Ventral striatum: a critical look at models of learning and evaluation

Extensive evidence implicates the ventral striatum in multiple distinct facets of action selection. Early work established a role in modulating ongoing behavior, as engaged by the energizing and directing influences of motivationally relevant cues and the willingness to expend effort in order to obtain reward. More recently, reinforcement learning models have suggested the notion of ventral striatum primarily as an evaluation step during learning, which serves as a critic to update a separate actor. Recent computational and experimental work may provide a resolution to the differences between these two theories through a careful parsing of behavior and the instrinsic heterogeneity that characterizes this complex structure.

► Evidence exists supporting a role for ventral striatum as a critic during learning.
► Evidence exists supporting a role for ventral striatum in mediating motivational influences on decision-making during performance.
► Ventral striatum may serve as a critic over both actual states and internally generated predictions, which would produce effects in both learning and performance.