Joan T. Brumaghim

Cognitive Brain Event-Related Potentials and Emotion Processing in Maltreated Children

Cognitive event-related potentials (ERPs) were recorded from 23 maltreated and 21 nonmaltreated children. Children were presented with slides of Ekman photographs of asingle model posing an angry (25%), a happy (25%), or a neutral (50%) facial expression. In 1 of 2 counterbalanced target conditions, children were asked to press a button in response to the angry face; in the other target condition, they responded to the happy face. Both samples, as expected, exhibited the largest amplitude of the P300 component of the ERP to target stimuli and the smallest amplitude to nontargets. For nonmaltreated children, the average amplitude of P300 across slides was comparable for the 2 target conditions. In contrast, maltreated children displaed larger P300 ampltude to stimuli when they were directed to attend to angry, as opposd children displayed larger p300 amplitude to stimuli whe they were directed to attend to angry, as opposed to happy, targets. These reaults suggest different cognitive processing for positive versus negative affective expressions by children with histories of atypical emotiaonal exotional experiences.

Methylphenidate speeds evaluation processes of attention deficit disorder adolescents during a continuous performance test.

Fortysix Attention Deficit Disorder (ADD) adolescents took a Continuous Performance Test (CPT) under placebo and methylphenidate (35.33 mg/day). The task required pressing one button for targets (p=133),and another button for nontargets. Subjects displayed a strong bias to make the more frequent negative response before completely evaluating stimuli. Consistent with this assumption, subjects responded faster (by an average of 87 ms) to nontargets than to targets. Methylphenidate increased accuracy and speeded reaction times (RTs) to targets. The drug also increased the amplitude of the P3b component of the eventrelated potential for nontargets and shortened the latency of P3b for both targets and nontargets. These results suggest increased capacity allocation to and faster evaluation of task stimuli. Finally, the stimulant lengthened relative motor processing time (RT-P3b latency) for nontargets, a finding implying that response processing was accomplished with the benefit of earlier completion of evaluation processes for these stimuli.

Clinical and cognitive effects of methylphenidate on children with attention deficit disorder as a function of aggression/oppositionality and age

Children diagnosed with attention deficit disorder (ADD; n = 44), ADD plus aggression/oppositionality (ADD/O; n = 34), and as not meeting ADD criteria (NC; n = 29) received methylphenidate and placebo for 21 consecutive days each. Parents and teachers rated all groups improved under medication, but teachers reported less improvement for NC than for ADD/O children. Methylphenidate and chronological age had generally similar effects in a Sternberg task: greater accuracy and speed (especially for nontargets at low memory loads), larger P3b waves of event-related potentials, more pronounced slowing of P3b latency by memory load, and a greater trend of earlier peaks for targets than for nontargets. Both methylphenidate and maturation promoted more efficient strategies involving differentiated evaluation of targets and nontargets. These results were comparable among ADD groups.

Paired-associate learning in attention-deficit/hyperactivity disorder as a function of hyperactivity-impulsivity and oppositional defiant disorder.

A paired-associate learning (PAL) test was administered to 22 community volunteers without disruptive disorders and 197 children (7.5–13.5 years-old) presenting with the inattentive and combined subtypes of attention-deficit/hyperactivity disorder (ADHD) either in combination with or without oppositional defiant disorder (ODD). Participants were screened for learning disorders. In comparison to non-ADHD participants, children with ADHD achieved worse PAL and made errors rated as more acoustically and less semantically similar to the correct paired associates. These deficits were not related to hyperactivity–impulsivity or comorbid ODD. These results suggest that ADHD children are less competent at PAL and use less efficient learning strategies than their non-ADHD peers.

Methylphenidate's effects on paired‐associate learning and event‐related potentials of young adults

The effects of methylphenidate (0.3 mg/kg) on young adults paired-associate learning (PAL) of consonant-vowel-consonant (CVC) pairs and concomitant event-related potentials were assessed. The stimulant elevated mood and heart rate but did not affect PAL performance. For the first CVC, there were amplitude increases with learning for P3b at Pz, P2 at midline sites, and for a negative slow wave at Cz. For the second CVC, P3b and positive slow wave amplitude declined with learning. Increases in P3b amplitude to the first CVC were attributed to increments in stimulus meaningfulness. Decreases in P3b amplitude to the second CVC were interpreted as resulting from fewer disconfirmed expectations of feedback. The negative slow wave following the first CVC was viewed as a contingent negative variation. Methylphenidate increased parietal P3b amplitude for CVC 2, averaged over learning phases.

Methylphenidate Does Not Modify the Impact of Response Frequency or Stimulus Sequence on Performance and Event-Related Potentials of Children with Attention Deficit Hyperactivity Disorder

Twenty-six children with attention deficit/hyperactivity disorder (ADHD) participated in a double-blind trial consisting of 2 consecutive weeks each of placebo and methylphenidate (M = 26.92 mg/day = 0.78 mg/kg/day). As expected, stimulant therapy resulted in moderate weight loss, increased somatic complaints, and teacher and parent reports of reduced inattentiveness, aggression, and oppositionality. In both phases of the trial, patients were tested in a choice reaction time task assessing two aspects of the task that presumably affect response selection: response frequency (ratio of targets/nontargets = 25/75 vs. 50/50) and stimulus sequence (alternations vs. repetitions). Both manipulations yielded expected results on performance and event-related potentials (ERPs). Stimulant treatment increased accuracy and speed among younger children and curtailed variability of reaction time for the sample as a whole. However, methylphenidate did not affect ERPs. In combination, the results imply that the enhancement of performance by methylphenidate does not involve the demands of response selection examined in this study.