Tracking the hemodynamic responses to reward and punishment in the striatum

Research suggests that the basal ganglia complex is a major component of th e neural circuitry that mediates reward-related processing. However, human studies have not yet characterized the response of the basal ganglia to an isolated reward, as has been done in animals. We developed an event-related functional magnetic resonance imaging paradigm to identify brain areas tha t are activated after presentation of a reward. Subjects guessed whether th e value of a card was higher or lower than the number 5, with monetary rewa rds as an incentive for correct guesses. They received reward, punishment, or neutral feedback on different trials. Regions in the dorsal and ventral striatum were activated by the paradigm, showing differential responses to reward and punishment. Activation was sustained following a reward feedback , but decreased below baseline following a punishment feedback.