Developmental Orgins of Human Extrastriate Areas

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DESCRIPTION (provided by applicant): This proposal is in response to PA-03-107 (NIH EXPLORATORY/DEVELOPMENTAL RESEARCH GRANT AWARD R21). FMRI investigations over the last decade have revealed the functional organization of human visual cortex in considerable detail, including the identification of a number of extrastriate areas, each of which responds quite selectively to a specific kind of visual information: the fusiform face area (FFA) for faces; the parahippocampal place area (PPA) for the spatial structure of scenes, the extrastriate body area (EBA) for bodies and their parts, the lateral occipital complex (LOC) for object shapes, and visual motion area MT. Almost nothing is known about the developmental origins of these extrastriate areas. The experiments described here will first behaviorally test children age 4-adult on a set of visual tasks, each designed to tap the function of a different extrastriate area, then characterize the development of these extrastriate regions directly using fMRI (in children age 7-adult), and finally test the relationship between the developmental changes observed neurally and those observed behaviorally. We will test the hypothesis that cortical specialization increases throughout childhood (as expected if the cortex is fine-tuned through experience), against the competing hypothesis that informational exchange between processing modules increases over development, thereby reducing domain-specific activation patterns in these areas. We will also test specific hypotheses about differences between areas in the time course of developmental change. Finally, we will test relationships between the developmental changes we observe behaviorally vs. neurally with longitudinal studies of individual subjects. Extrastriate cortex is an ideal test case for pediatric fMRI because BOLD signals are very large from this region of the brain, and because complex tasks are not required to activate this region. In addition to advancing the methodology of pediatric fMRI, this work is likely to provide important insights about i) the developmental origins of human extrastriate cortical areas, ii) the behavioral functions that each area subserves, iii) the nature and developmental change in visual shape representations across childhood, and iv) the domain-specificity of high-level vision and its neural substrate.