Fig. 3. Value assignment to sensory stimuli in the ventral striatum during reversal learning.

a To assess how stimulus-triggered neuronal responses are modified during reversal learning, we performed recordings in head-fixed mice of VTA and OTu. ChR2-expression in DAN allowed for optogenetic tagging. b Exemplary performance of a mouse learning the go-/no-go task (original phase). Once criterion was reached, the odor-reward contingency was reversed (reversal phase) within the session. To reveal changes after learning, each phase was divided into an ‘initial’ phase (comprising the first 12 CS+ and 12 CS− trials) and a ‘late’ phase (last 12 CS+ and 12 CS− trials). c, d The cosine distance of the population vector from baseline changed for CS+ (but not CS−) from the initial to the late trials (two-sided t-test, asterisks mark significance at α = 0.05 with Benjamini–Hochberg correction). Displayed mean ± S.E., n = 4 trial-averages of three trials, respectively, for both ‘initial’ and ‘late’. e Examples of normalized PSTH of responses to CS+ in the initial and late trials in 3 SPN. f Distribution of cosine distances between CS+ and CS− representation in initial and late trials, respectively. During learning, CS+ and CS− representations diverged both in the original and reversal phase (two-sided t-test). Source data are provided as a Source data file. See also Supplementary Figs. 6-7.