Infant Stress, Neuroplasticity, and Behavior

The fulfillment of an individual’s genome of the central nervous system ontogenetically involves a series of processes collectively termed developmental plasticity ([Perry & Pollard, 1998]). These processes govern cellular migration, synapse formation, and other aspects of the orderly development of the nervous system (Z. Hall, 1992). The term plasticity is used because of the presence and absence of transmitters, growth factors, and hormones that influence the appearance of cells and synaptic connections defining the species. Perturbations of these processes result in abnormal development ([Perry & Pollard, 1998]). Developing systems are not “fixed and immutable” but are susceptible to disturbances that reflect severity and point in developmental time ([Perry, 1997]). Experiential plasticity defines the neural changes that may occur following exogenous stimulation or social restriction. For fetuses and newborns experiential plasticity is superimposed upon the genetically synchronized developmental plasticity and both processes proceed simultaneously during early development. Experiential plasticity is understandable within the context of early stages of neural development; rate and asymptote of brain growth and maturity are very much dependent on environmental conditions and how those conditions impact the infant.