Pictures of disgusting foods and disgusted facial expressions suppress the tongue motor cortex

Abstract

The tongue holds a unique role in gustatory disgust. However, it is unclear whether the tongue representation in the motor cortex (tM1) is affected by the sight of distaste-related stimuli. Using transcranial magnetic stimulation (TMS) in healthy humans, we recorded tongue motor-evoked potentials (MEPs) as an index of tM1 cortico-hypoglossal excitability. MEPs were recorded while participants viewed pictures associated with gustatory disgust and revulsion (i.e. rotten foods and faces expressing distaste), non-oral-related disgusting stimuli (i.e. invertebrates like worms) and control stimuli. We found that oral-related disgust pictures suppressed tM1 cortico-hypoglossal output. This tM1 suppression was predicted by interindividual differences in disgust sensitivity. No similar suppression was found for disgusting invertebrates or when MEPs were recorded from a control muscle. These findings suggest that revulsion-eliciting food pictures trigger anticipatory inhibition mechanisms, possibly preventing toxin swallowing and contamination. A similar suppression is elicited when viewing distaste expressions, suggesting vicarious motor inhibition during social perception of disgust. Our study suggests an avoidant-defensive mechanism in human cortico-hypoglossal circuits and its ‘resonant’ activation in the vicarious experience of others’ distaste. These findings support a role for the motor system in emotion-driven motor anticipation and social cognition.

Design and Validation of Augmented Reality Stimuli for the Treatment of Cleaning Obsessive-Compulsive Disorder

“…These results can be related to the fact that taste is the sense that most relates with disgust, which is the most sensitized emotion in patients with OCD and which can generate anxiety (Pineda et al, 2015;Bhikram et al, 2017;Knowles et al, 2019). These findings agree with previous studies that show that edible contaminated stimuli generate more disgust and anxiety responses than nonedible ones (Vicario et al, 2017).…”

Transcranial direct current stimulation over the tongue motor cortex reduces appetite in healthy humans

“…On the other hand, limb regions of the motor cortex do not project to OFC or insular regions. Remarkably, we have documented that tnM1 excitability is modulated by nicotine craving [11], distaste [12], and moral disgust [13], which supports a functional link between tnM1 and reward-relevant processes in humans.…”

Mapping the sequence of brain events in response to disgusting food

“…Disgust is mostly characterized by sensations in the digestive system and around the throat region, which is consistent with activations observed in the anterior insula and frontal operculum. However, there is an emotion‐related inhibitory control from the PAG, amygdala, and insula on the motor cortex and supplementary motor area in situations of threat [Benarroch, ; Hassa et al, ; Vicario et al, ], which arguably may contribute to account for deactivations in our study. Of relevance, a recent transcranial magnetic stimulation study has demonstrated motor cortex inhibition at the tongue representation specifically in response to revulsion‐eliciting food pictures and disgusted facial expressions [Vicario et al, ].…”