Thus, while the human brain reaches its full size by about 16 years of age, the prefrontal cortex does not reach full maturity until this pruning is complete, and these gradual brain changes are associated with changes in behavior. The frontal cortex is associated with complex functions such as decision-making and evaluation of rewards and, because it takes so long to reach full maturity, adolescents tend to place great emphasis on gaining approval from their peers, and often engage in risky behavior to do so.
