Extended Data Fig. 4: The firing rate of a subset of CA2 cells significantly increased from the non-social to the social sessions.

a, An example cell that only began to fire in the social sessions. b, Firing rate distributions for all CA2 cells in nonsocial (blue bars) and social (orange bars) sessions, each fit with a Gaussian distribution. Six percent of CA2 cells that were active in the social sessions were classified as silent in the non-social sessions based on firing rates >2 SD below the median firing rate (<0.007 Hz). c, Mean CA2 firing rates in the social versus non-social sessions in the three-chamber task. Each circle is a different cell. Red circles, the 40 cells whose z-scored mean firing rates increased >2-fold in social versus non-social sessions. Blue circles, the 3 cells whose z-scored firing rates decreased >2-fold in the social versus non-social sessions. There was a significant increase in mean firing rate (two-sided paired t-test, p = 0.015) from the non-social (mean firing rate=1.69 Hz, sem=0.19) to the social sessions (mean firing rate=1.84 Hz, sem=0.19). d, Change in z-scored firing rate from the empty arena session to the social sessions (right) and to the novel object session (left). The two firing rate vectors differed significantly (two-sided Wilcoxon rank-sum test, p = 5.80 e-37). *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001.