Introduction

The field of neuropsychology has made great advances in understanding how the adult brain is organized and how functions. Relatively little is known, however, about the neural systems mediating normal cognitive development. At present, much of our understanding of brain–behavior relationships in children has been based primarily on adult models. Although valuable, these models have serious limitations when applied to children. Concepts such as critical periods, for example, refer exclusively to the developing organism. The immature brain differs from the mature brain in its neural organization. For example, while studies of laterality provide considerable data to suggest that hemisphere specialization begins early in life, the demarcation between cognitive functions that are differentially mediated by the two hemispheres is less clear cut in children than in adults (Luria, 1973). Concepts such as neural plasticity have been mostly applied to the developing brain, as the possibilities for neural re-organization and recovery of function following injury are remarkable in young organisms. Furthermore, the structure and function of the developing brain is profoundly responsive to and affected by experience. Adversity, whether through deprivation or through abusive environments, can have a deleterious and long-lasting impact on the brain's structural and functional organization (van der Kolk and Greenberg, 1987; Ito et al., 1993).

Recognition of the differences between the mature and the immature brain have led to the design of measures that are sensitive to developmental factors. Of all the techniques available neuroimaging provides a unique approach to the study of brain–behavior relationships children.