Abstract
This paper reviews the latest findings and understandings concerning the reward system in the brain. Dopamine neurons in the substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) play key roles in the representation of reward, by projecting axons to other reward-related brain areas, such as the nucleus accumbens, dorsal striatum, limbic structures, and prefrontal cortex. While dopamine neurons are concerned with the detection of reward prediction error, nucleus accumbens and related limbic structures may play major roles in inducing hedonic feelings and pleasure from the reward. The dorsal striatum is involved in learning the value of a specific stimulus or action, and plays a major role in Pavlovian and instrumental conditioning. The prefrontal cortex is involved in short-and long-range reward expectancy, which serves as an incentive background for executing on-going action as well as organizing future behavior. It is also involved in evaluating possible behavioral options and planned actions, as well as in monitoring the outcome of actions, which may be critical for reward-based decision-making. (Japanese Journal of Physiological Psychology and Psychophysiology, 26 (1) : 5-16, 2008.)
