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Resting-State Alpha Network Topology Links Prosodic Processing to Risk for Dyslexia: A Minimum Spanning Tree Approach
Poster Session D, Thursday, October 1, 4:30 - 6:30 pm, Wangari Maathai
Cyrille Magne1, Stephanie Powell1, Garrett McNeil1, Alexis Shumate1, Srishti Nayak2; 1Middle Tennessee State University, 2Vanderbilt University Medical Center
Developmental dyslexia affects approximately 5–10% of the population and is characterized by a core phonological deficit. Converging evidence now implicates suprasegmental processing as an independent contributor to reading: children and adults with dyslexia show reliable deficits in lexical stress perception and metrical sensitivity. Moreover, prosodic awareness explains unique variance in decoding above and beyond segmental phonological skills. Yet the neural substrates of prosodic processing in dyslexia remain underexplored. Resting-state EEG oscillations offer a theoretically motivated window into this question. Under Dynamic Attending Theory, endogenous attentional rhythms entrain to the temporal structure of speech. The Attention Bounce hypothesis extends this to metrical stress specifically, with stressed syllables acting as attentional attractors that periodically reset the oscillatory attentional cycle. Alpha-band activity is well positioned to instantiate this mechanism via top-down attentional gating, and resting alpha network topology has been shown to differ in dyslexia, with atypical hub organization and connectivity relative to typical readers. Resting alpha topology may therefore index trait-level efficiency of rhythmic attentional networks, with downstream consequences for prosodic sensitivity and reading fluency. Minimum Spanning Tree (MST) analysis provides a robust, threshold-free method for characterizing such topology. This study examined whether resting EEG MST metrics predict prosodic and reading skills, and whether lexical stress perception mediates the relationship between alpha network organization and dyslexia severity. Resting-state EEG was recorded from 76 adult participants. Three non-redundant MST metrics were selected based on low multicollinearity: leaf fraction (proportion of peripheral, minimally connected nodes), tree hierarchy (dominance of a central hub in the network), and degree assortativity (tendency of hubs to connect with other hubs). Reading ability was assessed across four measures spanning the phonological-to-comprehension continuum: lexical stress perception, reading fluency, dyslexia risk index (composite score of phonemic decoding and sight word recognition), and reading comprehension. Canonical correlation analysis (CCA) examined the multivariate relationship between alpha topology and reading skills. Bootstrapped mediation analysis (5,000 resamples) tested whether lexical stress perception mediated the relationship between alpha network hierarchy and dyslexia severity. CCA identified two dissociable canonical variates. The first one (r = .43) linked hub-and-spoke topology (high hierarchy, low assortativity) to lower dyslexia risk. The second one (r = .33) linked a centralized hub alpha topology — high tree hierarchy and degree assortativity — to superior lexical stress perception and reading fluency, suggesting that tightly interconnected hub networks support the rhythmic top-down processing underlying prosodic perception and reading automaticity. Furthermore, lexical stress perception significantly mediated the relationship between alpha hierarchy and dyslexia risk (indirect effect β = .131, 95% CI [.008, .236]), accounting for 52.3% of the total effect, consistent with partial mediation. In summary, two dissociable resting alpha network configurations differentially predict components of the phonological reading system, with lexical stress perception partially mediating the relationship between hierarchy and dyslexia risk. These findings extend phonological deficit accounts of dyslexia to encompass suprasegmental processing and situate resting alpha topology as a neural substrate of the rhythmic attentional mechanisms that stress perception requires.
Topic Areas: Reading, Prosody