Abstract
What aspects of visual cortex function are intrinsically determined and which are a result of visual experience during the lifespan? I will discuss insights into this question from studies with congenitally and late blind adults as well as children. We find that the visual cortex of individuals who are totally blind from birth acquires novel higher-order cognitive functions that are drastically different from vision. Occipital areas of blind individuals respond to linguistic information, such as sentence structure and the meanings of words. A different set of occipital areas responds to cognitive control demands. Occipital cortices also show increased connectivity with language and cognitive control areas of the prefrontal cortex. This drastic functional plasticity depends on absence of vision early in life. We observe occipital responses to language in congenitally but not late blind adults. Our studies with congenitally blind children further suggest that occipital plasticity emerges during early childhood during, in the course of brain development. Together these findings illustrate how early visual experience is a potent driver of visual cortex development. In the absence of early visual input, occipital circuits are invaded by higher-cognitive functions. A key question for future research concerns how non-visual invasion of the visual system affects potential recovery of visual function.