Oxyopia Abstract

June 30, 2009
Tuesday, 4:00 PM
489 Minor Hall

Donald Mitchell, PhD
Professor Emeritus, Department of Psychology, Faculty of Science, Dalhousie University, Nova Scotia, Canada
Host: Dennis Levi

Title

When daily visual input is mixed: A fresh look at the role of early visual experience in the development of vision

Abstract

Natural patterned visual input in early postnatal life is essential for the normal development of the mammalian central visual pathways and the visual capacities they sustain. At birth, visual input is processed by, and acts upon a visual pathway that has developed according to programs of gene action. The early postnatal visual input thus acts upon an anatomical and physiological substrate that may set limits to its ability to affect the further development of the visual pathways. Our approach has been to provide animals with mixed visual input each day that pits episodes of normal against abnormal (biased) visual exposure, specifically intervals of normal binocular and monocular exposure. Short periods of concordant binocular input, if continuous, can offset or protect against much longer episodes of monocular deprivation to allow normal development of V1 and of vision. The outcome for vision appears to be determined by the proportion of daily visual exposure that is binocular rather than by the absolute amount of such exposure. Experiments conducted on animals with abnormal cortical architecture at the time that mixed daily visual input was imposed point to a special role for binocular visual input in the development of V1 and of vision. The results hold implications for the treatment of amblyopia.

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