Fig. 1: 2P hippocampal imaging in a VR task with changing hidden reward locations.
From: A flexible hippocampal population code for experience relative to reward
a, Top-down (left) and side (right) view of the head-fixed VR setup. Adapted from previous work6. A 5% sucrose water reward is delivered when the mouse licks a capacitive port. b, Coronal histology showing imaging cannula implantation site and calcium indicator GCaMP7f expression under the pan-neuronal synapsin promoter (AAV1-Syn-jGCaMP7f, green) in dorsal hippocampal area CA1 (DAPI, blue). c, Example field of view (mean image) from the same mouse in b (mouse m12). Identified neurons in shaded colors (n = 1,780 cells). d, Task timeline. Reward remains at the same location on ‘stay’ days, and moves to a new location after the first 30 trials on ‘switch’ days (~80 trials per session). Colored bars indicate an example environment (ENV) order (n = 9 mice experienced ENV 1 then ENV 2; n = 2 mice experienced ENV 2 then ENV 1). e, Side views of virtual linear tracks showing an example reward switch sequence (reward zone switch order was counterbalanced across animals). Shaded regions illustrate hidden reward zones. f, Example behavior (mouse m14) on day 1 and first three switches. Top, smoothed lick rasters as a function of position (pos.). Rewarded trials, black; omission trials, magenta. Shaded regions, active reward zone. In f and g, data are presented as mean ± s.e.m. lick rate (middle row) or mean ± s.e.m. running speed (bottom row) for trials at each reward location (A, blue; B, purple; C, red). g, Same as f, but for an example mouse (m3) that experienced a different reward zone switch sequence. See Extended Data Fig. 1d for all sequence allocations. h, Behavior across animals performing reward switches (n = 11 mice). An anticipatory lick ratio of 1 indicates licking exclusively in the 50 cm before a reward zone (‘anticipatory zone’; Extended Data Fig. 1e) and 0 (horizontal dashed line) indicates chance licking across the whole track outside of the reward zone. Colored bars, example environment order as shown in d. Thin lines, individual mice; colored by the active reward zone for each mouse on a given set of trials (A, blue; B, purple; C, red). Black and teal lines show mean ± s.e.m. across mice for pre-switch and post-switch trials, respectively.
