Supplementary Figure 2: Transmodular grid cell pairs exhibit lower cross-correlation coefficients than intramodular grid cell pairs across waking and sleep states.

(a-c) These plots showing results for trans-modular grid cell pairs (n = 30) parallel those presented in Fig. 2 for intra-modular grid cell pairs. Each panel shows color-coded spike-time cross-correlations (divided by their average; see Methods) for all trans-modular pairs of grid cells sorted from highest rate map correlation coefficient (highest Cell Pair ID) to lowest rate map correlation coefficient (lowest Cell Pair ID) (See Methods). The leftmost three columns show results for RUN, REM, and NREM and are plotted across time lags of ± 5 s. The rightmost column shows results for NREM plotted across time lags of ± 1 s. Of note here is the reduced peakedness around zero-lag for these cell pairs relative to the intra-modular pairs in Fig. 2. (d) Scatterplots show the grid size ratio (x-axis) for trans-modular (black) and intra-modular (blue) grid cell pairs plotted against the z-scored spike-time cross-correlation coefficient summed between ± 5 ms. The vertical dashed line indicates the grid size ratio threshold (0.7) employed to sort cell pairs as either intra- or trans-modular. Bootstrapping tests (10,000 repetitions, two-sided) comparing the variance of near zero-lag cross-correlations between intra- and trans-modular cell pairs yielded significant results for RUN (p = 0.005, d = 2.55), REM (p = 0.003, d = 2.73), and NREM (p < 0.0001, d = 3.506). This result indicates that spike-time cross-correlations near zero-lag exhibited significantly higher amplitudes for intra-modular cell pairs relative to trans-modular cell pairs.