OBJECTIVE: Attention-deficit hyperactivity disorder (ADHD) has been postulated to be related to dysfunction of the prefrontal cortex. In the oculomotor delayed response task, a subject is cued as to where he or she should look (shift visual gaze to) but must delay a short period and then shift gaze to the location where the cue previously existed but no longer exists (a memory-guided saccade). Dependent measures from this task provide information on three functions tentatively tied to prefrontal cortex functioning: the ability to inhibit response (during the delay period), preparation of motor response (inversely tied to the latency of shifting visual gaze), and accuracy of working visuospatial memory (accuracy of the memory-guided saccade). METHOD: Thirteen children with ADHD and 10 normal controls, aged 9 to 12 years, were tested using an 800-msec delay period. RESULTS: Children with ADHD showed, relative to normal controls, deficits on inhibiting response during the delay period but no differences in latency (preparation of motor response) or accuracy of visuospatial memory. CONCLUSIONS: These results support the hypothesis that the primary deficit in ADHD is difficulty in inhibition of response. This deficit may be associated with pathology located outside the dorsolateral prefrontal cortex.
OBJECTIVE:Attention-deficit hyperactivity disorder (ADHD) has been postulated to be related to dysfunction of the prefrontal cortex. In the oculomotor delayed response task, a subject is cued as to where he or she should look (shift visual gaze to) but must delay a short period and then shift gaze to the location where the cue previously existed but no longer exists (a memory-guided saccade). Dependent measures from this task provide information on three functions tentatively tied to prefrontal cortex functioning: the ability to inhibit response (during the delay period), preparation of motor response (inversely tied to the latency of shifting visual gaze), and accuracy of working visuospatial memory (accuracy of the memory-guided saccade). METHOD: Thirteen children with ADHD and 10 normal controls, aged 9 to 12 years, were tested using an 800-msec delay period. RESULTS:Children with ADHD showed, relative to normal controls, deficits on inhibiting response during the delay period but no differences in latency (preparation of motor response) or accuracy of visuospatial memory. CONCLUSIONS: These results support the hypothesis that the primary deficit in ADHD is difficulty in inhibition of response. This deficit may be associated with pathology located outside the dorsolateral prefrontal cortex.