The relationship of working memory to the immediate recall of stories following unilateral temporal or frontal lobectomy

Abstract

Patients undergoing unilateral temporal lobectomy were tested preoperatively for working memory capacity, sentence comprehension, and rapid-naming ability, and were retested on these same measures 3 to 5 days and 2 weeks postoperatively. Immediate recall of stories was assessed twice only: preoperatively, and 2 weeks postoperatively. The left temporal-lobe group demonstrated transient deficits in working memory capacity, sentence comprehension, and rapid-naming ability over the 2 week postoperative period. No significant group differences in working memory capacity were evident two weeks after operation, even though the story recall of the left temporal-lobe group was impaired. A second experiment, with additional patients, explored the possible contribution of the hippocampus and of the frontal lobes to performance on these same tasks. Extent of hippocampal excision did not affect performance differentially on any task. Story recall was impaired following left temporal lobectomy, whereas left frontal lobectomy impaired sentence comprehension and rapid-naming ability. These results indicate a double dissociation of verbal deficits 2 weeks after left temporal- and left frontal-lobe excisions.