Mixed lateralization of phonological assembly in developmental dyslexia.

Developmental phonological dyslexia has been characterized as a deficit in phonological assembly. At a neural level, it is possible that this deficit is represented by weak connectivity between anterior and posterior language systems in the left hemisphere. This study used 3-Tesla functional magnetic resonance imaging to investigate phonological assembly in a developmental phonological dyslexic. The phonological dyslexic showed increased activation in the left hemisphere of the inferior frontal gyrus (BA 44/6) and increased activation in the right hemisphere of the parietal cortex (BA 7), occipital cortex (BA 18), and in the cerebellum, as phonological demands were systematically increased. Converging evidence suggests that the core dysfunction in phonological dyslexia resides in and around the angular gyrus of the left hemisphere. This study supports the compensatory role of posterior regions in the right hemisphere together with the left inferior frontal gyrus.