[Show abstract][Hide abstract] ABSTRACT: Dopamine plays an important role in orienting and the regulation of selective attention to relevant stimulus characteristics. Thus, we examined the influences of functional variants related to dopamine inactivation in the dopamine transporter (DAT1) and catechol-O-methyltransferase genes (COMT) on the time-course of visual processing in a contingent negative variation (CNV) task.
64-channel EEG recordings were obtained from 195 healthy adolescents of a community-based sample during a continuous performance task (A-X version). Early and late CNV as well as preceding visual evoked potential components were assessed.
Significant additive main effects of DAT1 and COMT on the occipito-temporal early CNV were observed. In addition, there was a trend towards an interaction between the two polymorphisms. Source analysis showed early CNV generators in the ventral visual stream and in frontal regions. There was a strong negative correlation between occipito-temporal visual post-processing and the frontal early CNV component. The early CNV time interval 500-1000 ms after the visual cue was specifically affected while the preceding visual perception stages were not influenced.
Late visual potentials allow the genomic imaging of dopamine inactivation effects on visual post-processing. The same specific time-interval has been found to be affected by DAT1 and COMT during motor post-processing but not motor preparation. We propose the hypothesis that similar dopaminergic mechanisms modulate working memory encoding in both the visual and motor and perhaps other systems.
[Show abstract][Hide abstract] ABSTRACT: Dopamine plays an important role in orienting, response anticipation and movement evaluation. Thus, we examined the influence of functional variants related to dopamine inactivation in the dopamine transporter (DAT1) and catechol-O-methyltransferase genes (COMT) on the time-course of motor processing in a contingent negative variation (CNV) task.
64-channel EEG recordings were obtained from 195 healthy adolescents of a community-based sample during a continuous performance task (A-X version). Early and late CNV as well as motor postimperative negative variation were assessed. Adolescents were genotyped for the COMT Val(158)Met and two DAT1 polymorphisms (variable number tandem repeats in the 3'-untranslated region and in intron 8).
The results revealed a significant interaction between COMT and DAT1, indicating that COMT exerted stronger effects on lateralized motor post-processing (centro-parietal motor postimperative negative variation) in homozygous carriers of a DAT1 haplotype increasing DAT1 expression. Source analysis showed that the time interval 500-1000 ms after the motor response was specifically affected in contrast to preceding movement anticipation and programming stages, which were not altered.
Motor slow negative waves allow the genomic imaging of dopamine inactivation effects on cortical motor post-processing during response evaluation. This is the first report to point towards epistatic effects in the motor system during response evaluation, i.e. during the post-processing of an already executed movement rather than during movement programming.
[Show abstract][Hide abstract] ABSTRACT: The current study investigated the relevance of semantic processing and stimulus salience for memory performance in young ADHD patients and healthy control participants. 18 male ADHD patients and 15 healthy control children and adolescents participated in an ERP study during a visual memory paradigm with two different encoding tasks requiring either perceptual or semantic processing of neutral and emotional pictures. ADHD patients and healthy controls both showed a more negative slow-wave in response to task cues signalling semantic as compared to perceptual stimulus processing. In contrast to ADHD patients, healthy control children showed a larger increase in memory performance for deeply processed neutral pictures which was accompanied by a more positive mid-latency ERP component (so-called P300) after stimulus onset. Our results demonstrate that ADHD patients succeeded in allocating neural resources in preparation of different task demands. However, this increase in preparatory activation to the semantic task cue did not suffice to support successful processing and encoding of neutral stimuli to the same extent as in healthy controls. These findings provide evidence that ADHD patients show deficits in translating pre-stimulus mobilization of neural resources to successful memory formation in the absence of salient stimulus material.
No preview · Article · Aug 2009 · Neuropsychologia
[Show abstract][Hide abstract] ABSTRACT: The present study investigated whether children and adolescents with attention deficit hyperactivity disorder (ADHD) and comorbid oppositional defiant disorder (ODD) or conduct disorder (CD) show a memory bias for negative emotional pictures. Subjects participated in an incidental memory paradigm involving neutral, positive and negative pictures. In ADHD only patients, memory performance was enhanced to the level of healthy control subjects both by positive and negative pictures, whereas in ADHD patients with comorbid ODD/CD, memory performance was only normalized by negative pictures.
No preview · Article · Dec 2008 · Journal of Neural Transmission
[Show abstract][Hide abstract] ABSTRACT: Patients with attention-deficit/hyperactivity disorder (ADHD) show episodic memory deficits especially in complex memory tasks. We investigated the neural correlates of memory formation in ADHD and their modulation by stimulus salience.
We recorded event-related functional magnetic resonance imaging during an episodic memory paradigm with neutral and emotional pictures in 12 male ADHD subjects and 12 healthy adolescents.
Emotional salience did significantly augment memory performance in ADHD patients. Successful encoding of neutral pictures was associated with activation of the anterior cingulate cortex (ACC) in healthy adolescents but with activation of the superior parietal lobe (SPL) and precuneus in ADHD patients. Successful encoding of emotional pictures was associated with prefrontal and inferior temporal cortex activation in both groups. Healthy adolescents, moreover, showed deactivation in the inferior parietal lobe.
From a pathophysiological point of view, the most striking functional differences between healthy adolescents and ADHD patients were in the ACC and SPL. We suggest that increased SPL activation in ADHD reflected attentional compensation for low ACC activation during the encoding of neutral pictures. The higher salience of emotional stimuli, in contrast, regulated the interplay between ACC and SPL in conjunction with improving memory to the level of healthy adolescents.
No preview · Article · Jul 2007 · Biological Psychiatry
[Show abstract][Hide abstract] ABSTRACT: To examine neurophysiological correlates of attentional processing in children with oppositional-defiant disorder (ODD) independent of ADHD symptoms.
Thirteen children with oppositional-defiant disorder without comorbid ADHD symptoms and 13 healthy control children (all 11 years) performed a cued Continuous Performance Test (CPT-AX). Event-related potentials (ERP) to cue and target stimuli were examined for group differences.
Children with ODD showed significantly reduced parietal P3a and P3b amplitudes to cues and to targets, compared with healthy controls. ERP amplitudes correlated with oppositional and aggressive behavior scores.
Event-related potentials revealed reduced orienting to cues and reduced executive target processing in children with ODD. These findings indicate that ODD children show neurophysiological deviances independent of ADHD comorbidity.
No preview · Article · Jun 2006 · Journal of Neural Transmission
[Show abstract][Hide abstract] ABSTRACT: Die Sprachentwicklung von 108Kindern (61Jungen, 47Mdchen) einer prospektiven Risikokinderstudie wurde vom Kleinkind- bis zum Vorschulalter mit dem Ziel verfolgt, ihre Stabilitt und den Vorhersagewert fr sptere Sprachentwicklungsverzgerungen zu bestimmen. Altersangemessene Kennwerte fr expressive und rezeptive Sprachleistungen sowie Intelligenz wurden im Alter von 10Monaten, 2 und 41/2Jahren mit Hilfe standardisierter Verfahren erhoben. Die Ergebnisse belegten eine gute Vorhersagbarkeit spterer sprachlicher Leistungen durch die frhkindliche Sprachkompetenz sowie einen deutlichen Einfluss des Geschlechts auf Sprach- und Intelligenzmae.The language development of 108children (61boys, 47girls) from a prospective risk study was followed from infancy to preschool age to examine the stability and predictive value for later language delays. Age-appropriate measures of expressive and receptive language as well as intelligence were obtained at the ages of 10 months, 2 and 4.5 years using standardized assessments. Results demonstrated the efficacy of infant language abilities in predicting later language skills as well as an effect of gender on language and intelligence measures.
No preview · Article · Jan 2005 · Monatsschrift Kinderheilkunde
[Show abstract][Hide abstract] ABSTRACT: To measure neurophysiological correlates of inhibition in children with anxiety disorders.
Anxiety-disordered children and healthy control children (11 years of age) performed a cued Continuous Performance Test (CPT-AX). Event-related potentials following NoGo and distractor stimuli as well as performance data were examined for group differences.
Anxious children displayed a significantly larger NoGo-related N1 global field power than did control children while no group differences were found for the N2 and P3 potentials. Groups did not differ in CPT performance.
Anxious children showed early attentional enhancement (N1) to stimuli indicating need for inhibition but not increased resource allocation to actual response inhibition.
No preview · Article · Aug 2004 · Journal of Neural Transmission