Social fearfulness in the human brain

Social fearfulness is expressed on a continuum of severity from moderate distress to incapacitating fear. The present article focuses on the brain states associated with this broad dimension of social anxiety in humans. In total, 70 published studies are summarized documenting the neural correlates of social anxiety during states of rest, threat-related cognitive-affective activation, and acute symptom provocation. Neural exaggeration in limbic (amygdala) and paralimbic (insula) regions appears to be associated with functional outcomes involving increased attention for and processing of social threat. Evidence is also reviewed showing that social anxiety is characterized by atypical functional connectivity in certain brain networks. Despite a higher prevalence of social anxiety disorder among females, males have been over-represented in the published clinical studies (constituting approximately 56% of the total participants). We evaluate the prospects of nonhuman animal models of social anxiety and discuss several promising directions for future research. The review highlights the need to adopt an integrative, network-based approach to the study of the neural substrates underlying social anxiety. (C) 2011 Elsevier Ltd. All rights reserved.