Highlights d Validation of a novel test that monitors habit development individually across time d Dopamine release during habit development is stable across relevant striatal regions d Only dopamine release in dorsomedial striatum correlates with habit development d Optogenetic stimulation of dorsomedial striatal dopamine accelerates habit formation

Significance Although it is undisputed that striatal dopamine plays a prominent role in motivated behavior and learning, the precise information conveyed by dopamine signals as such is under active debate. For a long time, the idea dominated that dopamine encodes a reward prediction error and that this signal is broadcast uniformly throughout the brain. However, here, we capture dopamine dynamics across many striatal regions and demonstrate that dopamine release is, regionally, extremely heterogeneous and that a reward prediction error–like signal is predominantly found in the relatively small limbic domain of the striatum. Another striking organizing principle is that stimulus valence directs dopamine concentration homogeneously across all regions (i.e., appetitive stimuli increase dopamine and aversive stimuli decrease dopamine).