Increased activation of the anterior cingulate cortex during processing of disgust faces in individuals with social phobia

Background: Researchers have examined the role of differential activation of various brain regions involved in processing emotional information in subjects with social phobia. These studies have focused mostly on the activation of the amygdala. The anterior cingulate cortex (ACC) also has been implicated in processing emotional information, but its role in social phobia has not been examined. Methods: We recruited subjects with social phobia and matched them with non-anxious control subjects. Participants viewed facial expressions of disgust ("disgust faces") and neutral facial expressions ("neutral faces"). We measured brain activation, focusing on the ACC, using functional magnetic resonance imaging. We also recorded participants' ratings of emotional valence of faces, as well as response latencies to make these valence judgments. We repeated this procedure using three different sets of facial expressions. Results: Individuals with social phobia exhibited a significant increase in ACC activity compared with non-anxious control subjects when processing disgust versus neutral faces. Additionally, compared with control subjects, subjects with social phobia were faster in their ratings of disgust faces and rated the neutral faces more negatively. Conclusions: Our findings demonstrate that the ACC might be involved in affective processing of negative information in socially phobic subjects.