Fig. 1. Reactivation of MEC cells manifests isolated theta waves during NREM sleep.
A, B Schematic diagram depicting LFP and EEG-EMG recording (A), and spatial memory task (B). C Representative trajectories on first and third day training sessions. D Distance that animals traveled in the maze (one-way repeated measures ANOVA followed by post hoc Fisher LSD Method, n = 6 mice, F2,5 = 7.069, P = 0.012; day 1 vs. day 3, P = 0.004; day 1 vs. day 2, P = 0.224; day 2 vs. day 3, P = 0.037). E MEC neuronal activity recorded during training phase (i), post-training wakefulness (ii) and post-training NREM sleep (iii) with a magnified view of a firing pattern (marked by magenta color). F Comparison of reactivation strength (two-tailed paired t test, n = 39 trials from 6 mice, t38 = −3.692, P = 0.000695). G LFP and corresponding power spectrum during NREM sleep. Isolated theta waves are indicated by red rectangle box. H Distributions of mean duration of isolated theta waves. I Percentage of theta power during isolated theta wave and non-isolated theta wave phases (Wilcoxon Signed Rank Test, n = 36 channels from 6 mice, Z = −5.243, P = 1.24 × 10−7). J, K Coupling of isolated theta power and delta phase. L Distribution of isolated theta waves in relation to the delta phase. M Modulation index for normal and shuffled data (Wilcoxon signed-rank test, n = 36 channels from 6 mice during post-training NREM sleep, Z = −5.232, P = 1.68 × 10−7). N Raw LFP trace, corresponding power spectrum and reactivation strength (Rs.). Freq., frequency. O Distribution of reactivation events (RT) during delta phase and a normal distribution fit to this distribution (red curve). P Theta power around the peak of reactivation strength. Inset, comparison of theta power in the period of RT and baseline (Basal.) (Two tailed paired t test, n = 39 trials, t38 = −8.998, P = 5.90×10−11). *P < 0.05, **P < 0.01, ***P < 0.001. Data are presented as mean ± s.e.m. Source data are provided as a Source Data file.