Early Reactivation of Emotion in ERPs to Neutral Retrieval Cues

Abstract

Memory retrieval is thought to involve the reactivation of encoding processes. Previous fMRI work has indicated that reactivation processes are modulated by the residual effects of the prior emotional encoding context; different spatial patterns emerge during retrieval of memories previously associated with negative compared to positive or neutral context. Other research suggests that ERP indicators of memory retrieval processes, like the left parietal old/new effect, can also be modulated by emotion, but the spatial distribution and temporal dynamics of these effects is unclear. In the current study, we examined when emotion affects memory reactivation and whether that timing reflects processes that come before and may guide successful retrieval or post-recollection recovery of emotional episodic detail. While recording EEG, participants (N = 25) viewed neutral words paired with negative, positive or neutral pictures during encoding, followed by a recognition test for the words. Analyses focused on ERPs during the recognition test. In line with prior ERP studies, we found an early positive-going parietally distributed effect starting around 200 ms post retrieval-cue onset. This effect emerged for words that had been encoded in an emotional compared to neutral context (no valence differences), before the general old/new effect. This emotion-dependent effect occurred in an early time window, suggesting emotion-related reactivation is a precursor to successful recognition.