Increased Neural Habituation in the Amygdala and Orbitofrontal Cortex in Social Anxiety Disorder Revealed by fMRI |
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Authors: | Ronald Sladky Anna H?flich Jacqueline Atanelov Christoph Kraus Pia Baldinger Ewald Moser Rupert Lanzenberger Christian Windischberger |
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Affiliation: | 1. MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.; 2. Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.; 3. Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria.; 4. Department of Psychiatry, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, United States of America.; University of Massachusetts Medical School, United States of America, |
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Abstract: | A characterizing symptom of social anxiety disorder (SAD) is increased emotional reactivity towards potential social threat in combination with impaired emotion and stress regulation. While several neuroimaging studies have linked SAD with hyperreactivity in limbic brain regions when exposed to emotional faces, little is known about habituation in both the amygdala and neocortical regulation areas. 15 untreated SAD patients and 15 age- and gender-matched healthy controls underwent functional magnetic resonance imaging during repeated blocks of facial emotion () and object discrimination tasks (). Emotion processing networks were defined by a task-related contrast (). Linear regression was employed for assessing habituation effects in these regions. In both groups, the employed paradigm robustly activated the emotion processing and regulation network, including the amygdalae and orbitofrontal cortex (OFC). Statistically significant habituation effects were found in the amygdalae, OFC, and pulvinar thalamus of SAD patients. No such habituation was found in healthy controls. Concurrent habituation in the medial OFC and the amygdalae of SAD patients as shown in this study suggests intact functional integrity and successful short-term down-regulation of neural activation in brain areas responsible for emotion processing. Initial hyperactivation may be explained by an insufficient habituation to new stimuli during the first seconds of exposure. In addition, our results highlight the relevance of the orbitofrontal cortex in social anxiety disorders. |
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