Reward Prediction in Prefrontal Cortex and Striatum

Abstract

The prefrontal cortex (PFC) and striatum have mutual connections through direct and indirect pathways, and both are involved in reward prediction. But it has been suggested that the PFC and striatum may have different mechanisms in reward prediction. To understand the nature of reward process in the two areas, we recorded single-unit activity from the lateral PFC (LPFC) and striatum in monkeys performing a reward inference task. We found that prefrontal neurons could predict the reward value of a stimulus even when the monkeys had not yet learned the stimulus-reward association directly. Striatal neurons, however, could predict the reward only after directly experiencing the stimulus-reward contingency. Our results suggested dissociable functions in reward predictions: the LPFC utilized causal structure of the task or higher-order conditioning in a generative process of reward inference, whereas the striatum applied direct experiences of stimulus-reward associations in the guidance of behavior.