LOCATION OF LESIONS IN STROKE PATIENTS WITH DEFICITS IN SYNTACTIC PROCESSING IN SENTENCE COMPREHENSION

Sixty patients, 46 with left-hemisphere strokes and 14 with right-hemi sphere strokes, and 21 normal control subjects were tested for the abi lity to use syntactic structures to determine the meaning of sentences . Patients enacted thematic roles (the agent, recipient and goal of an action) in 12 examples of each of 25 sentence types, which were desig ned to test a wide variety of syntactic operations. Both right- and le ft-hemisphere damaged patients performed worse than control subjects o n syntactically complex sentences, and left-hemisphere patients perfor med worse than right-hemisphere patients. Eighteen patients with left- hemisphere strokes underwent CT scanning to image the perisylvian asso ciation cortex. There was no difference between the performance of pat ients with anterior and posterior lesions, and no correlation between the degree of impairment and the size of lesions in different regions of the perisylvian cortex. There results are consistent with the view that syntactic processing involves an extensive neural system, whose m ost important region is the left perisylvian cortex. When these result s are combined with those of other studies, the picture that emerges i s one in which, within this cortical region, this system manifests fea tures of both distributed and localized processing.