Pictures of disgusting foods and disgusted facial expressions suppress the tongue motor cortex
Vicario, CM and Rafal, RD and Borgomaneri, S and Paracampo, R and Kritikos, A and Avenanti, A, Pictures of disgusting foods and disgusted facial expressions suppress the tongue motor cortex, Social Cognitive and Affective Neuroscience pp. 1-11. ISSN 1749-5024 (2016) [Refereed Article]
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 oralrelated
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.
: disgust; emotion recognition; transcranial magnetic stimulation; motor-evoked potentials; tongue motor area