Brain Development

Abstract

The adolescent brain undergoes marked developmental transformations that are regionally specific and bear considerable across-species similarities among humans and other mammalian species. These evolutionarily conserved developmental transformations involve both progressive and regressive maturational changes that serve to refine connectivity, speedup information flow across distant regions, and increase brain efficiency. Developmental dissociations are evident during adolescence between the predominance early in adolescence of brain regions important in responding to rewards and socioemotional stimuli, and the more protracted maturation of frontal regions and their integration into brain networks thought to be associated with improvements in behavioral control and other executive functions seen through adolescence. These adolescent brain changes not only serve as the substrate for emergence of the mature brain, but also drive adolescent-typical behaviors, including increases in peer-directed social interactions and transient developmental increases in risk taking. Developmental changes in brain reward systems and other regions of the brain may also alter sensitivity to a variety of alcohol/drug effects in ways that may promote enhanced intake, increasing sensitivity to the rewarding properties of alcohol/drugs of abuse, while decreasing their aversive properties. Developmental remodeling of the adolescent brain interacts with a variety of multifactorial contributors to increase the incidence of a number of psychological disorders among vulnerable youth during adolescence, including not only alcohol/substance abuse disorders, but also anxiety disorders, depression, externalizing disorders such as conduct disorder (CD), eating disorders, and schizophrenia. Some of the transformations of the adolescent brain may represent continued developmental plasticity that is able to customize the maturing brain to the experiences of the adolescent, although more work is needed to confirm such experience-dependent plasticity and determine the potential vulnerabilities and opportunities it affords.