Abstract
Adaptation of an organism to the environment occurs through numerous processes beginning in the prenatal period and continuing through the neonatal and early adolescent period. Environmental signals, through processes, such as activity dependent plasticity, interact with the concurrently unfolding genetic blueprint for the central nervous system giving rise to a stable, individual phenotype governing perception of, and responsiveness to, salient features of the environment. This process of adaptation may be viewed as “fine-tuning” or “environmental programming” of neural circuitry. Thus, the studies in this chapter have initially been focused on a comprehensive description of the phenotype resulting from exposure to neonatal handling or maternal separation at the level of behavior, neuroendocrine responsiveness, and the central nervous system circuitry. Seemingly beneficial adaptations in the short-term, may, under challenging environmental conditions, actually are maladaptive over the life span of the individual. Increasing basic, clinical, and epidemiological evidence supports the thesis that exposure to an adverse early environment may underlie vulnerability to, and later expression of, physio- and/or psychopathology.