CORPUS-CALLOSUM MORPHOLOGY, AS MEASURED WITH MRI, IN DYSLEXIC MEN

To test the hypothesis of anomalous anatomy in posterior brain regions associated with language and reading, the corpus callosum was imaged in the midsagittal plane with magnetic resonance, The areas of the ant erior, middle, and posterior segments were measured in 21 dyslexic men (mean age 27 yrs, SD 6) and in 19 matched controls. As predicted the area of the posterior third of the corpus callosum, roughly equivalent to the isthmus and splenium, was larger in dyslexic men than in contr ols, No differences were seen in the anterior or middle corpus callosu m. The increased area of the posterior corpus callosum may reflect ana tomical variation associated with deficient lateralization of function in posterior language regions of the cortex and their right-sided hom ologues, hypothesized to differ in patients with dyslexia.