Most important for the present argument is the evidence that 5HT and DA interact. Serotonergic systems, which appear important for information processing, have been found to influence certain dopaminergic pathways that may underlie approach behaviors (Patterson & Newman, 1993; Spoont, 1992). It appears that 5HT activity, which may contribute to affect-guided planning (Davidson, 2003), tends to inhibit high levels of disposition to act that are reflected in uninhibited DA activity. Authors have suggested that 5HT's inhibiting influence on DA reflects a process in which information processing reduces one's propensity to act, perhaps as one considers appropriate actions in light of newly arriving information and important long-term goals (Davidson, 2003; Spoont, 1992). Low levels of 5HT, then, imply a failure to inhibit the approach tendencies characteristic of high levels of DA. One result may be an overall reduction in affect-guided planning and accompanying higher rates of rash, ill-considered acts.
