The overall goal of this twice revised competitive continuation proposal is to further our investigation as to the relationship between variation in patterns in normal brain morphology and the neurolinguistic deficits documented as characterizing children and adolescents with developmental dyslexia. Based on the research that resulted from our first three years of funding, we are particularly interested in potential familial relationships that may exist in patterns of normal variation in brain morphology among dyslexics and their affected and non-affected biological parent. Significant revisions have been more accomplished and new data regarding gyral morphology patterns and their relationship to neurolinguistic ability are provided. In a series of on-going studies, we have (1) established that neurolinguistic and phonological coding deficits seem to characterize the core deficits in our dyslexic population, even when comorbid psychopathology exists (such as ADHD), (2) that reliable measurements ( r greater than .90) of the temporal and parietal banks of the bilateral planum temporale both correlate with and are theoretically related to neurolinguistic deficits and impoverished reading achievement, (3) that gyral morphology patterns in the posterior perisylvian region may be significantly different in some dyslexic individuals, and (4) that there may be a familial link in gyral morphology pattern which may in turn be related to transmission of deficient neurolinguistic processes so commonly reported in dyslexics. Based on the results of our studies to date, we wish to continue our examination of brain morphology variation in developmental dyslexia and its relationship to deficient neurolinguistic and phonological-orthographic coding processes with a particular eye on familial associations. Specifically, we intend to examine intact families (with a diagnosed dyslexic child) and an equal number of intact families with no history of any learning or behavioral problems and examine the familial link of brain morphology variation of the planum temporale, including sulcal morphology patterns, and neurolinguistic ability. Our studies to date would suggest that symmetry/reversed asymmetry (L=R;L less than R) of the plana, or Type II sulcal morphology in the left hemisphere, would be associated with significantly below average neurolinguistic and phonological processes in dyslexics and their affected parent.
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