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Reading proficiency is associated with the precision of high-level visual processing across domains in children with and without dyslexia
Poster Session A, Friday, September 12, 11:00 am - 12:30 pm, Field House
Florence Bouhali1, Ting Qi2, Maria-Luisa Mandelli3, Cheng Wang4, Rian Bogley3, Jocelyn Caballero3, Rayburn Tang3, Ellie Carpenter3, Maria Cecilia Ferre Ladao3, Christa Pereira Watson3, Kevin Weiner5, Maria-Luisa Gorno-Tempini3, Fumiko Hoeft6; 1Aix-Marseille University, CNRS, CRPN, France., 2Beijing University of Posts and Telecommunications, China., 3University of California, San Francisco., 4Fujian Medical University, Fuzhou, China., 5University of California, Berkeley., 6University of Connecticut Waterbury.
Learning to read constitutes a milestone in children's development, leading to profound changes in language processing and beyond. Illiterate adults notably differ from literates in visual processing across object categories, with reduced neural repetition suppression (i.e., a smaller activation decrease between the first and second occurrence of a repeated image, suggesting worse exemplar discrimination, Pegado et al., 2014) and less clearly defined category-selective regions in ventral occipito-temporal cortex (vOTC, Dehaene et al., 2010). Interestingly, adults with dyslexia also show difficulties in fine-grained visual tasks (Kristjánsson & Sigurdardottir, 2023) and reduced repetition suppression across categories (Perrachione et al., 2016). While these differences have been proposed as causes of dyslexia, parallels with illiteracy question the directionality of associations between reading proficiency and visual processing. Here, we investigated how reading proficiency relates to high-level visual processing in a developmental sample of 41 children with dyslexia and 36 without, aged 7 to 17. Children performed a standard repetition detection (one-back) localizer task in the fMRI, within blocks of words, numbers, limbs, faces, objects and places. Absolute reading proficiency was indexed by the principal component in children’s raw scores in word and pseudoword reading on the Test Of Word Reading Efficiency (TOWRE-2), reflecting overall differences in grade level on top of relative differences in achievement (including those due to dyslexia). We tested whether dyslexia group membership and absolute reading proficiency relate to the precision of visual processing across categories, both in brain and behavior, controlling for age, ADHD status and other confounding variables. We also explored whether such effects were shared, or more attributable to dyslexia diagnosis vs. raw reading skills. Repetition detection hit rates were lower in children with dyslexia across visual categories and negatively correlated with absolute reading proficiency. These shared behavioral differences suggest challenges in representing stimulus identity across domains, and were accompanied by neural differences in repetition effects. We also investigated the uniqueness of categorical representations by estimating the difference in multivariate similarity within vs. across categories in the left and right vOTC. We observed that both absolute reading proficiency and dyslexia impacted categorical distinctiveness for words and other categories across hemispheres, in different but complementary ways. Word distinctiveness positively correlated with absolute reading scores, especially in the left hemisphere, but did not differ between dyslexia groups overall. Absolute reading proficiency was also positively associated with the distinctiveness of limbs, and marginally for faces and places, while a specific increase in face distinctiveness was seen in dyslexia. Higher distinctiveness was further associated with higher repetition detection rates, demonstrating its behavioral relevance. Overall, lower reading proficiency and dyslexia both relate to poorer visual processing and noisier cognitive representations of stimulus identity and category across visual domains. Reading scores showed stronger effects on categorical representations, although children with dyslexia additionally showed a unique strength for faces. These findings reconcile visual processing challenges reported in dyslexia and illiteracy, altogether reinforcing the view that learning to read refines high-level visual processing across domains.
Topic Areas: Reading, Disorders: Developmental