EVENT-RELATED POTENTIALS AND THE RECOLLECTION OF ASSOCIATIVE INFORMATION

Event-related potentials (ERPs) were recorded from 13 scalp sites duri ng the performance of an associative recall task. At study, subjects w ere presented with a series of word pairs and were required to incorpo rate the two members of each pair into a sentence. At test, the first members of each pair were presented intermixed with an equal number of unstudied items. Subjects were required to discriminate between new a nd studied (old) words and, for each word judged old, to attempt to re call the word with which it had been associated at study. Compared to the ERPs elicited by new words, the ERPs elicited by words correctly j udged to be old and for which the associate was correctly recalled sho wed a sustained, positive-going shift (the ''parietal old/new effect'' ). This effect was strongly lateralised to the left hemisphere and was maximal at temporo-parietal electrodes. The effect was absent in ERPs elicited by words that were correctly judged to be old, but for which the studied associate could not be recalled. The findings are taken a s support for the idea that the parietal old/new effect reflects neura l activity associated with the recollection of specific past episodes, and hence that the effect may index retrieval operations supported by the medial temporal lobe memory system.