Figure 3.

(a) Examples of dendritic segments from primary cortex (left, lighter blue, S group) and CA1 (right, darker blue, S group) and lists of some of their structural differences. Probability densities (log-transformed) reveal a log-normal distribution of ASI size in cortex and a bimodal distribution in CA1. Results are described in detail in the original publications: primary cortex P30 [11]; CA1 stratum radiatum P30 [32]. (b) Two-dimensional images of cortical synapses ((i) and (iv)) and CA1 synapses ((ii), (v) and (iii),(vi)). (ii), (v) and (iii),(vi) show the two types of CA1 synapses, non-perforated (np, in blue) and perforated (p, in green), and some of the distinctive features of perforated synapses, including the presence of a spine apparatus (sp) and a discontinuous post-synaptic density (asterisk). Non-perforated synapses have a continuous post-synaptic density. (c) Probability density of ASI size (μm²) in cortex (left) and in CA1 (right) and summary of the results. In primary cortex, the decrease in ASI size after sleep is size-dependent: it occurs in small and medium synapses (grey circle and arrow), which represent approximately 80% of synapses, but spares the largest synapses. In CA1, the perforated synapses (green circle and arrows) show smaller ASI size after sleep (S) relative to spontaneous waking (SW) as well as after S relative to extended waking (EW). Non-perforated synapses (blue circle and arrow) show smaller ASI size after S relative to EW (but not relative to SW). Synapse density shows a trend to decrease in S relative to EW (p = 0.0832; details in [32].) The three experimental conditions are depicted in the (ii) (SW, EW and S) and are the same in the two studies.