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Poster B59, Wednesday, November 8, 3:00 – 4:15 pm, Harborview and Loch Raven Ballrooms

Orthographic priming for tactile Braille alphabet in the ventral Occipito-Temporal cortex of congenitally blind

Katarzyna Rączy1, Aleksandra Sadowska1, Jakub Szewczyk1, Paweł Hańczur2, Ewa Sumera3, Marianna Boros1, Maksymilian Korczyk1, Anna Bereś1, Marcin Szwed1;1Jagiellonian University, 2Warsaw University of Technology, 3Institute for the Blind and Partially Sighted Children

Several recent experiments, both in sensory-deprived subjects and in subjects with their senses intact have suggested that sensory-independent task specialization is a comprehensive principle shaping brain (re)organization (Amedi et al., 2017). For example, when blind or sighted subjects read Braille, a tactile alphabet, they activate the same brain area as sighted readers reading visual words, the Visual Word Form Area in the ventral Occipito-Temporal cortex (vOT). The blinds’ visual cortex, however, undergoes massive plasticity. Unlike the sighteds’ cortex, it is massively activated by memory and spoken language tasks (e.g. Lane et al., 2015). Here we sought to determine whether the response pattern in the vOT of the blind is indeed deeply similar to the VWFA of the sighted, or alternatively, whether this similarity is superficial, and the blind’s vOT is not a reading area, but a multimodal language area. A hallmark of the VWFA is its sensitivity to orthography: using fMRI orthographic priming (repetition suppression) Glezer et. al, (2009, 2015) have shown that the vOT contains neurons with selectivity to orthographical representation. We tested 15 right-handed congenitally blind adults with a repetition suppression paradigm. Subjects either read Braille prime-target pairs of 4-letter pseudowords in three experimental conditions (same, 1-letter different, different) or heard the same pseudowords in two experimental conditions (same, different) while undergoing an fMRI scans. In the same condtion, the same stimulus was presented twice. In 1-letter different condition, the first and second stimulus differed by one letter. In the different condition, the second stimulus shared no letters with the first. For both modalities, we used a task focusing on the physical aspects of the stimulus: for Braille, participants were asked to indicate whether the target pseudoword has one a two-dot Braille letter. For spoken stimuli, they were asked to indicate whether the target was spoken by a male or a female voice. Behavioral performance in the two task was similar, and slightly higher for tactile stimuli (92 vs. 84 %correct). Preliminary whole-brain and ROI analyses revealed an orthographic priming effect in the tactile modality (Braille) in the left ventral Occipito-Temporal cortex of the blind (peak MNI: -39, -70, -17). Crucially, and in a line with the VWFA in the sighted, the above-mentioned region showed only a weak response to auditory stimuli (same, different, spoken) with no orthographic priming effect for spoken letter strings. Conversely, orthographic priming effects for spoken letter stings, but not for Braille letter stings were observed in the STS. Neuroimaging studies in blind Braille readers consistently show a much weaker selectivity for tactile reading in the vOT (e.g. Burton et al., 2002, Bedny et al., 2010, Kim et al., 2015) and more sensitivity to linguistic information in the blind’s vOT than in the sighted. However, the existence of orthographic priming effects in that region indicate that it does contain an orthographic representation for Braille words. This suggests that the function of the vOT in the blind, although not identical, nevertheless overlaps to a large extent with the function of the VWFA in the sighted.

Topic Area: Perception: Orthographic and Other Visual Processes

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