To understand the contributions of 5HT and DA activity to emotion-based action in general, and to the urgency traits in particular, it is important to appreciate that 5HT activity appears often to modulate DA activity (Spoont, 1992). The interaction of these two neuromodulators, particularly in the OFC – amygdala brain system, appears to influence the level of rational, inhibitory control over appetitive drives or approach behaviors (Spoont, 1992; Zald & Depue, 2001). We first review relevant evidence for the activity of each neurotransmitter considered singly, before considering evidence of their interaction along with a brief discussion of the structural means by which 5HT activity appears to modulate DA activity.
