VEP, EEG and MEG studies of texture segregation processes: complete maturational course throughout adulthood

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The way in which our brain integrates all the information present in our visual world in order to form unified and coherent percepts relies on different mechanisms. One of these is the segregation of textures, which can be determined by various visual dimensions such as luminance, orientation, size of objects, color, motion, etc. Primary visual pathway function has been extensively studied during early development as well as in adults. However, more integrative visual processes have received much less attention. Thus, the developmental curve as well as the point at which texture segregation becomes mature has yet to be determined. Furthermore, the interactions and synchronization taking place between different cortical areas during such complex visual processes have just begun to receive attention. In recent years, techniques such as electrophysiology and magnetoencephalography (MEG), used to measure brain activity, have become precise enough to study such mechanisms in all age groups. The present research program aims at describing, with these tools: 1) how normal texture segregation processes develop during infancy and childhood; 2) when they reach adult-like function; 3) what are the exact cortical interactions and integration mechanisms involved. Low-level and texture-segregation visual evoked potentials as well as EEG gamma activity and MEG recordings will be obtained in children (1 month-16 years) as well as in adult groups of different ages (20-60 yrs). Visuo-perceptual measures of integration and segmentation will also be obtained in order to have behavioral correlates of the complex visual processes at study with electrophysiology and MEG. The suggested approach is original in that it combines state-of-the-art functional brain imaging techniques with traditional behavioral (neuropsychological) measures in the context of a study of the complete developmental course throughout adulthood of texture segregation mechanisms. Because texture segregation is so important in higher visual processing, such a research program will provide a better understanding of how these mechanisms develop, as well as of the type and localization of brain activity and interactions involved.