Modulation of gastric activity using appetizing and disgusting images.

Abstract

Interoception is the nervous system’s integration of internal bodily signals, including gastrointestinal inputs. This process is crucial for regulating homeostasis, cognition and emotion, and depends on bidirectional brain-body communication. Given recent evidence of brain-stomach synchronization, determining whether emotional images (e.g., appetizing and disgusting) alter gastric activity is important for characterizing gut-brain interactions. Using an electrogastrogram (EGG), we recorded the gastric myoelectric activity (i.e., stomach’s intrinsic rhythmicity) of 46 subjects (mostly undergraduate students, 37 females), while viewing 3 randomized blocks of appetizing, disgusting, or neutral images (70 per block, totaling 13 minutes), between 2024-2025. Participants then rated the appetite/disgust elicited by each image, completed a recall test, and answered psychological and interoception questionnaires. Linear mixed-effects models revealed significantly lower EGG power in the normogastric range (i.e., signal centered around 0.05 Hz) for disgusting compared to appetizing images. Additionally, a significantly higher proportion of normogastric power (i.e., normogastric activity) was found in the appetizing compared to the neutral condition. These differences were not accounted for by BMI, hours since last meal, hunger level, interoception/psychological questionnaire measures, or recall performance. These findings provide evidence that gastric activity can be modulated in a top-down manner, possibly reflecting a preparatory physiological response. The reduced EGG power in the disgusting condition may be interpreted as preparation for rejection of food, whereas the increased normogastric activity in the appetizing condition may be interpreted as preparation for digestion. Our study provides a methodological foundation for assessing this manipulation's effect on gut-brain synchronization using simultaneous EGG and neural recordings.