Evidence from imaging on the relationship between brain structure and developmental language disorders.

This article discusses findings using various imaging techniques regarding the neurological underpinnings of developmental language and learning disorders. Evidence from magnetic resonance imaging, functional magnetic resonance imaging, single photon emission spectroscopy, and positron emission tomography implicates the left perisylvian regions in the processing of phonemes and auditory information, as had been predicted from lesion data and from neurobiological theory. The areas of the planum temporale and angular gyrus have been found to be compromised in children and adults with dyslexia or language impairment. Emerging evidence suggests that these differences are also present in members of families with a history of developmental language disorders, which provides support for a transmittable, biological factor involved in such disorders. Dynamic imaging procedures are beginning to provide an understanding of the relationship between structure and function in normal and abnormal language acquisition.