Brain Morphology in Children With Specific Language Impairment

The planum temporale and pars triangularis have been found to be larger in the left hemisphere than the right in individuals with normal language skills. Brain morphology studies of individuals with developmental language disorders report reversed asymmetry or symmetry of the planum, although the bulk of this research has been completed on adults with dyslexia. Pars triangularis has not been studied in the developmental language impaired population. In this study, magnetic resonance imaging (MRI) was used for quantitative comparisons of the planum temporale (Wernicke's area) and pars triangularis (Broca's area) in children with specific language impairment (SLI) and children with normal language skills. The subjects were 11 children with SLI and 19 age- and sex-matched controls between 5.6 and 13.0 years old. Each subject received a neurolinguistic battery of tests and a high resolution volumetric MRI scan. Major results were that (a) pars triangularis was significantly smaller in the left hemisphere of children with SLI, and (b) children with SLI were more likely to have rightward asymmetry of language structures. Furthermore, anomalous morphology in these language areas correlated with depressed language ability. These findings support the hypothesis that language impairment is a consequence of an underlying neurobiological defect in areas of the brain known to subserve language.