Handbook of Early Childhood Intervention: The Neurobiological Bases of Early Intervention

The goal of this chapter is to lay the foundation for considering the possible neurobiological mechanisms that may underlie the success of early childhood intervention. The view espoused here is that the efficacy of any given intervention will depend on the capacity of the nervous system (at the cellular, metabolic, or anatomic levels) to be modified by experience. This process, referred to throughout the chapter as neural plasticity , is often bounded by time; that is, there may be a window of opportunity, or critical period, for altering neural function. However, it will also become apparent that critical periods often interact with different neural systems, such that some neural systems remain open to modification longer than others. Moreover, there is evidence that critical periods and neural systems may interact at yet a third level, that of the individual. Thus, there may be individual differences in both the timing and the extent to which neural systems can be modified by experience. To demonstrate that neural plasticity lies at the heart of early childhood intervention, it is necessary to begin this chapter with an exposition of the precise embryonic and fetal events that give rise to the human brain. Although much of this chronology is orchestrated by genetic and humoral (hormonal) signals, experience can exert its influence even on the embryonic and fetal brain. The examples that are provided also illustrate the vulnerability of this phase of the life cycle; specifically, how compromised prenatal environments (e.g., poor nutrition) may lead to poor neurodevelopmental outcomes.