Cognitive neuropsychology and its application to children.

Cognitive neuropsychology has been used successfully in the analysis of adult neuropsychological disorders in both verbal and nonverbal domains. When applied to children, it aims to construct models on the basis of functional lesions manifest within developing systems and provides a theoretical framework within which patterns of intact and deficient skills can be charted over time. These patterns constrain possible underlying models. In highlighting potential individual differences in the acquisition of skills and indicating intact skills within subjects, cognitive neuropsychology may also enable a precise description of the locus of difficulty and potential circumventory routes for remediation around it. The theoretical assumptions of cognitive neuropsychology and issues relevant to its methodology are discussed, including the terminology and principles of modularity, the significance of individual differences and the use of case studies, the dynamics of developing systems, current views on plasticity, and distinctions between developmental and acquired disorders. The application of cognitive neuropsychology to children is discussed in relation to three cognitive areas: face recognition disorders, language disorders and arithmetical disorders. These illustrate the similarities that there are between many developmental cognitive neuropsychological disorders and those seen in adults following brain injury. Models derived from studies of adults are helpful in enabling understanding of both face recognition disorders and arithmetical disorders in childhood. Within language systems, a variety of different types of disorder are evident, which not only relate to receptive and productive difficulties but differentially affect the core components of the language system. All of the disorders discussed illustrate the limitations of functional plasticity in development. In each case, there is not a generalised deficit resulting from degradation of capabilities independent of task requirements. Rather, there are focal and selective disorders which affect subcomponents of cognitive systems. In some cases, genetic factors may constrain compensatory mechanisms.