PROJECT SUMMARY Seeing depends on a network of over a dozen interconnected cortical areas, Retinal diseases such as macular degeneration have downstream effects on white matter and gray matter components of the central nervous system, which in turn affect the quality of visual function. In amblyopia and cases of late-in-life sight restoration, healthy eyes are not sufficient for healthy vision: abnormalities in the structure and function of retinotopic maps and in the white matter fiber tracts that communicate information between them prevent people from obtaining normal levels of visual function. The long-term goal of this project is to understand the relationship between the functional organization of the human visual cortex and its white matter structure. The functional organization of visual cortex is known to be closely, but not perfectly, related to the structure of its gray-matter. However, the relationship of white-matter structure to visual function is poorly understood. The proposed research will start by generating a database of co-registered white-matter and functional properties using data collected by the Human Connectome Project (HCP) [Aim 1]. This database will then be used to train machine learning tools and existing visual models to parcellate the visual cortex of individual subjects and to describe their retinotopic organizations [Aim 2). Finally, the project will analyze the individual variability and the heritability of occipital white matter and functional properties [Aim 3). Beyond the potential to elucidate how white-matter and gray-matter anatomy influence vision, the ability to quantitatively label and model the organization of visual cortex is invaluable for numerous clinical and basic applications. Studies of the effects of ocular disorders on cortex frequently cannot measure the functional organization of cortex directly and must instead rely on methods that can estimate it. Simultaneously, visual disorders that arise in cortex, such as amblyopia, dyslexia, and posterior cortical atrophy, require quantitative models of individual differences, such as those proposed here, in order for those measurements to be used in diagnosis. For basic researchers, the database generated by this project will provide substantial value as a training dataset and as a set of baseline cortical measurements, and the tools will be applicable to brain regions, especially perceptual regions, beyond the visual cortex.