Implication of right frontostriatal circuitry in response inhibition and attention-deficit/hyperactivity disorder

Objective: To examine the relation between specific frontostriatal structures (prefrontal cortex and basal ganglia) and response inhibition deficits observed in attention-deficit/hyperactivity disorder (ADHD). Method: Children with ADHD and age-matched normal controls were scanned using magnetic resonance imaging (MRI) and tested on three response inhibition tasks. Behavioral performance was correlated with MRI-based anatomical measures of frontostriatal circuitry (prefrontal cortex and basal ganglia) implicated in ADHD. Results: First, significant differences in performance by children with ADHD and normal volunteers were observed on all three response inhibition tasks. Second, performance on these tasks correlated only with those anatomical measures of frontostriatal circuitry observed to be abnormal in children with ADHD (e.g., the region of the prefrontal cortex, caudate, and globus pallidus, but not the putamen) in the authors' previous study. Third, significant correlations between task performance and anatomical measures of the prefrontal cortex and caudate nuclei were predominantly in the right hemisphere, supporting a role of right frontostriatal circuitry in response inhibition and ADHD. Conclusion: The data suggest a role of the right prefrontal cortex in suppressing responses to salient, but otherwise irrelevant events while the basal ganglia appear to be involved in executing these behavioral responses.