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Santani Teng, Radoslaw Cichy, Dimitrios Pantazis, Aude Oliva; The neural dynamics of letter perception in blind and sighted readers. Journal of Vision 2015;15(12):126. doi: 10.1167/15.12.126.
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© ARVO (1962-2015); The Authors (2016-present)
Functional changes in visual cortex as a consequence of blindness are a major model for studying crossmodal neuroplasticity. Previous studies have shown that traditionally visual cortical regions activate in response to a wide range of nonvisual tasks (Merabet & Pascual-Leone, 2010; Kupers & Ptito, 2013). However, the underlying computations, while often inferred to be similar for the blind and the sighted, have almost never been examined in detail. Here we used magnetoencephalography (MEG) and advanced multivariate pattern analysis to compare visual letter recognition with Braille reading (Sadato et al., 1996; Reich et al., 2011). We presented blind and sighted volunteers with 10 single letters in random order while recording brain activity. Sighted subjects were presented with Roman visual letters, while blind subjects were presented with Braille tactile letters. We used linear support vector machines to decode letter identity from MEG data. We found that the classification time course of letter recognition in sighted subjects was generally faster, briefer, and more consistent than in blind subjects. We then used representational similarity analysis (Kriegeskorte et al., 2008) to compare how sighted and blind subjects represented letters both within and across groups. This analysis revealed high within-group correlations at ~200 ms for sighted and ~600 ms for blind subjects. Correlations between groups were an order of magnitude lower, though overall significantly positive. The results suggest that blind and sighted letter reading may be largely driven by distinct processes, but that brain regions recruited crossmodally may be performing some common underlying computations for analogous tasks. This work was supported by NIH R01-EY020484 to A.O.
Meeting abstract presented at VSS 2015
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