Professor Bertram Opitz
Bertram Opitz studied Biophysics at the Russian State University in Moscow, Russia. He was a PhD student at the Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig and received his doctoral degree in 2000. Until autumn 2001 he continued working as a post-doc researcher and then moved to Saarland University as an Assistant Professor for Cognitive Neuroscience. Bertram joined the Brain & Behaviour Group in August 2012 as a Professor for Neuroimaging. Since 2015 he is leading the Brain and Behaviour Group.
Areas of specialism
University roles and responsibilities
- Section Lead Brain & Behaviour
- Co-Chair of UEC Review Panel 1
- Member of UEC Steering Panel
My research focuses on the neural underpinnings of learning and memory. I'm primarily interested in the neural mechanisms of language acquisition and what factors influence the learning process. Current projects aiming on the role of learning instructions and feedback on (mainly second) language acquisition.
I'm also interested in the functional architecture of different memory systems and the processes by which information is transferred between these memory systems. In current research projects I investigate the processes of creating new enduring memory traces and modulating existing ones. Other projects focus on how we can exert control over our memories, and how these control processes could be trained. The main focus of these projects lies on training induced changes in the neural network in healthy participants and patient samples.
To achieve a comprehensive understanding of learning and memory systems I primarily examine the neural organization of these systems using well established neuroimaging techniques, like event-related potentials and functional magnetic resonance tomography in combination with neural stimulation techniques like transcranial magnetic stimulation (TMS) to investigate the neural correlates of learning and memory.
Postgraduate research supervision
Courses I teach on
Feedback Processing & Cognitive Training
A few papers looking into possibilities to enhance learning. An important aspect that should be looked at is how the information provided by feedback is actually processed in the brain. Here the timing seems of special importance. In addition, training of some cognitive abilities like working memory seems to be beneficial for a broad variety of learning scenarios like second language acquisition
Jones DL, Nelson JD, Opitz B. Increased Anxiety is Associated with Better Learning from Negative Feedback. Psychology Learning & Teaching. 2021;20(1):76-90. doi:10.1177/1475725720965761
Dainton, C., Winstone, N., Klaver, P. & Opitz, B. (2019) Utility of feedback has a greater impact on learning than ease of decoding. Mind Brain Education. doi:10.1111/mbe.12227
Ferdinand, N. K. & Opitz, B. (2014) Different aspects of performance feedback engage different brain areas: Disentangling the neural correlates of valence and expectancy in feedback processing. Scientific Reports 4, doi:10.1038/srep05986.
Opitz, B., Ferdinand, N.K. & Mecklinger, A. (2011) Timing matters: The impact of immediate and delayed feedback on artificial language learning. Frontiers in Human Neuroscience 5:8, doi: 10.3389/fnhum.2011.00008
Ferdinand, N. K. & Opitz, B. (2014) Different aspects of performance feedback engage different brain areas: Disentangling the neural correlates of valence and expectancy in feedback processing. Scientific Reports 4, Article number: 5986 doi:10.1038/srep05986.
Artificial Language Learning
A few papers highlighting that two distinct learning mechanisms concur during the acquisition of a second (artificial) language. Initially, people learn the grammar of a language by judging the similarity of novel sentence in reference to known sentences previously encountered. During the course of learning grammatical rules are abstracted and used more and more effectively.
Opitz, B. & Hofmann, J. (2015) Concurrence of rule- and similarity-based mechanisms in artificial grammar learning. Cognitive Psychology 77, 77–99. doi:10.1016/j.cogpsych.2015.02.003
Opitz, B. & Friederici, A.D. (2003) Interactions of the hippocampal system and the prefrontal cortex in learning language like-rules. NeuroImage 19, 1730-1737. doi: 10.1016/S1053-8119(03)00170-8
Learning & Memory
Some publications highlighting the neural underpinnings of successful learning. While the hippocampus seems to be involved in learning the relationship between elements of the same learning event (e.g., a single lecture) the prefrontal cortex is capable of generalising the commonalities across multiple such events to generate a long-lasting memory of this newly learned knowledge.
Dunne, L., and Opitz, B. (2020). Attention control processes that prioritise task execution may come at the expense of incidental memory encoding. Brain and Cognition, 144(June), 105602. https://doi.org/10.1016/j.bandc.2020.105602
Bader, R., Opitz, B., Reith, W., Mecklinger, A. (2014) Is a novel conceptual unit more than the sum of its parts?: FMRI evidence from an associative recognition memory study. Neuropsychologia 61, 123-134
Opitz, B. (2010) Neural binding mechanisms in learning and memory. Neuroscience & Biobehavioral Reviews 34, 1036-1046 doi: 10.1016/j.neubiorev.2009.11.001
Spitzer, B.J., Hanslmayr, S., Opitz, B., Mecklinger, A. & Bäuml, K.-H. (2009) Oscillatory Correlates of Retrieval-Induced Forgetting in Recognition Memory. Journal of Cognitive Neuroscience 21, 976-990. doi:10.1162/jocn.2009.21072
Doeller, C. F., Opitz, B., Krick,C. M., Mecklinger, A. & Reith, W. (2005) Prefrontal-hippocampal dynamics involved in learning regularities across episodes. Cerebral Cortex 15, 1123-1133. doi: 10.1093/cercor/bhh211
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.
People are drawn toward personally meaningful places. Seeing or remembering those places improves mood and supports wellbeing. But existing evidence relies on self-reports and comparisons with unpleasant places. Using brain imaging techniques, we examined reactions towards images of personally meaningful places, meaningful objects, neutral places and objects, and pre-validated (IAPS) images, among 19 volunteers (10 female) between 19 and 53 years old. A whole brain analysis showed that meaningful places and IAPS images elicited the largest response in the amygdala, associated with the processing of emotion. Similarly high activity was found for the medial prefrontal cortex (mPFC),associated with self-referential processing, emotional appraisal, and memory processing. This was not found for meaningful objects or neutral places. The parahippocampal place area (PPA) showed enhanced activity only to personally meaningful places. Personally meaningful places clearly evoke distinctive neurological responses supporting the importance of this holistic and complex concept for human wellbeing.
There has been a long tradition in memory research of adopting the view of a vital role of the medial temporal lobe and especially the hippocampus in declarative memory. Despite the broad support for this notion, there is an ongoing debate about what computations are performed by the different substructures. The present chapter summarizes several accounts of hippocampal functions in terms of the cognitive processes subserved by these structures, the information processed, and the underlying neural operations. Firstly, the value of the distinction between recollection and familiarity for the understanding of the role the hippocampus plays in memory is discussed. Then multiple lines of evidence for the role of the hippocampus in memory are considered. Cumulating evidence suggests that the hippocampus fosters the binding of disparate cortical representations of items and their spatiotemporal context into a coherent representation by means of a sparse conjunctive neural coding. This association of item and context will then lead to the phenomenological experience of recollection. In contrast, surrounding cortical areas have broader neural coding that provide a scalar signal of the similarity between two inputs (e.g. between the encoding and the retrieval). By this they form the basis of a feeling of familiarity, but also might encode the commonalities between these different inputs. However, a more complete picture of the importance of the hippocampus for declarative memories can only be drawn when the interactions of the medial temporal lobe with other brain areas are also taken into account.
Two types of encoding tasks have been employed in previous research to investigate the beneficial effect of unitisation on familiarity-based associative recognition (unitised familiarity effect), namely the compound task and the interactive imagery task. Here we show how these two tasks could differentially engage subsequent recollection-based associative recognition and consequently lead to the turn-on or turn-off of the unitised familiarity effect. In the compound task, participants studied unrelated word pairs as newly learned compounds. In the interactive imagery task, participants studied the same word pairs as interactive images. An associative recognition task was used in combination with the Remember/Know procedure to measure recollection-based and familiarity-based associative recognition. The results showed that the unitised familiarity effect was present in the compound task but was absent in the interactive imagery task. A comparison of the compound and the interactive imagery task revealed a dramatic increase in recollection-based associative recognition for the interactive imagery task. These results suggest that unitisation could benefit familiarity-based associative recognition; however, this effect will be eliminated when the memory trace formed is easily accessed by strong recollection without the need for a familiarity assessment.
The possible transfer of musical expertise to the acquisition of syntactical structures in first and second language has emerged recently as an intriguing topic in the research of cognitive processes. However, it is unlikely that the benefits of musical training extend equally to the acquisition of all syntactical structures. As cognitive transfer presumably requires overlapping processing components and brain regions involved in these processing components, one can surmise that transfer between musical ability and syntax acquisition would be limited to structural elements that are shared between the two. We propose that musical expertise transfers only to the processing of recursive long-distance dependencies inherent in hierarchical syntactic structures. In this study, we taught fifty-six participants with widely varying degrees of musical expertise the artificial language BROCANTO, which allows the direct comparison of long-distance and local dependencies. We found that the quantity of musical training (measured in accumulated hours of practice and instruction) explained unique variance in performance in the long-distance dependency condition only. These data suggest that musical training facilitates the acquisition specifically of hierarchical syntactic structures.
Memory enhancement after repeated presentation of to-be-learned material is a wellknown phenomenon. It has been assumed that the repeated presentation of features common to a number of specific instances leads to decontextualized facts about the world, i.e., semantic knowledge. To investigate this issue, subjects studied celebrity faces along with faces of unknown individuals. Crucially, half of the unknown faces were repeated within the same study context (background and biographical information) while for the other half the contextual features changed across repetitions. Celebrity faces were chosen because they carry with them biographical information. The electrophysiological correlates of conceptual priming and explicit memory for these faces were examined. Explicit memory retrieval was associated with the early frontal old/new effect, the ERP correlate of familiarity, and the late parietal old/new effect, indexing recollection. Both ERP effects were elicited by celebrity faces and non-famous faces repeatedly studied in different contexts, whereas non-famous faces repeated in the same context elicited only the parietal old/new effect. Furthermore, conceptual priming was indexed by positive brain potentials over fronto-central regions, in addition to faster reaction times for previously presented faces. Again, a striking similarity between effects elicited by celebrity faces and non-famous faces repeated in varying contexts was observed. This indicates that repetition of features across different contexts bears some similarity to semantic knowledge.
•During top-down attention, coupling between lateral occipital cortex and fusiform gyrus indexed encoding success.•During top-down attention, coupling between dorsal parietal cortex and fusiform gyrus indexed encoding failure.•Bottom-up attention did not significantly modulate functional connectivity during encoding. Attention underpins episodic memory encoding by gating information processing. However, it is unclear how different forms of attention affect encoding. Using fMRI, we implemented a novel task that separates top-down and bottom-up attention (TDA; BUA) to test how these forms of attention influence encoding. Twenty-seven subjects carried out a scanned incidental encoding task that required semantic categorisation of stimuli. Trials either required visual search (TDA) to locate a target, or the target blinked and captured attention (BUA). After a retention period, subjects performed a surprise recognition test. Univariate analyses showed that ventral visual regions and right hippocampus indexed encoding success. Psychophysiological interaction analyses showed that, during TDA, there was increased coupling between dorsal parietal cortex and fusiform gyrus with encoding failure, and between lateral occipital cortex and fusiform gyrus with encoding success. No significant connectivity modulations were observed during BUA. We propose that increased TDA to objects in space is mediated by parietal cortex and negatively impacts encoding. Also, increases in connectivity within ventral visual cortex index the integration of stimulus features, promoting encoding. Finally, the influences of attention on encoding likely depend on task demands: as cognitive control increases, task execution is emphasised at the expense of memory encoding.
The study assessed a new mobile electroencephalography (EEG) system with water-based electrodes for its applicability in time-frequency and event related potential research. It was compared to a standard gel-based wired system. EEG was recorded on two occasions as participants completed the flanker task, first with the gel-based system followed by the water-based system. Technical and practical considerations for the application of the new water-based system are reported based on the participant and experimenter experiences. Empirical comparisons focused on EEG data noise levels, frequency power across four bands including theta, alpha, low beta and high beta and P300 and ERN event related potential components. The water-based system registered more noise compared to the gel-based system which resulted in increased loss of data during artefact rejection. Signal to noise ratio was significantly lower for the water-based system in the parietal channels which impacted the observed parietal beta power. It also led to a shift in topography of the maximal P300 activity from parietal to frontal regions. It is also evident, that the water-based system may be prone to slow drift noise which may affect the reliability and consistency of low frequency band analyses. Considerations for the use of this specific system for time-frequency and event related potentials are discussed.
Focused attention meditation (FAM) practices are cognitive control exercises where meditators learn to maintain focus and attention in the face of distracting stimuli. Previous studies have shown that FAM is both activating and causing plastic changes to the mesolimbic dopamine system and some of its target structures, particularly the anterior cingulate cortex (ACC) and striatum. Feedback-based learning also depends on these systems and is known to be modulated by tonic dopamine levels. Capitalizing on previous findings that FAM practices seem to cause dopamine release, the present study shows that FAM experience predicts learning from negative feedback on a probabilistic selection task. Furthermore, meditators exhibited attenuated feedback-related negativity (FRN) as compared with nonmeditators and this effect scales with meditation experience. Given that reinforcement learning and FRN are modulated by dopamine levels, a possible explanation for our findings is that FAM practice causes persistent increases in tonic dopamine levels which scale with amount of practice, thus altering feedback processing.
— While feedback is a key facilitator of learning , researchers have yet to determine the ideal feedback process for optimal performance in learners. The current study investigates the combined effects of ease of decoding, and utility of feedback during learning. Accuracy and rate of learning were recorded alongside changes to the feedback related negativity (FRN), an event-related potential (ERP) elicited by feedback stimuli. This study investigates the FRN within the context of future-focused directive feedback (DF), in addition to past-focused evaluative feedback (EF) typically seen in the neuroscience literature. Results indicate a main effect of utility together with an interaction with ease of decoding on the accuracy data, but only the main effect of utility on learning rate. DF produced an FRN, like EF, which was then larger during high-utility feedback, specifically following negative EF or when hard-to-decode. Implications and future research directions are discussed.
Motor proficiency reflects the ability to perform precise and coordinated movements in different contexts. Previous research suggests that different profiles of motor proficiency may be associated with different cognitive functioning characteristics thus suggesting an interaction between cognitive and motor processes. The current study investigated this interaction in the general population of healthy adults with different profiles of motor proficiency by focusing on error-related cognitive control and behavioral adaptation mechanisms. In addition, the impact of these processes was assessed in terms of trait anxiety and worries. Forty healthy adults were divided into high and low motor proficiency groups based on an assessment of their motor skills. Using electroencephalography during a flanker task, error-related negativity (ERN) was measured as the neural indicator of cognitive control. Post-error slowing (PES) was measured to represent behavioral adaptation. Participants also completed an anxiety assessment questionnaire. Participants in the high motor proficiency group achieved better task accuracy and showed relatively enhanced cognitive control through increased ERN. Contrastingly, individuals in the lower motor proficiency group achieved poorer accuracy whilst showing some evidence of compensation through increased PES. Trait anxiety reflecting general worries was found to be correlated with motor functioning, but the study could not provide evidence that this was related to cognitive or behavioral control mechanisms. The interaction between cognitive and motor processes observed in this study is unique for healthy and sub-clinical populations and provides a baseline for the interpretation of similar investigations in individuals with motor disorders.
Reading digital texts is a common practice in today's education. Prior studies showed that the coherence of a text can influence text comprehensibility with low degrees of coherence causing attention failures (mind wandering) and, consequently, negatively impacts reading comprehension. In addition, working memory capacity (WMC) and prior knowledge of the subject have been suggested to be related to both reading comprehension and mind wandering. However, results remain controversial as the interaction of these three factors has not yet been explored. Ninety participants either studying law or a different subject read either a coherent or incoherent version of the same unfamiliar hypertext about the copyright law. While reading, they reported self-caught mind wandering with task-embedded thought probes. After reading the hypertext, participants were tested on their text comprehension. Supporting prior findings, mind wandering did occur more frequently when participants read difficult rather than easy texts regardless of their undergraduate course. Moreover, this was modulated by WMC in that participants with lower WMC exhibited more frequent mind wandering than high WMC participants solely when reading low coherent texts. In addition, high WMC participants outperformed low WMC participants on all measures of text comprehension. With a low WMC it seems difficult to inhibit irrelevant information and access related information from working memory, especially when text complexity is high. Interestingly, the present results also indicate that prior knowledge benefits later text comprehension despite not affecting reader's attention. These findings provide insights into processing attention during reading online texts.
To explain varying previous results as to whether bilinguals show an advantage over monolinguals in inhibitory control, two hypotheses have been suggested. The Bilingual Inhibitory Control Advantage (BICA) hypothesis proposes a bilingual advantage specific to the presence of conflict. In contrast, the Bilingual Executive Processing Advantage (BEPA) hypothesis proposes a global advantage in processing, across all contexts. The present research contrasts these hypotheses by investigating the effects of second language immersion and similarity of colour terms across languages on the bilingual Stroop task. Ten English and ten German native speakers, residing in Munich, Germany, completed a bilingual Stroop task using stimuli with colour terms which were similar or dissimilar between the two languages. Event-related potentials were recorded alongside behavioural data. Dissimilar stimuli showed greater costs, reflected by increased reaction times (RTs), more negative N400 amplitudes and more positive Late Positive Component (LPC) amplitudes, than similar stimuli. Participants who were immersed in a second language environment experienced greater costs, which were specific to conflict trials for RT and LPC measures, but occurred across all trial types during the N400 window. It was concluded that in contrast to previous research only supporting BEPA, there is also evidence for the BICA hypothesis.
A current theoretical debate regards whether rule-based or similarity based learning prevails during artificial grammar learning (AGL). Although the majority of findings are consistent with a similarity based account of AGL it has been argued that these results were obtained only after limited exposure to study exemplars, and performance on subsequent grammaticality judgment tests has often been barely above chance level. In three experiments the conditions were investigated under which rule-and similarity based learning could be applied. Participants were exposed to exemplars of an artificial grammar under different (implicit and explicit) learning instructions. The analysis of receiver operating characteristics (ROC) during a final grammaticality judgment test revealed that explicit but not implicit learning led to rule knowledge. It also demonstrated that this knowledge base is built up gradually while similarity knowledge governed the initial state of learning. Together these results indicate that rule-and similarity-based mechanisms concur during AGL. Moreover, it could be speculated that two different rule processes might operate in parallel ; bottom-up learning via gradual rule extraction and top-down learning via rule testing. Crucially, the latter is facilitated by performance feedback that encourages explicit hypothesis testing.
Children with Developmental Coordination Disorder (DCD) are diagnosed based on motor difficulties. However, they also exhibit difficulties in several other cognitive domains, including visuospatial processing, executive functioning and attention. One account of the difficulties seen in DCD proposes an impairment in internal forward modelling, i.e., the ability to (i) detect regularities of a repetitive perceptual or motor pattern, (ii) predict future outcomes of motor actions, and (iii) adapt behaviour accordingly. Using electroencephalographic recordings , the present study aimed to delineate these different aspects of internal forward modelling across several domains. To this end, 24 children with DCD and 23 typically-developing children (aged 7–10 years) completed a serial prediction task in the visual, temporal, spatial and motor domains. This task required them to learn short sequences and to indicate whether a sequence was disrupted towards its end. Analyses revealed that, across all domains, children with DCD showed poorer discrimination between intact and disrupted sequences, accompanied by a delayed late parietal positivity elicited by disrupted sequences. These results indicate an impairment in explicit sequence discrimination in DCD across motor and cognitive domains. However, there is no evidence for an impairment in implicit performance on the visuomotor task in DCD. These results suggest an impairment of the updating of an internal forward model in DCD resulting in a blurred representation of that model and, consequently, in a reduced ability to detect regularities in the environment (e.g., sequences). Such a detailed understanding of internal forward modelling in DCD could help to explain the wide range of co-occurring difficulties experienced by those with a diagnosis of DCD.
Anxiety is one of the most prevalent mental health problems; it is known to impede cognitive functioning. It is believed to alter preferences for feedback-based learning in anxious and non-anxious learners. Thus, the present study measured feedback processing in adults ( N = 30) with and without anxiety symptoms using a probabilistic learning task. Event-related potential (ERP) measures were used to assess how the bias for either positive or negative feedback learning is reflected by the feedback-related negativity component (FRN), an ERP extracted from the electroencephalogram. Anxious individuals, identified by means of the Penn State Worry Questionnaire, showed a diminished FRN and increased accuracy after negative compared to positive feedback. Non-anxious individuals exhibited the reversed pattern with better learning from positive feedback, highlighting their preference for positive feedback. Our ERP results imply that impairments with feedback-based learning in anxious individuals are due to alterations in the mesolimbic dopaminergic system. Our finding that anxious individuals seem to favor negative as opposed to positive feedback has important implications for teacher–student feedback communication.
Febrile seizures (FS) are assumed to not have adverse long-term effects on cognitive development. Nevertheless, FS are often associated with hippocampal sclerosis which can imply episodic memory deficits. This interrelation has hardly been studied so far. In the current study 13 children who had suffered from FS during infancy and 14 control children (7-9 years old) were examined for episodic and semantic memory with standardized neuropsychological tests. Furthermore, using functional magnetic resonance imaging (fMRI) we studied neuronal activation while the children performed a continuous recognition memory task. The analysis of the behavioral data of the neuropsychological tests and the recognition memory experiment did not reveal any between group differences in memory performance. Consistent with other studies fMRI revealed repetition enhancement effects for both groups in a variety of brain regions (e.g. right middle frontal gyrus, left parahippocampal gyrus) and a repetition suppression effect in the right superior temporal gyrus. Different neural activation patterns between both groups were obtained selectively within the right supramarginal gyrus (BA 40). In the control group correct rejections of new items (CRs) were associated with stronger activation than correctly identified old items (HITs) whereas in the FS group no difference occurred. On the background that the right supramarginal gyrus is assumed to mediate a top-down process to internally direct attention towards recollected information, the results could indicate that control children used strategic recollection in order to reject new items (recall-to-reject). In contrast, the missing effect in the FS group could reflect a lack of strategy use, possibly due to impaired recollective processing. This study demonstrates that FS, even with mainly benign courses, can be accompanied by selective modifications in the neural structures underlying recognition memory. © 2012 Kipp, Opitz, Becker, Hofmann, Krick, Gortner and Mecklinger.
The detection of unexpected or unfavorable events is crucial for successful behavioral adaptation. There is a family of ERP components, the so-called error negativities, that has been associated with these detection processes. In the current study, we explored the functional characteristics of one of these components, the N2b which reflects the detection of unexpected events in a stream of stimuli in our environment, in more detail. In a sequence learning task, we found that the same type of deviant event elicited an N2b only when it conveyed information about the to-be-learned sequence, but not when it was rendered learning-irrelevant by means of task instruction. This supports the view that deviant events generate an error negativity in a similar way as committed errors and negative feedback. It also demonstrates that error monitoring processes are very flexible and can be tailored to the specific demands of the task at hand, i.e., expectancy violations only activate the error system when the detected mismatch is classified as relevant for the specific goals in the current learning context. Additionally, a P3 to all deviant types was found reflecting a higher-order form of performance monitoring associated with evaluation of task-relevant events and updating of working memory contents.
The neural correlates of the selection of grammatical gender during overt picture naming were investigated by event-related functional magnetic resonance imaging in the left hemisphere. Relative to simply naming a picture, the production of the definite determiner of the picture name (requiring gender selection) resulted exclusively in pronounced activation of a single region in the superior portion of Broca's area. This activation was not present in contrasts reflecting lexical access (naming a picture vs. saying “jaja” to a smiley) or articulation (saying “jaja” vs. rest). Rather, lexical access activated other inferior frontal regions, insula, fusiform and inferior temporal gyrus. Articulation involved insula, Rolandic operculum, motor and premotor cortex and superior temporal gyrus. The results are discussed with respect to data from studies investigating gender processing during language comprehension.
One of the most influential views on the hippocampal function suggests that this brain region is critically involved in relational memory processing, that is, binding converging inputs to mediate the representation of relationships among the constituents of episodes. It has been proposed that this binding is automatic and obligatory during learning and remembering In addition, neuroimaging studies have highlighted the importance of the prefrontal cortex, in learning, memory, and language processing. However, the posited importance of hippocampal-prefrontal interaction remains to be empirically tested. In the present study we used functional magnetic resonance imaging to examine in detail this interaction by assessing learning-related changes in hemodynamic activity during artificial language acquisition. It has been shown previously that artificial grammar systems might be learned by evaluating pattern-based relations in word sequences and generalizing beyond specific word order, that is, rule abstraction. During scanning, participants learned an artificial language whose miniature grammar meets the universal principles of a natural language. Increased proficiency level of the artificial language is associated with decreased left hippocampal activity. In contrast, we observed an increased recruitment of the left inferior frontal gyrus (Broca's area), a region that contributes to syntax processing in natural language. The present results, therefore, indicate a learning-related change in brain circuitry underlying relational processes of language learning, with a transition from a similarity-based learning system in the medial temporal lobes to a language-related processing system in the left prefrontal cortex.
Previous research on artificial grammar has indicated that the human ability to classify sentences or letter strings according to grammaticality relies on two types of knowledge. One is a superficial, familiarity-based understanding of a grammar the other is the knowledge of rules and critical features underlying a grammar. The fundamentally different characteristics of these systems permit an analysis of receiver-operating characteristics (ROC), which measures the extent to which each type of knowledge is used in grammaticality judgments. Furthermore, violations of a grammar can be divided into hierarchical and local violations. The present study is the first to combine the use of ROC analyses, fMRI and a grammaticality dichotomy. Based on previous neuroimaging studies, it was hypothesized that judgments based on rule knowledge, as extracted from individual ROC analyses, involve the left inferior frontal gyrus (IFG), whereas similarity would involve right IFG, as well as left hippocampal regions. With regards to violation types, it was hypothesized that hierarchical violations would recruit the opercular part of the left IFG as well as the posterior operculum, whereas local violations would bilaterally activate the premotor cortex (PMC). Results indicated that for greater reliance on rule knowledge, a ventral part of the left PMC was activated for ungrammatical items, whereas other PMC areas show a differentiated response for grammaticality for individuals less reliant on similarity. The right IFG was related to ungrammatical items as a function of similarity. Results are discussed with regards to possible error detection systems and differentiated efficiencies for respective classification strategies.
Logographic Chinese differs from alphabetic languages in aspects of orthography and phonology. While there are different neural networks involved in processing orthography across these language systems, there is evidence for a common neural network across languages for auditory phonology. Since lexical tones are phonemically relevant in Chinese only, learning Chinese phonology should benefit more from auditory than visual working memory (WM) training and result in activation decreases in its underlying neural circuitry. We used an n-back WM training procedure to investigate the differential impact of auditory and visual WM training on phonological proficiency while Germans learned the phonology of Chinese words. Training-inducedmodulations in language-related networkswere examined bymeans offMRI. Behavioral data did not show any transfer from auditory and visual WM training to phonological proficiency compared to a control group. Brain imaging analyses during pretest revealed activations in the left medial frontal gyrus, anterior cingulate gyrus and pallidum. Importantly, volume-of-interest analyses in these regions showed training-induced activation decreases in the medial frontal gyrus for the auditory training group but not for the other two groups. These results suggest that the training of auditoryWMleads - even in the absence of behavioral transfer effects - to more efficient processing within the left dorsal prefrontal cortex when learning Chinese phonology probably reflecting facilitated attentional selection of phonetic information in spoken Chinese words.
The present study investigated the well acknowledged phenomenon of a different sense of emotionality in a person's first (L1) and second language (L2). Event-related potentials were recorded during the reading of pleasant, unpleasant and neutral words in L1 and L2. Enhanced processing of both emotional compared to neutral words was reflected in an amplified early posterior negativity (EPN) about 280–430 ms after word onset. While the EPN did not differ in amplitude between L1 and L2, it was delayed for L2. Interestingly, a better task performance in L2 but not L1 predicted longer delays of the EPN. These results might indicate that the affective valence of L2 words is processed in a less immediate way due to delayed lexical access. This is interpreted in terms of interference in a highly integrated L1/L2 mental lexicon.
Recent functional magnetic resonance imaging (fMRI) evidence shows differential involvement of the inferior frontal gyrus (IFG) and the ventral premotor cortex (PMv) in syntactic processing. Our main goal is to specify the precise role of the PMv in the processing of sequential structures and whether these processes are a necessary prerequisite for the successful acquisition of grammatical structure.
In the present experiment, we used event-related potentials (ERP) to investigate the role of immediate and delayed feedback in an artificial grammar learning (AGL) task. Two groups of participants were engaged in classifying non-word strings according to an underlying rule system, not known to the participants. Visual feedback was provided after each classification either immediately or with a short delay of 1 s. Both groups were able to learn the artificial grammar system as indicated by an increase in classification performance. However, the gain in performance was significantly larger for the group receiving immediate feedback as compared to the group receiving delayed feedback. Learning was accompanied by an increase in P300 activity in the ERP for delayed as compared to immediate feedback. Irrespective of feedback delay, both groups exhibited learning related decreases in the feedback-related positivity (FRP) elicited by positive feedback only. The feedback-related negativity (FRN), however, remained constant over the course of learning. These results suggest, first, that delayed feedback is less effective for AGL as task requirements are very demanding, and second, that the FRP elicited by positive prediction errors decreases with learning while the FRN to negative prediction errors is elicited in an all-or-none fashion by negative feedback throughout the entire experiment.
Febrile seizures (FS) are assumed to not have adverse long-term effects on cognitive development. Nevertheless, FS are often associated with hippocampal sclerosis which can imply episodic memory deficits. This interrelation has hardly been studied so far. In the current study 13 children who had suffered from FS during infancy and 14 control children (7 to 9-years-old) were examined for episodic and semantic memory with standardized neuropsychological tests. Furthermore, using functional magnetic resonance imaging (fMRI) we studied neuronal activation while the children performed a continuous recognition memory task. The analysis of the behavioral data of the neuropsychological tests and the recognition memory experiment did not reveal any between-group differences in memory performance. Consistent with other studies fMRI revealed repetition enhancement effects for both groups in a variety of brain regions (e.g., right middle frontal gyrus, left parahippocampal gyrus) and a repetition suppression effect in the right superior temporal gyrus. Different neural activation patterns between both groups were obtained selectively within the right supramarginal gyrus (BA 40). In the control group correct rejections of new items were associated with stronger activation than correctly identified old items (HITs) whereas in the FS group no difference occurred. On the background that the right supramarginal gyrus is assumed to mediate a top-down process to internally direct attention toward recollected information, the results could indicate that control children used strategic recollection in order to reject new items (recall-to-reject). In contrast, the missing effect in the FS group could reflect a lack of strategy use, possibly due to impaired recollective processing. This study demonstrates that FS, even with mainly benign courses, can be accompanied by selective modifications in the neural structures underlying recognition memory.
Working memory training has been widely used to investigate working memory processes. We have shown previously that visual working memory benefits only from intra-modal visual but not from across-modal auditory working memory training. In the present functional magnetic resonance imaging study we examined whether auditory working memory processes can also be trained specifically and which training-induced activation changes accompany theses effects. It was investigated whether working memory training with strongly distinct auditory materials transfers exclusively to an auditory (intra-modal) working memory task or whether it generalizes to a (across-modal) visual working memory task. We used adaptive n-back training with tonal sequences and a passive control condition. The memory training led to a reliable training gain. Transfer effects were found for the (intra-modal) auditory but not for the (across-modal) visual transfer task. Training-induced activation decreases in the auditory transfer task were found in two regions in the right inferior frontal gyrus. These effects confirm our previous findings in the visual modality and extents intra-modal effects in the prefrontal cortex to the auditory modality. As the right inferior frontal gyrus is frequently found in maintaining modality-specific auditory information, these results might reflect increased neural efficiency in auditory working memory processes. Furthermore, task-unspecific (amodal) activation decreases in the visual and auditory transfer task were found in the right inferior parietal lobule and the superior portion of the right middle frontal gyrus reflecting less demand on general attentional control processes. These data are in good agreement with amodal activation decreases within the same brain regions on a visual transfer task reported previously.
Retrieval practice on a subset of previously studied material enhances later memory for practiced material but can inhibit memory for related unpracticed material. The present study examines the effects of prior retrieval practice on evoked (ERPs) and induced (oscillatory power) measures of electrophysiological activity underlying recognition of practiced and unpracticed words. Compared to control material, recognition of unpracticed words was characterized by reduced amplitudes of the P2 ERP component and by reduced early (200–400 msec) oscillatory theta power. The reduction in P2 amplitude was associated with decreased evoked theta power but not with decreased theta phase locking (phase-locking index). Recognition of unpracticed material was further accompanied by a reduction in occipital gamma power (>250 msec). In contrast, the beneficial effects of retrieval practice on practiced words were reflected by larger parietal ERP positivity (>500 msec) and by a stronger decrease in oscillatory alpha power in a relatively late time window (>700 msec). The results suggest that the beneficial and detrimental effects of retrieval practice are mediated by different processes. In particular, they suggest that reduced theta (4–7 Hz) and gamma (60–90 Hz) power reflect the specific effects of inhibitory processes on the unpracticed material's memory representation.
Working memory training is a useful tool to examine dissociations between specific working memory processes. Although current models propose a distinction between modality-specific working memory processes, to our knowledge no study has directly examined the effects of visual versus auditory working memory training. Functional magnetic resonance imaging was used to investigate whether visual working memory processes can be trained specifically and whether those effects can be separated from across-modal training effects. We found decidedly larger training gains after visual working memory training compared with auditory or no training on a visual 2-back task. These effects were accompanied by specific training-related decreases in the right middle frontal gyrus arising from visual training only. Likewise, visual and auditory training led to decreased activations in the superior portion of the right middle frontal gyrus and the right posterior parietal lobule. We infer that the combination of effects resulted from increased neural efficiency of intra-modal (visual) processes on the one hand and of across-modal (general control) processes on the other hand. Therefore, visual processes of working memory can be trained specifically, and these effects can be functionally dissociated from alterations in general control processes common to both working memory trainings.
One widely acknowledged way to improve our memory performance is to repeatedly study the to be learned material. One aspect that has received little attention in past research regards the context sensitivity of this repetition effect, that is whether the item is repeated within the same or within different contexts. The predictions of a neuro-computational model (O'Reilly & Norman, 2002) were tested in an experiment requiring participants to study visual objects either once or three times. Crucially, for half of the repeated objects the study context (encoding task, background color and screen position) remained the same (within context repetition) while for the other half the contextual features changed across repetitions (across context repetition). In addition to behavioral measures, event-related potentials (ERP) were recorded that provide complementary information on the underlying neural mechanisms during recognition. Consistent with dual-process models behavioral estimates (remember/know-procedure) demonstrate differential effects of context on memory performance, namely that recognition judgements were more dependent on familiarity when repetition occurs across contexts. In accordance with these behavioral results ERPs showed a larger early frontal old/new effect for across context repetitions as compared to within context repetitions and single presentations, i.e. an increase in familiarity following repetition across study contexts. In contrast, the late parietal old/new effect, indexing recollection did not differ between both repetition conditions. These results suggest that repetition differentially affects familiarity depending on whether it occurs within the same context or across different contexts.
Binding mechanisms are considered as basic cognitive operations, performing different functions in learning and memory. This review will cover two of these binding mechanisms: relational binding of information about stimuli and actions with their spatio-temporal context into a circumscribed cognitive event and representational binding of feature representations common to a number of such events, thereby integrating these representations with existing knowledge and, thus, leading to decontextualized knowledge about the world. I will survey evidence from recent neuropsychological, electrophysiological and neuroimaging studies, including my own work, demonstrating that relational binding operations are performed within the hippocampal system, whereas representational binding is subserved by the surrounding medial-temporal lobe cortex and prefrontal brain areas. I then present examples of conditions that differentially implement both binding mechanisms. Lastly, summarizing the extant literature on binding mechanisms I speculate on whether these binding mechanism operate in a similar way across different cognitive domains or whether they are domain-specific.