Effects of negative emotion on neural correlates of item and source memory during encoding and retrieval

The enhancing effect of emotion on item memory is well-established, but emotion's influence on source memory has proven more elusive. Previous studies recording event-related potentials (ERPs) associated with memory encoding (Dms) and retrieval (old/new effects) showed an emotional enhancement of ERPs related to item memory, whereas ERPs related to source memory yielded contradictory results in the presence of emotion. The present study examined the influence of item emotionality on the neural correlates of memory encoding and retrieval for items and temporal source details. Participants studied negative and neutral pictures in two temporally distinct blocks and, 24 h later, were asked to recognize the studied pictures and the blocks in which they appeared. Our results showed that negative items were more often remembered, with or without source information, than neutral images. This finding of an overall memory advantage for negative images was confirmed by the Dm effects, which demonstrated significant and indistinguishable Dms for negative images remembered with or without source. Overall, Dm effects were greater for negative as compared to neutral images. In contrast to the behavioral and Dm results, an emotional enhancement of the source-related old/new effect was seen over the left hemisphere, suggesting that only negative (and not neutral) images retrieved with correct source were accompanied by memory for additional details. These results suggest that retrieval of temporal source information is not enhanced for negative images but that item emotionality could lead to an enhancement for the retrieval of additional details, contingent on retrieval of temporal source information.