In sections two and three, we considered the issue of specific behavioral components. Recently, it has been proposed that research in mental disorders, including ADHD, begin to focus on defining the underlying neurobiology of behavior dimensions instead of relying on a classification based on cluster of symptoms (which is currently used) (Hyman, 2007). This new strategy would permit the identification of pathways leading to specific behavioral phenotypes and, consequently, would contribute to better characterize the spectrum of variation in behavioral traits of each disorder (Hyman, 2007). Following this idea, we used a larger sample, for which we had available delay discounting data, to assess how discounting of delayed rewards relates to functional connectivity of NAcc; we then evaluated which atypical connections were associated with impulsive decision making in ADHD.
