years of schooling, and time of day as covariates, giving a heritability of 0.21. Schooling had the highest moderating effect. The highest heritability (0.17) was observed in the first quartile, decreasing to 0.09, 0.12, and 0.0003 in the following ones. Heritability for average production starting point (intercept) was 0.18, indicating genetic influences for automatic cognitive processes. Production decay (slope), indicative of controlled processes, was not significant. The genetic influence on different quartiles of the semantic verbal fluency test could potentially be exploited in clinical practice and genome-wide association studies.
S Jehoel, PT Sowden, S Ungar, A Sterr (2009)Tactile elevation perception in blind and sighted participants and its implications for tactile map creation., In: Human Factors51(2)pp. 208-223 SAGE journals
To determine the optimal elevation of tactile map symbols. Background: Tactile perception research predicts that symbol elevation (vertical height) and texture on tactile maps could influence their readability. However, while research has shown that elevation influences detection and discrimination thresholds for single tactile stimuli, and that the physiological response of fingertip receptors varies with texture, little is known about the influence of these parameters on the identification of stimuli in the context of multiple symbols as found on tactile maps. Method: Sighted and visually impaired participants performed tactile symbol identification tasks. In Experiment 1, we measured the effect of elevation on identification accuracy. In Experiment 2, we measured the effect of elevation and symbol texture on identification speed. Results: Symbol elevation influenced both speed and accuracy of identification with thresholds being higher than found in work on detection and discrimination but lower than on existing tactile maps. Further, as predicted from existing knowledge of tactile perception, rough features were identified more quickly than smooth ones. Finally, visually impaired participants performed better than sighted ones. Conclusion: The symbol elevations necessary for identification (0.040 to 0.080 mm) are considerably lower than would be expected on the basis of existing tactile maps (generally 0.5 mm or higher) and design guidelines (0.4 mm). Application: Tactile map production costs could be reduced and map durability increased by reducing symbol elevation. Further, legibility of maps could be improved by using rough features, which are read more easily, and smaller symbols, which reduces crowding of graphics.
DP Szameitat, K Alter, AJ Szameitat, D Wildgruber, A Sterr, CJ Darwin (2009)Acoustic profiles of distinct emotional expressions in laughter., In: J Acoust Soc Am126(1)pp. 354-366
Although listeners are able to decode the underlying emotions embedded in acoustical laughter sounds, little is known about the acoustical cues that differentiate between the emotions. This study investigated the acoustical correlates of laughter expressing four different emotions: joy, tickling, taunting, and schadenfreude. Analysis of 43 acoustic parameters showed that the four emotions could be accurately discriminated on the basis of a small parameter set. Vowel quality contributed only minimally to emotional differentiation whereas prosodic parameters were more effective. Emotions are expressed by similar prosodic parameters in both laughter and speech.
AM Sterr, A Bastos Conforto (2012)Plasticity of Adult Sensorimotor System in Severe Brain Infarcts: Challenges and Opportunities, In: Neural Plasticitypp. ?-? Hindawi Publishing Corporation
Functional reorganization forms the critical mechanism for the recovery of function after brain damage. These processes are driven by inherent changes within the central nervous system (CNS) triggered by the insult and further depend on the neural input the recovering system is processing. Therefore these processes interact with not only the interventions a patient receives, but also the activities and behaviors a patient engages in. In recent years, a wide range of research programs has addressed the association between functional reorganization and the spontaneous and treatment-induced recovery. The bulk of this work has focused on upper-limb and hand function, and today there are new treatments available that capitalize on the neuroplasticity of the brain. However, this is only true for patients with mild to moderated impairments; for those with very limited hand function, the basic understanding is much poorer and directly translates into limited treatment opportunities for these patients. The present paper aims to highlight the knowledge gap on severe stroke with a brief summary of the literature followed by a discussion of the challenges involved in the study and treatment of severe stroke and poor long-term outcome.
T Minarik, P Sauseng, L Dunne, B Berger, A Sterr (2015)Effects of anodal transcranial direct current stimulation on visually guided learning of grip force control., In: Biology (Basel)4(1)pp. 173-186
Anodal transcranial Direct Current Stimulation (tDCS) has been shown to be an effective non-invasive brain stimulation method for improving cognitive and motor functioning in patients with neurological deficits. tDCS over motor cortex (M1), for instance, facilitates motor learning in stroke patients. However, the literature on anodal tDCS effects on motor learning in healthy participants is inconclusive, and the effects of tDCS on visuo-motor integration are not well understood. In the present study we examined whether tDCS over the contralateral motor cortex enhances learning of grip-force output in a visually guided feedback task in young and neurologically healthy volunteers. Twenty minutes of 1 mA anodal tDCS were applied over the primary motor cortex (M1) contralateral to the dominant (right) hand, during the first half of a 40 min power-grip task. This task required the control of a visual signal by modulating the strength of the power-grip for six seconds per trial. Each participant completed a two-session sham-controlled crossover protocol. The stimulation conditions were counterbalanced across participants and the sessions were one week apart. Performance measures comprised time-on-target and target-deviation, and were calculated for the periods of stimulation (or sham) and during the afterphase respectively. Statistical analyses revealed significant performance improvements over the stimulation and the afterphase, but this learning effect was not modulated by tDCS condition. This suggests that the form of visuomotor learning taking place in the present task was not sensitive to neurostimulation. These null effects, together with similar reports for other types of motor tasks, lead to the proposition that tDCS facilitation of motor learning might be restricted to cases or situations where the motor system is challenged, such as motor deficits, advanced age, or very high task demand.
M Neumann, D Claros-Salinas, R Gütler, C Dettmers, A Sterr, R Ulrich (2014)Modulation of alertness by sustained cognitive demand in MS as surrogate measure of fatigue and fatigability, In: Journal of the Neurological Sciences340(1-2)pp. 178-182
Objective This study used reaction time (RT) as an objective marker of cognitive fatigue and fatigability in patients with multiple sclerosis (MS). Method RT was measured in fifteen healthy controls and in thirty MS patients with cognitive fatigue identified with the Fatigue Scale for Motor and Cognitive Function (FSMC). Secondary fatigue was excluded through the Epworth Sleepiness Scale and the Beck Depression Inventory. RT was measured at rest (t1), following a 2.5 hour test session inducing high cognitive load (t2), and a one hour recovery period (t3). Results At rest mean RT was longer in patients than in controls (391 ms vs 205 ms). After exerting cognitive load (t2), RT in patients increased dramatically but remained unchanged in controls. After the recovery period (t3), RT returned to baseline levels in most patients. Patients further showed a significant correlation between RT and FMSC scores at t1, t2 and t3. Conclusion RT performance is a suitable surrogate marker for assessing fatigue. RT is sensitive to cognitive load and the recovery from cognitive demand. It hence represents an objective index for fatigability which can inform the management and treatment of MS. © 2014 Elsevier B.V. All rights reserved.
The response-priming paradigm is frequently employed to study motor control by means of behavioural as well as psychophysiological methods. In this paradigm, response performance is studied under various preparation conditions, but in all cases participants are generally primed for action. This setting neglects an essential ability of the motor system in everyday situations, i.e. the efficient execution of a movement with and without warning. In this context the present experiment assessed the behavioural effects of a modified response-priming paradigm, in which participants were asked to execute movements when primed for action, and when the prime predicted that no response would be required. Thirty volunteers participated the experiment, which tested whether the insertion of no-response trials would affect the validity effect, and assessed the differences between invalid trials and reactions performed subsequent to no-response primes. The data showed that the validity effect is not modulated by the added no-response condition, which suggests that movement preparation mechanisms can be studied with this particular task. In addition, responses in invalid trials were substantially different from responses executed after no-response primes. These results are interpreted in relation to psychophysiological evidence on advance movement preparation. It is proposed that the performance differences between response- and no-response priming conditions may be due to different preactivations of motor regions evoked by the prime stimuli, a hypothesis to be addressed with psychophysiological measures in the future. (c) 2005 Elsevier B.V. All rights reserved.
A Sterr, T Elbert, I Berthold, S Kolbel, B Rockstroh, E Taub (2002)Longer versus shorter daily constraint-induced movement therapy of chronic hemiparesis: An exploratory study, In: Archives of Physical Medicine and Rehabilitation83(10)pp. 1374-1377
Objective: To evaluate and compare the effects of 3-hour versus 6-hour daily training sessions in constraint-induced movement therapy (CIMT). Design: Intervention study, 2-group randomized trial; baseline, pretreatment, and posttreatment measures; 1-month follow-up (weekly measures). Setting: University department of psychology in Germany. Participants: A convenience sample of 15 adults with chronic hemiparesis (13 stroke, 2 traumatic brain injury). Intervention: CIMT (14 consecutive days; constraint of unaffected hand for a target of 90% of waking hours) with either 6 hours (6h/d group, n=7) or 3 hours (3h/d group, n=8) of shaping training with the affected hand per day. Main Outcome Measures: The Motor Activity Log and Wolf Motor Function Test. Results: Significant improvements in motor function in the laboratory and increased use of the affected hand in the real-world environment were found in both groups. The beneficial effects were significantly greater in the 6h/d group than in the 3h/d group. Conclusion: The 3-hour CIMT training schedule significantly improved motor function in chronic hemiparesis, but it was less effective than the 6-hour training schedule.
A Sterr, T Elbert, B Rockstroh (2002)Functional reorganization of the human cerebral cortex and its perceptual concommitants, In: Perceptual Learningpp. 125-144 MIT Press
L Krone, L Frase, H Piosczyk, P Selhausen, S Zittel, F Jahn, M Kuhn, B Feige, F Mainberger, S Klöppel, D Riemann, K Spiegelhalder, C Baglioni, Annette Sterr, C Nissen (2016)Top-down control of arousal and sleep: Fundamentals and clinical implications., In: Sleep medicine reviews Elsevier
Mammalian sleep emerges from attenuated activity in the ascending reticular arousal system (ARAS), the main arousal network of the brain. This system originates in the brainstem and activates the thalamus and cortex during wakefulness via a well-characterized 'bottom-up' pathway. Recent studies propose that a less investigated cortico-thalamic 'top-down' pathway also regulates sleep. The present work integrates the current evidence on sleep regulation with a focus on the 'top-down' pathway and explores the potential to translate this information into clinically relevant interventions. Specifically, we elaborate the concept that arousal and sleep continuity in humans can be modulated by non-invasive brain stimulation (NIBS) techniques that increase or decrease cortical excitability. Based on preclinical studies, the modulatory effects of the stimulation are thought to extend to subcortical arousal networks. Further exploration of the 'top-down' regulation of sleep and its modulation through non-invasive brain stimulation techniques may contribute to the development of novel treatments for clinical conditions of disrupted arousal and sleep, which are among the major health problems worldwide.
Descriptors: glucose, LRP, flanker task Behavioural studies suggest that elevated blood glucose concentrations accelerate response times in complex tasks (Owens and Benton, 2004, Neuropsychobiology). With the present study we aimed to explore the mechanisms subserving elevated blood glucose effects (7 mmol/litre versus fasting levels of 5 mmol/litre) by studying EEG-derived indices of sensorimotor processing. More specifically, the Eriksen flanker task was used to examine glucose-dependent modulations of the P300, the stimulus lateralized readiness potentials (LRPs), and response-locked LRP, to see whether enhanced blood glucose levels affect stimulus evaluation, response planning, and response selection respectively. 10 participants took part in a within-participant double-blind 2-session experiment where either glucose (25 g) or placebo drinks were administered. Initial data suggests slower reaction times, higher error rates and delayed stimulus-locked LRP onset in incongruent compared to congruent and neutral trials. With placebo administration error rates were increased for the non-dominant hand but not the dominant hand; no effects were found for the EEG parameters. This suggests that hyperglycaemia does not affect senorimotor processing in the flanker task. However, the placebo-related increase in error rates together with the findings of (Donohoe and Benton, 2000) support the proposition that beneficial effects of increased blood glucose levels on cognition might only occur when cognitive demands are high.
AJ Szameitat, J Rummel, DP Szameltat, A Sterr (2009)Behavioral and emotional consequences of brief delays in human-computer interaction, In: INTERNATIONAL JOURNAL OF HUMAN-COMPUTER STUDIES67(7)pp. 561-570 ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
Descriptors: motor preparation, hemiparesis, CNV Movement preparation in patients with left hand hemiparesis (n 5 26) was investigated using a response priming paradigm, and in addition compared to age-matched controls (n 5 26). In this experiment, trials with valid, neutral and no response cues were presented 1300 ms before the imperative stimulus. Behavioral results showed validity effects for the control and the patient group’s affected and unaffected hand. In addition, patients responded slower with both the affected and the unaffected hand compared to the control group. Analysis of CNV amplitude within the patient group revealed validity effects over the contralateral left hemisphere for the unaffected hand. Interestingly, similar validity effects where found for both hemispheres for the affected hand. This additional usage of the ipsilateral left hemisphere might reflect a greater effort required for movement preparation. A comparison between conditions of patient and control groups showed reduced CNV amplitude over central and centro-parietal right hemisphere for validly prepared trials of the unaffected hand compared to the control group’s right hand. This might suggest a reduced usage of the lesioned ipsilateral cortex side possibly reflecting reduced innervation after the acute phase of the stroke. The competition for resources in the left hemisphere between the affected and unaffected hand and the reduced usage of the right ipsilateral hemisphere for the unaffected hand might explain why patients are generally slower than controls in the task.
S Shen, AJ Szameitat, A Sterr (2008)Detection of infarct lesions from single MRI modality using inconsistency between voxel intensity and spatial location - A 3-D automatic approach, In: Ieee Transactions on Information Technology in Biomedicine12(4)pp. 532-540 Institute of Electrical and Electronics Engineers
Detection of infarct lesions using traditional segmentation methods is always I problematic due to intensity similarity between lesions and normal tissues, so that multispectral MRI modalities were often employed for this purpose. However, the high costs of MRI scan and the severity of patient conditions restrict the collection of multiple images. Therefore, in this paper, a new 3-D automatic lesion detection approach was proposed, which required only a single type of anatomical MRI scan. It was developed on a theory that, when lesions were present, the voxel-intensity-based segmentation and the spatial-location-based tissue distribution should be inconsistent in the regions of lesions. The degree of this inconsistency was calculated, which indicated the likelihood of tissue abnormality. Lesions were identified when the inconsistency exceeded a defined threshold. In this approach, the intensity-based segmentation was implemented by the conventional fuzzy c-mean (FCM) algorithm, while the spatial location of tissues was provided by prior tissue probability maps. The use of simulated MRI lesions allowed us to quantitatively evaluate the performance of the proposed method, as the size and location of lesions were pre-specified. The results showed that our method effectively detected lesions with 40-80% signal reduction compared to normal tissues (similarity index > 0.7). The capability of the proposed method in practice was also demonstrated on real infarct lesions from 15 stroke patients, where the lesions detected were in broad agreement with true lesions. Furthermore, a comparison to a statistical segmentation approach presented in the literature suggested that our 3-D lesion detection approach was more reliable. Future work will focus on adapting the current method to multiple sclerosis lesion detection.
A Sterr (2007)Neuroplasticity, In: Handbook of Neurophysiology Springer Verlag
A Sterr, D Schmalohr, S Kolbel, S Freivogel (2001)Functional reorganization of motor areas following forced-use rehabilitation training in hemiparetic patients: A TMS study, In: Biomedical Engineering46pp. 102-108
DP Szameitat, B Kreifelts, K Alter, AJ Szameitat, A Sterr, W Grodd, D Wildgruber (2010)It is not always tickling: distinct cerebral responses during perception of different laughter types., In: Neuroimage53(4)pp. 1264-1271
Laughter is highly relevant for social interaction in human beings and non-human primates. In humans as well as in non-human primates laughter can be induced by tickling. Human laughter, however, has further diversified and encompasses emotional laughter types with various communicative functions, e.g. joyful and taunting laughter. Here, it was evaluated if this evolutionary diversification of ecological functions is associated with distinct cerebral responses underlying laughter perception. Functional MRI revealed a double-dissociation of cerebral responses during perception of tickling laughter and emotional laughter (joy and taunt) with higher activations in the anterior rostral medial frontal cortex (arMFC) when emotional laughter was perceived, and stronger responses in the right superior temporal gyrus (STG) during appreciation of tickling laughter. Enhanced activation of the arMFC for emotional laughter presumably reflects increasing demands on social cognition processes arising from the greater social salience of these laughter types. Activation increase in the STG for tickling laughter may be linked to the higher acoustic complexity of this laughter type. The observed dissociation of cerebral responses for emotional laughter and tickling laughter was independent of task-directed focusing of attention. These findings support the postulated diversification of human laughter in the course of evolution from an unequivocal play signal to laughter with distinct emotional contents subserving complex social functions.
Erkan Alkan, T P Taporoski, A Sterr, M von Schantz, H Vallada, J E Krieger, A C Pereira, R Alvim, A R V R Horimoto, S Pompéia, A B Negrão, Simon Evans (2019)Metabolic syndrome alters relationships between cardiometabolic variables, cognition and white matter hyperintensity load, In: Scientific Reports94356 Nature Publishing Group
Cardiometabolic risk factors influence white matter hyperintensity (WMH) development: in metabolic syndrome (MetS), higher WMH load is often reported but the relationships between specific cardiometabolic variables, WMH load and cognitive performance are uncertain. We investigated these in a Brazilian sample (aged 50-85) with (N=61) and without (N=103) MetS. Stepwise regression models identified effects of cardiometabolic and demographic variables on WMH load (from FLAIR MRI) and verbal recall performance. WMH volume was greater in MetS, but verbal recall performance was not impaired. Age showed the strongest relationship with WMH load. Across all participants, systolic blood pressure (SBP) and fasting blood glucose were also contributors, and WMH volume was negatively associated with verbal recall performance. In non-MetS, higher HbA1c, SBP, and number of MetS components were linked to poorer recall performance while higher triglyceride levels appeared to be protective. In MetS only, these relationships were absent but education exerted a strongly protective effect on recall performance. Thus, results support MetS as a construct: the clustering of cardiometabolic variables in MetS alters their individual relationships with cognition; instead, MetS is characterised by a greater reliance on cognitive reserve mechanisms. In non-MetS, strategies to control HbA1c and SBP should be prioritised as these have the largest impact on cognition.
Background: Mild traumatic brain injury (MTBI) can sometimes lead to persistent postconcussion symptoms. One well accepted hypothesis claims that chronic PCS has a neural origin, and is related to neurobehavioral deficits. But the evidence is not conclusive. In the attempt to characterise chronic MTBI consequences, the present experiment used a group comparison design, which contrasted persons (a) with MTBI and PCS, (b) MTBI without PCS, and (c) matched controls. We predicted that participants who have experienced MTBI but show no signs of PCS would perform similar to controls. At the same time, a subgroup of MTBI participants would show PCS symptoms and only these volunteers would have poorer cognitive performance. Thereby, the performance deficits should be most noticeable in participants with highest PCS severity. Method: 38 patients with a single MTBI that had occurred at least 12 month prior to testing, and 38 matched controls, participated in the experiment. A combination of questionnaires and neuropsychological test batteries were used to assess the extent of PCS and related deficits in neurobehavioral performance. Results: 11 out of 38 MTBI participants (29%) were found to suffer from PCS. This subgroup of MTBI patients performed poorly on neuropsychological test batteries. Thereby, a correlation was found between PCS symptom severity and test performance suggesting that participants with more pronounced PCS symptoms performed worse in cognitive tasks. In contrast, MTBI patients with no PCS showed performed similar to matched control. We further found that loss of consciousness, a key criterion for PCS diagnosis, was not predictive of sustained PCS. Conclusion: The results support the idea that MTBI can have sustained consequences, and that the subjectively experienced symptoms and difficulties in everyday situations are related to objectively measurable parameters in neurocognitive function.
N Landmann, M Kuhn, J-G Maier, K Spiegelhalder, C Baglioni, L Frase, D Riemann, A Sterr, C Nissen (2015)REM sleep and memory reorganization: Potential relevance for psychiatry and psychotherapy, In: NEUROBIOLOGY OF LEARNING AND MEMORY122pp. 28-40 ACADEMIC PRESS INC ELSEVIER SCIENCE
C Kranczioch, C Zich, I Schierholz, A Sterr (2013)Mobile EEG and its potential to promote the theory and application of imagery-based motor rehabilitation., In: Int J Psychophysiol
Studying the brain in its natural state remains a major challenge for neuroscience. Solving this challenge would not only enable the refinement of cognitive theory, but also provide a better understanding of cognitive function in the type of complex and unpredictable situations that constitute daily life, and which are often disturbed in clinical populations. With mobile EEG, researchers now have access to a tool that can help address these issues. In this paper we present an overview of technical advancements in mobile EEG systems and associated analysis tools, and explore the benefits of this new technology. Using the example of motor imagery (MI) we will examine the translational potential of MI-based neurofeedback training for neurological rehabilitation and applied research.
A Sterr, S Shen, C Kranczioch, AJ Szameitat, W Hou, B Sorger (2009)fMRI effects of task demand and feedback accuracy on grip force tracking., In: Neurosci Lett457(2)pp. 61-65
Previous research showed that force control in a visually guided continuous tracking task is influenced by feedback accuracy and force-varying rate. More specifically it was found that higher feedback accuracy and greater force-varying rate led to decreased task performance. Here we studied the neural signature of these effects using functional MRI. We hypothesised that performance costs were due to increased task demand and reflected by increased activations in the visuomotor network. Using the fMRI-BOLD response as an indirect measure of enhanced brain activity we found that the task induced activations in the visuomotor network. The different task conditions thereby modulated the BOLD response such that those conditions with poorest performance showed highest activation levels and vice versa. This indicates a parametric modulation of the BOLD response according to task difficulty and force production. The effects point towards the interdependent and parallel control of visual feedback information and force output rate, which is probably achieved through a joint neural network.
A Sterr, S Shen, A Zaman, N Roberts, A Szameitat (2007)Activation of SI is modulated by attention: a random effects fMRI study using mechanical stimuli, In: Neuroreport18(6)pp. 607-611
Animal experiments on tactile attention suggest a modulation of sensory processing on the level of sensory representations but correspondent neuroimaging data in humans is inconclusive. The present experiment used mechanical stimuli to study tactile processing while varying the focus of attention. Activations were contrasted between attend and ignore conditions, both of which employed identical stimulation characteristics and an active task. Random effects analysis revealed significant attention effects in area SI (primary somatosensory cortex) in that the blood oxygenation level-dependent response was greater for attended than for ignored stimuli. Modulations were further found in the secondary somatosensory cortex and the middle temporal gyrus. These findings suggest that stimulus processing at the level of primary representations in area SI is modulated by attention.
AJ Szameitat, J Lepsien, DY von Cramon, A Sterr, T Schubert (2006)Task-order coordination in dual-task performance and the lateral prefrontal cortex: an event-related fMRI study, In: Psychological Research-Psychologische Forschung70(6)pp. 541-552
A crucial demand in dual tasks suffering from a capacity limited processing mechanism is task-order scheduling, i.e. the control of the order in which the two component tasks are processed by this limited processing mechanism. The present study aims to test whether the lateral prefrontal cortex (LPFC) is associated with this demand. For this, 15 participants performed a psychological refractory paradigm (PRP) type dual task in an event-related functional magnetic resonance (fMRI) experiment. In detail, two choice reaction tasks, a visual (response with right hand) and an auditory (response with left hand), were presented with a temporal offset of 200 ms, while the participants were required to respond to the tasks in the order of their presentation. Importantly, the presentation order of the tasks changed randomly. Based on previous evidence, we argue that trials in which the present task order changed as compared to the previous trial (different-order trials) impose higher demands on task coordination than same-order trials do. The analyses showed that cortical areas along the posterior part of the left inferior frontal sulcus as well as the right posterior middle frontal gyrus were more strongly activated in different-order than in same-order trials, thus supporting the conclusion that one function of the LPFC for dual-task performance is the temporal coordination of two tasks. Furthermore, it is discussed that the present findings favour the active scheduling over the passive queuing hypothesis of dual-task processing.
S Shen, AJ Szameitat, Annette Sterr (2007)VBM lesion detection depends on the normalization template: a study using simulated atrophy, In: Magnetic Resonance Imaging25(10)pp. 1385-1396 Elsevier
Structural neuroimaging studies are of great interest for neuroscientists, which are reflected in the rising number of papers using voxel-based morphometry (VBM). One major step in VBM is the transformation of images to a standard template, a spatial normalization necessary to ensure that homologous regions are compared while interindividual characteristics are maintained. Templates can be created in different ways, and this may affect the likelihood that differences in gray/white matter density between groups are detected. However, studies investigating the interaction of normalization template and VBM accuracy are sparse. Existing work is based on patient control group comparisons, and the emerging results are inconclusive. The present paper therefore used simulated atrophy in a simplified one-lesion model to systematically study template effects of VBM analyses implemented in SPM. This allowed us to characterize template-specific biases in reference to a set of prespecified parameters of anatomical difference. The data suggest that the likelihood of correctly detecting the prespecified lesion is modulated by the normalization template. Thereby, the relationship between template-related VBM accuracy and specific group/study characteristics is complex, and there does not appear to be one `best template.' Our data show that template effects are critical and clearly suggest that the choice of template needs careful consideration in relation to the specific research question and study constraints. (c) 2007 Elsevier Inc. All rights reserved.
The present study explores the link between brain metabolites, PCS symptoms and cognitive ability in participants who have experienced an mTBI. Lactate has been previously been shown to be elevated in acute mTBI (Son, Park et al. 2000), however, 2 month post-incidence lactate levels had returned to normal. The present study suggests that PCS symptoms as well as metabolite abnormalities may persist. More specifically the data provides initial evidence for a link between the elevation of lactate and with severity of long-term PCS following mTBI. Poster presented in Session: Other Spectroscopy Methodology Proceedings of the International Society for Magnetic Resonance in Medicine, 18 (2010); p. 937. ISSN 1545-4428. Available at: http://www.ismrm.org/meetings-workshops/2010-annual-meeting-3/
The application of automatic segmentation methods in lesion detection is desirable. However, such methods are restricted by intensity similarities between lesioned and healthy brain tissue. Using multi-spectral magnetic resonance imaging (MRI) modalities may overcome this problem but it is not always practicable. In this article, a lesion detection approach requiring a single MRI modality is presented, which is an improved method based on a recent publication. This new method assumes that a low similarity should be found in the regions of lesions when the likeness between an intensity based fuzzy segmentation and a location based tissue probabilities is measured. The usage of a normalized similarity measurement enables the current method to fine-tune the threshold for lesion detection, thus maximizing the possibility of reaching high detection accuracy. Importantly, an extra cleaning step is included in the current approach which removes enlarged ventricles from detected lesions. The performance investigation using simulated lesions demonstrated that not only the majority of lesions were well detected but also normal tissues were identified effectively. Tests on images acquired in stroke patients further confirmed the strength of the method in lesion detection. When compared with the previous version, the current approach showed a higher sensitivity in detecting small lesions and had less false positives around the ventricle and the edge of the brain.
Basic neuroscience research on brain plasticity, motor learning and recovery has stimulated new concepts in neurological rehabilitation. Combined with the development of set methodological standards in clinical outcome research, these findings have led to a double-paradigm shift in motor rehabilitation: (a) the move towards evidence-based procedures for the assessment of clinical outcome & the employment of disablement models to anchor outcome parameters, and (b) the introduction of practice-based concepts that are derived from testable models that specify treatment mechanisms. In this context, constraint-induced movement therapy (CIT) has played a catalytic role in taking motor rehabilitation forward into the scientific arena. As a theoretically founded and hypothesis-driven intervention, CIT research focuses on two main issues. The first issue is the assessment of long-term clinical benefits in an increasing range of patient groups, and the second issue is the investigation of neuronal and behavioural treatment mechanisms and their interactive contribution to treatment success. These studies are mainly conducted in the research environment and will eventually lead to increased treatment benefits for patients in standard health care. However, gradual but presumably more immediate benefits for patients may be achieved by introducing and testing derivates of the CIT concept that are more compatible with current clinical practice. Here, we summarize the theoretical and empirical issues related to the translation of research-based CIT work into the clinical context of standard health care.
Z-X Mou, W-S Hou, X-L Zheng, X-Y Wu, S Shen, AM Sterr, C-L Peng (2008)An fMR1 based pilot study on the nerve excitability for force-regulating speed, In: Chinese Journal of Medical Imaging Technology24(3)pp. 341-345
Jonathan G. Maier, Hannah Piosczyk, Johannes Holz, Nina Landmann, Christoph Deschler, Lukas Frase, Marion Kuhn, Stefan Klöppel, Kai Spiegelhalder, Annette Sterr, Dieter Riemann, Bernd Feige, Ulrich Voderholzer, Christoph Nissen (2017)Brief periods of NREM sleep do not promote early offline gains but subsequent on-task performance in motor skill learning, In: Neurobiology of Learning and Memory145pp. 18-27 Elsevier
Sleep modulates motor learning, but its detailed impact on performance curves remains to be fully characterized. This study aimed to further determine the impact of brief daytime periods of NREM sleep on ‘offline’ (task discontinuation after initial training) and ‘on-task’ (performance within the test session) changes in motor skill performance (finger tapping task). In a mixed design (combined parallel group and repeated measures) sleep laboratory study (n = 17 ‘active’ wake vs. sleep, n = 19 ‘passive’ wake vs. sleep), performance curves were assessed prior to and after a 90 min period containing either sleep, active or passive wakefulness. We observed a highly significant, but state- (that is, sleep/wake)-independent early offline gain and improved on-task performance after sleep in comparison to wakefulness. Exploratory curve fitting suggested that the observed sleep effect most likely emerged from an interaction of training-induced improvement and detrimental ‘time-on-task’ processes, such as fatigue. Our results indicate that brief periods of NREM sleep do not promote early offline gains but subsequent on-task performance in motor skill learning.
Constraint-induced movement therapy (CIT) is a highly specialized form of rehabilitation for those with upper-limb paresis. The intervention uses a combination of motor training elements and psychological concepts to facilitate increased use of the affected limb as well as improved movement quality and control. Importantly, CIT is designed to achieve real-world improvements through behavioral measures that facilitate the incorporation of regained abilities into the person's spontaneous behavior. © Springer Science + Business Media, LLC 2009.
AJ Szameitat, S Shen, A Bastos Conforto, A Sterr (2012)Cortical activation during executed, imagined, observed, and passive wrist movements in healthy volunteers and stroke patients, In: Neuroimage62(1)pp. 266-280 Elsevier
Motor imagery, passive movement, and movement observation have been suggested to activate the sensorimotor system without overt movement. The present study investigated these three covert movement modes together with overt movement in a within-subject design to allow for a fine-grained comparison of their abilities in activating the sensorimotor system, i.e. premotor, primary motor, and somatosensory cortices. For this, 21 healthy volunteers underwent functional magnetic resonance imaging (fMRI). In addition we explored the abilities of the different covert movement modes in activating the sensorimotor system in a pilot study of 5 stroke patients suffering from chronic severe hemiparesis. Results demonstrated that while all covert movement modes activated sensorimotor areas, there were profound differences between modes and between healthy volunteers and patients. In healthy volunteers, the pattern of neural activation in overt execution was best resembled by passive movement, followed by motor imagery, and lastly by movement observation. In patients, attempted overt execution was best resembled by motor imagery, followed by passive movement, and lastly by movement observation. Our results indicate that for severely hemiparetic stroke patients motor imagery may be the preferred way to activate the sensorimotor system without overt behavior. In addition, the clear differences between the covert movement modes point to the need for within-subject comparisons.
Diana P. Szameitat, Benjamin Kreifelts, Kai Alter, AndréJ. Szameitat, Annette Sterr, Grodd Wolfgang, Dirk Wildgruber (2010)It is not always tickling: Distinct cerebral responses during perception of different laughter types, In: NeuroImage53pp. 1264-1271 Elsevier
Laughter is highly relevant for social interaction in human beings and non-human primates. In humans as well as in non-human primates laughter can be induced by tickling. Human laughter, however, has further diversified and encompasses emotional laughter types with various communicative functions, e.g. joyful and taunting laughter. Here, it was evaluated if this evolutionary diversification of ecological functions is associated with distinct cerebral responses underlying laughter perception. Functional MRI revealed a double-dissociation of cerebral responses during perception of tickling laughter and emotional laughter (joy and taunt) with higher activations in the anterior rostral medial frontal cortex (arMFC) when emotional laughter was perceived, and stronger responses in the right superior temporal gyrus (STG) during appreciation of tickling laughter. Enhanced activation of the arMFC for emotional laughter presumably reflects increasing demands on social cognition processes arising from the greater social salience of these laughter types. Activation increase in the STG for tickling laughter may be linked to the higher acoustic complexity of this laughter type. The observed dissociation of cerebral responses for emotional laughter and tickling laughter was independent of task-directed focusing of attention. These findings support the postulated diversification of human laughter in the course of evolution from an unequivocal play signal to laughter with distinct emotional contents subserving complex social functions
N Landmann, M Kuhn, H Piosczyk, B Feige, C Baglioni, K Spiegelhalder, L Frase, D Riemann, A Sterr, C Nissen (2014)The reorganisation of memory during sleep, In: SLEEP MEDICINE REVIEWS18(6)pp. 531-541 W B SAUNDERS CO LTD
Annette Sterr, Shan Shen, Cornelia Kranczioch, Andre J. Szameita, Wengshen Hou, Bettina Sorger (2009)fMRI effects of task demand and feedback accuracy on grip force tracking, In: Neuroscience Letters457pp. 61-65 Elsevier
Previous research showed that force control in a visually guided continuous tracking task is influenced by feedback accuracy and force-varying rate. More specifically it was found that higher feedback accuracy and greater force-varying rate led to decreased task performance. Here we studied the neural signature of these effects using functional MRI. We hypothesised that performance costs were due to increased task demand and reflected by increased activations in the visuomotor network. Using the fMRI-BOLD response as an indirect measure of enhanced brain activity we found that the task induced activations in the visuomotor network. The different task conditions thereby modulated the BOLD response such that those conditions with poorest performance showed highest activation levels and vice versa. This indicates a parametric modulation of the BOLD response according to task difficulty and force production. The effects point towards the interdependent and parallel control of visual feedback information and force output rate, which is probably achieved through a joint neural network.
Pascal Halder, Annette Sterr, Silvia Brem, Kerstin Bucher, Spyros Kollias, Daniel Brandeis (2005)Electrophysiological evidence for cortical plasticity with movement repetition, In: European Journal of Neurosciencepp. 1-7
Keywords: evoked potentials, human, learning, motor cortex, neuronal plasticity The role of movement repetition and practice has been extensively studied as an aspect of motor skill learning but has rarely been investigated in its own right. As practice is considered a prerequisite for motor learning we expected that even the repetitive execution of a simple movement would rapidly induce changes in neural activations without changing performance. We used 64-channel eventrelated potential mapping to investigate these effects of movement repetition on corresponding brain activity in humans. Ten healthy right-handed young adults performed a power grip task under visual force control to ensure constant behaviour during the experimental session. The session consisted of two parts intersected by a break. For analysis each part was subdivided into two runs to control for potential attention or fatigue effects, which would be expected to disappear during the break. Microstate analysis revealed that distinct topographies and source configurations during movement preparation, movement execution and feedback integration are responsive to repetition. The observed patterns of changes differed for the three microstates, suggesting that different, repetition-sensitive neural mechanisms are involved. Moreover, this study clearly confirms that movement repetition, in the absence of skill learning, is capable of inducing changes in neural networks.
M Kuhn, E Wolf, JG Maier, F Mainberger, B Feige, H Schmid, J Buerklin, S Maywald, V Mall, NH Jung, J Reis, K Spiegelhalder, S Kloeppel, A Sterr, A Eckert, D Riemann, C Normann, C Nissen (2016)Sleep recalibrates homeostatic and associative synaptic plasticity in the human cortex, In: Nature Communications712455 Nature Publishing Group
Sleep is ubiquitous in animals and humans, but its function remains to be further determined. The synaptic homeostasis hypothesis of sleep–wake regulation proposes a homeostatic increase in net synaptic strength and cortical excitability along with decreased inducibility of associative synaptic long-term potentiation (LTP) due to saturation after sleep deprivation. Here we use electrophysiological, behavioural and molecular indices to non-invasively study net synaptic strength and LTP-like plasticity in humans after sleep and sleep deprivation. We demonstrate indices of increased net synaptic strength (TMS intensity to elicit a predefined amplitude of motor-evoked potential and EEG theta activity) and decreased LTP-like plasticity (paired associative stimulation induced change in motor-evoked potential and memory formation) after sleep deprivation. Changes in plasma BDNF are identified as a potential mechanism. Our study indicates that sleep recalibrates homeostatic and associative synaptic plasticity, believed to be the neural basis for adaptive behaviour, in humans.
Philip Dean, G Arikan, Bertram Opitz, Annette Sterr (2017)Potential for use of creatine supplementation following mild traumatic brain injury, In: Concussion2(2) Future Medicine
There is significant overlap between the neuropathology of mild traumatic brain injury (mTBI) and the cellular role of creatine, as well as evidence of neural creatine alterations after mTBI. Creatine supplementation has not been researched in mTBI, but shows some potential as a neuroprotective when administered prior to or after TBI. Consistent with creatine’s cellular role, supplementation reduced neuronal damage, protected against the effects of cellular energy crisis and improved cognitive and somatic symptoms. A variety of factors influencing the efficacy of creatine supplementation are highlighted, as well as avenues for future research into the potential of supplementation as an intervention for mTBI. In particular, the slow neural uptake of creatine may mean that greater effects are achieved by pre-emptive supplementation in at-risk groups.
WS Hou, S Shen, A Sterr (2005)An MRI compatible visual force-feedback system for the study of force control mechanics, In: 2005 27th Annual International Conference of the Ieee Engineering in Medicine and Biology Society, Vols 1-7pp. 3687-3690 IEEE
Motor task experiments play an essential role in exploring the brain mechanisms of movement control, and visual force-feedback is an important factor in these motor experiments. In this paper, the authors proposed a visual force-feedback system suitable for neuroscience experiment. With this system, the force output produced by participants can be detected and recorded in real time, while force output was visually displayed as a feedback cue to the participants simultaneously. Furthermore, this force feedback system is MRI compatible, and can be used both in fMRI and ERP experiments. The proposed system has been applied in hand-grip tasks and finger movement experiments, which were designed to explore the relationship between force output and brain activation mode in normal subject and stroke patient. The results demonstrated that various force levels were well detected and visual feedback signals enabled the accomplishment of experiments with both fixed and variable target force levels.
Shan Shen, William Sandham, Malcolm Granat, Annette Sterr (2005)MRI fuzzy segmentation of brain tissue using neighborhood attraction with neural-network optimization, In: IEEE Transactions on Information Technology in Biomedicine9(3)pp. 459-467

Image segmentation is an indispensable process in the visualization of human tissues, particularly during clinical analysis of magnetic resonance (MR) images. Unfortunately, MR images always contain a significant amount of noise caused by operator performance, equipment, and the environment, which can lead to serious inaccuracies with segmentation. A robust segmentation technique based on an extension to the traditional fuzzy c-means (FCM) clustering algorithm is proposed in this paper. A neighborhood attraction, which is dependent on the relative location and features of neighboring pixels, is shown to improve the segmentation performance dramatically. The degree of attraction is optimized by a neural-network model. Simulated and real brain MR images with different noise levels are segmented to demonstrate the superiority of the proposed technique compared to other FCM-based methods. This segmentation method is a key component of an MR image-based classification system for brain tumors, currently being developed.

A Sterr, D O'Neill, PJA Dean, KA Herron (2014)CI therapy is beneficial to patients with chronic low-functioning hemiparesis after stroke, In: Frontiers in Neurology5205pp. 1-10
CI therapy is effective in patients with relatively good levels of residual arm function but its applicability to patients with low-functioning hemiparesis is not entirely clear. In the present study, we examined the feasibility and efficacy of the CI therapy concept in patients with very limited upper arm function prior to treatment, and further tested how the length of daily shaping training and constraining the good arm affects treatment outcome. In a baseline-controlled design, 65 chronic patients were treated with 2weeks of modified CI therapy. Patients were randomly allocated to four treatment groups receiving 90 or 180 min of daily shaping training applied with or without constraint, respectively. Outcome was measured through the Reliable Change Index, which was calculated for parameters of motor function, health, and psychological wellbeing. Follow-up data were collected at 6 and 12 months.Two analyses were conducted, a whole-group analysis across all 65 participants and a sub-group analysis contrasting the four treatment variants. The whole-group analysis showed a significant treatment effect, which was largely sustained after 1 year. The sub-group analysis revealed a mixed picture; while improvements against the baseline period were observed in all four subgroups, 180 min of daily shaping training coupled with the constraint yielded better outcome on the MAL but not the WMFT, while for 90 min of training the level of improvement was similar for those who wore the constraint and those who did not. Together these results suggest that, at least in those patients available for follow-up measures, modified CI therapy induces sustained improvements in motor function in patients with chronic low-functioning hemiparesis. The absence of clear differences between the four treatment variants points to a complex relationship between the length of daily shaping training and the constraint in this patient group, which is likely to be mediated by fatigue and/or compliance with the constraint.
Annette Sterr, Philip Dean (2007)Neural correlates of movement preparation in healthy ageing, In: European Journal of Neuroscience Blackwell Publishing
Motor disorders increase dramatically with age; however, little is known about non-clinical ageing of motor control mechanisms and their respective neural correlates. With the present experiment we aimed to study age effects on advance movement preparation, a key characteristic of motor behaviour that is known to involve premotor and primary motor circuits. The respective brain regions are subject to age-related brain atrophy of grey and white matter, and we therefore hypothesized that motor preparation mechanisms may be altered in older persons.Using a motor priming paradigm, performance data and event-related potentials were recorded in older (68–83 years) and younger (21–25 years) participants. The effect pattern observed for the younger group fully replicated previous findings, showing significant reaction time benefits and greater foreperiod activity for valid trials, as well as lateralized activation over motor regions. In older participants, the validity effect was insignificant, which corresponded to markedly reduced foreperiod amplitudes and the absence of lateralized activity. At the same time, the event-related potential showed a frontocentrally distributed positive component peaking in the P300 latency range after presentation of the prime. The amplitude of this potential was enhanced in elderly compared with young participants.The data suggest that the information processing related to the anticipation and preparation of an upcoming response changes substantially with age. In contrast to younger participants, older participants show no indication of effector-specific activation and recruit frontal areas in anticipation of a response signal. It is therefore not only movement execution that changes with age but also motor cognition. Keywords: ageing, contingent negative variation, electroencephalography, event-related laterality, lateralised readiness potential, movement preparation
Annette Sterr, Susanna Freivogel (2003)Motor-improvement following intensive training in low-functioning chronic hemiparesis, In: Neurology61pp. 842-844
Constraint-induced movement therapy can improve chronic hemiparesis, but this technique has proven difficult to transfer into clinical practice. The authors studied the benefits of a modified regimen designed to be applicable in the clinical environment. Affected arm movements were trained for 90 min/d for 3 weeks using the learning principle “shaping.” The outcome measures indicated a significant increase in performance after the intervention compared with the performance during the 3-week baseline interval.
PJ Dean, JR Sato, G Vieira, A McNamara, A Sterr (2015)Long-term structural changes after mTBI and their relation to post-concussion symptoms., In: Brain Injpp. 1-8
To investigate sustained structural changes in the long-term (>1 year) after mild traumatic brain injury (mTBI) and their relationship to ongoing post-concussion syndrome (PCS).
L Furlan, AB Conforto, LG Cohen, A Sterr (2016)Upper Limb Immobilisation: A Neural Plasticity Model with Relevance to Poststroke Motor Rehabilitation, In: NEURAL PLASTICITYARTN 81762 HINDAWI PUBLISHING CORP
M O'Sullivan, E Glorney, A Sterr, M Oddy, S de Silva Ramos (2013)Traumatic brain injury and violent behaviour in females: a systematic review, In: Aggression and Violent Behavior
Annette Sterr, Lisa Green, Thomas Elbert (2003)Blind Braille readers mislocate tactile stimuli, In: Biological Psychology63pp. 117-127 Elsevier
In a previous experiment, we observed that blind Braille readers produce errors when asked to identify on which finger of one hand a light tactile stimulus had occurred. With the present study, we aimed to specify the characteristics of this perceptual error in blind and sighted participants. The experiment confirmed that blind Braille readers mislocalised tactile stimuli more often than sighted controls, and that the localisation errors occurred significantly more often at the right reading hand than at the non-reading hand. Most importantly, we discovered that the reading fingers showed the smallest error frequency, but the highest rate of stimulus attribution. The dissociation of perceiving and locating tactile stimuli in the blind suggests altered tactile information processing. Neuroplasticity, changes in tactile attention mechanisms as well as the idea that blind persons may employ different strategies for tactile exploration and object localisation are discussed as possible explanations for the results obtained. Keywords: Touch; Tactile perception; Somatosensory; Spatial discrimination
Wensheng Hou, Shan Shen, Andre J Szameitat, Yingtao Jiang, Jun Zheng, Monique van Loon, Annette Sterr A behaviour study of the effects of visual feedback on fluctuating isometric force production with force tracking tasks, In: International Journal of Biomedical Engineering and Technology1(4)pp. 367-381
The primary goal of this study is to explore the impacts of visual feedback gain and the force varying rate on the continuously fluctuating isometric force production. Twelve recruited participants have been instructed to complete the handgrip tasks that require the participant to control his or her grip force level to track a moving target bar which is proportional to the real-time force production. Two visual feedback gain levels and two force varying rates have been tested. The results show that high visual feedback gain and force varying rate will lead to larger errors of force production. Keywords: visual feedback; gain; force production; Fitts’ law.
A. Sterr, S. Freivogel, A. Voss (2002)Exploring a repetitive training regime for upper limb hemiparesis in an in-patient setting: a report on three case studies, In: Brain Injury16(12)pp. 1093-1107 Taylor & Francis
Primary objective: To explore the efficacy of a task-oriented repetitive training protocol (RTx) in chronic hemiparetic patients in an in-patient rehabilitation unit. Research design: Three case studies; ABAB design (AˆRTx; Bˆregular rehabilitation programme; 1 week per phase, respectively) in case P1, pre± post intervention comparison in case P2; repeated measure design in case P3. Methods and procedures: Daily training of task-oriented affected hand movements using shaping procedures developed in Constraint-Induced (CI) Movement Therapy. Patients 1 and 2 were trained daily for 90 minutes over 2 weeks. Patient 3 received 60 minutes of daily training for a period of 4 weeks. Outcome measures were Wolf Motor Function Test (WMFT), Frenchay Arm Test, nine-hole peg test, upper extremity MRC, and grip force. Main outcomes and results: Substantial clinical benefits were achieved in all patients. The subjective observations mirrored significant improvements in the outcome parameters. Conclusion: The affected hand training improves upper limb motor functions in chronic patients. It is a 'practicable’ approach for in-patient rehabilitation units.
Annette Sterr, Thomas Elbert, Irina Berthold, Sabine Köhlbel, Brigitte Rockstroh, Edward Taub (2002)Longer Versus Shorter Daily Constraint-Induced Movement Therapy of Chronic Hemiparesis: An Exploratory Study, In: Archives of Physical Medicine and Rehabilitation83pp. 1374-1377 Elsevier
Objective: To evaluate and compare the effects of 3-hour versus 6-hour daily training sessions in constraint-induced movement therapy (CIMT). Design: Intervention study, 2-group randomized trial; baseline,pretreatment, and posttreatment measures; 1-month follow-up (weekly measures). Setting: University department of psychology in Germany. Participants: A convenience sample of 15 adults with chronic hemiparesis (13 stroke, 2 traumatic brain injury). Intervention: CIMT (14 consecutive days; constraint of unaffected hand for a target of 90% of waking hours) with either 6 hours (6h/d group, n=7) or 3 hours (3h/d group, n=8) of shaping training with the affected hand per day. Main Outcome Measures: The Motor Activity Log and Wolf Motor Function Test. Results: Significant improvements in motor function in the laboratory and increased use of the affected hand in the realworld environment were found in both groups. The beneficial effects were significantly greater in the 6h/d group than in the 3h/d group. Conclusion: The 3-hour CIMT training schedule significantly improved motor function in chronic hemiparesis, but it was less effective than the 6-hour training schedule. Key Words: Arm; Motor activity; Physical therapy; Rehabilitation; Stroke.
S Shen, A Sterr (2013)Is DARTEL-based voxel-based morphometry affected by width of smoothing kernel and group size? A study using simulated atrophy, In: JOURNAL OF MAGNETIC RESONANCE IMAGING37(6)pp. 1468-1475 WILEY-BLACKWELL
People with Obsessive Compulsive Disorder (OCD) have deficits in decision making under ambiguity, also known as probabilistic reward-based learning (RBL). In these tasks participants are not aware about the target probabilities of each option and need to use trial-by-trial feedback to learn these probabilities during the task in order to improve their performance. An open question from the previous literature is why OCD participants present this specific deficit. The review of the limitations of previous RBL studies with OCD patients and the use of a new task paradigm allowed us to explore new directions in this research field. Firstly, previous studies had the following limitations: sometimes they did not control for the use of medication, for the presence of common comorbidities associated with OCD, or for differences between distinct OCD subtypes. In addition, previous tasks usually manipulated several factors at the same time, such as feedback direction (positive vs. negative feedback) and feedback magnitude (e.g. less vs. more positive feedback), for instance. Therefore, it is not possible to know which factor affected the RBL performance in OCD patients. Furthermore, previous studies did not consider the effect of symptom-related feedback on RBL. Secondly, task performance was only measured with accuracy, even though RBL involves the use of previous trials to make predictions for the current decision. Finally, while it is reported that participants do use distinct previous trials to perform these tasks, sequential effects were not previously investigated in OCD patients, neither for random-sequences nor for patterns sequences. Based on this, the presented PhD thesis addressed some of these gaps in the literature. The investigation was restricted to subclinical checkers which is the most common OCD subtype. A binary decision making task was designed that allowed us to separately manipulate feedback direction and feedback magnitude. In addition, the study compared probabilistic RBL performances between checkers and non-checkers for random and pattern sequences. New analyses techniques were employed to investigate the use of previous trial information for the current decision making, e.g. win-shift, lose-shift, and cross-correlations. Studies 2 and 3 examined the effect of feedback direction (positive vs. negative feedback) on decision making in subclinical checkers. Results showed that subclinical checkers were more biased towards exploitation when using negative feedback. Studies 4 and 5 examined the effect of the feedback magnitude for both the positive and the negative feedback direction. Results showed that subclinical checkers were able to change their bias towards exploitation within the positive direction experiments depending on the feedback magnitude of the experiment. They were more biased towards exploitation in the positive task presenting a higher error magnitude. In addition, checkers were always biased towards exploitation within the negative direction experiments, irrespectively of the feedback magnitude. Study 6 examined the effect of the manipulation of feedback magnitude when a symptom related feedback was added as an increment of the negative feedback. Results showed that subclinical checkers were not affected by the presence of the symptom-related feedback and, in terms of feedback magnitude, they continued to present a bias towards exploitation. The findings show that checkers were able to adapt towards exploitation in the positive experiments when higher feedback magnitudes are given. This strategic shift might be related to the higher error magnitude associated with the absence of reward, when the incorrect option was chosen. In contrast, checkers were not able to adapt their exploitation behaviour within the negative experiments when enhancing the feedback magnitude. In this way, this indicates that subclinical checkers present a deficit that bias their responses towards exploitation, when the magnitude associated with the error in the task surpasses a certain value of negative magnitude. This bias could reflect deficits regarding negative prediction errors in OCD or a hyperactivation of brain areas related with exploitation. Both explanations could be linked with a hyperactive dopaminergic system in OCD, so these results could encourage new research about the role of dopamine and prediction errors deficits associated with OCD. Additionally, heightened emotions and reward magnitudes might reduce treatment success because of the enhanced exploitation behaviour, so one crucial aspect of future therapies might be to carefully study the employment of stimuli with such higher error magnitudes.
Transcranial direct current stimulation (tDCS) as a means for enhancing learning and memory has received a lot of attention in recent times. However, its applicability in a wider context has been limited due to lack of replicability across the literature. This may likely stem from inter-individual differences such as age, gender, nutrition, stress, brain morphology and sleep. Sleep in particular may be a source of inter-individual differences in tDCS-effect because of its link to brain plasticity mechanism such as long-term potentiation (LTP). The extent to which sleep may account for inter-individual differences in tDCS outcomes has not been assessed in the literature. Therefore, the central aim of this thesis is to investigate 1) the effect of sleep quality 2) circadian mis- /alignment 3) prior sleep compared to wake on tDCS-enhanced learning. Findings from this thesis suggests that sleep quality does not affect variability in tDCS-effect on cognitive performance, while circadian mis/-alignment and prior wakefulness before task may modulate tDCS-efficacy. In conclusion, data suggests that tDCS-effect is greater in a brain which is in a non-optimal state in terms of circadian misalignment and prolonged wake, and in this context, sleep may be responsible for variabilities in tDCS studies. These findings have implications for researchers and clinicians using tDCS. Further studies are required to fully characterise the findings from this thesis.
Imagined movements (MI) are a complex behaviour, borne of the neural circuitry and cognitions shared with real actions. They have been implemented in many clinical and elite performance programmes, although these programme outcomes are inconsistent. Applying current models of MI to understand these inconsistencies is confounded by an ineffective discrimination between effects of MI on performance and those of simple preparation for action (MP). Critically, empirical comparisons have yet to be drawn between MI and MP. This thesis presents the results of four behavioural studies and one electroencephalographic (EEG) study which attempted to resolve neurocognitive aspects of this confound. In Experiment 1 (n=18), participants prepared for a lower limb response, or imagined then responded in a repeated measures design. Response time congruency priming was significantly larger following MI than MP, driven by increased costs. Three follow-up experiments were conducted. First (n=16), it was shown that the enhanced priming effect did not depend on optimal temporal preparation. Second (n=13), these effects were also present following imagination and preparation of finger responses. Third (n=21), non-motor cognitive load was manipulated in an additional task, and indicated that the MI priming effects could not be explained more simply as a distracting secondary task. A hypothetical view derived from this data was proposed, suggesting that MI priming can interact with normal MP processes by amplifying the gain of information received from proprioceptive channels prior to response, thus enhancing the difference between correctly and incorrectly primed responses compared to MP alone. Using EEG, the final experiment (n=11) showed the MI priming effect held up when controlling for unwanted muscular activation, and that it may be due to stronger corticomotor activity following MI, supporting the hypothetical view. This thesis therefore provides an integrative neurocognitive perspective on the role of MI in enhancing real performance at short time-scales.
Emotions play a pivotal role in guiding our behaviour within society and our environment. In particular, emotions enable interpersonal social interactions through non-verbal communication that may be below conscious awareness. However, when there is some disruption to normal emotional processing, such as in anxiety disorders, quality of life of the individual can be severely disrupted. Anxiety disorders account for nearly a quarter of all mental health diagnoses, however the aetiology and underpinning neural correlates of anxiety are still not fully understood. This thesis sought to investigate the neurobiological mechanisms of emotion processing, specifically in the amygdala, in a healthy sub-clinical cohort. Six different studies are presented using quantitative methodology to explore amygdala activation and connectivity during emotion processing, and structural differences, as modulated by gender and sub-clinical anxiety. Overall results reveal a modulating effect of sub-clinical anxiety on amygdala habituation, fronto-amygdala connectivity (at rest and during emotion processing) and neural structure. In addition, results presented in this thesis suggest that there may be an attentional component to characteristic hyper-responsivity of the amygdala during emotion processing seen in clinical anxiety patients that should be incorporated into future models of maladaptive emotion. Furthermore, various different chapters in this thesis present evidence that the left amygdala appears to be more specialised for responses to more socially salient stimuli and the right amygdala appears to be more responsive to threat related stimuli indicating that key theoretical models of emotion (the dual processing model, and the salience detection model) should be integrated into one cohesive model of emotion processing. In addition to these theoretical implications, results demonstrating the modulating effect of anxiety and gender presented in this thesis suggest that research on emotion should account for individual differences as a matter of standard practice. This thesis also supports the use of resting state -functional magnetic resonance imaging (fMRI) as a low cost, valid alternative, to task based fMRI within the study of anxiety. Finally, results suggest that investigation of structural differences in sub-clinical populations, and the use of analytical methods such machine learning classification techniques, could aid the development of diagnostic tools that can track disease progression and identify individuals at risk of developing anxiety disorders. The possibility of identifying such neural biomarkers will allow research to look for therapeutic treatments and interventions, which could prevent individuals from transitioning from sub-clinical anxiety to chronic anxiety disorders.
An estimated 60.25% of offenders have a history of traumatic brain injury (TBI). There is currently no established valid or reliable screening tool for identifying female prisoners with a TBI and associated cognitive impairment available in the UK. Using a cross-sectional design, this study aimed to investigate the retest reliability and construct validity of the Brain Injury Screening Index (BISI). Convergent validity was explored using self-report measures of mood and neurodisability, as well as a battery of neuropsychological assessments of cognitive functioning. Of a planned sample of 73 participants, preliminary data from 23 participants has been analysed. 69.56% of participants were identified as having a history of TBI, with a mean of 2.09 TBIs. Intraclass correlation coefficients reached statistical significance for six of 10 identified key clinical indicators on the BISI. The BISI variables did not reach statistically significant convergence with most of the test battery. Two of the four BISI summary variables demonstrated correlations in the hypothesised directions across the full assessment battery, however only one BISI variable reached statistical significance with one subscale in the battery. Analyses provide support for further investigation into the construct validity and retest reliability of the BISI with a larger sample. The implications of these findings, particularly in refining the BISI, and future research and practice are considered.
Mnemonic operations are vital in our everyday life and comprise a vast array of sub-processes that need to be co-ordinated constantly to ensure smooth functioning. The goal of this work was to investigate the superimposed control component responsible for the co-ordination of those individual sub-processes. Furthermore, by using neuroscientific methods like electroencephalography (EEG) and transcranial magnetic stimulation (TMS), the underlying oscillatory signatures were explored and their behavioural relevance tested. It will be shown that increase in theta frequency (4-8 Hz) over medial frontal cortical areas is a local indicator of increasing task demand and task complexity. Moreover, findings will be presented that indicate that the phase of this local oscillation (frontal-midline theta, FMtheta) enables task-relevant processes in posterior cortical areas (represented by increased activity in the gamma frequency range, 30-80 Hz) to flexibly access prefrontal cognitive resources. This mechanism is implemented in a way that bursts of posterior gamma frequency are locked to specific phases of a FMtheta cycle. The higher the task complexity, i.e. the more prefrontal control processes are needed for its execution, the closer to the excitatory phase of FMtheta (trough) the posterior gamma bursts are nested. In contrast, when only very little cognitive control needs to be employed, the posterior fast frequency bursts are locked near the inhibitory FMtheta phase (peak) rather. By using repetitiveTMS it was furthermore possible to show the behavioural relevance of this mechanism and how the disruption thereof has a highly selective and immediate deteriorating effect on working memory performance. Moreover, it will be demonstrated that this mechanism does not only depend on task difficulty but can be influenced and controlled voluntarily by information prioritisation. Finally, based on these findings a model will be introduced that could potentially explain the mechanism of such flexible allocation of and access to prefrontal control processes.
Physical load carriage is an essential duty for military personnel. Physical load carriage induces psychological and physiological effects, but the influence of load carriage on brain activity and subsequent cognitive performance is largely unknown. This due to difficulties in disentangling the subtle behavioural effects under load carriage in complex occupational settings. To investigate how load carriage influences cognition directly, continuous measures of brain activity must be obtained in realistic settings. Mobile EEG is ideally suited to this task. Across four studies, mobile EEG recordings were used to assess to what extent load carriage influences attention. Four objectives were defined. 1. To evaluate mobile EEG as a viable tool in real-life settings (studies 1-4). 2. Investigate the influence of walking on attentional processes (study 1, selective attention; study 2, change detection). 3. Establish the impact of load carriage on brain activity during walking (study 3). 4. Assess the interaction of load carriage on attentional processes during walking (study 4). Interpretations of resulting data were conceptualised in the proposed dynamic resource allocation model of cognitive performance. Successful application of Mobile EEG was evident and found signal quality comparable to EEG recorded in a laboratory. Moreover, walking influenced attentional processes in an indirect way, moderated by the environment and concurrent perceptual load. While a steady state neural index of walking was recorded in a natural setting, this was invulnerable to load carriage effects. Further, and most pressing for this thesis, load carriage had little influence on neural indices of attention. Despite this, there is some indication from the data that fatigue plays a prominent role in the interaction of load carriage and cognitive function, and further exploring the neural underpinnings of motivation may prove fruitful in future studies of load carriage and cognitive function.
Although anecdotally sex differences and the impact they may have on cognition is a hot topic in the media, and indeed in research, very little consensus has been found for hormone-related changes in behaviour. Previous work in this area tends to use a two-time repeated measures method to investigate the impact of hormones across the menstrual cycle. However this method has been shown to be relatively ineffective. The female menstrual cycle is roughly 28 days long with very a dynamic, and rapidly changing, mixture of hormone concentrations across the cycle. To capture this fully we suggest it is necessary to collect data at a significantly greater number of time points with more rigorous methods and suitably sensitive analysis. Four studies are presented in this thesis which focus on capturing more accurately the effect of hormones on cognition across the menstrual cycle. Studies One – Three present data from 13 participants using the standard two-time repeated measure method to investigate categorisation behaviour. This is a completely novel area of research in terms of cognition and hormones. Previous research has focused on various aspects of cognition, yet despite categorisation behaviour being a clearly distinct area of cognition, research into the impact of hormone changes has neglected to look for differences here. The focus on categorisation behaviour provides us with a more holistic picture of the impact of hormones on performances and cognition. Study Four provided a novel approach to the way in which studies are conducted in the area. Here we present a multiple repeated measures study with data from 22 participants using a figural comparison task with measurements at twelve time points across their cycles. A previous study by Hausmann et al,. (2002) using a figural comparison task showed clear impact of the menstrual cycle on cognitive performance using 15 time-point measurements in a sample of 12 participants. In addition to an increase in measurement sensitivity using more time points, we also developed a novel mathematical approach to model the performance change over the menstrual cycle. From Studies One to Three we determined that categorisation performance does not appear to be influenced by changes in cyclical hormone changes. However we did find an influence of hormonal changes on performance in a 1-dimensional categorisation task which demonstrates that hormones may have an impact upon Rule-based categorisation. From Study 4 we were unable to replicate Hausmann and colleagues findings. However we were able to successfully develop a novel modelling method that could accurately predict participant performance on a figural comparison task across the menstrual cycle. Overall this thesis presents a comprehensive investigation into hormone related changes in cognition across the menstrual cycle. We looked into a novel area of behavioural categorisation to determine the impact of hormone related changes in performance on such a task. Through which we demonstrated that in this one area there is little impact despite most other areas of cognition being influenced by cyclical hormonal changes. We then investigated the methodology used in the field in an attempt to improve and develop more accurate and sensitive measures. We were unable to replicate a previous study using multiple time points, however the success of developing a model to predict performance on the figural comparison task provides a useful tool for researchers in the area in the future. The thesis clearly demonstrates that this is an area in the field of psychology and neurobiology that is still in need of further investigation and that we still have much to understand in terms of the ways in which our hormones can impact our behaviour.
Objective: The aim of this study was to investigate the associations of Traumatic Brain Injury (TBI) in a female prison sample with violent crime and reoffending, psychological and neurobehavioural functioning, and performance on neuropsychological tests. Design: This cross-sectional study was conducted at a female prison in the UK and used a between-participants design to compare a TBI group with a no-TBI group across a range of measures including violent crime, number of times in prison, scores on standardised clinical questionnaires, and scores on performance-based cognitive assessments. In-depth interviews were used to elicit incidence of TBI and forensic history, with forensic information cross-checked against the prison database. Participants: Participants were 56 female inmates admitted to the prison between September 2014 and May 2015. 29 reported TBI and 27 reported no TBI. Results: Those in the TBI group were more likely to be convicted for a violent offence, had committed a greater number and a greater proportion of violent offences, had been to prison a greater number of times, and reported greater psychological and neurobehavioural difficulties. No difference was found between groups in terms of neuropsychological-test performance. Conclusions: The findings suggest that TBI may be a significant risk factor for violent crime and re-offending, and that TBI is associated with a range of psychological and neurobehavioural difficulties in this population. This highlights the need for the routine screening of TBI in prisons alongside interventions that mitigate the attendant psychological and neurobehavioural difficulties.