Fig. 4: Different ripple and spindle patterns during two reactivations.

A Memory change score (mean values ± SEM) in the memory strengthening condition (red) and the memory decaying condition (blue), N = 11. B The heat map shows the difference of reactivation (RSS, difference of retrieval-sleep similarity) between strengthening and decaying items averaged across patients (N = 11). Two temporal clusters (outlined in black, i.e., two shaded areas) survived after cluster-based permutation test based on one-sided paired-sample t-test (p = 0.018, p = 0.020, from left to right, respectively). C Example of detected spindle events in cortical recordings during sleep. From top to bottom: raw cortical LFP; spindle-band filtered LFP (12–16 Hz); spindle-band envelope used for spindle detection. D Grand average peri-ripple field potential (left) and spectrogram (right) during sleep (n = 6991 ripple events from 11 patients). E Grand average peri-spindle field potential (left) and spectrogram (right) during sleep (n = 69,947 spindle events from 11 patients). F Hippocampal ripple rate (mean values ± SEM) of the strengthening condition is significantly higher than that of the control conditions (t(10) = 2.31, p = 0.043, two-sided paired-sample t-test, N = 11) and showed an increasing trend than that of the decaying conditions, but did not reach statistical significance (t(10) = 2.174, p = 0.054, two-sided paired-sample t-test, N = 11) during the first reactivation (left), but not the second reactivation (right). G Cortical spindle rate (mean values ± SEM) of the strengthening condition is significantly higher than that of the decaying and control conditions during the second reactivation (t(10) = 2.637, p = 0.025; t(10) = 3.226, p = 0.009, respectively, two-sided paired-sample t-test, N = 11), but not the first reactivation (left). ^†p < 0.1, *p < 0.05, **p < 0.01.