Differential roles of sleep spindles and sleep slow oscillations in memory consolidation
Fig 3
Spontaneous sequence replay mediates synaptic changes underlying memory consolidation during sleep.
a) The change of synaptic weights relative to the initial values after training (left), N2 (middle) and N3 sleep (right). The synaptic weights between neurons in direction of sequence activation (grey box) were enhanced due to the sequence replay. b) The dynamics of the mean synaptic weights (grey box in a) shows the progressive increase in synaptic strength during normal N2+N3 sleep (left), only N2 sleep (middle right); only N3 sleep (right). Note the lack of synaptic changes when sleep was supplemented by awake state of the same duration (middle left). Orange bar represents training period. The blocks in the top summarize the protocol of each experiment: Pink block—awake, purple block—N2 sleep, dark green block—N3 sleep. The patch error bar represents standard deviation. c) The bar plots of performance during test sessions after training (before sleep) and after sleep in four different experimental conditions corresponding to b. Error bars indicate SEM. * p<0.05, ** p<0.01, *** p<0.001. N.S. represents no significant difference. d) Characteristic examples of sequence (“ABCDE”) replay during sleep spindles and slow oscillations. e) The fraction of correct replayed sequence (“ABCDE”) during four difference experimental protocols. 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.