Wednesday, April 2, 2025
4/2/2025
Neural basis of Braille literacy in blind adults and children - PROJECT SUMMARY The current project examines the neural basis of Braille reading in proficient congenitally blind adults, late blind readers with varying degrees of proficiency and blind children learning to read, using fMRI and high-density diffusion imaging (dMRI). These studies of Braille literacy provide insights into human brain plasticity and the neural basis of culture. Reading changes the anatomy and function of the human brain. In sighted people, reading experience enhances anatomical pathways within and across visual and language networks. Sighted readers develop a ‘visual word form area’ (VWFA) in lateral ventral occipito-temporal cortex (lVOT), tuned to letters and words. Braille offers insights into the mechanisms of cultural recycling by disentangling which aspects of the reading brain are modality invariant and which are modality specific. The current proposal distinguishes between two alternative hypotheses. According to the task-based hypothesis, blind readers develop the same neural mechanisms for reading as the sighted in the lVOT and show similar connectivity changes, because lVOT is intrinsically predisposed for modality-invariant shape recognition. By contrast, the connectivity-based hypothesis proposes that connectivity and experience heavily influence reading localization. It therefore predicts that blind individuals develop tactile word form areas (TWFAs) in parietal regions with strong connectivity to somatosensory and language networks. It also predicts that Braille literacy enhances anatomical connectivity of these parietal network. Aim 1 investigates the neural changes support this expert reading in congenitally blind adults. Proficient Braille readers can achieve speeds of 200 words per minute and more. What neural changes enable this ability? In a series of fMRI experiments with congenitally blind proficient readers we use MVPA and fMRI adaptation to test our hypothesis that proficient blind readers develop ‘tactile word form areas’ TWFAs in posterior parietal cortex and connected dorsal occipital areas. Aim 2 tests the prediction that individual differences in the connectivity (dMRI) and functional specialization of parietal areas predicts individual differences in reading proficiency among congenitally and late blind adults, whereas individual differences in early visual areas only predict individual differences in the congenitally blind population. Aim 3 tests the key prediction that TWFA specialization and Braille-reading associated connectivity changes emerge as a result of literacy by working with congenitally blind children (dMRI and fMRI) longitudinally, as they learn to read. Uncovering neural markers of successful Braille literacy will test theories of human brain plasticity and facilitate and inform strategies for enhancing Braille literacy among people who are blind.
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