Extended Data Fig. 10: latSC photostimulation reveals the same topographic map when conducted in a cued lick task.
a, Example histological confirmation of latSC photoactivation sites (−3.1, −3.4, −3.7 and −3.9 mm AP) and AAV2-hSyn-ChR2 expression (green). DiI and DiD tracts corresponding to a single fibre implant site are orange and purple, respectively. Sites were excluded if fibre tracts were outside of the latSC or in regions with little viral expression (white, in contrast to yellow). b, Schematic of experimental timeline. Two latSC photostimulation sites were probed per session, with two trial blocks each. In block 1, mice performed ~120 trials of a cued lick task, where no laser trials (Cue only) were interleaved with latSC photostimulation trials (Stim w/cue, Methods). In block 2, mice were photostimulated (Stim only) with no task structure (40 trials). This was repeated for each site on each day. c, Trial structure for Stim w/cue (top) and Stim only (bottom) conditions. Red and cyan dashed lines are cue and laser onset, respectively. Cyan bar indicates photostimulation duration. Black pulse trains indicate lick duration for each lick. d, Polar plots of L1 protrusion endpoints for an example left (left) and right latSC (right) photostimulation session in the ‘Stim w/cue’ condition. Colours as in a. e, latSC-evoked L1 protrusion angles similarly depended on latSC photostimulation site in a cued lick task (n = 8 mice, left). Black line and coloured dots are median ± IQR across mice for each stimulation site. Grey lines are individual mice. Right, R2 for the observed correlation between photostimulation site and L1 protrusion angle (black) compared to shuffled data (grey) for the ‘Stim w/cue’ condition. **p < 0.01, two-sided shuffle test. f-g, L1 protrusion probability (f) and protrusion latency (g) did not significantly differ in post-hoc tests between latSC stimulation sites for the ‘Stim w/cue’ and ‘Cue only’ conditions. Kruskal–Wallis test. h-m, Lick kinematics during latSC photostimulation for each condition. L1 protrusion latency (h), L1 duration (i), the L1 - L2 ILI (j), L1 pathlength (k), peak L1 speed (l) and the number of acceleration peaks in L1 (m) are shown for all trial types. Note that protrusion latencies were briefer and licks were slightly slower following latSC stimulation than with a cue alone. *corrected p < 0.05, **corrected p < 0.01, two-sided hierarchical bootstrap test; n.s., not significant. Exact statistics are in Supplementary Tables 14, 15.
