Cortical Maps and White Matter Tracts following Long Period of Visual Deprivation and Retinal Image Restoration

SummaryAbnormal visual input during development has dramatic effects on the visual system. How does the adult visual system respond when input is corrected? MM lost his left eye and became blind in the right due to corneal damage at the age of 3. At age 46, MM regained his retinal image, but his visual abilities, even seven years following the surgery, remain severely limited, and he does not rely on vision for daily life. Neuroimaging measurements reveal several differences among MM, sighted controls, sighted monocular, and early blind subjects. We speculate that these differences stem from damage during the critical period in development of retinal neurons with small, foveal receptive fields. In this case, restoration of functional vision requires more than improving retinal image contrast. In general, visual restoration will require accounting for the developmental trajectory of the individual and the consequences of the early deprivation on cortical circuitry.

► Seven years after visual input restoration, MM's visual acuity and performance are poor
► MM has altered V1 BOLD responses—no foveal responses and odd receptive field sizes
► DTI of MM's optic tract show smaller interhemispheric connections than controls.