The insula is deeply connected to the amygdala, and both regions display activation in response to processing negative emotional stimuli. Hyperactivity in the insula has been found in individuals with SAD, specific phobias, and PTSD.

When individuals with SAD were tasked with giving an impromptu speech about a randomly generated topic, they demonstrated an increased activation in the right insula compared to healthy controls. This hyperactivity was correlated with self-reported increases in unpleasantness, arousal, and anxiety following the anticipation of giving the speech.

Insula and SAD

The amygdala is involved in threat detection, processing of emotional stimuli, and generating a fear response to said threat or negative stimulus. Neuroimaging studies show increased amygdalar activation in individuals with symptoms of social anxiety following the anticipation of, and subsequent exposure to, aversive images (as determined by the International Affective Picture System). Additionally, individuals with SAD demonstrated hyperactivity in the amygdala when tasked with giving an impromptu speech. Increased activity in the amygdala is therefore associated with symptoms of SAD, namely the fear of aversive social situations.

Amygdala and SAD

The anterior cingulate cortex (ACC), as part of the limbic system, is involved in emotional regulation. Specifically, the dorsal, or cognitive, ACC is involved in conflict resolution, while the rostral, or affective, ACC is involved in determining the valence of emotional stimuli. Individuals with social phobia show increased activation of the ACC when viewing "disgusted" facial expressions as opposed to neutral expressions. These individuals also rated the expressions as more negative, with a faster response time than healthy controls. Cingulectomy was shown to significantly improve symptoms in patients with anxiety neurosis. Taken together, these findings suggest a role for the rostral ACC in the pathology of SAD.

Anterior Cingulate Cortex and SAD

The prefrontal cortex (PFC) spans the anterior portion of the frontal lobe and is involved in a wide range of cognitive and executive functions. With regards to anxiety, the right PFC is highly activated in response to negative affect, particularly when their specific type of anxiety was triggered (i.e. social phobics being asked to give a speech). For SAD, studies have found strong connections between the PFC and anterior cingulate cortex.

Prefrontal Cortex and SAD

- Amygdala
- Insula
- Prefrontal cortex
- Anterior cingulate cortex

Pomona College

Functional neuroimaging has identified several brain regions and circuits involved in pathological anxiety, such as the amygdala, insula, and prefrontal cortex. Neural dysfunction associated with SAD varies from reduced regional volume to increased or decreased activation and functional connectivity.

The Neural Basis of Social Anxiety Disorder

Boehme, S., Ritter, V., Tefikow, S., Stangier, U., Strauss, B., Miltner, W. H. R., & Straube, T. (2014). Brain activation during anticipatory anxiety in social anxiety disorder. Social Cognitive and Affective Neuroscience, 9(9), 1413–1418. https://doi.org/10.1093/scan/nst129

Brain activation during anticipatory anxiety in social anxiety disorder (2014)

Brain Regions Involved in SAD

Functional magnetic resonance imaging (fMRI) is an effective tool for analyzing brain functionality. It is capable of tracking the functional response of the brain through Blood Oxygen Level Dependent (BOLD) contrast. Increased neuronal activity leads to local increase in energy and oxygen consumption. Essentially, the BOLD effect is a contrast caused by the relative decrease in the magnetic field irregularities due to relative increase in the oxyHb level contributed by the blood flowing in the brain region with increased activity.

Functional MRI

Functional connectivity (FC) is defined as the temporal coincidence of spatially distant neurophysiological events, wherein two regions are considered to show functional connectivity if there is a statistical relationship between the measures of activity recorded for them. Extensions of this include both static and dynamic FC.

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