7 - Functional Imaging Studies of Aphasia

Abstract

This chapter focuses on the functional neuroimaging studies of aphasic patients that can contribute to normal and abnormal models of language processing. The most important contribution that functional imaging of aphasic patients can make to models of abnormal language processing is an understanding of the mechanisms involved in recovery. Such studies are only in preliminary stages and rely on both technological and analytical advances. Functional imaging of aphasic patients provides information about neuronal and cognitive performance that is not available from either structural or behavioral assessments. First, functional imaging can determine whether a region that appears damaged on structural scans maintains any residual function in or around the lesion. Second, it can identify the effects of a lesion on undamaged tissue. Third, dysfunction in undamaged cortex can also be revealed in patients who have no detectable damage on structural scans. Fourth, functional imaging of the patient provides a means of testing directly the disconnection models first proposed by the nineteenth century neurologists. Neurological studies of aphasic patients date back more than a century and are based on the application of the lesion-deficit model to human subjects. This approach equates selective brain lesions to selective cognitive deficits.