Leaving a bad taste in your mouth but not in my insula.

Previous research has implicated regions of anterior insula/frontal operculum in processing conspecific facial expressions of disgust. It has been suggested however that there are a variety of disgust facial expression components which relate to the disgust-eliciting stimulus. The nose wrinkle is predominantly associated with irritating or offensive smells, the mouth gape and tongue extrusion with distaste and oral irritation, while a broader range of disgust elicitors including aversive interpersonal contacts and certain moral offenses are associated primarily with the upper lip curl. Using functional magnetic resonance imaging, we show that activity in the anterior insula/frontal operculum is seen only in response to canonical disgust faces, exhibiting the nose wrinkle and upper lip curl, and not in response to distaste facial expressions, exhibiting a mouth gape and tongue protrusion. Canonical disgust expressions also result in activity in brain regions linked to social cognition more broadly, including dorsal medial prefrontal cortex, posterior cingulate cortex, temporo-parietal junction and superior temporal sulcus. We interpret these differences in relation to the relative functional and communicative roles of the different disgust expressions and suggest a significant role for appraisal processes in the insula activation to facial expressions of disgust.