age-dependent changes in the rate of spine turnover suggest that spine stability impacts developmental learning. in youth, dendritic spine turnover is relatively high and produces a net loss of spines. this high rate of spine turnover may characterize critical periods of development and reflect learning capacity in adolescence—different cortical areas exhibit differing levels of synaptic turnover during development, possibly reflecting varying critical periods for specific brain regions. in adulthood, however, most spines remain persistent, and the half-life of spines increases. this stabilization occurs due to a developmentally regulated slow-down of spine elimination, a process which may underlie the stabilization of memories in maturity.