Topic: D2 receptor-expressing neurons

Midbrain dopamine (DA) activity is implicated in reinforcement learning (RL). DA activity is observed to signal reward prediction error (RPE), a key quantity in many RL algorithms used to modulate updates to state-reward and state-action associations. How the state representations underlying these associations are themselves learned is typically outside the scope of RL models of the basal ganglia. However, modern RL algorithms in machine learning typically employ deep RL, in which state representations are learned as part of the RL algorithm, to attain state-of-the-art performance. In this wor