Alerting deficits in children with attention deficit/hyperactivity disorder: event-related fMRI evidence

Attention deficit/hyperactivity disorder (ADHD) is one of the most common but poorly understood developmental disorders in childhood. Although neuropsychological studies demonstrate that children with ADHD have attentional alerting deficits, the neurobiological bases of such deficits have not been examined extensively. In this study, by using functional magnetic resonance imaging (fMRI), we explored the neural correlates of intrinsic alertness and phasic alertness deficits in ADHD by comparing twelve boys with ADHD (13.4+/-1.7 years) with 13 age-matched normal controls (13.2+/-1.2 years) in a cued target detection task. Behaviorally, compared with the controls, the ADHD group showed a higher overall error rate and a larger reaction time variability in performing the task. At the neural level, children with ADHD showed less activation than the controls in frontal (middle and superior frontal gyrus), parietal (inferior parietal lobe, precuneus) and putamen regions. These results demonstrate that children with ADHD have deficits in alerting functions and these deficits are related to the abnormal activities in frontal and parietal regions subserving top-down attention control processes.