Annette Sterr

Professor Annette Sterr


Professor of Cognitive Neuroscience and Neuropsychology
PhD, Dipl Psych, CPsychol, HPCP
+44 (0)1483 682883
02 AC 04
Wednesdays 13-15h
Startlet Gwendolyn Rosalind Brettoner-Sterr

Biography

Biography

Annette studied Psychology and Biology at the University of Konstanz where she obtained her PhD in 1998. She was a lecturer (2000-2002) and reader (2002-2003) in the School of Psychology at the University of Liverpool before she joined the University of Surrey as a chair in Cognitive Neuroscience in 2003. She was head of Psychology from 2008-2011, and served as associate dean international from 2009-2011. At present she is leading the Brain and Behaviour Research group.

Research interests

My research focuses on clinical neuroscience brain plasticity with particular emphasis on functional brain organization, neurological rehabilitation, and most recently sleep. A second strand of studies aims to understand the neuromodulatory effects of glucose and hormones on cognition.

My publications

Publications

Shen S, Sterr A (2012) Is DARTEL-based voxel-based morphometry affected by width of smoothing kernel and group size? A study using simulated atrophy, JOURNAL OF MAGNETIC RESONANCE IMAGING 37 (6) pp. 1468-1475 WILEY-BLACKWELL
Herron K, Dijk D, Ellis J, Sanders J, Sterr A (2008) Sleep actigraphy in brain injured patients with chronic low functioning upper limb hemiparesis,
Sleep actigraphy in brain injured patients with chronic low
functioning upper limb hemiparesis
K. HERRON1, D. DIJK2, J. ELLIS3, J. SANDERS1 and
A. STERR1
1Department of Psychology, University of Surrey, Guildford, United
Kingdom, 2Surrey Sleep Research Centre, University of Surrey,
Guildford, United Kingdom and 3Section of Psychological Medicine,
University of Glasgow, Glasgow, United Kingdom
Introduction: Few studies have used actigraphy to examine sleep
behaviour in brain injured patients with chronic hemiparesis. This
is possibly due to suggestions that actigraphy recordings in those
with motor difficulties are likely to produce inaccurate sleep/wake
detection (Sadeh and Acebo, 2002). However, actigraphy provides
a favourable alternative to PSG when observing long term sleep
behaviour. Therefore, we aimed to further validate the use of
actigraphy in low functioning hemiparetic patients by comparing
subjective sleep diaries (SD) with actigraphy recordings to examine:
1) concordance between SD and actigraphy, and 2) the relationship
between motor deficits and activity.
Method: Twelve patients with chronic upper limb hemiparesis
(412 months) completed SDs and wore an actiwatch (Cambridge
Neurotechnology Ltd.) on the non-affected wrist for two weeks.
Residual motor ability was assessed through a series of neurobehavioural
motor tests.
Results: Comparison of SD and actigraphy revealed significant
dissociations between final wake time, sleep efficiency, number and
duration of night awakenings. Good concordance between SD
and actigraphy was found for retiring time, get up time, time in
bed, total sleep time and sleep onset latency. Mean activity
counts, during the day or night, were not associated with residual
motor ability.
Discussion and Conclusion: Actigraphy of the non-affected wrist, in
conjunction with SDs, are a valid apparatus for assessing long term
sleep behaviour in patients with hemiparesis. The results are in line
with previous studies in healthy persons without motor difficulties
whereby SDs and actigraphy correlate well, apart from parameters
which rely on subjective night time awakenings (Lockley et al. 1999). The latter can only be determined by PSG studies.
Hope C, Seiss E, Dean PJA, Williams K, Sterr A (2013) Consumption of glucose drinks slows sensorimotor processing: Double-blind placebo-controlled studies with the Eriksen flanker task, Frontiers in Human Neuroscience 7 651 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.
Kranczioch C, Zich C, Schierholz I, Sterr A (2013) Mobile EEG and its potential to promote the theory and application of imagery-based motor rehabilitation., 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.
Szameitat AJ, McNamara A, Shen S, Sterr A (2012) Neural Activation and Functional Connectivity during Motor Imagery of Bimanual Everyday Actions., PLoS One 7 (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.
Hou WS, Wu XY, Zheng XL, Shen S, Sterr AM (2006) A behavior study on the effect of visual feedback gain to force production, Chinese Journal of Biomedical Engineering 25 (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.
Szameitat DP, Alter K, Szameitat AJ, Darwin CJ, Wildgruber D, Dietrich S, Sterr A (2009) Differentiation of emotions in laughter at the behavioral level., Emotion 9 (3) pp. 397-405
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.
Anjos SM, Cohen LG, Sterr A, De Andrade KNF, Conforto AB (2014) Translational neurorehabilitation research in the third world: What barriers to trial participation can teach us, Stroke 45 (5) pp. 1495-1497
BACKGROUND AND PURPOSE-: Most stroke rehabilitation studies have been performed in high-income countries. The aim of this study was to identify the main barriers for patient inclusion in a research protocol performed in Brazil. METHODS-: We evaluated reasons for exclusion of patients in a pilot, randomized, double-blinded clinical trial of stroke rehabilitation. Descriptive statistical analysis was performed. RESULTS-: Only 5.6% of 571 screened patients were included. Recurrent stroke was responsible for exclusion of 45.4% of potentially eligible patients. CONCLUSIONS-: Recurrent stroke represented a big barrier to enroll patients in the protocol. External validity of rehabilitation trials will benefit from definition of study criteria according to regional characteristics of patients, including rates of recurrent stroke. © 2014 American Heart Association, Inc.
Sterr A, Shen S, Kranczioch C, Szameitat A, Hou W, Sorger B (2009) fMRI effects of task demand and feedback accuracy on grip force tracking., Neurosci Lett 457 (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.
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.
Sterr A, Elbert T, Rockstroh B (2002) Functional reorganization of the human cerebral cortex and its perceptual concommitants, In: Fahle M, Poggio T (eds.), Perceptual Learning pp. 125-144 MIT Press
Landmann N, Kuhn M, Piosczyk H, Feige B, Baglioni C, Spiegelhalder K, Frase L, Riemann D, Sterr A, Nissen C (2014) The reorganisation of memory during sleep., Sleep Med Rev 18 (6) pp. 531-541
Sleep after learning promotes the quantitative strengthening of new memories. Less is known about the impact of sleep on the qualitative reorganisation of memory, which is the focus of this review. Studies have shown that, in the declarative system, sleep facilitates the abstraction of rules (schema formation), the integration of knowledge into existing schemas (schema integration) and creativity that requires the disbandment of existing patterns (schema disintegration). Schema formation and integration might primarily benefit from slow wave sleep, whereas the disintegration of a schema might be facilitated by rapid eye movement sleep. In the procedural system, sleep fosters the reorganisation of motor memory. The neural mechanisms of these processes remain to be determined. Notably, emotions have been shown to modulate the sleep-related reorganisation of memories. In the final section of this review, we propose that the sleep-related reorganisation of memories might be particularly relevant for mental disorders. Thus, sleep disruptions might contribute to disturbed memory reorganisation and to the development of mental disorders. Therefore, sleep-related interventions might modulate the reorganisation of memories and provide new inroads into treatment.
Szameitat A, McNamara A, Shen S, Sterr AM (2012) Neural Activation and Functional Connectivity during Motor Imagery of Bimanual Everyday Actions, PLoS One 7 (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.
Shen S, Sandham W, Granat M, Sterr A (2005) MRI fuzzy segmentation of brain tissue using neighborhood attraction with neural-network optimization, Ieee Transactions on Information Technology in Biomedicine 9 (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.
Sterr A, Saunders A (2006) CI therapy distribution: Theory, evidence and practice, NEUROREHABILITATION 21 (2) pp. 97-105 IOS PRESS
Szameitat AJ, Shen S, Sterr A (2007) Effector-dependent activity in the left dorsal premotor cortex in motor imagery, European Journal of Neuroscience 26 (11) pp. 3303-3308 Wiley
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.
Pieridi C, Brown D, Sterr A (2012) The experience of returning to work following a traumatic brain injury, Brain Injury 26 (4-5) pp. 625-625 Informa Healthcare
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.
Dean PJA, McNamara A, Vieira G, Sato J, Sterr A (2013) Structural and functional changes in mTBI and their relationship to persistent PCS: DTI, cortical
thickness and fMRI analysis.,
British Neurosci. Assoc. Abstr. 22 pp. 892-892
Mild traumatic brain injury (mTBI) can induce persistent somatic, affective and cognitive symptoms, collectively
known as post-concussion syndrome (PCS). Standard structural imaging only detects lesions in a small
proportion of those with mTBI, and these lesions are not associated with PCS. However, subtle changes in
structure have been observed with imaging techniques such as diffusion tensor imaging (DTI). Furthermore,
these changes have been shown to correlate with cognitive and behavioural outcome in mTBI participants. This
study aims to further this research by investigating the relationship between changes in neural structure and
function, cognitive outcome and PCS symptomatology in the long term (>1 year) after mTBI.
DTI and functional magnetic resonance imaging (fMRI) data were acquired from participants with chronic (>1
year) mTBI and persistent PCS (n=10), participants with mTBI and no on-going PCS (n=8) and non-head injured
controls (n=10). Fractional Anisotropy (FA) and cortical thickness were calculated from DTI and standard
structural data acquisitions. Two cognitive tasks were presented to participants in the fMRI study, one assessing
working memory (n-Back) and the other assessing information processing speed (paced visual serial addition
task [PVSAT]). We hypothesised that participants with mTBI would show greater structural damage and larger
BOLD response during the cognitive tasks. In addition, these changes should be related to the persistent PCS symptoms reported.
Preliminary analysis demonstrates a reduction in cortical (cingulate, frontal and temporal cortex) and white matter
(corpus callosum, internal capsule) integrity in participants with mTBI compared to controls. Reductions in similar
areas were associated with higher PCS symptom report (figure A and B). The fMRI analysis revealed little
difference between groups for the n-Back, but evidence of increased prefrontal activity (figure C) in participants
with mTBI and persistent PCS during PVSAT performance. This early analysis supports the hypothesis that
persistent PCS symptoms may have a biological element, with those reporting greater symptoms having greater structural damage and functional changes.
Wolf E, Kuhn M, Norman C, Mainberger F, Maier JG, Maywald S, Bredl A, Klöppel S, Biber K, van Calker D, Riemann D, Sterr A, Nissen C (2015) Synaptic plasticity model of therapeutic sleep deprivation in major depression., Sleep medicine reviews 30 pp. 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.
Dean PJA, Sterr A (2008) Advance movement preparation is intact in
hemiparetic patients: Validity effects seen in a
response priming task with the affected arm,
Brain Injury Supplement 1 (22) pp. 168-169
Objectives: Brain injury, including stroke, can cause
a partial or total loss of movement of the body
contralateral to the affected area. Movementexecution is dependent on movement preparation
for optimal motor performance and studying
advance movement preparation in those with
hemiparesis will help elucidate whether this process
is involved in the observed motor impairment.
Motor control can be studied using response
priming paradigms, in which prime stimuli give
some degree of prior information that allows
preparation of the forthcoming response.
Dependent on the level of advance information,
participant?s reaction times are modulated, with
reaction time costs for incorrect prime information
and reaction time benefits for correct information
when compared with an uninformative prime. This
reaction time pattern is termed the validity effect
and is indicative of cognitive processing of the
prime and subsequent movement preparation. The
presence of such an effect in hemiparetic patients
would reveal this ability to be intact, which would
aid in the construction of therapeutic interventions.
Method: Twenty-nine participants with hemiparesis
(at least 1 year post-injury) and 16 age matched
control (non-brain injured, non-hemiparetic) subjects
were recruited. They performed a response
priming task whereby they were expected to press
buttons with their hands dependent on a left or right
button cue. Priming stimuli presented before that
were either informative (Valid) or uninformative
(Neutral). Reaction times were recorded for the
affected and unaffected arms.
Results: Within-group means comparison revealed a
significant validity effect in control and hemiparetic
participants, with both groups taking longer to
respond to the neutral prime trial than to the valid
prime trial. For the affected arm this difference was
210 ms, for the unaffected arm this was 125 ms and
for controls this was 58 ms. In addition, hemiparetic
participants were significantly slower than control
participants in both affected and unaffected arms.
However, the affected arm reaction time differed
from the controls to a greater extent (325 ms for
valid prime) than the unaffected arm (179 ms for
valid prime).
Conclusions: Our study shows that hemiparetic
participants are generally slower to respond to
visual stimuli than a control group, as would be
expected in a group with motor impairment.
However, despite the deficit the validity effect is
preserved for both their affected and unaffected
a
Seiss E, Hope C, Guinn A, Dean PJA, Sterr A (2013) THE EFFECT OF ELEVATED BLOOD SUGAR LEVELS ON ENCODING AND RETRIEVAL IN A VERBAL MEMORY TASK, PSYCHOPHYSIOLOGY 50 pp. S92-S93 WILEY-BLACKWELL
Jehoel S, Sowden PT, Ungar S, Sterr AM (2009) Tactile elevation perception in blind and sighted participants and its implications for tactile map creation, Human Factors 51 pp. 208-223
Herron K, Dijk D, Ellis J, Sanders J, Sterr AM (2008) Sleep actigraphy in brain injured patients with chronic low functioning upper limb hemiparesis, Journal of Sleep Research 17 pp. 102-102
Grossheinrich N, Reinl M, Mulert C, Pogarell O, Fast K, Karch S, Sterr A, Padberg F (2007) Modulation of event-related potentials by repetitive transcranial magnetic stimulation of the prefrontal cortex, Elsevier Science Inc
Landmann N, Kuhn M, Maier JG, Spiegelhalder K, Baglioni C, Frase L, Riemann D, Sterr A, Nissen C (2015) REM sleep and memory reorganization: Potential relevance for psychiatry and psychotherapy., Neurobiol Learn Mem 122 pp. 28-40
Sleep can foster the reorganization of memory, i.e. the emergence of new memory content that has not directly been encoded. Current neurophysiological and behavioral evidence can be integrated into a model positing that REM sleep particularly promotes the disintegration of existing schemas and their recombination in the form of associative thinking, creativity and the shaping of emotional memory. Particularly, REM sleep related dreaming might represent a mentation correlate for the reconfiguration of memory. In a final section, the potential relevance for psychiatry and psychotherapy is discussed.
Szameitat AJ, Shen S, Sterr A (2007) Motor imagery of complex everyday movements. An fMRI study, NEUROIMAGE 34 (2) pp. 702-713 ACADEMIC PRESS INC ELSEVIER SCIENCE
Lukoschek C, Sterr A, Claros-Salinas D, Gütler R, Dettmers C (2015) Fatigue in Multiple Sclerosis Compared to Stroke., Front Neurol 6
OBJECTIVES: Fatigue is typically associated with multiple sclerosis (MS), but recent studies suggest that it is also a problem for patients with stroke. While a direct comparison of fatigue in, e.g., Stroke and MS is desirable, it is presently not easily possible because of different definitions and assessment tools used for the two conditions. In the present study, we therefore assessed fatigue in Stroke and MS using a generic, not disease-specific instrument to allow transdiagnostic comparison. METHOD: A total of 137 patients with MS and 102 patients with chronic stroke completed the SF-36, a generic questionnaire assessing health related quality of life. Fatigue was measured through the vitality scale of the SF-36. The vitality scale consists of two positive items ("lot of energy," "full of life") and two negative ones ("worn out," "tired"). The two negative ones were scaled in reverse order. The vitality scale has been recommended as reciprocal index of fatigue. RESULTS: Normalized vitality scores in MS (35.3) and stroke (42.1) were clearly lower than published reference values from the SF-36 in age-matched healthy controls. The sum score of the vitality items was lower in MS than in stroke patients. This difference could not be explained by age, gender, or the Physical Functioning Scale of the SF-36. Both patient groups showed no positive correlation between fatigue and physical functioning. Fatigue - as determined with the vitality scale of the SF-36 - correlated with the estimated working capacity in MS patients, but not in stroke patients. CONCLUSION: These findings confirm high fatigue in MS and stroke patients with higher values in MS. Fatigue has a higher impact on working capacity in MS than in stroke. Fatigue in both patient groups is not a direct consequent of physical functioning/impairment. Vitality score of the SF-36 is a suitable transdiagnostic measure for the assessment of fatigue in stroke and MS.
Landmann N, Kuhn M, Maier JG, Spiegelhalder K, Baglioni C, Frase L, Riemann D, Sterr A, Nissen C (2015) REM sleep and memory reorganization: Potential relevance for psychiatry and psychotherapy, Neurobiology of Learning and Memory 122 pp. 28-40
© 2015 Elsevier Inc.Sleep can foster the reorganization of memory, i.e. the emergence of new memory content that has not directly been encoded. Current neurophysiological and behavioral evidence can be integrated into a model positing that REM sleep particularly promotes the disintegration of existing schemas and their recombination in the form of associative thinking, creativity and the shaping of emotional memory. Particularly, REM sleep related dreaming might represent a mentation correlate for the reconfiguration of memory. In a final section, the potential relevance for psychiatry and psychotherapy is discussed.
Krone L, Frase L, Piosczyk H, Selhausen P, Zittel S, Jahn F, Kuhn M, Feige B, Mainberger F, Klöppel S, Riemann D, Spiegelhalder K, Baglioni C, Sterr A, Nissen C (2016) Top-down control of arousal and sleep: Fundamentals and clinical implications., 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.
Sterr A, Müller MM, Elbert T, Rockstroh B, Pantev C, Taub E (1998) Perceptual correlates of changes in cortical representation of fingers in blind multifinger Braille readers., J Neurosci 18 (11) pp. 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.
Kolbel S, Elbert T, Rockstroh B, Sterr A, Jahn T, Taub E (1998) Constraint-induced (CI) movement therapy in patients treated according to German rehabilitation programs, JOURNAL OF PSYCHOPHYSIOLOGY 12 (2) pp. 206-206
Conti J, Sterr A, Brucki SM, Conforto AB (2015) Diversity of approaches in assessment of executive functions in stroke: limited evidence?, eNeurologicalSci 1 (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.
Herron K, Dijk D, Ellis J, Sanders J, Sterr AM (2008) Sleep correlates of motor recovery in chronic stroke: a pilot study using sleep diaries and actigraphy., Journal of Sleep Research 17 pp. 103-103
Sterr A, Dean PJ, Szameitat AJ, Conforto AB, Shen S (2013) Corticospinal Tract Integrity and Lesion Volume Play Different Roles in Chronic Hemiparesis and Its Improvement Through Motor Practice., Neurorehabil Neural Repair
. 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.
Elbert T, Candia V, Altenmüller E, Rau H, Sterr A, Rockstroh B, Pantev C, Taub E (1998) Alteration of digital representations in somatosensory cortex in focal hand dystonia., Neuroreport 9 (16) pp. 3571-3575
Focal hand dystonia involves a loss of motor control of one or more digits; it is associated with the repetitive, synchronous movements of the digits made by musicians over periods of many years. Magnetic source imaging revealed that there is a smaller distance (fusion) between the representations of the digits in somatosensory cortex for the affected hand of dystonic musicians than for the hands of non-musician control subjects. The data suggest that use-dependent susceptibility to digital representation fusion in cortex may be involved in the etiology of focal dystonia. A successful therapy for the condition has been developed based on this consideration.
Hou WS, Shen S, Sterr A (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 1-7 pp. 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.
Sterr AM, Bastos Conforto A (2012) Plasticity of Adult Sensorimotor System in Severe Brain Infarcts: Challenges and Opportunities, Neural Plasticity 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.
Mou Z-X, Hou W-S, Zheng X-L, Wu X-Y, Shen S, Sterr AM, Peng C-L (2008) An fMR1 based pilot study on the nerve excitability for force-regulating speed, Chinese Journal of Medical Imaging Technology 24 (3) pp. 341-345
Shen S, Sterr A (2010) Analyzing diffusion tensor images with ghosting artifacts: the effects of direct and indirect normalization., Magnetic Resonance Imaging 28 (10) pp. 1507-1513
The current study aims to assess the applicability of direct or indirect normalization for the analysis of fractional anisotropy (FA) maps in the context of diffusion-weighted images (DWIs) contaminated by ghosting artifacts. We found that FA maps acquired by direct normalization showed generally higher anisotropy than indirect normalization, and the disparities were aggravated by the presence of ghosting artifacts in DWIs. The voxel-wise statistical comparisons demonstrated that indirect normalization reduced the influence of artifacts and enhanced the sensitivity of detecting anisotropy differences between groups. This suggested that images contaminated with ghosting artifacts can be sensibly analyzed using indirect normalization.
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.
Szameitat AJ, Shen S, Bastos Conforto A, Sterr A (2012) Cortical activation during executed, imagined, observed, and passive wrist movements in healthy volunteers and stroke patients, Neuroimage 62 (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.
Ellis J, Thomsom A, Gregory AM, Sterr AM (2012) Biased Processing of Sleep-Related Stimuli
in Children of Parents With Insomnia,
Behavioral Sleep Medicine 10 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.
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.
Hou WS, Zheng J, Jiang YT, Shen S, Sterr A, Szatneitat AJ, van Loon M, Ieee (2006) A behavior study of the effects of visual feedback on motor output, pp. 4777-4780 Ieee
Visual feedback is a crucial factor that impacts the motor function, and a number of parameters, such as gain, delay and frequency, all play a role in regulating the motor output. In this paper, we conduct a behavioral study on 12 volunteers to determine the effects of visual feedback in the physical movement by measuring the grasp force output under different visual feedback gain levels. To this end, two force tracking tasks with different incremental/decremental rates of the force have been designed, and the force deviation and the error rate from the 12 participants are recorded when they are exposed to different visual gains. Further statistical anal, is on the experimental data reveals that the gain of visual stimuli as a significant influence on the force output. For the same force tracking task, visual feedback with high gain tends to enhance the regulation of force production. The results also suggest that different visual feedback gains may be mapped onto different cortex function areas governing different motor tasks.
Sterr A, Herron K, Sanders JC (2009) Constraint-induced movement therapy (CIT) for restoration of Upper-Limb function: Hemipareses Application, In: Soderback I (eds.), International Handbook of Occupational Therapy Interventions pp. 309-316 Springer
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.
Mou Z-X, Hou W-S, Zheng X-L, Wu X-Y, Shen S, Sterr AM, Peng C-L (2009) fMRI observation of the effect of visual feedback gain on force production, Chinese Journal of Medical Imaging Technology 25 (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.
Sterr A, Dean P (2008) Neural correlates of movement preparation in healthy ageing, European Journal of Neuroscience 27 (1) pp. 254-260
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. © The Authors (2007).
Hope C, Seiss E, Dean PJA, Williams K, Guinn A, Sterr A (2011) Response time slowing by glucose dependent on strength of stimulus response association: investigations with the flanker task, Frontiers in Human Neuroscience: ICON XI, Conference Abstracts Frontiers
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.
Mathews S, Dean PJA, Harrison N, Williams N, Sterr A (2005) Movement preparation and execution following a no-response pre-cue: A pilot study using behavioural and EEG data.,
Ellis JG, Thomson A, Gregory AM, Sterr A (2013) Biased Processing of Sleep-Related Stimuli in Children of Parents With Insomnia, Behavioral Sleep Medicine 11 (2) pp. 108-119
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. © 2013 Copyright Taylor and Francis Group, LLC.
Kranczioch C, Zich C, Schierholz I, Sterr A (2014) Mobile EEG and its potential to promote the theory and application of imagery-based motor rehabilitation, International Journal of Psychophysiology 91 (1) pp. 10-15
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. © 2013 Elsevier B.V.
Sterr A, Nissen C, Funk S, Ettine D, Unbehaun T, Kuemmerer D, Riemann D (2013) CHANGES OF POLYSOMNOGRAPHIC SLEEP CHARACTERISTICS IN CHRONIC POST-STROKE HEMIPLEGIA, PSYCHOPHYSIOLOGY 50 pp. S40-S40 WILEY-BLACKWELL
Wallace A, Dewar L, Pietrusz A, Dudziec M, Sterr A, Laura M, Skorupinska I, Skorupinska M, Hanna M, Trenell M, Baio G, Reilly M, Ramdharry G (2015) Evaluating the benefits of community based aerobic training on the physical health and well-being of people with neuromuscular diseases: A pilot study, NEUROMUSCULAR DISORDERS 25 pp. S273-S274 PERGAMON-ELSEVIER SCIENCE LTD
Shen S, Sandham WA, Granat MH, Sterr A (2005) Intensity non-uniformity correction of magnetic resonance images using a fuzzy segmentation algorithm, In: 2005 27th Annual International Conference of the Ieee Engineering in Medicine and Biology Society, Vols 1-7 pp. 3035-3038 IEEE
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 to demonstrate the superiority of the algorithm.
Sterr A, Müller M, Elbert T, Rockstroh B, Taub E (1999) Development of cortical reorganization in the somatosensory cortex of adult Braille students., Electroencephalogr Clin Neurophysiol Suppl 49 pp. 292-298
Furlan L, Conforto AB, Cohen LG, Sterr A (2016) Upper Limb Immobilisation: A Neural Plasticity Model with Relevance to Poststroke Motor Rehabilitation, NEURAL PLASTICITY ARTN 8176217 HINDAWI PUBLISHING CORP
Sterr AM, Herron K, Dijk D, Ellis J (2009) Time to wake-up: Sleep problems and daytime sleepiness in long-term stroke survivors, Brain Injury 22 (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.
Sterr A, Müller MM, Elbert T, Rockstroh B, Pantev C, Taub E (1998) Changed perceptions in Braille readers., Nature 391 (6663) pp. 134-135
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/

Sterr AM, Shen S, Kranczioch C, Hou W, Sorger B (2009) Neural activities induced by tracking isometric grip force changes through visual feedback, Neuroscience Letters 457 (2) pp. 61-65
Shen S, Szameitat A, Sterr A (2008) Detection of infarct lesions from single MRI modality using inconsistency between voxel intensity and spatial location - A 3-D automatic approach, Ieee Transactions on Information Technology in Biomedicine 12 (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.
dos Santos-Fontes RL, Ferreiro de Andrade KN, Sterr A, Conforto AB (2013) Home-Based Nerve Stimulation to Enhance Effects of Motor Training in Patients in the Chronic Phase After Stroke: A Proof-of-Principle Study, NEUROREHABILITATION AND NEURAL REPAIR 27 (6) pp. 483-490 SAGE PUBLICATIONS INC
O'Sullivan M, Glorney E, Sterr A, Oddy M, Ramos SDS (2013) Traumatic brain injury and violent behavior in females: A systematic review, AGGRESSION AND VIOLENT BEHAVIOR 25 pp. 54-64 PERGAMON-ELSEVIER SCIENCE LTD
Minarik T, Sauseng P, Dunne L, Berger B, Sterr A (2015) Effects of anodal transcranial direct current stimulation on visually guided learning of grip force control., 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.
Dean PJ, Sato JR, Vieira G, McNamara A, Sterr A (2015) Long-term structural changes after mTBI and their relation to post-concussion symptoms., Brain Inj pp. 1-8
PRIMARY OBJECTIVE: 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). RESEARCH DESIGN: Morphological and structural connectivity magnetic resonance imaging (MRI) data were acquired from 16 participants with mTBI and nine participants without previous head injury. MAIN OUTCOMES AND RESULTS: Participants with mTBI had less prefrontal grey matter and lower fractional anisotropy (FA) in the anterior corona radiata and internal capsule. Furthermore, PCS severity was associated with less parietal lobe grey matter and lower FA in the corpus callosum. CONCLUSIONS: There is evidence for both white and grey matter damage in participants with mTBI over 1 year after injury. Furthermore, these structural changes are greater in those that report more PCS symptoms, suggesting a neurophysiological basis for these persistent symptoms.
Encke M, Dean PJA, Seiss E, Sterr A (2013) EFFECTS OF AGING ON MOTOR PREPARATION PROCESSES, PSYCHOPHYSIOLOGY 50 pp. S87-S87 WILEY-BLACKWELL
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
Sterr A, Schmalohr D, Kolbel S, Freivogel S (2001) Functional reorganization of motor areas following forced-use rehabilitation training in hemiparetic patients: A TMS study, Biomedical Engineering 46 pp. 102-108
Hou W, Zheng J, Jiang Y, Shen S, Sterr A, Szameitat AJ, van Loon M (2006) A behavior study of the effects of visual feedback on motor output., Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference pp. 1273-1276
Visual feedback is a crucial factor that impacts the motor function, and a number of parameters, such as gain, delay and frequency, all play a role in regulating the motor output. In this paper, we conduct a behavioral study on 12 volunteers to determine the effects of visual feedback in the physical movement by measuring the grasp force output under different visual feedback gain levels. To this end, two force tracking tasks with different incremental/decremental rates of the force have been designed, and the force deviation and the error rate from the 12 participants are recorded when they are exposed to different visual gains. Further statistical analysis on the experimental data reveals that the gain of visual stimuli has a significant influence on the force output. For the same force tracking task, visual feedback with high gain tends to enhance the regulation of force production. The results also suggest that different visual feedback gains may be mapped onto different cortex function areas governing different motor tasks.
Sterr A (2004) Training-based interventions in motor rehabilitation after stroke: Theoretical and clinical considerations, BEHAVIOURAL NEUROLOGY 15 (3-4) pp. 55-63
Sterr AM (2004) Attention performance in young adults with learning disabilities, Learning and Individual Differences 14 (2) pp. 125-133
Attention acts as the mind's "gatekeeper" by regulating and prioritizing the stimuli processed by the central nervous system. It is essential for cognitive performance, memory, and behavior, and we know that even slight deficiencies in attention compromise learning. Basic neuroscience research further indicates that attention consists of (fairly) independent subcomponents, which rely on distinct neural structures, and serve different functions in everyday behavior. Disturbances of brain function, such as those suggested to be related to learning disabilities, may lead to different patterns of attention performance (i.e., some attention systems may work sufficiently well, while others are substantially impaired). The present experiment describes a pilot study that aimed to characterize the extent and range of individual variations in attention performance in persons classified as learning disabled. Specifically, we tested the hypothesis that attention is not uniformly impaired in these individuals. Rather, we expected some subcomponents to be more severely impaired than others, and substantial heterogeneity in the individual "deficit patterns. " The Test of Everyday Attention (TEA) was used to assess visual selective attention, attentional switching, sustained attention, and auditory-verbal working memory in students with nondyslexic learning disability (LD group) and matched controls. The group comparison revealed a significantly weaker performance in the LD group. Analysis of subtest-specific scaled scores further indicated great individual differences in the performance pattern. Thus, in each student with LD, we found normal performance in at least two subtests, while other subcomponents where severely impaired. The study supports the idea of differential attention deficits in the learning disabled, and suggests individual patterns of "strengths and weaknesses." Taking the relationship of attention and learning into account, this finding is important with respect to the design of individual learning programs and the teaching techniques chosen for the acquisition of skills and knowledge. (C) 2003 Elsevier Inc. All rights reserved.
Röder B, Teder-Sälejärvi W, Sterr A, Rösler F, Hillyard SA, Neville HJ (1999) Improved auditory spatial tuning in blind humans., Nature 400 (6740) pp. 162-166
Despite reports of improved auditory discrimination capabilities in blind humans and visually deprived animals, there is no general agreement as to the nature or pervasiveness of such compensatory sensory enhancements. Neuroimaging studies have pointed out differences in cerebral organization between blind and sighted humans, but the relationship between these altered cortical activation patterns and auditory sensory acuity remains unclear. Here we compare behavioural and electrophysiological indices of spatial tuning within central and peripheral auditory space in congenitally blind and normally sighted but blindfolded adults to test the hypothesis (raised by earlier studies of the effects of auditory deprivation on visual processing) that the effects of visual deprivation might be more pronounced for processing peripheral sounds. We find that blind participants displayed localization abilities that were superior to those of sighted controls, but only when attending to sounds in peripheral auditory space. Electrophysiological recordings obtained at the same time revealed sharper tuning of early spatial attention mechanisms in the blind subjects. Differences in the scalp distribution of brain electrical activity between the two groups suggest a compensatory reorganization of brain areas in the blind that may contribute to the improved spatial resolution for peripheral sound sources.
Anjos SM, Cohen LG, Sterr A, de Andrade KN, Conforto AB (2014) Translational neurorehabilitation research in the third world: what barriers to trial participation can teach us., Stroke 45 (5) pp. 1495-1497
BACKGROUND AND PURPOSE: Most stroke rehabilitation studies have been performed in high-income countries. The aim of this study was to identify the main barriers for patient inclusion in a research protocol performed in Brazil. METHODS: We evaluated reasons for exclusion of patients in a pilot, randomized, double-blinded clinical trial of stroke rehabilitation. Descriptive statistical analysis was performed. RESULTS: Only 5.6% of 571 screened patients were included. Recurrent stroke was responsible for exclusion of 45.4% of potentially eligible patients. CONCLUSIONS: Recurrent stroke represented a big barrier to enroll patients in the protocol. External validity of rehabilitation trials will benefit from definition of study criteria according to regional characteristics of patients, including rates of recurrent stroke. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT01333579.
Billows IJ, Khan S, Sterr A (2013) Exploring sleep, sleepiness and fatigue in chronic stroke: A mixed methods study, INTERNATIONAL JOURNAL OF STROKE 8 pp. 73-73 WILEY-BLACKWELL
Noone DM, Harkness F, Ogilvie J, Gregory AM, Willis TA, Cox J, Sterr A, Forbes E (2013) Catastrophizing and Poor Sleep Quality in Early Adolescent Females, Behavioral Sleep Medicine
Catastrophizing about sleeplessness has been investigated in adults and children, but little is known about adolescents. This article aimed to (a) investigate whether early adolescent girls catastrophized about consequences of sleeplessness, (b) describe topics in catastrophizing sequences, (c) examine the association between sleep quality and catastrophizing, and (d) assess whether puberty moderated this association. Girls (n = 115) between 11 and 12 years old completed adapted versions of the Pittsburgh Sleep Quality Index, the Pubertal Developmental Scale, and the Catastrophizing Interview. Twenty-four (21%) participants produced catastrophizing sequences, including concerns about school and mood. Sleep quality was associated with catastrophizing (² = 0.19, p =.042); however, puberty did not moderate this association (² = 0.15, p =.126). Findings highlight the importance of sleep-related cognitions in adolescent girls. © 2013 Copyright Taylor and Francis Group, LLC.
Baglioni C, Nissen C, Schweinoch A, Riemann D, Spiegelhalder K, Berger M, Weiller C, Sterr A (2016) Polysomnographic Characteristics of Sleep in Stroke: A Systematic Review and Meta-Analysis, PLOS ONE 11 (3) ARTN e0148496 PUBLIC LIBRARY SCIENCE
Szameitat DP, Darwin CJ, Szameitat AJ, Wildgruber D, Sterr AM, Dietrich S, Alter K (2011) Format characteristics of human laughter, Journal of Voice 25 (1) pp. 32-37 Elsevier
Although laughter is an important aspect of nonverbal vocalization, its acoustic properties are still not fully understood. Extreme articulation during laughter production, such as wide jaw opening, suggests that laughter can have very high first formant (F1) frequencies. We measured fundamental frequency and formant frequencies of the vowels produced in the vocalic segments of laughter. Vocalic segments showed higher average F1 frequencies than those previously reported and individual values could be as high as 1100 Hz for male speakers and 1500 Hz for female speakers. To our knowledge, these are the highest F1 frequencies reported to date for human vocalizations, exceeding even the F1 frequencies reported for trained soprano singers. These exceptionally high F1 values are likely to be based on the extreme positions adopted by the vocal tract during laughter in combination with physiological constraints accompanying the production of a ?pressed? voice.
Szameitat AJ, Rummel J, Szameitat DP, Sterr AM (2009) Detrimental Behavioral and Emotional Consequences of Brief Delays in Human-Computer Interaction, International Journal of Human-Computer Studies 67 (7) pp. 561-570
Sterr A, Muller MM, Elbert T, Rockstroh B, Taub E (1998) Expansion of cortical hand representation and tactile sensory thresholds in blind Braille readers: A link between cortical organization and perception, JOURNAL OF PSYCHOPHYSIOLOGY 12 (2) pp. 193-194
Kranczioch C, Mathews S, Dean PJA, Sterr A (2010) Task complexity differentially affects executed and imagined movement preparation: evidence from movement-related potentials., PLoS ONE 5 (2) 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.

Sterr A, O'Neill D, Dean PJA, Herron KA (2014) CI therapy is beneficial to patients with chronic low-functioning hemiparesis after stroke, Frontiers in Neurology 5 205 pp. 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.
Nissen C, Frase L, Piosczyk H, Feige B, Sterr A, Riemann D (2014) The modulation of sleep continuity through transcranial direct current stimulation (TDCS), JOURNAL OF SLEEP RESEARCH 23 pp. 39-39 WILEY-BLACKWELL
Sterr A, Green L, Elbert T (2003) Blind Braille readers mislocate tactile stimuli, Biological Psychology 63 (2) pp. 117-127
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. (C) 2003 Elsevier Science B.V. All rights reserved.
Sterr A, Elbert T, Berthold I, Kolbel S, Rockstroh B, Taub E (2002) Longer versus shorter daily constraint-induced movement therapy of chronic hemiparesis: An exploratory study, Archives of Physical Medicine and Rehabilitation 83 (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.
Elbert T, Sterr A, Flor H, Rockstroh B, Knecht S, Pantev C, Wienbruch C, Taub E (1997) Input-increase and input-decrease types of cortical reorganization after upper extremity amputation in humans., Exp Brain Res 117 (1) pp. 161-164
A plastic remodeling of regions in somatosensory cortex has previously been observed to occur in separate experimental paradigms in response to loss of somatosensory input and to increase in input. In this study, both types of cortical reorganization have been observed to occur concurrently in the same adult human nervous system as a result of a single intervention. Following upper extremity amputation, magnetic source imaging revealed that tactile stimulation of the lip evoked responses not only in the area of the somatosensory cortex corresponding to the face, but also within the cortical region that would normally correspond to the now absent hand. This "invasion" of the cortical amputation zone was accompanied by a significant increase in the size of the representation of the digits of the intact hand, presumably as a result of an increased importance of sensory stimulation consequent to increased dependence on that hand imposed by the loss of the contralateral extremity.
Szameitat D, Alter K, Szameitat A, Wildgruber D, Sterr A, Darwin C (2009) Acoustic profiles of distinct emotional expressions in laughter., J Acoust Soc Am 126 (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.
Rockstroh B, Watzl H, Kowalik ZJ, Cohen R, Sterr A, Müller M, Elbert T (1997) Dynamical aspects of the EEG in different psychopathological states in an interview situation: a pilot study., Schizophr Res 28 (1) pp. 77-85
Dynamical brain states can be characterized by non-linear measures of EEG. The present study shows that critical transitions, i.e., abrupt changes from one dynamic pattern of neural mass activity to another one, may be detected by abrupt variations in local chaoticity. Using an ambulatory device, EEG was recorded from 10 patients with a schizophrenic and two patients with an affective disorder during a series of 25-min interviews. Dynamical aspects, in particular, phase transitions in the EEG-dynamics of the EEG were characterized by means of a measure that continuously estimates the chaoticity of the EEG signal and is thus related to its predictability. Results indicate simpler dynamics of the EEG time series in paranoid-hallucinatory patients, while at the same time these patients tended to exhibit more abrupt transitions/unit of time between different dynamical EEG states. Such sudden phase transitions in brain activity were significantly enhanced prior to expressions of thought disorders that were detected by the interviewer and an observer in the conversation, compared with time periods during the interview without such symptoms.
Hou W, Shen S, Szameitat AJ, Jiang Y, Zheng J, van Loon M, Sterr A (2009) A behaviour study of the effects of visual feedback on fluctuating isometric force production with force tracking tasks, International Journal of Biomedical Engineering and Technology 1 (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. © 2008, Inderscience Publishers.
Hope C, Sterr A, Elangovan P, Geades N, Windridge D, Young K, Wells K (2013) High throughput screening for mammography using a human-computer interface with Rapid Serial Visual Presentation (RSVP), Proceedings of SPIE - The International Society for Optical Engineering 8673
The steady rise of the breast cancer screening population, coupled with data expansion produced by new digital screening technologies (tomosynthesis/CT) motivates the development of new, more efficient image screening processes. Rapid Serial Visual Presentation (RSVP) is a new fast-content recognition approach which uses electroencephalography to record brain activity elicited by fast bursts of image data. These brain responses are then subjected to machine classification methods to reveal the expert's 'reflex' response to classify images according to their presence or absence of particular targets. The benefit of this method is that images can be presented at high temporal rates (
Dean PJA, Sterr A (2010) Post concussion syndrome without head injury?
A survey study,
Brain Injury 3 (24) pp. 423-423
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 p¼0.2), 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 greater scores for all questionnaires p had greater scores for the RPQ, CFQ and HADS
than both groups without PCS (p was only one difference when comparing the two
groups with mTBI to those without (CFQ: mTBI+PCS greater than Control+PCS (p 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
Szameitat D, Kreifelts B, Alter K, Szameitat A, Sterr A, Grodd W, Wildgruber D (2010) It is not always tickling: distinct cerebral responses during perception of different laughter types., Neuroimage 53 (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.
Noone DM, Willis TA, Cox J, Harkness F, Ogilvie J, Forbes E, Sterr A, Gregory AM (2014) Catastrophizing and Poor Sleep Quality in Early Adolescent Females, Behavioral Sleep Medicine 12 (1) pp. 41-52
Catastrophizing about sleeplessness has been investigated in adults and children, but little is known about adolescents. This article aimed to (a) investigate whether early adolescent girls catastrophized about consequences of sleeplessness, (b) describe topics in catastrophizing sequences, (c) examine the association between sleep quality and catastrophizing, and (d) assess whether puberty moderated this association. Girls (n = 115) between 11 and 12 years old completed adapted versions of the Pittsburgh Sleep Quality Index, the Pubertal Developmental Scale, and the Catastrophizing Interview. Twenty-four (21%) participants produced catastrophizing sequences, including concerns about school and mood. Sleep quality was associated with catastrophizing (² = 0.19, p =.042); however, puberty did not moderate this association (² = 0.15, p =.126). Findings highlight the importance of sleep-related cognitions in adolescent girls. © 2014 Copyright Taylor and Francis Group, LLC.
Sterr A, Freivogel S (2003) Motor-improvement following intensive training in low-functioning chronic hemiparesis, Neurology 61 (6) pp. 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.
Sterr A, Shen S, Szameitat AJ, Herron KA (2010) The role of corticospinal tract damage in chronic motor recovery and neurorehabilitation: a pilot study., Neurorehabilitation and Neural Repair 24 (5) pp. 413-419 Sage
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 constraint-induced movement therapy (CIMT).
Landmann N, Kuhn M, Piosczyk H, Feige B, Baglioni C, Spiegelhalder K, Frase L, Riemann D, Sterr A, Nissen C (2014) The reorganisation of memory during sleep, Sleep Medicine Reviews 18 (6) pp. 531-541
© 2014 Elsevier Ltd.Sleep after learning promotes the quantitative strengthening of new memories. Less is known about the impact of sleep on the qualitative reorganisation of memory, which is the focus of this review. Studies have shown that, in the declarative system, sleep facilitates the abstraction of rules (schema formation), the integration of knowledge into existing schemas (schema integration) and creativity that requires the disbandment of existing patterns (schema disintegration). Schema formation and integration might primarily benefit from slow wave sleep, whereas the disintegration of a schema might be facilitated by rapid eye movement sleep. In the procedural system, sleep fosters the reorganisation of motor memory. The neural mechanisms of these processes remain to be determined. Notably, emotions have been shown to modulate the sleep-related reorganisation of memories. In the final section of this review, we propose that the sleep-related reorganisation of memories might be particularly relevant for mental disorders. Thus, sleep disruptions might contribute to disturbed memory reorganisation and to the development of mental disorders. Therefore, sleep-related interventions might modulate the reorganisation of memories and provide new inroads into treatment.
Hou W, Zheng J, Jiang Y, Shen S, Sterr A, Szameitat AJ, van Loon M (2006) A behavior study of the effects of visual feedback on motor output., Conf Proc IEEE Eng Med Biol Soc 1 pp. 1273-1276
Visual feedback is a crucial factor that impacts the motor function, and a number of parameters, such as gain, delay and frequency, all play a role in regulating the motor output. In this paper, we conduct a behavioral study on 12 volunteers to determine the effects of visual feedback in the physical movement by measuring the grasp force output under different visual feedback gain levels. To this end, two force tracking tasks with different incremental/decremental rates of the force have been designed, and the force deviation and the error rate from the 12 participants are recorded when they are exposed to different visual gains. Further statistical analysis on the experimental data reveals that the gain of visual stimuli has a significant influence on the force output. For the same force tracking task, visual feedback with high gain tends to enhance the regulation of force production. The results also suggest that different visual feedback gains may be mapped onto different cortex function areas governing different motor tasks.
Szameitat AJ, Rummel J, Szameltat DP, Sterr A (2009) Behavioral and emotional consequences of brief delays in human-computer interaction, INTERNATIONAL JOURNAL OF HUMAN-COMPUTER STUDIES 67 (7) pp. 561-570 ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
Neumann M, Claros-Salinas D, Guetler R, Ulrich R, Sterr A, Dettmers C (2013) Modulation of alertness by sustained cognitive demand in MS as surrogate measure of fatigue and fatigability,
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.
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 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

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

Dean P, Sato JR, Sterr A (2012) The relationship between structural changes in mTBI and persistent PCS: DTI and cortical thickness analysis, Brain Injury 26 (4-5) pp. 509-509 Informa Healthcare
Mild traumatic brain injury (mTBI) can induce
persistent somatic, affective and cognitive symptoms,
collectively known as post-concussion syndrome
(PCS). It is debated whether this syndrome is
due to biological or psychological factors. Standard
structural imaging only detects lesions in a small
proportion of those with mTBI, and these lesions are
not associated with PCS in the acute ( or chronic (> 3 months) stage. However, microlesions
and diffuse axonal injury (DAI) have been
observed using novel imaging techniques such as
diffusion tensor imaging (DTI). White matter
damage examined in acute and post-acute/chronic
mTBI has been correlated with cognitive and
behavioural measures, as well as outcome from
injury. Increased damage within the white matter
tracts of the corpus callosum and thalamic radiations
is observed in those with poorer outcome at 3
months, whereas grey matter damage is independent
of outcome. This present study aims to investigate
the relation of structural changes and long-term
consequences in more detail by assessing the correlation
between DTI-based indices and persistent
PCS symptomatology. Structural changes were
investigated in participants with chronic (>1 year)
mTBI and persistent PCS (n¼10), participants with
mTBI and no on-going PCS (n¼8) and non-head
injured controls (n¼10). Fractional Anisotropy (FA)
and cortical thickness were compared between
groups to assess white matter integrity and focal
damage respectively. In addition, the association
between neural structure and level of PCS symptom
report was evaluated. We hypothesised that long
fibre white matter bundles, such as the corpus
callosum, would be damaged in participants with
chronic mTBI, with cortical thinning around these
areas. Furthermore, we hypothesised that this
damage would be related to the persistent PCS
symptoms seen after mTBI. If PCS has a biological
basis, then participants with mTBI and persistent
PCS may have sustained greater damage to these areas at the time of injury than participants without
ongoing symptoms. Preliminary analysis demonstrates
a reduction in cortical thickness and white
matter integrity in participants with chronic (>1
year) mTBI, independent of PCS, compared to
controls. Diminished cortical thickness and white
matter integrity were seen for cingulate cortex and
corpus callosum. In addition, similar reductions
were observed when comparing mTBI participants
without PCS to those with PCS. This suggests that
persistent PCS m
Sterr A, Dean PJA, Mathews S (2006) Ageing in Motor Control: Behavioural and ERP correlates of Motor Priming in the Elderly.,
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.
Szameitat AJ, Lepsien J, von Cramon DY, Sterr A, Schubert T (2006) Task-order coordination in dual-task performance and the lateral prefrontal cortex: an event-related fMRI study, Psychological Research-Psychologische Forschung 70 (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.
Herron K, Dijk DJ, Dean P, Seiss E, Sterr A (2009) EEG-Derived biomarkers for daytime sleepiness in patients with chronic stroke, Special Issue: Society for Psychophysiological Research Abstracts for the Forty-Ninth Annual Meeting 46 (Supplement s1) Wiley-Blackwell
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.
Dean P, Perkins L, McNamara A, Sauseng P, Sterr A (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, BRAIN INJURY 28 (5-6) pp. 656-656 INFORMA HEALTHCARE
Mathews S, Dean PJA, Sterr A (2006) EEG dipole analysis of motor-priming foreperiod activity reveals separate sources for motor and spatial attention components, CLINICAL NEUROPHYSIOLOGY 117 (12) pp. 2675-2683 ELSEVIER IRELAND LTD
Dean PJ, Otaduy MC, Harris LM, McNamara A, Seiss E, Sterr A (2013) Monitoring long-term effects of mild traumatic brain injury with magnetic resonance spectroscopy: a pilot study., Neuroreport 24 (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.
Grunze H, Amann B, Schafer M, Sterr A, Schaerer L, Wild E, Walden J (2000) Efficacy, safety and practicability of valproate delayed release minitablets in bipolar affective disorders, Fortschritte der Neurologie Psychiatrie 68 (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.
Sterr A (2004) Training-based interventions in motor rehabilitation after stroke: Theoretical and clinical considerations, Behavioural Neurology 15 (3-4) pp. 55-63
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.
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.
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 d
McNamara A, Moakes K, Aston P, Gavin C, Sterr A (2014) The importance of the derivative in sex-hormone cycles: a reason why behavioural measures in sex-hormone studies are so mercurial., PLoS One 9 (11)
To study the dynamic changes in cognition across the human menstrual cycle, twenty, healthy, naturally-cycling women undertook a lateralized spatial figural comparison task on twelve occasions at approximately 3-4 day intervals. Each session was conducted in laboratory conditions with response times, accuracy rates, eye movements, salivary estrogen and progesterone concentrations and Profile of Mood states questionnaire data collected on each occasion. The first two sessions of twelve for the response variables were discarded to avoid early effects of learning thereby providing 10 sessions spread across each participant's complete menstrual cycle. Salivary progesterone data for each participant was utilized to normalize each participant's data to a standard 28 day cycle. Data was analysed categorically by comparing peak progesterone (luteal phase) to low progesterone (follicular phase) to emulate two-session repeated measures typical studies. Neither a significant difference in reaction times or accuracy rates was found. Moreover no significant effect of lateral presentation was observed upon reaction times or accuracy rates although inter and intra individual variance was sizeable. We demonstrate that hormone concentrations alone cannot be used to predict the response times or accuracy rates. In contrast, we constructed a standard linear model using salivary estrogen, salivary progesterone and their respective derivative values and found these inputs to be very accurate for predicting variance observed in the reaction times for all stimuli and accuracy rates for right visual field stimuli but not left visual field stimuli. The identification of sex-hormone derivatives as predictors of cognitive behaviours is of importance. The finding suggests that there is a fundamental difference between the up-surge and decline of hormonal concentrations where previous studies typically assume all points near the peak of a hormonal surge are the same. How contradictory findings in sex-hormone research may have come about are discussed.
Plow EB, Sankarasubramanian V, Cunningham DA, Potter-Baker K, Varnerin N, Cohen LG, Sterr A, Conforto AB, Machado AG (2016) Models to Tailor Brain Stimulation Therapies in Stroke, NEURAL PLASTICITY ARTN 4071620 HINDAWI PUBLISHING CORP
Dean P, Sterr A (2012) Long-term effects of mild traumatic brain injury on cognitive performance, Brain Injury 26 (4-5) pp. 395-396 Informa Healthcare
Impairments in attention, memory, executive function and information processing have been observed in chronic mild traumatic brain injury (mTBI) participants. However, the results have been variable and inconsistent, with many studies reporting no observable deficit. This variability is not unexpected as participants with mTBI form a relatively heterogeneous group, with differing severity of initial injury and subsequent outcome. More consistent results may be possible if studies reduce this variability by considering the extent of post-concussion syndrome (PCS) in their samples. If PCS is caused by biological processes at the time of injury, then greater damage should prompt longer lasting PCS symptoms. However, the symptoms used to diagnose PCS are not specific to mTBI, but are also observed in clinical populations (e.g. depression, chronic pain, post-traumatic stress) as well as healthy non-head injured individuals. Therefore, studies of long-term deficits arising from mTBI should monitor PCS in both patients and healthy volunteers. Consequently, the current study compared cognitive performance in four groups (all n=18), with both chronic (> 1 year) mTBI and control (non-head injured) participants split by level of PCS symptom report. We hypothesised that mTBI participants reporting on-going PCS symptoms would have sustained greater damage at the time of injury, and would consequently have greater cognitive deficit. In contrast, head-injured individuals whose PCS symptoms have recovered, and those without prior head injury (controls) are likely to have no evidence of cognitive dysfunction. Cognitive function was assessed with a working memory (n-Back) and an information processing (Paced Visual Serial Addition Task, PVSAT) task, each with four levels of difficulty. This experimental manipulation was chosen because of the assumption that cognitive deficits in participants with chronic mTBI would be more prominent in high task-demand conditions. Results showed that only the group with mTBI and persistent PCS had significantly more errors on both tasks. This difference was observed at every difficulty level for both PVSAT and n-Back (except 0-Back) tasks, suggesting impaired performance on even the easiest working memory and information processing tasks. Moreover, mTBI participants with greater PCS severity exhibited inferior performance in the 3-Back condition.This finding supports the assumption that symptom severity in the chronic state is likely to be
Sterr A, Szameitat A, Shen S, Freivogel S (2006) Application of the CIT concept in the clinical environment - Hurdles, practicalities, and clinical benefits, COGNITIVE AND BEHAVIORAL NEUROLOGY 19 (1) pp. 48-54 LIPPINCOTT WILLIAMS & WILKINS
Wallace A, Dewar L, Sterr A, Hanna M, Trenell M, Pietrusz A, Dudziec M, Hennis P, Stokes R, Reilly M, Ramdharry G (2015) Normative aerobic exercise values in CMT, NEUROMUSCULAR DISORDERS 25 pp. S285-S286 PERGAMON-ELSEVIER SCIENCE LTD
Shen S, Szameitat AJ, Sterr A (2010) An improved lesion detection approach based on similarity measurement between fuzzy intensity segmentation and spatial probability maps., Magn Reson Imaging 28 (2) pp. 245-254
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.
Sterr A, Freivogel S, Schmalohr D (2002) Neurobehavioral aspects of recovery: Assessment of the learned nonuse phenomenon in hemiparetic adolescents, Archives of Physical Medicine and Rehabilitation 83 (12) pp. 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. Setting: Rehabilitation clinic in southwest Germany. 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 spontaneoususe 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. © 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.
Elbert T, Sterr A, Rockstroh B, Charbonnier D, Flor H, Pantev C, Wienbruch C, Knecht S, Taub E (2000) Cortical reorganization in arm amputees: Alterations of the somatosensory representation of the intact arm, BIOMAG 96: PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON BIOMAGNETISM, VOLS I & II pp. 999-1002
Sterr A (2007) Neuroplasticity, In: Gauggel S, Herrmann M (eds.), Handbook of Neurophysiology Springer Verlag
Herron K, Dijk D, Ellis J, Sanders J, Sterr A (2008) Sleep correlates of motor recovery in chronic stroke: a pilot study using sleep diaries and actigraphy,
Introduction: Sleep facilitates neuroplasticity (Tononi & Cirelli,
2006), an important process for post-stroke recovery, particularly
when re-learning motor skills. Associations between poor sleep and
poorer recovery during the acute phase have been reported (Good
et al. 1996; Gottselig et al. 2002). In addition, increased subjective
sleep needs have been associated with poorer outcome during the
chronic phase (Hermann, et al. 2008). However motor recovery,
which is of particular relevance for sleep dependent neuroplasticity,
has not been addressed. We aimed to investigate sleep behaviour in
the context of motor recovery within a homogenous stroke patient
sample during the chronic phase.
Method: Twelve patients with chronic upper limb hemiparesis
(412 months) completed sleep diaries (SD) and wore an actiwatch
(Cambridge Neurotechnology Ltd.) for two weeks. The SD
included twice daily Karolinska Sleepiness Scale (KSS) and Daily
Fatigue Scale (D-FIS) measures. Residual motor ability was
assessed through a series of neurobehavioural motor tests.
Results: Increasing daytime nap length (SD and actigraphy)
significantly correlated, or by near significant trend with better
motor ability on all neurobehavioural tests. Age was not associated
with napping behaviour or residual motor ability. Chronicity,
psychological adjustment, health, or nocturnal sleep did not
correlate with napping behaviour (SD and actigraphy) or motor
ability. Furthermore, increased subjective fatigue was associated
with increased napping behaviour.
Discussion and Conclusion: Patients who habitually napped had
better residual movement ability at least one year after stroke. It
may be that the benefits of napping facilitate performance as well as
consolidating motor learning. This has been shown in healthy
persons (Backhaus & Junghanns, 2006; Nishida & Walker, 2007)
which may translate into motor skill re-learning during stroke
recovery. Although the data is suggestive, previous rehabilitation
and medical care will contribute to residual motor ability in addition to the reported napping behaviour, therefore further clarification is required.
Rockstroh B, Clementz BA, Pantev C, Blumenfeld LD, Sterr A, Elbert T (1998) Failure of dominant left-hemispheric activation to right-ear stimulation in schizophrenia., Neuroreport 9 (17) pp. 3819-3822
Schizophrenia is associated with an absence of the lateralizations that typify the human brain. Previous evidence emphasized structural changes, particularly reduced asymmetry in extension and surface of the planum temporale, although gross structural deviations occur only in a minority of patients. The present study describes an absence of lateralization on a robust functional measure that characterized schizophrenia patients: healthy subjects but not schizophrenics displayed a contralateral left-hemispheric dominance of the auditory evoked magnetic field to right-ear auditory stimulation. Absence of contralateral dominance in response to auditory stimuli among schizophrenia patients may indicate a failure to establish unequivocal left-hemispheric dominance of the phonological loop as hypothesized by Crow.
Kuhn M, Wolf E, Maier JG, Mainberger F, Feige B, Schmid H, Buerklin J, Maywald S, Mall V, Jung NH, Reis J, Spiegelhalder K, Kloeppel S, Sterr A, Eckert A, Riemann D, Normann C, Nissen C (2016) Sleep recalibrates homeostatic and associative synaptic plasticity in the human cortex, Nature Communications 7 12455 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.
Dean PJ, O'Neill D, Sterr A (2012) Post-concussion syndrome: Prevalence after mild traumatic brain injury in comparison with a sample without head injury., Brain Injury 26 (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.
Berger B, Omer S, Minarik T, Sterr A, Sauseng P (2014) Interacting memory systems-does EEG alpha activity respond to semantic long-term memory access in a working memory task?, 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.
Kranczioch C, Mathews S, Dean PJA, Sterr A (2009) On the Equivalence of Executed and Imagined Movements: Evidence from Lateralized Motor and Nonmotor Potentials, HUMAN BRAIN MAPPING 30 (10) pp. 3275-3286 WILEY-BLACKWELL
Magalhaes SC, Kaelin-Lang A, Sterr A, do Prado GF, Eckeli AL, Conforto AB (2015) Transcranial magnetic stimulation for evaluation of motor cortical excitability in restless legs syndrome/Willis-Ekbom disease, SLEEP MEDICINE 16 (10) pp. 1265-1273 ELSEVIER SCIENCE BV
Jehoel S, Sowden PT, Ungar S, Sterr A (2009) Tactile elevation perception in blind and sighted participants and its implications for tactile map creation., Human Factors 51 (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.
Sterr A, Dean PJA, Sato JR, Vieira G, Conforto AB, Shen S (2013) Cortical thickness changes in the non-lesioned hemisphere associated with non-paretic arm immobilization in modified CI therapy, NeuroImage: Clinical 2 (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.
Sterr A, Freivogel S (2004) Intensive training in chronic upper limb hemiparesis does not increase spasticity or synergies, Neurology 63 (11) pp. 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.
Hope C, Seiss E, Dean P, Sterr A (2009) An electrophysiological investigation of glucose administration effects on movement preparation and execution, Psychophysiology. Special Issue: Society for Psychophysiological Research Abstracts for the Forty-Ninth Annual Meeting 46 (Supplement s1) Wiley-Blackwell
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.
Sterr A, Shen S, Zaman A, Roberts N, Szameitat A (2007) Activation of SI is modulated by attention: a random effects fMRI study using mechanical stimuli, Neuroreport 18 (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.
Sterr A, Furlan L (2015) A case to be made: theoretical and empirical arguments for the need to consider fatigue in post-stroke motor rehabilitation, NEURAL REGENERATION RESEARCH 10 (8) pp. 1195-1197 MEDKNOW PUBLICATIONS & MEDIA PVT LTD
Szameitat AJ, Lepsien J, von Cramon DY, Sterr A, Schubert T (2006) Task-order coordination in dual-task performance and the lateral prefrontal cortex: an event-related fMRI study., Psychol Res 70 (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.
Elbert T, Sterr AM, Rockstroh B, Pantev C, Muller M, Taub E (2002) Expansion of the tonotopic area in the auditory cortex of the blind, Journal of Neuroscience 22 (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.
Neumann M, Claros-Salinas D, Gütler R, Dettmers C, Sterr A, Ulrich R (2014) Modulation of alertness by sustained cognitive demand in MS as surrogate measure of fatigue and fatigability, Journal of the Neurological Sciences 340 (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.
Dean PJ, Seiss E, Sterr A (2012) Motor Planning in Chronic Upper-Limb Hemiparesis: Evidence from Movement-Related Potentials., PLoS One 7 (10) 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.

Sterr A, Schmalohr D, Kolbel S, Freivogel S (2000) Transcranial magnetic stimulation-based investigation of motor cortex reorganization after repetitive training in brain-injured patients, PSYCHOPHYSIOLOGY 37 pp. S95-S95
Sterr A, Freivogel S, Voss A (2002) Exploring a repetitive training regime for upper limb hemiparesis in an in-patient setting: A report on three case studies, Brain Injury 16 (12) pp. 1093-1107
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 (A = RTx; B = regular 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.
Shen S, Sterr A, Szameitat A (2005) A template effect study on voxel-based morphometry in Statistic Parametric Mapping, In: 2005 27th Annual International Conference of the Ieee Engineering in Medicine and Biology Society, Vols 1-7 pp. 3051-3054 IEEE
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.
Herron K, Dijk D, Dean PJA, Seiss E, Sterr A (2014) Quantitative Electroencephalography and Behavioural
Correlates of Daytime Sleepiness in Chronic Stroke,
BioMed Research Internationl 2014 794086
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.
Halder P, Sterr A, Brem S, Bucher K, Kollias S, Brandeis D (2005) Electrophysiological evidence for cortical plasticity with movement repetition, European Journal of Neuroscience 21 (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.
Mathews S, Dean P, Sterr AM (2006) EEG dipole analysis of motor-priming foreperiod activity
reveals separate sources for motor and spatial attention components.,
Clinical Neurophysiology 117 (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.
Sterr A, Shen S, Kranczioch C, Szameita A, Hou W, Sorger B (2009) fMRI effects of task demand and feedback accuracy on grip force tracking, Neuroscience Letters 457 pp. 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.

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.

Parker Wendy, Gage Heather, Sterr Annette, Williams Peter (2017) Holiday play for disabled children in England: access, choice and parents? views about integration, International Journal of Disability, Development and Education 64 (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.
Dean PJA, Sterr AM (2013) Long-term effects of mild traumatic brain injury on cognitive performance, Frontiers in Human Neuroscience 7 30 pp. 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.
Dean PJA, Sato J, Vieira G, McNamara A, Sterr AM (2014) Multimodal imaging of mild traumatic brain injury and persistent postconcussion syndrome, 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.
Frase L, Piosczyk H, Zittel S, Jahn F, Selhausen P, Krone L, Feige B, Mainberger F, Maier J, Kuhn M, Kloppel S, Normann C, Sterr AM, Spiegelhalder K, Riemann D, Nitsche M, Nissen C (2016) Modulation of total sleep time by transcranial direct current stimulation (tDCS), 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.
Sterr AM, Müller M, Elbert T, Rockstroh B, Pantev C, Taub E (1998) Perceptual Correlates of Changes in Cortical Representation of Fingers in Blind Multifinger Braille Readers, The Journal of Neuroscience 18 pp. 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.

Sterr AM, Dean PJA, Mathews S (2008) Preparing the unlikely event - when no-response priming activates the motor system, In: Conti G (eds.), 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.
Kranczioch C, Athanassiou S, Shen S, Gao G, Sterr AM (2008) Short-term learning of a visually guided power-grip task is associated with dynamic changes in EEG oscillatory activity, Clinical Neurophysiology 119 (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.
Sterr AM, Shen S, Szameitat A, Herron K (2010) The Role of Corticospinal Tract Damage in Chronic Motor Recovery and Neurorehabilitation: A Pilot Study, Neurorehabilitation and Neural Repair 24 (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

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.
Shen S, Szameitat A, Sterr AM (2007) VBM lesion detection depends on the normalization template: a study using simulated atrophy, Magnetic Resonance Imaging 25 (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.
Dean PJA, Arikan G, Opitz B, Sterr AM (2017) Potential for use of creatine supplementation following mild traumatic brain injury, Concussion 2 (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.
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
Kidd T, Carey N, Mold F, Westwood S, Miklaucich M, Konstantara E, Sterr A, Cooke D (2017) A Systematic Review of the Effectiveness of Self-Management Interventions in People with Multiple Sclerosis at Improving Depression, Anxiety and Quality of Life., PLoS ONE 12 (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.

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.
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.
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.
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

Szameitat D, Kreifelts B, Alter K, Szameitat A, Sterr A, Wolfgang G, Wildgruber D (2010) It is not always tickling: Distinct cerebral responses during perception of different laughter types, NeuroImage 53 pp. 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
Shen S, Szameitat A, Sterr A (2008) Detection of Infarct Lesions From Single MRI Modality Using Inconsistency Between Voxel Intensity and Spatial Location?A 3-D Automatic Approach, IEEE Transactions on Information Technology in Biomedicine 12 (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.

Sterr A., Kuhn M., Nissen C., Ettine D., Funk S., Feige B., Umarova R., Urbach H., Weiller C., Riemann D. (2018) Post-stroke insomnia in community-dwelling patients with chronic motor stroke: Physiological evidence and implications for stroke care, Scientific Reports 8 (1) 8409 pp. 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.
Maier Jonathan G., Piosczyk Hannah, Holz Johannes, Landmann Nina, Deschler Christoph, Frase Lukas, Kuhn Marion, Klöppel Stefan, Spiegelhalder Kai, Sterr Annette, Riemann Dieter, Feige Bernd, Voderholzer Ulrich, Nissen Christoph (2017) Brief periods of NREM sleep do not promote early offline gains but subsequent on-task performance in motor skill learning, Neurobiology of Learning and Memory 145 pp. 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.