Age-related changes in source memory retrieval: an ERP replication and extension.

Event-related potentials (ERPs) were recorded (62 scalp sites) from young (M=22) and older (M=66) adults during tests of item recognition and source memory, in a replication and extension of a previous study [Psychol. Aging 14 (1999) 390-413]. Participants studied two temporally distinct lists of sentences (each with two unassociated nouns). At test, in response to studied and unstudied nouns, participants made old/new, followed by source (i.e., list) judgments. Several measures were employed to enhance the source memory performance of the older adults. These were successful, as the old adults showed source memory performance comparable to that of the young subjects from the previous study (67%). Nonetheless, the younger adults significantly outperformed the older adults on measures of item and source memory performance. The ERPs revealed that both age groups showed a robust early, posterior-maximal episodic memory (EM) effect. However, despite their enhanced source memory performance, the ERPs of the old failed to show a robust late, right-prefrontal EM effect, which was again present in the ERPs of the young. By contrast, the older adults showed a central negative component not seen in the ERPs of the young. These results are consistent with the frontal lobe deficit hypothesis of aging and provide some evidence that old and young may use distinct cortical networks during source memory retrieval.