Dissociable neural responses in human reward systems

Reward is one of the most important influences shaping behavior. Single-uni t recording and lesion studies in experimental animals have implicated a nu mber of regions in response to reinforcing stimuli, in particular regions o f the extended limbic system and the ventral striatum. In this experiment, functional neuroimaging was used to assess neural response within human rew ard systems under different psychological contexts. Nine healthy volunteers were scanned using functional magnetic resonance imaging during the perfor mance of a gambling task with financial rewards and penalties. We demonstra ted neural sensitivity of midbrain and ventral striatal regions to financia l rewards and hippocampal sensitivity to financial penalties. Furthermore, we show that neural responses in globus pallidus, thalamus, and subgenual c ingulate were specific to high reward levels occurring in the context of in creasing reward. Responses to both reward level in the context of increasin g reward and penalty level in the context of increasing penalty were seen i n caudate, insula, and ventral prefrontal cortex. These results demonstrate dissociable neural responses to rewards and penalties that are dependent o n the psychological context in which they are experienced.