Common and Distinct Brain Activation to Threat and Safety Signals in Social Phobia

Background: Little is known about the functional neuroanatomy underlying the processing of emotional stimuli in social phobia.

Objectives: To investigate specific brain activation that is associated with the processing of threat and safety signals in social phobics.

Methods: Using functional magnetic resonance imaging, brain activation was measured in social phobic and nonphobic subjects during the presentation of angry, happy and neutral facial expressions under free viewing conditions.

Results: Compared to controls, phobics showed increased activation of extrastriate visual cortex regardless of facial expression. Angry, but not neutral or happy, faces elicited greater insula responses in phobics. In contrast, both angry and happy faces led to increased amygdala activation in phobics.

Conclusions: The results support the hypothesis that the amygdala is involved in the processing of negative and positive stimuli. Furthermore, social phobics respond sensitively not only to threatening but also to accepting faces and common and distinct neural mechanisms appear to be associated with the processing of threat versus safety signals.