From the Bronfenbrenner Center for Translational Research

To understand adolescent behavior, it is helpful to look at what is happening in the adolescent brain – and this is a story that begins much earlier in life. In the developing human brain, there is a massive early overgrowth in the number of connections or synapses between neurons (thus allowing a high degree of malleability in the brains of the very young). This early overabundance of synapses is countered by two major bouts of synaptic pruning, the first of which occurs in early childhood (around age three) and the second of which occurs during adolescence. Pruning drives a 50 to 55% decrease in the number of synapses across the entire cortex between late childhood and early adulthood. This cortical thinning is a marker of brain maturation and is associated with more adult-like cognitive abilities.  Read more