Mental imagery of emotions: Electrophysiological evidence

Affective stimuli such as emotional words, scenes or facial expressions elicit well-investigated emotional responses. For instance, two distinct event-related brain potentials (ERPs) have been reported in response to emotional facial expressions, the early posterior negativity (EPN), associated with enhanced attention and perception of affective stimuli, and a later centro-parietal positivity (LPP) that is taken to reflect evaluations of the intrinsic relevance of emotional stimuli. However, other rich sources of emotions that have as yet received little attention are internal mental events such as thoughts, memories and imagination. Here we investigated mental imagery of emotional facial expressions and its time course using ERPs. Participants viewed neutral familiar and unfamiliar faces, and were subsequently asked to imagine the faces with an emotional or neutral expression. Imagery was compared to visually perceiving the same faces with the different expressions. Early ERP modulations during imagery resemble the effects frequently reported for perceived emotional facial expressions, suggesting that common early processes are associated with emotion perception and imagination. A later posterior positivity was also found in the imagery condition, but with a different distribution than for perception. These findings underscore the similarity of the brain's responses to internally generated and external sources of emotions.