Fig. 2. The normal trajectory of synaptic density over age, reflecting an initial phase of net synaptic production, followed by net synaptic elimination from late childhood/adolescence into early adulthood, and then relatively balanced synaptic elimination and production in middle age.

Adapted from post-mortem data reported by Petanjek et al. for basal dendritic spine density of pyramidal cells from layer IIIc [34].