Network dynamics and sequence learning paradigm.

<p><b>a</b>) The cortical network activity during transitions from awake state (pink block, <i>top</i>), to N2 sleep (purple block), to N3 sleep (dark green block) and back to the awake. Raster plot (<i>middle</i>) shows membrane voltages of cortical pyramidal cells. Broadband filtered local field potential (LFP, <i>bottom</i>) from the cortical population. The sequence was learned during the training period (orange bar). Grey bar represents the period of sleep. The performance was tested in three test sessions: before training, after training before sleep, and after sleep. <b>b</b>). The expanded view of characteristic spatiotemporal patterns (<i>top</i>), LFP (<i>middle</i>) and single cell activity of neuron #200 (<i>bottom</i>) during awake (<i>left</i>), N2 sleep (<i>middle</i>) and N3 sleep (<i>right</i>) from where pink, purple, dark green bars are shown in <b>a</b> (<i>bottom</i>). The spindle activity during N2 sleep revealed a typical waxing-waning pattern, consisted of 7–14 Hz brief bursts of rhythmic waves. The slow oscillations (<1Hz) during N3 sleep consisted of a typical Up and Down state transitions. <b>c</b>) The characteristic examples of a training session and three test sessions. The training included stimulating sequentially at groups A, B, C, D, and E. The test included stimulating only at group A (“pattern completion”). The sequence started at neuron #200. Each group included five neurons and it was stimulated for 10 ms. The delay between groups was 5 ms. <b>d</b>). The dot represents the string match between an ideal sequence (“ABCDE”) and each recalled sequence during test sessions for one trial. The value one represents a perfect match. The red line and the light red patch error bar represent mean and SEM of a moving average string match (window size = 10) over all trials (n = 10). <b>e</b>). The bar plot of the performance that was defined by the probability of recalled sequence with 80% similarity to the ideal sequence “ABCDE” (SM> = 0.8) during each test session. Error bars indicate standard error of the mean (SEM). For the boxplot in the right panel, the central mark indicates the median, and the bottom and top edges of the box indicate the 25th and 75th percentiles, respectively. <i>Left</i>: trained sequence; <i>Right</i>: untrained sequence tested at all other locations. * p<0.05, ** p<0.01, *** p<0.001.