Daniel Brandeis

University of Freiburg, Freiburg, Baden-Württemberg, Germany

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Publications (183)718.41 Total impact

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    ABSTRACT: Working memory (WM) processes depend on our momentary mental state and therefore exhibit considerable fluctuations. Here, we investigate the interplay of task-preparatory and task-related brain activity as represented by pre-stimulus BOLD-fluctuations and spectral EEG from the retention periods of a visual WM task. Visual WM is used to maintain sensory information in the brain enabling the performance of cognitive operations and is associated with mental health. We tested 22 subjects simultaneously with EEG and fMRI while performing a visuo-verbal Sternberg task with two different loads, allowing for the temporal separation of preparation, encoding, retention and retrieval periods. Four temporally coherent networks (TCNs)-the default mode network (DMN), the dorsal attention, the right and the left WM network-were extracted from the continuous BOLD data by means of a group ICA. Subsequently, the modulatory effect of these networks' pre-stimulus activation upon retention-related EEG activity in the theta, alpha, and beta frequencies was analyzed. The obtained results are informative in the context of state-dependent information processing. We were able to replicate two well-known load-dependent effects: the frontal-midline theta increase during the task and the decrease of pre-stimulus DMN activity. As our main finding, these two measures seem to depend on each other as the significant negative correlations at frontal-midline channels suggested. Thus, suppressed pre-stimulus DMN levels facilitated later task related frontal midline theta increases. In general, based on previous findings that neuronal coupling in different frequency bands may underlie distinct functions in WM retention, our results suggest that processes reflected by spectral oscillations during retention seem not only to be "online" synchronized with activity in different attention-related networks but are also modulated by activity in these networks during preparation intervals.
    Frontiers in Behavioral Neuroscience 05/2015; 9. DOI:10.3389/fnbeh.2015.00111 · 4.16 Impact Factor
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    ABSTRACT: Learning a foreign language in a natural immersion context with high exposure to the new language has been shown to change the way speech sounds of that language are processed at the neural level. It remains unclear, however, to what extent this is also the case for classroom-based foreign language learning, particularly in children. To this end, we presented a mismatch negativity (MMN) experiment during EEG recordings as part of a longitudinal developmental study: 38 monolingual (Swiss-) German speaking children (7.5 years) were tested shortly before they started to learn English at school and followed up one year later. Moreover, 22 (Swiss-) German adults were recorded. Instead of the originally found positive mismatch response in children, an MMN emerged when applying a high-pass filter of 3Hz. The overlap of a slow-wave positivity with the MMN indicates that two concurrent mismatch processes were elicited in children. The children's MMN in response to the non-native speech contrast was smaller compared to the native speech contrast irrespective of foreign language learning, suggesting that no additional neural resources were committed to processing the foreign language speech sound after one year of classroom-based learning. Copyright © 2015. Published by Elsevier Ltd.
    Neuropsychologia 04/2015; DOI:10.1016/j.neuropsychologia.2015.04.029 · 3.45 Impact Factor
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    ABSTRACT: Epigenetic modulations are a hypothesized link between environmental factors and the development of psychiatric disorders. Research has suggested that patients with depression or bipolar disorder exhibit higher methylation levels in the glucocorticoid receptor gene NR3C1. We aimed to investigate whether NR3C1 methylation changes are similarly associated with externalizing disorders such as aggressive behavior and conduct disorder. NR3C1 exon 1F methylation was analyzed in young adults with a lifetime diagnosis of an externalizing disorder (N = 68) or a depressive disorder (N = 27) and healthy controls (N = 124) from the Mannheim Study of Children at Risk. The externalizing disorders group had significantly lower NR3C1 methylation levels than the lifetime depressive disorder group (p = 0.009) and healthy controls (p = 0.001) This report of lower methylation levels in NR3C1 in externalizing disorders may indicate a mechanism through which the differential development of externalizing disorders as opposed to depressive disorders might occur.
    Behavior Genetics 04/2015; DOI:10.1007/s10519-015-9721-y · 2.84 Impact Factor
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    Journal of the American Academy of Child and Adolescent Psychiatry 03/2015; · 6.35 Impact Factor
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    ABSTRACT: The authors performed meta-analyses of randomized controlled trials to examine the effects of cognitive training on attention-deficit/hyperactivity disorder (ADHD) symptoms, neuropsychological deficits, and academic skills in children/adolescents with ADHD. The authors searched Pubmed, Ovid, Web of Science, ERIC, and CINAHAL databases through May 18, 2014. Data were aggregated using random-effects models. Studies were evaluated with the Cochrane risk of bias tool. Sixteen of 695 nonduplicate records were analyzed (759 children with ADHD). When all types of training were considered together, there were significant effects on total ADHD (standardized mean difference [SMD] = 0.37, 95% CI = 0.09-0.66) and inattentive symptoms (SMD = 0.47, 95% CI = 0.14-0.80) for reports by raters most proximal to the treatment setting (i.e., typically unblinded). These figures decreased substantially when the outcomes were provided by probably blinded raters (ADHD total: SMD = 0.20, 95% CI = 0.01-0.40; inattention: SMD = 0.32, 95% CI = -0.01 to 0.66). Effects on hyperactivity/impulsivity symptoms were not significant. There were significant effects on laboratory tests of working memory (verbal: SMD = 0.52, 95% CI = 0.24-0.80; visual: SMD = 0.47, 95% CI = 0.23-0.70) and parent ratings of executive function (SMD = 0.35, 95% CI = 0.08-0.61). Effects on academic performance were not statistically significant. There were no effects of working memory training, specifically on ADHD symptoms. Interventions targeting multiple neuropsychological deficits had large effects on ADHD symptoms rated by most proximal assessors (SMD = 0.79, 95% CI = 0.46-1.12). Despite improving working memory performance, cognitive training had limited effects on ADHD symptoms according to assessments based on blinded measures. Approaches targeting multiple neuropsychological processes may optimize the transfer of effects from cognitive deficits to clinical symptoms. Copyright © 2015 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.
    Journal of the American Academy of Child & Adolescent Psychiatry 03/2015; 54(3):164-174. DOI:10.1016/j.jaac.2014.12.010 · 6.35 Impact Factor
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    ABSTRACT: We assessed intra-individual variability of response times (RT) and single-trial P3 amplitudes following targets in healthy adults during a Flanker/NO-GO task. RT variability and variability of the neural responses coupled at the faster frequencies examined (0.07-0.17 Hz) at Pz, the target-P3 maxima, despite non-significant associations for overall variability (standard deviation, SD). Frequency-specific patterns of variability in the single-trial P3 may help to understand the neurophysiology of RT variability and its explanatory models of attention allocation deficits beyond intra-individual variability summary indices such as SD.
    Journal of Neural Transmission 02/2015; DOI:10.1007/s00702-015-1382-8 · 2.87 Impact Factor
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    ABSTRACT: Brain activation stability is crucial to understanding attention lapses. EEG methods could provide excellent markers to assess neuronal response variability with respect to temporal (intertrial coherence) and spatial variability (topographic consistency) as well as variations in activation intensity (low frequency variability of single trial global field power). We calculated intertrial coherence, topographic consistency and low frequency amplitude variability during target P300 in a continuous performance test in 263 15-year-olds from a cohort with psychosocial and biological risk factors. Topographic consistency and low frequency amplitude variability predicted reaction time fluctuations (RTSD) in a linear model. Higher RTSD was only associated with higher psychosocial adversity in the presence of the homozygous 6R-10R dopamine transporter haplotype. We propose that topographic variability of single trial P300 reflects noise as well as variability in evoked cortical activation patterns. Dopaminergic neuromodulation interacted with environmental and biological risk factors to predict behavioural reaction time variability. Copyright © 2015. Published by Elsevier B.V.
    Biological Psychology 01/2015; 106. DOI:10.1016/j.biopsycho.2015.01.013 · 3.47 Impact Factor
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    ABSTRACT: Attention-deficit/hyperactivity disorder (ADHD) is a common disabling psychiatric disorder associated with consistent deficits in error processing, inhibition and regionally decreased grey matter volumes. The diagnosis is based on clinical presentation, interviews and questionnaires, which are to some degree subjective and would benefit from verification through biomarkers. Here, pattern recognition of multiple discriminative functional and structural brain patterns was applied to classify adolescents with ADHD and controls. Functional activation features in a Flanker/NoGo task probing error processing and inhibition along with structural magnetic resonance imaging data served to predict group membership using support vector machines (SVMs). The SVM pattern recognition algorithm correctly classified 77.78 % of the subjects with a sensitivity and specificity of 77.78 % based on error processing. Predictive regions for controls were mainly detected in core areas for error processing and attention such as the medial and dorsolateral frontal areas reflecting deficient processing in ADHD (Hart et al., in Hum Brain Mapp 35:3083-3094, 2014), and overlapped with decreased activations in patients in conventional group comparisons. Regions more predictive for ADHD patients were identified in the posterior cingulate, temporal and occipital cortex. Interestingly despite pronounced univariate group differences in inhibition-related activation and grey matter volumes the corresponding classifiers failed or only yielded a poor discrimination. The present study corroborates the potential of task-related brain activation for classification shown in previous studies. It remains to be clarified whether error processing, which performed best here, also contributes to the discrimination of useful dimensions and subtypes, different psychiatric disorders, and prediction of treatment success across studies and sites.
    European Child & Adolescent Psychiatry 01/2015; DOI:10.1007/s00787-015-0678-4 · 3.55 Impact Factor
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    ABSTRACT: Die klinische Diagnostik in der Psychiatrie und die Klassifizierungssysteme DSM-5 [1] und ICD-10 [2] werden immer wieder kritisiert, da sie abhängig sind von subjektiv getönten Einschätzungen und keine ausreichend zuverlässigen und validen Diagnosen zulassen. Das NIMH verfolgt seit 2009 ein neues Klassifizierungssystem (RDoC: Research Domain Criteria), welches Informationen aus der Genetik, Bildgebung und Neuropsychologie mit Verhaltensmaßen integriert. Dieser Ansatz weist darauf hin, dass der Einbezug von Biomarkern bei der Diagnosestellung valider sein könnte, um komplexe psychische Erkrankungen wie beispielsweise ADHS zu klassifizieren. Aber das ist Zukunftsmusik und hat trotz intensiver Diskussionen keinen Eingang ins DSM-5 gefunden. Wo stehen wir heute mit den Biomarkern in der Psychiatrie? Biomarker sind messbare und charakteristische Parameter, die biologische Prozesse abbilden. Sie sollen für klinische Vorhersagen wie Prognose, Rückfallrisiko, Ansprechen auf ein Medikament und Nebenwirkungen verwendet werden [3]. Diskussionen um Biomarker sind oft vom Missverständnis geprägt, dass statistische Gruppenzusammenhänge auch individuell zuverlässig und klinisch bedeutsam sind. Da nach heutigem Kenntnisstand ein einzelner Biomarker nicht für eine zuverlässige Diagnose einer komplexen psychischen Störung ausreicht, geht der Trend in der Psychiatrie dahin, dass man stattdessen eine Reihe von Biomarkern identifiziert. Es gibt einige vielversprechende Biomarker, die zwar alleine betrachtet nicht für eine frühzeitige Diagnose oder Prognoseeinschätzung ausreichen, allerdings in Kombination eingesetzt bei ADHS möglicherweise Anwendung finden könnten. Sehr ähnlich sieht es auch für andere psychiatrische Störungsbilder aus, es gibt jedoch für kein Störungsbild eine routinemäßige Anwendung. Was spricht für Biomarker, außer, dass wir unser klinisches Urteil besser durch biologische Parameter abstützen wollen? Je höher die Vererbbarkeit (bei ADHS und Autismus sind dies zwischen 70 und 90 %), umso mehr erwartet man, dass man für diese biologische Vulnerabilität auch biologische Korrelate detektieren kann. Metaanalysen zu genetischen Markern weisen darauf hin, dass viele Varianten, die mit ADHS assoziiert sind, jeweils immer nur einen sehr kleinen Teil der Erblichkeit erklären. Der polygenetische Ansatz hat in den letzten Jahren an Bedeutung gewonnen und ist als eine Methode anerkannt, um die niedrigen Effektstärken der einzelnen Genvarianten zu überbrücken [4] [5]. Allerdings kann bislang kein Biomarker bei Patienten mit psychischen Störungen eine fundierte klinische Diagnostik ersetzen. Auch Neuropsychologische Tests sind in der Regel nur ergänzend einsetzbar und ohne klinische Diagnostik nicht ausreichend aussagekräftig. Ebenso zeigen neue Studien, dass auch vielversprechende einfache EEG-basierte Biomarker keine Einzelfalldiagnostik erlauben [6]. Aktuell ist der Einbezug von Biomarkern der Genetik und aus der funktionellen oder multimodalen Bildgebung zwar wissenschaftlich sehr interessant, aber sehr viel zeitaufwendiger und kostenintensiver als eine klinische Diagnostik. Die Bestimmung solcher potenzieller Biomarker ist daher für die Praxis deshalb kaum bezahlbar. Die Zukunft ruft nach personalisierter Medizin und maßgeschneiderter Therapie, dafür brauche es Biomarker. Die Forschung zu validen Biomarkern ist wichtig und könnte die Diagnostik und Behandlung in Zukunft weiter verbessern. Aber bereits heute können wir unseren Patienten eine personalisierte Therapie auf Basis leitlinienorientierter Diagnostik und Behandlung unter Einbezug des Umfelds und mittels klinischem Monitoring anbieten. Zürich ADHD Biomarker Working Group: Susanne Walitza, Edna Grünblatt, Silvia Brem, Dani Brandeis und Renate Drechsler
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    ABSTRACT: While issues of efficacy and specificity are crucial for the future of neurofeedback training, there may be alternative designs and control analyses to circumvent the methodological and ethical problems associated with double-blind placebo studies. Surprisingly, most NF studies do not report the most immediate result of their NF training, i.e., whether or not children with ADHD gain control over their brain activity during the training sessions. For the investigation of specificity, however, it seems essential to analyze the learning and adaptation processes that take place in the course of the training and to relate improvements in self-regulated brain activity across training sessions to behavioral, neuropsychological and electrophysiological outcomes. To this aim, a review of studies on neurofeedback training with ADHD patients which include the analysis of learning across training sessions or relate training performance to outcome is presented. Methods on how to evaluate and quantify learning of EEG regulation over time are discussed. "Non-learning" has been reported in a small number of ADHD-studies, but has not been a focus of general methodological discussion so far. For this reason, selected results from the brain-computer interface (BCI) research on the so-called "brain-computer illiteracy", the inability to gain control over one's brain activity, are also included. It is concluded that in the discussion on specificity, more attention should be devoted to the analysis of EEG regulation performance in the course of the training and its impact on clinical outcome. It is necessary to improve the knowledge on characteristic cross-session and within-session learning trajectories in ADHD and to provide the best conditions for learning.
    Frontiers in Human Neuroscience 01/2015; 9:135. DOI:10.3389/fnhum.2015.00135 · 2.90 Impact Factor
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    ABSTRACT: Variation in the gene encoding for the norepinephrine transporter (NET, SLC6A2) has repeatedly been linked with ADHD, although there is some inconsistency regarding the association with specific genes. The variants for which most consistent association has been found are the NET variants rs3785157 and rs28386840. Here, we tested for their association with ADHD diagnosis and ADHD-related phenotypes during development in a longitudinal German community sample. Children were followed from age 4 to age 15, using diagnostic interviews to assess ADHD. Between the ages of 8 and 15 years, the Child Behavior Checklist (CBCL) was administered to the primary caregivers. The continuous performance task (CPT) was performed at age 15. Controlling for possible confounders, we found that homozygous carriers of the major A allele of the functional promoter variant rs28386840 displayed a higher rate of ADHD lifetime diagnosis. Moreover, homozygous carriers of the minor T allele of rs3785157 were more likely to develop ADHD and showed higher scores on the CBCL externalizing behavior scales. Additionally, we found that individuals heterozygous for rs3785157 made fewer omission errors in the CPT than homozygotes. This is the first longitudinal study to report associations between specific NET variants and ADHD-related phenotypes during the course of development. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    Psychiatry Research 12/2014; 226(2-3). DOI:10.1016/j.psychres.2014.12.029 · 2.68 Impact Factor
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    ABSTRACT: Attention-deficit/hyperactivity disorder (ADHD) is associated with cognitive performance and functional brain changes that are sensitive to task conditions, indicating a role for dynamic impairments rather than stable cognitive deficits. Prominent hypotheses consistent with this observation are a failure to optimise brain arousal or activation states. Here we investigate cortical activation during different conditions. Using a sample of 41 non-comorbid adults with ADHD and 48 controls, we examine quantitative EEG activity during a resting state, a cued continuous performance test with flankers (CPT-OX) and the Sustained Attention to Response Task (SART). We further investigate the effects of methylphenidate in a subsample of 21 ADHD cases. Control participants showed a task-related increase in theta activity when engaged in cognitive tasks, primarily in frontal and parietal regions, which was absent in participants with ADHD. Treatment with methylphenidate resulted in normalisation of the resting state to task activation pattern. These findings suggest that ADHD in adults is associated with insufficient allocation of neuronal resources required for normal cortical activation commensurate with task demands. Further work is required to clarify the causal role of the deficit in cortical activation and provide a clearer understanding of the mechanisms involved.
    European Neuropsychopharmacology 11/2014; 25(1). DOI:10.1016/j.euroneuro.2014.09.015 · 5.40 Impact Factor
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    ABSTRACT: Error processing and conflict monitoring are essential executive functions for goal directed actions and adaptation to conflicting information. Although medial frontal regions such as the anterior cingulate cortex (ACC) and the pre-supplementary motor area (pre-SMA) are known to be involved in these functions, there is still considerable heterogeneity regarding their spatio-temporal activations. The timing of these functions has been associated with two separable event-related potentials (ERPs) usually localized to the medial frontal wall, one during error processing (ERN — error related negativity) and one during conflict monitoring (N2).
    NeuroImage 10/2014; 105. DOI:10.1016/j.neuroimage.2014.10.028 · 6.13 Impact Factor
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    ABSTRACT: Converging evidence emphasizes the role of an interaction between monoamine oxidase A (MAOA) genotype, environmental adversity, and sex in the pathophysiology of aggression. The present study aimed to clarify the impact of this interaction on neural activity in aggression-related brain systems. Functional magnetic resonance imaging was performed in 125 healthy adults from a high-risk community sample followed since birth. DNA was genotyped for the MAOA-VNTR (variable number of tandem repeats). Exposure to childhood life stress (CLS) between the ages of 4 and 11 years was assessed using a standardized parent interview, aggression by the Youth/Young Adult Self-Report between the ages of 15 and 25 years, and the VIRA-R (Vragenlijst Instrumentele En Reactieve Agressie) at the age of 15 years. Significant interactions were obtained between MAOA genotype, CLS, and sex relating to amygdala, hippocampus, and anterior cingulate cortex (ACC) response, respectively. Activity in the amygdala and hippocampus during emotional face-matching increased with the level of CLS in male MAOA-L, while decreasing in male MAOA-H, with the reverse pattern present in females. Findings in the opposite direction in the ACC during a flanker NoGo task suggested that increased emotional activity coincided with decreased inhibitory control. Moreover, increasing amygdala activity was associated with higher Y(A)SR aggression in male MAOA-L and female MAOA-H carriers. Likewise, a significant association between amygdala activity and reactive aggression was detected in female MAOA-H carriers. The results point to a moderating role of sex in the MAOA× CLS interaction for intermediate phenotypes of emotional and inhibitory processing, suggesting a possible mechanism in conferring susceptibility to violence-related disorders.
    Cerebral Cortex 10/2014; DOI:10.1093/cercor/bhu249 · 8.31 Impact Factor
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    ABSTRACT: Converging evidence has highlighted the association between poverty and conduct disorder (CD) without specifying neurobiological pathways. Neuroimaging research has emphasized structural and functional alterations in the orbitofrontal cortex (OFC) as one key mechanism underlying this disorder. The present study aimed to clarify the long-term influence of early poverty on OFC volume and its association with CD symptoms in healthy participants of an epidemiological cohort study followed since birth. At age 25 years, voxel-based morphometry was applied to study brain volume differences. Poverty [0=non-exposed (N=134), 1=exposed (N=33)] and smoking during pregnancy were determined using a standardized parent interview, and information on maternal responsiveness was derived from videotaped mother-infant interactions at the age of 3 months. CD symptoms were assessed by diagnostic interview from 8-19 years of age. Information on life stress was acquired at each assessment and childhood maltreatment was measured using retrospective self-report at the age of 23 years. Analyses were adjusted for sex, parental psychopathology and delinquency, obstetric adversity, parental education and current poverty. Individuals exposed to early-life poverty exhibited a lower OFC volume and more CD symptoms. Moreover, we replicated previous findings of increased CD symptoms as a consequence of childhood poverty. This effect proved statistically mediated by OFC volume and exposure to life stress and smoking during pregnancy, but not by childhood maltreatment and maternal responsiveness. These findings underline the importance of studying the impact of early-life adversity on brain alterations and highlight the need for programs to decrease income-related disparities.Neuropsychopharmacology accepted article preview online, 15 October 2014. doi:10.1038/npp.2014.277.
    Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 10/2014; 40(4). DOI:10.1038/npp.2014.277 · 7.83 Impact Factor
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    ABSTRACT: Considerable scientific effort has been directed at developing effective treatments for attention-deficit/hyperactivity disorder (ADHD). Among alternative treatment approaches, neurofeedback has gained some promising empirical support in recent years from controlled studies as a treatment of core ADHD symptoms. However, a recent stringent meta-analysis of 8 randomized controlled trials published in 2013 found that the effects were stronger for unblinded measures and 3 recent subsequently published well-controlled trials found no effects for the most blinded ADHD outcome. Firmer conclusions must await upcoming evidence from larger controlled studies and future meta-analyses contrasting different forms of neurofeedback and different outcome measures.
    Child and Adolescent Psychiatric Clinics of North America 10/2014; 23(4):789-806. DOI:10.1016/j.chc.2014.05.006 · 2.60 Impact Factor
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    ABSTRACT: There has been an increasing interest in and the use of computer-based cognitive training as a treatment of attention-deficit/hyperactivity disorder (ADHD). The authors' review of current evidence, based partly on a stringent meta-analysis of 6 randomized controlled trials (RCTs) published in 2013, and an overview of 8 recently published RCTs highlights the inconsistency of findings between trials and across blinded and nonblinded ADHD measures within trials. Based on this, they conclude that more evidence from well-blinded studies is required before cognitive training can be supported as a frontline treatment of core ADHD symptoms.
    Child and Adolescent Psychiatric Clinics of North America 10/2014; 23(4):807-824. DOI:10.1016/j.chc.2014.05.009 · 2.60 Impact Factor
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    ABSTRACT: Adolescence is associated with quickly changing environmental demands which require excellent adaptive skills and high cognitive flexibility. Feedback-guided adaptive learning and cognitive flexibility are driven by reward prediction error (RPE) signals, which indicate the accuracy of expectations and can be estimated using computational models. Despite the importance of cognitive flexibility during adolescence, only little is known about how RPE processing in cognitive flexibility deviates between adolescence and adulthood. In this study, we investigated the developmental aspects of cognitive flexibility by means of computational models and functional magnetic resonance imaging (fMRI). We compared the neural and behavioral correlates of cognitive flexibility in healthy adolescents (12–16 years) to adults performing a probabilistic reversal learning task. Using a modified risk-sensitive reinforcement learning model, we found that adolescents learned faster from negative RPEs than adults. The fMRI analysis revealed that within the RPE network, the adolescents had a significantly altered RPE-response in the anterior insula. This effect seemed to be mainly driven by increased responses to negative prediction errors. In summary, our findings indicate that decision making in adolescence goes beyond merely increased reward-seeking behavior and provides a developmental perspective to the behavioral and neural mechanisms underlying cognitive flexibility in the context of reinforcement learning.
    NeuroImage 09/2014; 104. DOI:10.1016/j.neuroimage.2014.09.018 · 6.13 Impact Factor
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    ABSTRACT: Elevated theta or theta/beta ratio is often reported in attention deficit hyperactivity disorder (ADHD), but the consistency across studies and the relation to hypoarousal are increasingly questioned. Reports of elevated delta related to maturational lag and of attenuated beta activity are less well replicated. Some critical inconsistencies could relate to differences in recording context. We examined if resting-state EEG power or global field synchronization (GFS) differed between recordings made at the beginning and end of a 1.5 h testing session in 76 adolescents and young adults with ADHD, and 85 controls. In addition, we aimed to examine the effect of IQ on any potential group differences. Both regional and midline electrodes yielded group main effects for delta, trends in theta, but no differences in alpha or theta/beta ratio. An additional group difference in beta was detected when using regions. Group by time interactions in delta and theta became significant when controlling for IQ. The ADHD group had higher delta and theta power at time-1, but not at time-2, whereas beta power was elevated only at time-2. GFS did not differ between groups or condition. We show some ADHD-control differences on EEG spectral power varied with recording time within a single recording session, with both IQ and electrode selection having a small but significant influence on observed differences. Our findings demonstrate the effect of recording context on resting-state EEG, and highlight the importance of accounting for these variables to ensure consistency of results in future studies.
    Brain Topography 09/2014; DOI:10.1007/s10548-014-0395-1 · 2.52 Impact Factor
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    ABSTRACT: The classical phonological deficit account of dyslexia is increasingly linked to impairments in grapho-phonological conversion, and to dysfunctions in superior temporal regions associated with audiovisual integration. The present study investigates mechanisms of audiovisual integration in typical and impaired readers at the critical developmental stage of adolescence. Congruent and incongruent audiovisual as well as unimodal (visual only and auditory only) material was presented. Audiovisual presentations were single letters and three-letter (consonant-vowel-consonant) stimuli accompanied by matching or mismatching speech sounds. Three-letter stimuli exhibited fast phonetic transitions as in real-life language processing and reading. Congruency effects, i.e. different brain responses to congruent and incongruent stimuli were taken as an indicator of audiovisual integration at a phonetic level (grapho-phonological conversion). Comparisons of unimodal and audiovisual stimuli revealed basic, more sensory aspects of audiovisual integration. By means of these two criteria of audiovisual integration, the generalizability of audiovisual deficits in dyslexia was tested. Moreover, it was expected that the more naturalistic three-letter stimuli are superior to single letters in revealing group differences. Electrophysiological and hemodynamic (EEG and fMRI) data were acquired simultaneously in a simple target detection task. Applying the same statistical models to event-related EEG potentials and fMRI responses allowed comparing the effects detected by the two techniques at a descriptive level. Group differences in congruency effects (congruent against incongruent) were observed in regions involved in grapho-phonological processing, including the left inferior frontal and angular gyri and the inferotemporal cortex. Importantly, such differences also emerged in superior temporal key regions. Three-letter stimuli revealed stronger group differences than single letters. No significant differences in basic measures of audiovisual integration emerged. Convergence of hemodynamic and electrophysiological signals appeared to be limited and mainly occurred for highly significant and large effects in visual cortices. The findings suggest efficient superior temporal tuning to audiovisual congruency in controls. In impaired readers, however, grapho-phonological conversion is effortful and inefficient, although basic audiovisual mechanisms seem intact. This unprecedented demonstration of audiovisual deficits in adolescent dyslexics provides critical evidence that the phonological deficit might be explained by impaired audiovisual integration at a phonetic level, especially for naturalistic and word-like stimulation.
    Neuropsychologia 09/2014; 62. DOI:10.1016/j.neuropsychologia.2014.07.024 · 3.45 Impact Factor

Publication Stats

5k Citations
718.41 Total Impact Points

Institutions

  • 2015
    • University of Freiburg
      Freiburg, Baden-Württemberg, Germany
  • 2003–2015
    • Central Institute of Mental Health
      • Klinik für Abhängiges Verhalten und Suchtmedizin
      Mannheim, Baden-Württemberg, Germany
  • 2012–2014
    • Universität Heidelberg
      Heidelburg, Baden-Württemberg, Germany
    • University of Leipzig
      Leipzig, Saxony, Germany
  • 1981–2014
    • University of Zurich
      • • Center for Integrative Human Physiology
      • • Division of Neuropsychology
      Zürich, Zurich, Switzerland
  • 1993
    • University of Vienna
      Wien, Vienna, Austria
  • 1992
    • San Francisco VA Medical Center
      San Francisco, California, United States