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Poster A29, Wednesday, November 8, 10:30 – 11:45 am, Harborview and Loch Raven Ballrooms

Abnormal cortical folding and neurite architecture during brain maturation in children with developmental dyslexia

Eduardo Caverzasi1,2,7, Maria Luisa Mandelli1, Christa Watson1, Marita Meyer1, Fumiko Hoeft3, Claudia A Gandini Wheeler-Kingshott4,5,6, Elysa J Marco7,8,9, Bruce L Miller10, Robert Hendren1, Kevin Shapiro1, Maria Luisa Gorno-Tempini1,7;1Dyslexia Center, Department of Neurology, University of California, San Francisco, San Francisco, CA, USA, 2Biomedical Sciences PhD, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy, 3Langley Porter Psychiatry Institute Langley Porter Psychiatric Hospital and Clinics, Department of Psychiatry, University of California, San Francisco, CA, USA, 4Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of Neurology, Russel Square House, London, United Kingdom, 5Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy, 6Brain MRI 3T Mondino Research Center, C. Mondino National Neurological Institute, Pavia, Italy, 7Department of Neurology, University of California, San Francisco, San Francisco, CA, USA, 8Department of Psychiatry, University of California, San Francisco, San Francisco, CA, USA, 9Department of Pediatrics; University of California, San Francisco, San Francisco, CA, USA, 10Memory and Aging Center, Department of Neurology; University of California, San Francisco, San Francisco, CA, USA

There is increasing recognition of a relationship between regional variability in cerebral gyrification and differences in cognition and neurodevelopment. Recent neuroimaging data suggests that cortical folding changes are associated with neurodevelopmental disorders such as autism spectrum disorder, attention-deficit hyperactivity disorder, and dyslexia. However, regional patterns of folding are not fixed at birth, and recent work in morphometric MRI has shown that the local gyrification index generally decreases with age in adolescence and young adulthood. Little is known about how these changes in brain maturation interact with neurodevelopmental differences. In this study, we analyzed local gyrification index using Freesurfer in 39 children with developmental dyslexia and 56 typically developing children between the ages of 7 and 15. We also investigated the microstructural changes underlying gyrification differences, specifically the relationship between gyrification and neurite architecture, by using neurite orientation dispersion and density imaging (NODDI), an advanced diffusion MRI model. NODDI provides two key metrics, the neurite density and the orientation dispersion index, which characterize the microstructural organization of dendritic projections and axons. We found significant differences in gyrification between dyslexic and typically developing children in left mid-frontal and left lateral temporal regions. Specifically, children with developmental dyslexia failed to show an age-related decrease in local gyrification index in this region, which was seen (as expected) in typically developing children. This was not explained by differences in cortical thickness, but did correlate with measures of neurite architecture. Our findings suggest that gyrification changes in developmental dyslexia are related to abnormal neurite architecture, likely due to an interaction between genetic factors, experience-dependent plasticity, and pruning.

Topic Area: Language Disorders

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