Pain to remember: a single incidental association with pain leads to increased memory for neutral items one year later

Negative and positive experiences can exert a strong influence on later memory. Our emotional experiences are composed of many different elements - people, place, things - most of them neutral. Do emotional experiences lead to enhanced long-term for these neutral elements as well? Demonstrating a lasting effect of emotion on memory is particularly important if memory for emotional events is to adaptively guide behavior days, weeks, or years later. We thus tested whether aversive experiences modulate very long-term episodic memory in an fMRI experiment. Participants experienced episodes of high or low pain in conjunction with the presentation of incidental, trial- unique neutral object pictures. In a scanned surprise immediate memory test, we found no effect of pain on recognition strength. Critically, in a follow-up memory test one year later we found that pain significantly enhanced memory. Neurally, we provide a novel demonstration of activity predicting memory one year later, whereby greater insula activity and more unique distributed patterns of insular activity in the initial session correlated with memory for pain-associated objects. Generally, our results suggest that pairing episodes with arousing negative stimuli may lead to very long-lasting memory enhancements.