Fig. 4: Common engram cells are coactivated with engram-to-be cells during postlearning sleep.

A Raster plot for all neurons of a representative animal (left). Magenta, yellow, and light green blocks represent activity (time bin, 250 ms) of engram-to-be, common, and specific engram cells, respectively (top right). Schematic diagram of activity in each block and total coactivities between neuron groups (bottom right). B Schematic diagram of engram subclassification based on their activity in session B, engram-to-be, and other nonengram cells. Ensembles activities across sessions are presented in same manner as Fig. 2A. C Normalized calcium event co-occurrences between common engram and engram-to-be, compared with specific engram and engram-to-be across all sessions. D Normalized single calcium events of common and specific engrams during postlearning sleep. Statistical analysis was performed using a two-tailed t test between common engrams and specific engrams, n = 5 mice, t = 0.1939, p = 0.8557. E Number of neurons of common and specific engrams. Statistical analysis was performed using a two-tailed t test between common and specific engrams, n = 5 mice, t = 0.09713, p = 0.9273. F Normalized calcium event co-occurrences between common engrams and other nonengrams vs specific engrams and other nonengrams during postlearning sleep. **p < 0.01, n.s., nonsignificant. **p < 0.01, n.s., nonsignificant. Statistical comparisons were made using Repeated-measures two-way ANOVA with Sidak’s multiple comparisons test (C; between groups) and Holm Sidak’s multiple comparisons test (C; within group), Paired t test two-tailed (D–F). Data represent the mean ± s.e.m. The Experiment was independently repeated five times. Source data are provided as a Source Data file. Detailed statistics are shown in Supplementary Data 1.