The Psychobiology of Adolescence

Abstract

In studies of brain development, the focus is often on the rapid growth of the brain before birth and for the first few years thereafter during which the rapidly growing infant begins to interact with and learn about the world. But brain development is a lifelong process. New nerve cells are formed into adulthood (van Praag et al., 2002), and throughout life the brain retains the ability to alter its microstructure based on life experiences (Greenbush, Cohen, & Juraska, 1999; Kleim et al., 1998). For the most part, the magnitude of brain remodeling and plasticity is relatively modest after infancy, with one notable exception: adolescence. Adolescence is a time of rapid physical change that includes periods of abrupt growth and the emergence of secondary sexual characteristics, along with sometimes striking changes in mood and behavior. Although these changes in body appearance and behavior are more obvious, they are no more dramatic than the physiologic changes occurring internally in the adolescent, transitions that include substantial increases in hormone release as well as a dramatic metamorphosis of brain. The magnitude of these brain alterations is difficult to fathom. For instance, it has been estimated that as many as 30,000 connections (synapses) between nerve cells may be lost per second during portions of the pubertal/adolescent period across the entire cortical region of primate brain (Rakic, Bourgeois, & Goldman-Rakic, 1994). Before reviewing some of the major characteristics of this brain metamorphosis during adolescence, the stage will first be set by defining adolescence and considering the potential evolutionary underpinnings of this developmental transition. (PsycINFO Database Record (c) 2015 APA, all rights reserved)