Although previous studies have shown that Braille reading and other tactile discrimination tasks activate the visual cortex of blind and sighted people [1-5], it is not known whether this kind of crossmodal reorganization is influenced by retinotopic organization. We have addressed this question by studying "S," a visually impaired adult with the rare ability to read print visually and Braille by touch. S had normal visual development until 6 years of age, and thereafter severe acuity reduction due to corneal opacification, but no evidence of visual-field loss. Functional magnetic resonance imaging revealed that, in S's early visual areas, tactile information processing activated what would be the foveal representation for normally sighted individuals, and visual information processing activated what would be the peripheral representation. Control experiments showed that this activation pattern was not due to visual imagery. S's high-level visual areas, which correspond to shape- and object-selective areas in normally sighted individuals, were activated by both visual and tactile stimuli. The retinotopically specific reorganization in early visual areas suggests an efficient redistribution of neural resources in the visual cortex.
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“S” is author G.E.L. We thank Thomas A. Carlson and Serena Thompson for assistance in data collection, Deyue Yu for conducting the tangent-field measurements on S, Allen M.Y. Cheong for conducting the fixation stability measurements on S, and Scott O. Murray and Bosco S. Tjan for comments on earlier drafts of this manuscript. This study was supported by a University of Minnesota Doctoral Dissertation Fellowship to S.-H.C. and US National Institutes of Health (NIH) grant EY002934 to G.E.L. Use of the 3T magnetic resonance scanner at the Center for Magnetic Resonance Research of the University of Minnesota was supported by NIH National Center for Research Resources (NCRR) grant P41 RR008079 and the Mental Illness and Neuroscience Discovery (MIND) Institute.