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The role of speech reading during visual word processing in hearing children: an fMRI study
Poster Session E, Sunday, September 14, 11:00 am - 12:30 pm, Field House
Neelima Wagley1,2, Anna Banaszkiewicz2,3, Clara Plutzer2,4, Rachael Rice2,5, James R Booth2; 1Arizona State University, 2Vanderbilt University, 3Nencki Institute of Experimental Biology, Polish Academy of Sciences, 4University of Maryland, 5University of South Carolina
Speech reading, or the ability to identify speech components from visual cues of the face, contributes to the development of phonological awareness which in turn supports reading acquisition. The left superior temporal sulcus (STS) is a key region known to be involved in multisensory integration of speech stimuli. Previous studies have shown a behavioral relation between speech reading and reading skill, and separately, engagement of the STS in audiovisual integration for speech reading and word reading. No prior study has directly demonstrated that speech reading mechanisms in the STS are related to word reading skill. This study’s research questions, hypotheses, and analytical plan were pre-registered on OSF prior to data analysis. Using functional magnetic resonance imaging (fMRI) we evaluate the role of the left STS in 10- to 16-year-old hearing children (N=39) during a speech reading localizer task to measure visual-to-phonological mapping which requires converting mouth movements into likely phonemes. To identify the voxels most sensitive to phonological processing, we computed a voxel-wise regression of the activation in the left STS during the speech reading task with a standardized measure of phonological awareness collected outside of the scanner. The top 1000 voxels from this analysis formed our functional STS mask of interest. We then examined 1) how these identified voxels were engaged in a visual word-rhyming task in the scanner that requires grapheme-to-phoneme mapping, 2) whether these voxels were related to individual differences in a standardized measure of reading skill. We further investigated 3) whether the activation in the left STS and its association with reading skill is selective to phonological processing in comparison to semantic processing and 4) in a set of behavioral analyses, the relations between performance on the in-scanner tasks and measures of phonological awareness and word reading skill. Across a series of pre-registered and exploratory analyses, we report three main findings. First, the left STS, functionally localized using an independent speech reading task, was significantly engaged during a visual word-rhyming task. Second, there was weak evidence that the activation of the left STS during word-rhyming was related to word reading skills. Third, there was strong evidence that reading skill was more strongly related to phonological processing than to semantic processing in the STS. Overall, our study adds to the growing body of evidence that better reading skill in children is supported by more robust engagement of specific phonological mechanisms, including those conveyed by visual speech gestures. Moreover, our results show that this relation is facilitated by the left STS – a key region for multisensory integration of various linguistic stimuli. These findings contribute to the current knowledge of the development of reading abilities and how neurobiological mechanisms of speech reading moderate the improvement of these skills.
Topic Areas: Multisensory or Sensorimotor Integration, Reading