Children with dyslexia frequently present with poor phonological processing and working memory (WM). Furthermore, there is a strong association between their poor phonological processing skills and their inability to store verbal material. Several brain regions have been found to be structurally atypical in dyslexia in MRI studies, and these brain abnormalities have been linked to poor phonological processing. Nonetheless, the relationship between brain structure and WM has received limited attention in the dyslexia literature. Children with ADHD also present with WM deficits. However, the central executive (CE) is primarily affected in ADHD. Hence, there is an interesting dichotomy between the 2 disorders with dyslexia displaying impaired verbal short-term storage and intact CE functioning, and ADHD displaying intact verbal storage but impaired CE functioning. Similar to research on dyslexia, the relationship between WM and brain morphology has received limited attention in the ADHD literature using structural MRI techniques. Thus, the goal of this project is to ascertain the relationship between brain structure and WM functioning in children with dyslexia, ADHD or controls, while determining the extent linguistic processing influences this relationship. Participants will include children with dyslexia, ADHD and controls between the ages of 8-12 years. They will engage in neuropsychological testing of their WM, linguistic functioning, intelligence, and reading ability. Along with cognitive testing, a structural MRI scan will be conducted on each child. Each scan will be analyzed using quantitative structural neuroimaging techniques. Through a correlational design, the relationships between brain morphology, WM and linguistic processing will be examined in children with and without neurodevelopmental disorders. This study will benefit children with dyslexia in terms of providing knowledge that may aid in diagnosis and intervention. For example, through a better understanding of the biological correlates of dyslexia and ADHD, a more rapid diagnosis may be possible than is provided by traditional techniques. Furthermore, earlier diagnosis will allow for earlier placement into intervention, and early intervention has been linked with better treatment outcome than intervention started later. ? ? ?
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