Emotional memories are resilient to time: evidence from the parietal ERP old/new effect.

Emotional memories can be extremely robust and long-lasting and can contribute to the development of anxiety disorders. Despite tremendous work on neural responses underlying the memory formation of emotional events, less is known about long-term retention. In the present study, behavioral and electrophysiological measures were used to investigate long-term recognition memory for emotional (unpleasant and pleasant) and neutral pictures after two retention intervals (1 week vs. 1 year) in 21 male subjects. The results show enhanced recognition performance for emotional relative to neutral pictures for both test delays. On the neural side, the retrieval of emotional pictures compared to neutral pictures was accompanied after 1 week by an enhanced old/new effect (500-800 ms), originating in the parietal cortex. After 1-year retention delay, only unpleasant but not pleasant pictures were different from neutral pictures in the recollection-sensitive ERP component. Analysis of the subjective awareness (confidence ratings) during recognition indicated that behavioral and electrocortical response patterns were exclusively driven by high confidence responses, an indication for recollection-based recognition. These results suggest that high arousing emotional memories were highly consistent over time relative to neutral memories.