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Background: 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., Methods: 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)., Results: 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., Conclusions: 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.

Background: 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., Methods: 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., Results: 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., Conclusions: 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.

Agenesis of the corpus callosum is associated with a wide range of neuropsychiatric symptoms. Cranial MRI confirms the diagnosis. We report a case of a 13-year-old boy with global developmental delay, mental retardation as well as neurological and psychiatric symptoms but without symptoms of ADHD who is unable to cope with school demands. Agenesis of the corpus callosum is a relatively rare, but possibly underestimated differential diagnosis of unclear retardations in development in children or suspicion of ADHD respectively.

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.

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.

Background: 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., Methods: 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., Results: 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., Conclusions: 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.

Our study compares the efficiency and acceptance of two different methods of treating dyslexia in children. The first method addresses the most commonly encountered deficits in sequential processing. It relies primarly upon the "Kieler Lese-Rechtschreibaufbau". The second proceeds from the child's relative resources with regard to simultaneous processing as described by Kaufman. Training materials are those prescribed by Kaufman. Normally gifted primary school third-graders were trained in two groups (n = 13 and n = 12) and achieved a mean SIF score of SW = 101 on the K-ABC. As expected, the children scored significantly lower on the SED scale (SW = 95) than on the SGD scale (SW = 105). At the beginning of the respective training program their spelling ability fell 1.5 SD below the class mean. One year of regular weekly one-hour training according to the simultaneous processing method was significantly more successful than training in sequential processing, whereas girls improved significantly more than boys regardless of the method used. Acceptance of the methods did not vary. This result requires careful consideration and should be replicated in younger samples such as first- and second-graders in the early stages of learning to read and write, and/or in children whose dyslexia is more severe than that encountered in the current sample. It underscores that determination of an adequate method of remediation entails more than the mere identification of the underlying deficits.