Fig. 3: Projection-based imaging reveals choice-related information in the M2-SC pathway.

a Design for projection-based imaging experiments (top) and example histology that shows the selective expression of GCaMP6s in SC-projecting M2 neurons (bottom). b Percentage and the actual number of side-selective neurons for different animals. c Dynamics of all side-selective neurons separated by the choice of the animals, sorted by the time of peak activity on the preferred side. White lines mark the timing of the sound period. d Responses (∆F/F) of an example choice-selective ROI from one imaging session. Each row shows the response for one trial. Red ticks mark RT across trials. Each of the four panels shows one trial type. Diagonal panels correspond to the same type of choice. e Schematic that shows the relevant time window of responses extracted for different behavioral epochs. f Simplified response profile for the same ROI as d. Top, average activity across frames in each behavioral epoch for individual trials. Each block of trials corresponds to one of the four trial types. Bottom, red and blue traces show the average ∆F/F responses for right and left trials (solid for correct, dashed for error trials) across behavioral epochs. g Histograms and Gaussian fits (smooth lines) to distributions of AUC values of all the ROIs from one example animal (n = 148 ROIs), during the sound, delay, response, and lick epochs. Black lines show individually significant neurons. Right, distributions across epochs are plotted together to reveal a gradual increase of contralateral selectivity over time.