Neurocognitive Foundations of Morphological Processing in Children with Dyslexia

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Project Summary Developmental dyslexia is a specific learning disability characterized by word reading difficulties that impacts 5- 12% of children in the US. Dyslexia is most commonly associated with impaired sensitivity to language sounds (phonological awareness). However the ultimate goal of reading is not to access sound, but to access meaning. Although the neurocognitive mechanisms underlying sound processing and its impairments in dyslexia are relatively well understood, little is known about the role and neurocognitive basis of sensitivity to units of meaning (morphological awareness) in dyslexia. This is a major gap in knowledge, as children with dyslexia typically demonstrate poor morphological awareness, and decoding polymorphemic words becomes increasingly important for academic success through elementary and middle school. Guided by the Lexical Quality framework and Connectionist theories of reading, the current proposal will investigate the neurocognitive mechanisms underlying morphological processing in relation to word reading children with dyslexia (4th-5th grade) as well as age-matched (4th-5th grade) and skill-matched (2nd-3rd grade) typical readers. I will collect structural and functional magnetic resonance imaging (MRI) data during a novel morphological processing task. Participants will also complete a comprehensive assessment of oral language, reading, and cognitive skills. First I will characterize the neurocognitive basis of morphological processing and its development in typical readers. I will then test the hypothesis that the neurocognitive basis of morphological processing differs between typically developing children and those with dyslexia. Finally, I will identify the neural correlates of morphological processing that are associated with behavioral measures of word reading (dis)ability, advancing our understanding of dyslexia by connecting brain to behavior. This work is of theoretical and practical importance, as morphology becomes increasingly important for successful reading over time, yet neurocognitive models of reading and dyslexia rarely include morphological processes. Additionally, morphology may be one powerful way to compensate for phonological deficits in dyslexia. Findings may inform educational and clinical practices to capitalize on morphological processing as a promising compensatory mechanism, and provide research-based intervention for struggling readers. The proposed study will provide ample opportunities to complete the fellowship training goals by advancing the trainee’s: 1) conceptual knowledge of dyslexia, 2) technical training in fMRI neuroimaging, 3) advanced methodological knowledge, and 4) translational skills in working with educators and clinicians. This work will be conducted at MIT and MGH IHP, both vibrant academic communities with extensive resources for pediatric neuroimaging, and supervised by leading experts in the field with decades of experience conducting research related to reading and dyslexia.