Anticipation of increasing monetary reward selectively recruits nucleus accumbens

Comparative studies have implicated the nucleus accumbens (NAcc) in the ant icipation of incentives, but the relative responsiveness of this neural sub strate during anticipation of rewards versus punishments remains unclear. U sing event-related functional magnetic resonance imaging, we investigated w hether the anticipation of increasing monetary rewards and punishments woul d increase NAcc blood oxygen level-dependent contrast (hereafter, "activati on") in eight healthy volunteers. Whereas anticipation of increasing reward s elicited both increasing self-reported happiness and NAcc activation, ant icipation of increasing punishment elicited neither. However, anticipation of both rewards and punishments activated a different striatal region (the medial caudate). At the highest reward level ($5.00), NAcc activation was c orrelated with individual differences in self-reported happiness elicited b y the reward cues. These findings suggest that whereas other striatal areas may code for expected incentive magnitude, a region in the NAcc codes for expected positive incentive value.