MEMORY ENCODING FOLLOWING COMPLETE CALLOSOTOMY

Three patients with complete resection of the corpus callosum were tes ted in a series of memory tasks to determine the effects of callosotom y on the encoding and retrieval of information in memory. Verbal and p ictorial conjunction tests were administered to measure patients' abil ity to consolidate the elements of a stimulus into an accurate composi te memory. Patients were also tested in a paired-associate learning ta sk to determine the consequences of callosotomy on the encoding and re trieval of associations between stimuli. Although callosotomy patients were unimpaired in the verbal conjunction task, results from both the pictorial conjunction task and the paired-associate learning task sug gest that the absence of callosal cross-talk impairs encoding in these patients. In addition, the pattern of results in the paired-associate learning task suggests that callosotomy impairs retrieval processes. The role of the callosum in the formation of memory traces for nonverb al material and associations between verbal stimuli is discussed.