By early adolescence, the brain is a fairly close approximation of the adult version, with adult densities of neurons and synapses, and the process of myelinating the brain already achieved. Except for one brain region which, amazingly, won’t fully mature for another decade. The region? The frontal cortex, of course. Maturation of this region lags way behind the rest of the cortex—to some degree in all mammals, and dramatically so in primates.[29]
