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Aakash Agrawal, K.V.S. Hari, S. P. Arun; How does reading expertise influence letter representations in the brain? An fMRI study. Journal of Vision 2018;18(10):1161. doi: https://doi.org/10.1167/18.10.1161.
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© ARVO (1962-2015); The Authors (2016-present)
Learning to read results in the formation of the Visual Word Form Area (VWFA) within the visual cortex, but precisely how letter shape representations in VWFA and other visual regions in the brain change with reading is not well understood. We investigated these issues by selecting two Southern Indian languages, Telugu and Malayalam, which have entirely distinct scripts with relatively little overlap among readers. We identified two groups of subjects: one fluent in reading Telugu but not Malayalam, and the other fluent in Malayalam but not Telugu. Using fMRI, we measured the brain activity while subjects viewed Telugu and Malayalam words in a 1-back task. Our main findings are as follows: (1) BOLD activation in hV4, VWFA and Middle Temporal Gyrus (MTG) was larger for familiar letters compared to unfamiliar letters but smaller in the Lateral Occipital Complex (LOC). Both findings are double dissociations, thereby eliminating any confound due to subject group or letter shape. (2) The location of the VWFA peak was systematically different for Telugu and Malayalam letters; (3) VWFA voxel activations were correlated more strongly with MTG for native letters compared to non-native letters; (4) VWFA activations were positively correlated with language fluency across subjects. Taken together, our results suggest that reading expertise alters letter shape representations throughout the visual cortex. Furthermore, VWFA appears to be an intermediate stage of the reading network that integrates visual and auditory letter representations.
Meeting abstract presented at VSS 2018
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