Saccadic eye movements and visual fixation in children with ADHD

Attention deficit hyperactivity disorder (ADHD) is a prevalent developmental disorder, which is characterized by symptoms of impulsiveness, hyperactivity, and/or inattention. The neurobiological foundations of this disorder are still a matter of debate. Here, we discuss important implications of modern eye-tracking systems in ADHD research. In addition, we report a dual-task study, investigating the ability of time-reproduction (interval timing), prosaccade inhibition, and prosaccade initiation in healthy control children and in medicated children with a diagnosis of ADHD. The results showed comparable abilities in the two groups with regards to precise time-reproduction, active inhibition, and initiation of prosaccades. In addition, our data revealed a comparable number, latency, amplitude, and duration of prosaccades in medicated ADHD children and in control subjects. The data suggest that ADHD medication is effective at compensating for deficits in executive control. However, compared to unmedicated healthy control subjects medicated children demonstrated accelerated peak velocities in trials requiring a prosaccade to peripheral targets, indicating changes in brainstem processing. Precise measurement of peak velocities might be useful to further improve the diagnosis of ADHD.