Functional magnetic resonance imaging of story listening in adolescents and young adults with Down syndrome: evidence for atypical neurodevelopment.

BACKGROUND: Previous studies have documented differences in neural activation during language processing in individuals with Down syndrome (DS) in comparison with typically developing individuals matched for chronological age. This study used functional magnetic resonance imaging (fMRI) to compare activation during language processing in young adults with DS to typically developing comparison groups matched for chronological age or mental age. We hypothesised that the pattern of neural activation in the DS cohort would differ when compared with both typically developing cohorts.

METHOD: Eleven persons with DS (mean chronological age = 18.3; developmental age range = 4-6 years) and two groups of typically developing individuals matched for chronological (n = 13; mean age = 18.3 years) and developmental (mental) age (n = 12; chronological age range = 4-6 years) completed fMRI scanning during a passive story listening paradigm. Random effects group comparisons were conducted on individual maps of the contrast between activation (story listening) and rest (tone presentation) conditions.

RESULTS: Robust activation was seen in typically developing groups in regions associated with processing auditory information, including bilateral superior and middle temporal lobe gyri. In contrast, the DS cohort demonstrated atypical spatial distribution of activation in midline frontal and posterior cingulate regions when compared with both typically developing control groups. Random effects group analyses documented reduced magnitude of activation in the DS cohort when compared with both control groups.

CONCLUSIONS: Activation in the DS group differed significantly in magnitude and spatial extent when compared with chronological and mental age-matched typically developing control groups during a story listening task. Results provide additional support for an atypical pattern of functional organisation for language processing in this population.