Dissociation of recognition memory components following temporal lobe lesions

It has been proposed that recognition decisions are based on contextual retrieval of specific trace information, in addition to an assessment of item strength. The retrieval component is maximal after a single presentation, whereas the strength component increases with multiple repetition. We report that unilateral anterior temporal lobectomy (ATL) in the language dominant (left) hemisphere impairs initial recognition accuracy without affecting the rate at which repetition improves performance. The implication that the temporal lobe contributes to retrieval rather than strength during recognition is supported by simultaneous event-related potential (ERP) recordings. In normal subjects, the large ERP difference between repeated and nonrepeated words does not increase with increasing study and is associated with contextual integration in other tasks. Thus, the lack of a repetition-induced ERP difference after left-ATL reported here provides converging evidence for a critical role of the temporal lobe in contextual retrieval during recognition.