A Saccade Study Of The Inhibition And Working Memory In Subtypes Of ADHD

The present study was conducted to examine the inhibition and working memory in subtypes of ADHD(Attention Deficit Hyperactivity Disorder). Saccade tasks are well-established means to investigate inhibition and working memory. ADHD have been attributed to deficits in frontal-striatal circuitry, which underlie inhibition and working memory. voluntary saccades depend on structures implicated in attention and in motor control are consistent with the areas of dysfunction in ADHD. Therefore we used saccade tasks as a tool to analyze inhibition and working memory dysfunctions in two subtypes of ADHD.Participants, aged 10-13 years, with ADHD-C (n=19), ADHD-I (n=11), and control subjects(n=18), were selected according to DSM-IV diagnosis, Conners teacher rating scale and parent symptom questionnaire.Every participants performed 4 different saccade tasks: a prosaccade, two antisaccades and a delayed response task, antisaccades were executed in a single-task and a dual-task situation. Goal-directed and stimulus-driven processes mutually cooperates in the prosaccade task. Antisaccade task require a subject to inhibit an incorrect but prepotent response to a salient distractor, goal-directed and stimulus-driven processes Mutually competes. Another antisaccade task were performed under the verbal secondary task conditions to investigate verbal working memory . Delayed response task require to inhibit a saccade to prepotent stimuli and generate an accurate response to a remembered spatial location.Saccades were registered by Eyelink II Tracker. Correct rate, performance accuracy, latency, peak velocity, average velocity and others were analyzed, the conclusions as follows:(1) Each group showed a longer response latency, a quicker peak velocity and average velocity as well as a worse accuracy with angle enlargement on the prosaccade task. The ADHD group exhibited a higher rate of early saccades, a lower peak velocity and average velocity than children without ADHD.(2) ADHD group exhibited more response suppression errors than children without ADHD on the antisaccade task. No differences were observed between ADHD-I and ADHD-C when Stimulates angle is 5°and 10°, However, Correct rate was higher in ADHD-I children when the angle is 15°. The ADHD group exhibited longer latency and re-correction time than children without ADHD.(3) The ADHD group demonstrated impairments in response inhibition on the delayed response task, they had difficulties in suppressing saccades toward the stimuli during the delay period, no differences were observed between ADHD-I and ADHD-C. Correct rate and peak velocity were not different for children without ADHD when delay time lengthened, but for ADHD. The ADHD group exhibited a longer latency and a lower average velocity than children without ADHD.(4) ADHD performed as accurately as controls on a 1s condition on the delayed response task, but showed a significant impairment in spatial accuracy on 3s and 5s condition, explained spatial working memory deficits in ADHD.(5) The interactions with group and load were not significant in error rate, but in re-correct rate. ADHD group were affected more by the secondary task load than non-ADHD, their re-correct rates tended to decrease under verbal working memory load, these are usually explained by an impairment of verbal working memory.The present study was the first study which used antiaccade tasks to analyze verbal working memory in ADHD, as well as the first saccade study in Domestic. Through a Series of detailed indicators, we can understand better about inhibition and working memory dysfunctions in ADHD subtypes.