Memory, simple and complex language, and the temporal lobe

Nineteen patients with intractable temporal lobe epilepsy who underwent anterior temporal lobectomy were given a highly specific memory battery (23 tests) pre- and post- (1 week; 1, 2, and 6 months; 1 and 2 years) resection. Sixteen of 23 tests revealed that memory performance of temporal lobe epilepsy patients was worse than normal controls prior to surgery (p < .001), while the most profound differences were seen in the remembering and generation of inferences from connected discourse. Almost no differences were observed in delayed nonmatching to sample tasks (recognition without language task). MRI results revealed that anterior, middle, and posterior hippocampal abnormality was extensive in 12 of 19 patients, and 12 also showed medial temporal lobe abnormalities and volume loss. Hippocampal damage was negatively correlated with extended delay memory performance for connected discourse: worse performance was associated with greater damage. Few differences in less complex memory performance were observed pre-postsurgery. While ordinary recognition functions were preserved, results demonstrated that dominant medial temporal lobe structures appeared heavily involved in language-generated memory, and hippocampus is heavily implicated in both simple and complex language.