Extended Data Fig. 3: Extracellular recording in mouse retrosplenial cortex.

(a) Tetrode drive¹² implants targeting mouse retrosplenial cortex (RSC). See Methods for details. (b) Example band-passed (100Hz-5kHz) raw voltage traces from 16 tetrodes. (c) Verification of drive implant locations in RSC via histology in all 4 mice. White arrowheads indicate electrolytic lesion sites. (d) Histograms of mean firing rates of all 984 neurons across LM0 (green), LM1 (blue), and LM2 (black) conditions. Neurons are treated as independent samples. Overall rates did not shift significantly across these states. (e) Relative per-neuron changes in firing rates across conditions. Despite the lack of a population-wide shift in average rates, the firing rates of individual cells varied significantly across conditions with heterogeneous patterns of rates. Each grouping shows rates per cell, relative to the rate in LM0 (left) LM1 (middle), and LM2 (right) as individual rates (grey lines and histograms). Bar graphs show the 50% and 95% quantiles. (f) Spatial firing profiles of 42 example neurons split by hypothesis state. Number insets denote Max. firing rate in Hz per condition. For clarity, missing data is that was not due to exclusion via landmark visibility in LM1 is plotted as the darkest color in each plot. (g) Spatial firing rate profiles for all neurons from one example session (52 total), from the main task phase. Profiles were computed in 25×25 bins, and individually normalized to their 99^th percentile. (h) same as panel g, but from the separate trial initialization task (‘dot-hunting’) in which mice had to hunt for a series of blinking dots that appeared in random positions. (i) 36 example neurons from multiple sessions and animals, chosen to represent the broad range of tuning profiles. For each neuron, the main task tuning and the ‘dot-hunting’ are plotted together on the same brightness scale, normalized to their total maximal rate. In the dot-hunting task there is no conserved radial tuning due to the absence of consistent landmarks, however some cells retain angular spatial tuning due to olfactory cues in the arena. Tuning to eccentricity (distance to arena wall or center) is maintained across task phases in many neurons. Small numbers indicate maximum firing rates in Hz for each plot (color scale is same across the pairs).