NEUROBIOLOGICAL CONSTRAINTS ON BEHAVIORAL-MODELS OF MOTIVATION

The application of neurobiological tools to behavioral questions has p roduced a number of working models of the mechanisms mediating the rew arding and aversive properties of stimuli. The authors review and comp are three models that differ in the nature and number of the processes identified. The dopamine hypothesis, a single system model, posits th at the neurotransmitter dopamine plays a fundamental role in mediating the rewarding properties of all classes of stimuli. In contrast, both nondeprived/deprived and saliency attribution models claim that separ ate systems make independent contributions to reward. The former ident ifies the psychological boundary defined by the two systems as being b etween states of nondeprivation (e.g. food sated) and deprivation (e.g . hunger). The latter identifies a boundary between liking and wanting systems. Neurobiological dissociations provide tests of and explanato ry power for behavioral theories of goal-directed behavior.