The angular gyrus in developmental dyslexia: Task-specific differences in functional connectivity within posterior cortex

Converging evidence from neuroimaging studies of developmental dyslexia rev eals dysfunction at posterior brain regions centered in and around the angu lar gyrus in the left hemisphere. We examined functional connectivity (cova riance) between the angular gyrus and related occipital and temporal lobe s ites, across a series of print tasks that systematically varied demands on phonological assembly. Results indicate that for dyslexic readers a disrupt ion in functional connectivity in the language-dominant left hemisphere is confined to those tasks that make explicit demands on assembly. In contrast , on print tasks thar do not require phonological assembly, functional conn ectivity is strong for both dyslexic and nonimpaired renders. The findings support the view that neurobiological anomalies in developmental dyslexia a re largely confirmed to the phonological-processing domain. In addition, th e findings suggest that right-hemisphere posterior regions serve a compensa tory role in mediating phonological performance in dyslexic readers.