ABSTRACT

The sensory deprivation model provides an opportunity to study the dependence of brain functions on experience in humans. This chapter reports studies on spatial and memory functions in blind humans to demonstrate that the lack of a particular environmental input results in specific behavioral and neural adaptations. It is concluded that neural networks established during development set the limits of adaptive capacities later in life.

INTRODUCTION

The capability of the brain to adapt to new requirements is called neuronal plasticity. Research has shown that the ability to change is a lifelong feature characteristic of the central nervous system (CNS) and is indeed the basis for learning and memory. Nevertheless, the extent of possible changes varies across the lifespan, and experience early in life may essentially determine the dynamic range for adaptations later in life. The existence of so-called critical periods in development (i.e., time windows during which adequate experience can cause normal development) is well accepted. The windows vary for different functions and seem to exist for basic sensory processes, as well as for more complex functions such as social behavior (e.g., Chapter 3). Although the time windows of increased plasticity vary for different functions, the principles of how experience shapes brain systems are most likely similar across functional domains (Bavelier & Neville, 2002). Therefore, research on the developmental principles of perceptual-cognitive functions will contribute to the understanding of biocultural co-constructivism in lifespan development.