This proposal is based on neurobiological theory and research and is guided by recommendations found in the 1987 NIH Interagency Committee on Learning Disabilities report to Congress. Specifically, this three-year study examines the interactions between deviations in brain morphology in congenital dyslexics, normals, and a group of clinic controls (ADD/Hyperactivity), and patterns of neurolinguistic ability. Unique to this study is the inclusion of a group of clinic controls in order to judge the specificity of deviations in brain morphology in the dyslexic syndrome. Also unique, is the examination of neurolinguistic ability and deviations in normal patterns of brain morphology in affected dyslexic parents of children diagnosed as dyslexic. It is hypothesized that dyslexic children with concomitant oral language dysfunction will show theoretically consistent deviations in brain morphology compared to the normal and clinic control children. A particular focus in this study relates to a very careful clinical assessment of the children so that possible relationships among various forms of co-occuring childhood psychopathology can be examined. In support of this project two preliminary pilot studies were conducted. In Study #1, (published in Archives of Neurology, 1990) the MRI scans of 10 dyslexic, 10 ADD/Hyperactive, 10 normal children were examined. very significant group differences were found in the incidence of normal patterns or asymmetry (L > R) in the length of the plana. Ninety percent (90%) of the dyslexics had either symmetrical or reversed (L < R) asymmetry, while only 30% of the ADD/Hyperactive and normal children showed such a pattern. Deviations in brain morphology were significantly related to the neurolinguistic deficits characteristic of these dyslexics. In a further analysis (published in Learning and Individual Differences, 1991) we found that word attack skills, passage comprehension, and rapid naming performance was significantly depressed (> 1 standard deviation) in those children who had symmetry or reversed asymmetry (L< R) of the plana. In Study #2, (accepted for publication in Archives of Neurology) data from volumetric acquisitions revealed anomalous asymmetry or duplicated gyri in the dyslexics in Heschl's region; the planum temporale and the posterior sylvian fissure generally. The results of our preliminary studies provide strong support for further investigation that address the relationship between deviations in normal patterns of brain morphology and the nature of neurolinguistic deficits that characterize development dyslexics.
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