Deficits in recall following partial and complete commissurotomy.

There have been reports in the literature of both impaired (Zaidel and Sperry, 1974) and intact (LeDoux et al., 1977) memory performance following callosotomy. In the present article, memory is examined in patients who received either partial or complete callosotomy in an effort to determine (1) if there is a memory deficit following callosotomy, (2) if certain types of callosotomy are more likely to lead to a deficit (i.e., anterior vs posterior), and (3) if there is a global memory deficit or if some mnemonic functions are affected more than others. Patients receiving either partial or complete section of the corpus callosum were examined pre- and postoperatively on standardized memory tests and tests of recall and recognition. In addition, two patients with complete callosotomy and matched control subjects were given tests of verbal recall and recognition. A deficit in both visual and verbal recall was found in patients with posterior section, but not those receiving anterior section. No impairment was found on tests of verbal recognition for any patients. Posterior callosal section generally includes the hippocampal commissure and other hippocampal connections, while anterior sectioning does not. Given the known importance of the hippocampus (Milner, 1970) and the differences between recall and recognition memory (Bransford and Johnson, 1972) in normal memory functioning, several hypotheses are proposed as to why these results might be expected.