Problem with any function of language and communication.

In adults, much of what is known about the organization of language functions in the brain has come from the study of patients with focal brain lesions. It has been known for hundreds of years that a left-hemisphere injury to the brain is more likely to cause language disturbance—aphasia—than a right hemisphere injury, especially but not exclusively in right-handed persons. For about a hundred years, certain areas in the adult left hemisphere—B roca's area in the posterior frontal lobe, and Wernicke's area in the temporal lobe—have been identified as centrally involved in language functions. However, researchers in the field of adult aphasia are divided over the exact role these brain areas play in language processing and production. Damage to Broca's area results in marked problems with language fluency; with shortened sentences, impaired flow of...