Electrophysiological correlates of remembering emotional pictures.

Extensive evidence shows that emotional events tend to be remembered in greater detail and with an enhanced sense of vividness compared to neutral events. The current study investigated the neural correlates of this phenomenon during retrieval using the event-related potentials technique (ERP). Participants were asked to perform a memory recognition test of previously studied ("Old") and unstudied ("New") emotional and neutral pictures encoded a week before the test session. Next, they were asked to perform a Remember-Know task (Gardiner and Java, 1993) for each "old" decision. ERPs were created for retrieval activity corresponding to six conditions: Remember-Emotional, Remember-Neutral, Know-Emotional, Know-Neutral, New-Emotional and New-Neutral. Results showed that negative emotion enhanced three distinct subtypes of the electrophysiological old-new effect specifically for old items associated with a "Remember" judgment. This effect was observed for ERP old-new effects conforming to an early frontal P2 old-new effect peaking at ~180 ms, a midfrontal old-new effect starting at ~300 ms (the "FN400") and a late positive complex (LPC) with parietal maxima observed at 500-700 ms. In addition, a breakdown of our data in different levels of emotional arousal revealed that the relationship between ERP correlates of retrieval and arousal conformed to a nonlinear, inverted U-shaped function for posterior late effects (500-700) and to a linear function for early effects (P2 and FN400). Taken together, these results suggest that multiple retrieval subprocesses contribute to the emotional enhancement of recollective experience.