Fig. 4. Impaired replay with preserved reactivation of a novel experience.

(A and B) Examples of replay and reactivation for (A) the Stim OFF and (B) the Stim ON experience, respectively. (Top) Decoded position during replay events (color coded by decoded position). (Middle) Raster plots of neuronal firing; colored circles indicate activations of assemblies composed of neurons with nearby place fields (colored ticks; colors of assemblies reflect their peak activation position). (Bottom) Assembly reactivation strength curves. (C) Increase in proportion significant replay (left) and sequence scores (right) of SWRs in post-task sleep as compared with pre-task sleep. Unlike the OFF direction, there was no significant replay in the ON direction (n = 4437 events; Stim OFF: studenťs t test, ***P = 7 × 10⁻¹¹; Stim ON: P = 0.29 for proportions; and Wilcoxon signed-rank test: OFF ***P = 3 × 10⁻¹⁷ and ON P = 0.29 for scores). Only the first session in the maze was included (n = 5 sessions). (D) Reactivation strength of task-related assemblies centered on post-task sleep SWR, increased relative to baseline (Stim OFF post-task sleep versus baseline sleep during SWRs: Wilcoxon signed-rank test, n = 31 components, **P = 0.0096; Stim ON post-task sleep versus baseline sleep during SWRs: Wilcoxon signed-rank test, n = 27 components, **P = 0.0026). (E) Reactivation of pairwise neuronal correlation as measured by explained variance (EV) in post-task sleep was significant for both directions (Stim OFF: *P = 0.031; Stim ON: Wilcoxon signed-rank test, *P = 0.031; Stim OFF versus Stim ON, Wilcoxon signed-rank test, P = 0.81; n = 5 sessions). (F) Correlation between replay scores and assembly reactivation strength for post-task SWRs computed independently for Stim OFF and Stim ON replay events. Reactivation and replay were correlated in Stim OFF (Pearson’s correlation coefficient r = 0.11, ***P = 3 × 10⁻¹²) but not in Stim ON (Pearson’s r = −0.028, P = 0.06).