Chopped Arms & Big Macs: ERP Correlates of Viewing and Imagining Aversive and Food Photos

Abstract

OBJECTIVESWe investigated the Event-Related Potential (ERP) correlates of perceived and imagined food photos and their relation to the perception and imagery of unpleasant emotional photos. Our aim was to determine whether similar or different patterns of neural activity were associated with viewing and imagining food photos versus emotional photos. METHODS Nine volunteers with prescreened normal mood and anxiety levels wore a 32 channel Cap with embedded electrodes (10/20 international system) connected to a high-density low-noise Neuroscan EEG system. Participants were tested during two different blocks: a hunger block (containing 25 neutral and food photos) and an emotional block (containing 3 sets of 20 neutral, unpleasant and pleasant photos). The photos were selected from the International Affective Picture System (Lang, Bradley, & Cuthbert, 1999). In both blocks, each trial began with a blank screen followed by presentation of a centered fixation point, displayed for 1 second. A photo was displayed for 3 seconds followed by a 1-second blank mask. For the next 3 seconds, participants were asked to form a mental image of the photo they had just viewed and then rate its vividness (i.e., the self-reported imagery intensity, D’Angiulli & Reeves, 2002) on a 5-point rating scale (1 = no image, 5 = very vivid). RESULTSGrand averages of ERPs recorded during perception of unpleasant and food photos revealed an early negative deflection (150-250 milliseconds post-stimulus) in the anterior areas (Centro-Frontal electrodes) followed by a late positive waveform (850-950 milliseconds post-stimulus) in the posterior areas (Parietal and Occipital electrodes). A similar pattern was observed for the ERPs recorded during the imagery of unpleasant photos, except that it was observed across the entire scalp and at significantly lower amplitudes. For food imagery, we found a negative deflection (450-550 milliseconds post-stimuli) followed by a late positive waveform for all anterior and posterior areas. Importantly, unpleasant imagery was rated as less vivid than food imagery. CONCLUSION These results suggest that unpleasant and food photos involve similar top-down EEG activation patterns during perception, but not during imagery. Indeed, the vividness data strongly suggest that the negative deflection may indicate suppression of unpleasant imagery. Our findings may have important application for desensitization and conditioning in the treatment of eating disorders.

Event-related potential signatures of perceived and imagined emotional and food real-life photos

“…Then two experimental blocks were performed -one containing 25 neutral and 25 food photos, and one containing 20 neutral, 20 pleasant, and 20 unpleasant photos. This block design and the use of the two sets of intermixed "buffering" neutral images minimize confounds between food and unpleasant/pleasant content [53,54] . After the experimental blocks, participants were shown 20 emotionally pleasant photos to displace potential negative emotions caused by the unpleasant photos.…”

Brief Myofascial Intervention Modulates Visual Event-Related Potential Response to Emotional Photographic Contents: A Pilot Study

“…In phase 3, the participant repeated the same procedure as phase 1. Two sets of buffering neutral images were presented to minimize confounds of unpleasant/pleasant content [49]. After each experimental phases 1 and 2, participants were shown 20 pleasant photos to counteract possible negative emotions following unpleasant stimuli.…”