Extended Data Fig. 4: Bidirectional modulation of DAN activity during behaviour.

a, Schematic describing the experimental procedure. Left, expression of stGtACR2, ChrimsonR and GCaMP6f in DANs. Middle, injection of three viral vectors into VTA of a DAT-IRES-cre mouse. Right, the NAc fibre was used to collect terminal GCaMP signal. The VTA fibre was used to collect somatic GCaMP signal and to optogenetically activate (ChrimsonR) or inactivate (stGtACR2) DANs. b, VTA GCaMP (top) and NAc GCaMP (middle) response (normalized to 99th percentile of the single session) to unpredicted rewards in naive (untrained) mice. Mean NAc GCaMP signal normalized to the control response was compared between control and inactivation trials (bottom, paired t-test, P = 0.002). Dotted line represents time of pellet dispensing. c, VTA GCaMP (top) and NAc GCaMP (middle) response (normalized to 99^th percentile of trained mouse sessions) to reward predictive LED cue in trained mice. Comparison of mean NAc GCaMP signal during control and inactivation trials (bottom, paired t-test, P = 0.027). Dotted line represents time of LED onset. d, VTA GCaMP (top) and NAc GCaMP (middle) response (normalized to 99th percentile of trained mouse sessions) to predicted reward (reward following LED cue) in trained mice. Comparison of mean NAc GCaMP signal during control and inactivation trials (bottom, paired t-test, P = 0.065). Dotted line represents time of pellet dispensing. e, VTA GCaMP (top) and NAc GCaMP (middle) response (normalized to 99th percentile of trained mouse sessions) to reward omission in trained mice. Comparison of mean NAc GCaMP signal during control and activation trials (bottom, 2 of 3 lines overlapping, paired t-test, P = 0.029). Dotted line represents time of expected reward delivery. (*)P < 0.10, *P < 0.05, **P < 0.01 for paired t-test. All graphs are plotted as mean ± s.e.m. across mice (n = 3 mice) and dot = mouse average. Average of signal (0–10 s) normalized to the control response was used for the comparison between control and optogenetic trials. The average response of each mouse was calculated from 5 or 6 trials. Blue and red bars indicate the periods of blue-laser illumination for stGtACR2 and red-laser illumination for ChrimsonR, respectively. VTA GCaMP signal could not be collected for blue-laser illumination period owing to optical crosstalk. All t-tests are two-sided.