Representational Similarity Analysis of the Neural Representations of Orthographic, Phonologic, and Semantic Processing

Poster Session D - Monday, April 15, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Deanne Wah¹ (dwah@uwo.ca), Marc Joanisse^1,2; ¹The University of Western Ontario, ²Haskins Laboratories

Contemporary reading models propose two word recognition processes: decoding from orthography to phonology, and whole-word reading from orthography to semantics. Prior neuroimaging studies localized regions involved in reading, while emerging techniques enable the comparison of activation patterns with cognitive models outside the brain. Our study uses Representational Similarity Analysis to investigate patterns of activity in sub-regions of the reading network and evaluates their similarity to orthographic, phonologic, and semantic models during word reading. We also explore how individual differences in the strength of these representations relate to reading skill. Forty neurologically healthy, monolingual English-speaking adults participated in two sessions. The first included standardized reading and intelligence measures, demographics questionnaires, and a word naming task. In the second, participants silently read monosyllabic words while detecting person names in a 3.0T fMRI scanner. Word-by-word theoretical representational dissimilarity matrices (RDM) were constructed, with the orthographic model using Levenshtein Distance, the phonological model using Phonological Edit Distance, and the semantic model using cosine distance of Global Vectors. Empirical RDMs were calculated using Euclidean distance. Spearman Rank Correlations were used to correlate the theoretical and empirical RDMs. One-sample t-tests determined whether the correlations were distinct from 0. Linear regression models were used to examine individuals’ orthographic, phonologic, and semantic similarity per sub-region against the standardized measures. Results indicate distributed patterns of activation in the reading network. Of note, in the left inferior temporal gyrus, individuals with higher similarity to orthographic and semantic processing showed stronger sight word reading efficiency.

Topic Area: LANGUAGE: Other