Extended Data Fig. 14: Behavioral controls of VEVS.

To ascertain whether systematic changes in behavior caused VEVS, we employed a ‘behavioral clamp’ approach and estimated tuning strength using only the subset of data where the hypothesized behavioral variable was held constant. a, Example aVEVS tuned cells maintained its tuning even if we used only the data when the rat was (b) stationary (running speed <5 cm/sec, blue, left). This was comparable to a random subsample of behavior, obtained by shuffling the indices of spikes and behavior when the animal was stationary (orange, middle) (see Methods). 38% of cells were aVEVS tuned (sparsity z > 2) when using only the stationary data which is significantly greater than chance, whereas 42% were significantly tuned in the equivalent, random subsample and this difference was significant (KS-test p = 0.02). c, Similar to b but using only the data when the rat’s head was immobile (head movement velocity <10 mm/sec). 43% and 42% of cells were significant tuned in actual behavioral clamp and equivalent subsample, and these were not significantly different (KS-test p = 0.93). d, Similar to b, but removing data within 5 s after reward dispensing, called void post-reward. 43% cells were tuned in “void post-reward” data, 43% for equivalent subsample (KS-test p = 0.56). e, Similar to d, but removing data within 5 s before reward dispensing, called void pre-reward. 39% cells were tuned for void pre-reward, 42% for equivalent subsample (KS-test p = 0.43). f, Using a subsample of data, from when the rat’s head was within the central 20 percentile of head positions (typically <10^o), rat was stationary and there were no rewards in the last 5 s. This condition was called “analytical head fixation”. 28% of cells were aVEVS tuned under this behavioral clamp, which was lesser than that in an equivalent subsample (31%, KS-test p = 0.05), but significantly greater than chance. g, Tuning curves for head positions to the leftmost 20 percentile and rightmost 20 percentile were similar, with 31% and 32% cells tuned in the two conditions (KS-test p = 0.67). The preferred angles of tuning were highly correlated (circular correlation r = 0.67 p = 1.3 x 10⁻¹¹) and not significantly different (circular KS-test p > 0.1). h, aVEVS tuning was recomputed in the head centric frame, by accounting for the rat’s head movements (obtained by tracking overhead LEDs attached to the cranial implant) and obtaining a relative stimulus angle, with respect to the body centric head angle. Overall tuning levels were comparable, between allocentric and this head centric estimation. First panel of h is the same as that in a since all aVEVS tuning reported earlier was in the allocentric or body centric frame. Using a subset of data when both overhead LEDs were reliably detected, 25% and 26% of cells were significantly tuned for the stimulus angle in the allocentric and egocentric frames (KS-test p = 0.9). Preferred angle of aVEVS tuning for tuned cells was highly correlated (r = 0.81 p = 1.8 x 10⁻¹⁵) and not significantly different between the two frames (circular KS-test p > 0.1).