Extended Data Fig. 1: Histology, baseline behavior, and effects of iSPN stimulation on the next trial.

a. Example histology (left) showing CoChR expression (green) and the tapered fiber location as revealed by glial fibrillary acidic protein (GFAP) staining (magenta). Scale bar: 1 mm. The CoChR expression in striatum averaged across mice is also shown (right). b. Baseline expert behavior after two weeks of training. Percentages of correct (grey), incorrect (green) and miss (orange) outcomes for left- and right-cued trials (n = 7 mice). c. left, Median lick latency measured from tone onset to spout contact for left- (blue) and right- (red) cued trials. right, Mode of inter-trial-interval for licks to the left (blue) and right (red) ports. d. Functional map of optogenetic perturbations at 8 striatal sites showing changes in percentages of incorrect (left) and miss (right) outcomes (see Fig.1e). The color and size of each circle denote the effect size and p-value (bootstrap), respectively (n = 5 mice, 9 sessions). e. Effect of VLS iSPN stimulation on the next trial (n+1 trial) relative to control trials (excluding all n+1 trials). For n+1 trials, only those following left-cued trials were included as optogenetic stimulation only affected left-cued trials (i.e. contraversive to the stimulation site in the right striatum) (n = 7 mice) (see Fig.1e; Methods) (n.s.: P>0.05, two-tailed t-test). f. Median latency to first lick in no stimulation trials (separated into left vs. right; blue/red) and stimulation trials (sorted into incorrect vs. correct; green/grey). Correct licks during stimulation trials to the left were delayed compared to those during no stimulation trials (P*<0.05, two-tailed t-test) (left licks: n = 6 sessions, right licks: n = 9 sessions, see Methods).