Rewriting the past: Reconsolidation of emotional episodic memories

Our memory is a living canvas that is constantly being updated with new information. In this context, emotional events, compared to neutral ones, are generally believed to yield stronger memory traces. Yet, it is unclear whether the latter are more resistant to subsequent changes upon reactivation. Moreover, it is unknown whether new emotional experiences, compared to neutral ones, are more effective in altering preexisting memories. Here, we report a series of five experiments investigating the relationship between emotion and memory updating. We first replicate a prior observation by Hupbach et al. (2007) that memories for neutral events can be changed by integrating new, neutral information upon reactivation (Experiment 1). We then show that emotional memories, when reactivated, also integrate new, neutral information (Experiment 2). However, the integration of new neutral information does not occur immediately after reactivating the emotional pre-existing memories, but rather after a 48-hour period of reconsolidation (Experiment 3). Finally, we did not find evidence of integration between new emotional information into emotional (Experiment 4) or neutral (Experiment 5) pre-existing memories when presented after memory reactivation. Together, these studies shed light on the dynamic nature of memory, revealing that our memories are flexible constructs constantly reshaped by ongoing experiences. Moreover, these findings may have therapeutic or legal implications, such as altering or preserving highly emotional memory traces, as in the case of post-traumatic disorder and stress eyewitness testimony respectively.