ABSTRACT
Temperament models approach attention deficit hyperactivity disorder (ADHD) in terms of neural systems involved in motivation, emotion, arousal, and attention. This chapter emphasizes individual differences in two motivational systems that are activated in appetitive and defensive situations, along with an attentional system related to voluntary or effortful control. The basic framework suggests that the two motivational systems exert relatively reactive or involuntary effects on behavior and attention. With the development of frontal circuits, however, the motivational systems become capable of recruiting executive attentional systems that allow for more refined and voluntary motivational functions. Individual differences across these systems leave some children vulnerable to impulsive disorders such as ADHD, as characterized by hyperactivity, attentional deficits, and impulsive behavior.
