Adaptive Coding of Reward Value by Dopamine Neurons

TLDR

Animals must accurately estimate reward values, allocating limited neural resources to better discriminate likely outcomes over unlikely ones. Midbrain dopamine neurons rapidly adapt to reward‑predicting stimuli, shifting responses relative to expected reward value and adjusting gain to reward variance, thereby maintaining sensitivity across a wide range of reward values.

Abstract

It is important for animals to estimate the value of rewards as accurately as possible. Because the number of potential reward values is very large, it is necessary that the brain's limited resources be allocated so as to discriminate better among more likely reward outcomes at the expense of less likely outcomes. We found that midbrain dopamine neurons rapidly adapted to the information provided by reward-predicting stimuli. Responses shifted relative to the expected reward value, and the gain adjusted to the variance of reward value. In this way, dopamine neurons maintained their reward sensitivity over a large range of reward values.