Model-based predictions for dopamine

Phasic dopamine responses are thought to encode a prediction-error signal consistent with model-free reinforcement learning theories. However, a number of recent findings highlight the influence of model-based computations on dopamine responses, and suggest that dopamine prediction errors reflect more dimensions of an expected outcome than scalar reward value. In this talk I will focus on these challenges to the scalar prediction-error theory of dopamine, and to the strict dichotomy between model-based and model-free learning, suggesting that these may better be viewed as a set of intertwined computations rather than two alternative systems. Alas, phasic dopamine signals, until recently a beacon of computationally-interpretable brain activity, may not be as simple as we once hoped they were.