ABSTRACT
The concept of developmental risk has recently expanded to focus on the nature of adverse circumstances that, by virtue of their severity, may result in physiological damage or the loss of behavioral function (Garmezy, this volume). These adverse circumstances may sometimes be determined by the individual’s specific biology. Studying the biological processes contributing to abnormal development is necessary for improving our treatment of individuals who are at risk; it may also permit us to better understand normal development (Cicchetti, 1989). However, the biological processes responsible for aberrant outcomes are varied and complex. Moreover, it is well recognized that a host of protective mechanisms exist to buffer the organism against environmental insult. The developing nervous system has a remarkable capacity for reorganization that allows it to respond in an adaptive fashion to injury or environmental change. This capacity for plasticity may make it difficult to infer processes of normal neural development directly from studying children at risk. At the same time, however, “… plasticity means that capacities and organizations appear which admit the possibility of systematic variations appropriate to new environmental conditions” (Schneirla, 1957, p. 82). Plasticity in this sense clearly plays a central role in normal development in that it permits learning, behavioral adaptations, and a “fine tuning” of the nervous system’s structure. Understanding the nervous system’s capacity to recover from damage, and the limits on this capacity, may well contribute to our understanding of plasticity in normal development.
