Abstract
Phasic dopamine responses demonstrate remarkable simplicity; they code for the differences between received and predicted reward values. Yet this simplicity belies the subtle complexity of the psychological, computational, and contextual factors that influence this signal. Advances in behavioral paradigms and models, in monkeys and rodents, have demonstrated that phasic dopamine responses reflect numerous behavioral computations and factors including choice, subjective value, confidence, and context. The application of optogenetics has provided evidence that dopamine reward prediction error responses cause value learning. Furthermore, studies using advanced circuit tracing techniques have begun to uncover the biological network implementation of the reward learning algorithm. The purpose of this review is to summarize the recent advances in dopamine neurophysiology and synthesize an updated account of the behavioral function of dopamine signals.