Rapid habituation to repeated presentations of stimuli that are neither threatening nor rewarding is crucial for effectively navigating the constantly changing environment. Failure to habituate has been proposed as a neuronal mechanism underlying social anxiety. In this study, we test the hypothesis that social fearfulness is associated with reduced neural habituation to social stimuli. Twenty-nine individuals representing the full dimension of social fearfulness (low to high) viewed repeated presentations (up to 7) of neutral social and nonsocial stimuli during an fMRI study. Percent signal change was extracted from a priori regions of interestincluding the amygdala, hippocampus, medial orbitofrontal cortex (mOFC), ventromedial prefrontal cortex (vmPFC), fusiform face area (FFA), extrastriate cortex, and primary visual cortex (V1)areas that have been previously implicated in social anxiety disorder. Social fearfulness was correlated with elevated initial response to faces in the hippocampus and vmPFC, and habituation differences to faces in the amygdala, hippocampus, mOFC, vmPFC, extrastriate, and V1 (p < .05). Higher social fear was associated with a sustained response relative to individuals with low social fear, who showed rapid habituation to repeated social stimuli. Social fearfulness was also correlated with sustained functional connectivity between the amygdala and two visual cortex regionsthe extrastriate cortex and V1. Importantly, social fearfulness findings were similar when controlling for neural response to non-social stimuli (objects), suggesting that differences were specific to social stimuli. Individual differences in habituation to social stimuli may provide an important neurobiological marker for risk for psychiatric illness, such as social anxiety disorder.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-07312015-102916 |
| Date | 31 July 2015 |
| Creators | Avery, Suzanne Nicole |
| Contributors | David Zald, Jennifer Blackford, Brandon Ally, Bunmi Olatunji |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-07312015-102916/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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