8. PROJECT SUMMARYAttention-Deficit/Hyperactivity Disorder (ADHD) is the most common neurodevelopmental disorder; however, themechanisms underlying attention problems in individuals with the disorder are unclear. Prominentneurobiological models hypothesize that task-negative regions of the brain (i.e., default-mode network) are notadequately suppressed during task performance which culminate in increased reaction time variability (i.e.,attentional lapse model). Recent evidence, however, indicates that increased reaction time variability can reflectboth the failure to recruit task-positive (i.e., dorsal attention network [DAN]) regions of the brain as well asinadequate suppression of task-negative regions (i.e., default-mode network [DMN]) – a possibility that has notbeen examined in children with ADHD. The current proposal seeks to evaluate the utility of a novel approach toisolating the unique contribution of DAN and DMN to reaction time variability in children with ADHD. Specifically,our aims are 1) to examine RTV related activations in the DAN and DMN in children with ADHD, 2) to comparethe RTV related activations in DAN and DMN between children with and without ADHD, and 3) examine themediating effect of brain network activity (DAN, DMN) on the relation between RTV and behavioral symptoms ofthe disorder (i.e., inattention, hyperactivity, impulsivity) in children with ADHD and whether these relationshipsare moderated by distinct neurobiologically impaired subgroups of children with ADHD (i.e., DAN impaired, DMNimpaired). This proposal attempts to synthesize neurobiological and behavioral data to further explicate themechanisms underlying attention problems in children with ADHD. These findings will likely have importantimplications for the refinement of existing interventions based on distinct neurodevelopmental profiles and willlay the foundation for incorporating multiple levels of analysis (i.e., neurobiological, neurocognitive, behavioral)into a precision medicine approach to treatment of the disorder.
