Trajectories of brain development: point of vulnerability or window of opportunity?
Brain development is a remarkable process. Progenitor cells are born, differentiate, and migrate to their final locations. Axons and dendrites branch and form important synaptic connections that set the stage for encoding information potentially for the rest of life. In the mammalian brain, synapses and receptors within most regions are overproduced and eliminated by as much as 50% during two phases of life: immediately before birth and during the transitions from childhood, adolescence, to adulthood. This process results in different critical and sensitive periods of brain development. Since Hebb (1949) first postulated that the strengthening of synaptic elements occurs through functional validation, researchers have applied this approach to understanding the sculpting of the immature brain. In this manner, the brain becomes wired to match the needs of the environment. Extensions of this hypothesis posit that exposure to both positive and negative elements before adolescence can imprint on the final adult topography in a manner that differs from exposure to the same elements after adolescence. This review endeavors to provide an overview of key components of mammalian brain development while simultaneously providing a framework for how perturbations during these changes uniquely impinge on the final outcome.
Laboratory of Development Psychopharmocology, Department of Psychiatry, McLean Hospital and Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA. sandersen@mclean.harvard.edu
Susan L
SL
Andersen
D000367:Age Factors; D000818:Animals; D001685:Biological Factors; D001921:Brain / Q000002:abnormalities / Q000254:growth & development*; D003210:Concept Formation / Q000502:physiology*; D004777:Environment; D006803:Human Development; D006801:Humans; D007398:Interpersonal Relations; D011618:Psychotic Disorders / Q000453:epidemiology / Q000209:etiology; D012727:Sex Characteristics
D001685:Biological Factors