A step-by-step guide to dopamine

摘要

There is an odd irony associated with the by-now almost ineluctable tie between reinforcement learning's temporal difference learning rule (1) and the phasic activity of dopamine neurons (2). Although temporal difference learning was designed to enable the acquisition of whole sequences of actions and predictions, a task that its ancestors (3) would flub, there are very few direct tests of this characteristic. In a penetrating new study, Was-sum and colleagues (4) measured and manipulated dopamine in a sequence learning taskfor sucrose reward, revealing four correlates of the neuromodulator: its fine- and gross-scale dynamics during learning, its involvement in two aspects of energizing behavior, and its necessity for learning.