Vigilance for Threat Interacts with Amygdala Responses to Subliminal Threat Cues in Specific Phobia

doi:10.1016/j.biopsych.2011.04.005

Biological Psychiatry

Volume 70, Issue 5, 1 September 2011, Pages 472-478

https://doi.org/10.1016/j.biopsych.2011.04.005 Get rights and content

Background

The amygdala has been strongly implicated in the processing of threat-relevant information in specific phobia. However, there is an ongoing debate as to whether the amygdala may also be engaged outside of conscious stimulus awareness. Furthermore, considering that sustained vigilance for threat constitutes a crucial characteristic of specific phobias, we hypothesized a possible role of this symptom in modulating amygdala sensitivity to disorder-relevant cues. Using event-related functional magnetic resonance imaging, we examined responses of the amygdala to subliminal and supraliminal phobogenic stimuli in spider-phobic subjects and whether these responses might be specifically associated with disorder-related hypervigilance.

Methods

Eighteen female spider-phobic subjects and 18 healthy female control subjects were exposed to pictures of spiders and phobia-irrelevant objects, presented briefly during two backward-masking conditions used to manipulate stimulus awareness. Brain activation data were analyzed as a function of subjects' perceptual performance on each single trial and were tested for correlations with different components of the phobic symptomatology, such as vigilance, as assessed by self-report scales.

Results

Compared with control subjects, phobic participants showed stronger responses of both amygdalae to consciously perceived spiders versus nonspider targets, whereas during unconscious stimulus processing, enhanced activation was only apparent in the right amygdala. Moreover, the intensity of disorder-related vigilance was positively correlated with right amygdala activation specifically during the subliminal condition.

Conclusions

These findings provide evidence for unconscious threat processing in specific phobia, with the magnitude of amygdala responses specifically potentiated by sustained hypervigilance for threat. Aberrations in this vigilance system may be critically involved in anxiety disorders.

Section snippets

Subjects

Eighteen subjects with spider phobia and 18 healthy female control subjects participated in the study (group characteristics are summarized in Table 1). They were recruited via public announcements in newspapers, on radio, and at the university campus and were paid for their participation. All phobic subjects fulfilled the diagnostic criteria for spider phobia according to DSM-IV as assessed by a structured clinical interview (22). Additionally, spider-phobic subjects scored highly on the

Behavioral Data

Behavioral data are summarized in Table 1. Mean discrimination performance did not differ significantly between the two groups during the subliminal condition. Eight of 18 phobic subjects and 7 of 18 control subjects, respectively, were able to discriminate between subliminally presented spiders versus neutral targets at above chance levels (AUC values significantly greater than .5). However, during the supraliminal condition, although all 36 participants were able to discriminate spiders from

Discussion

Using visual backward-masking, we found evidence to support the controversial position that enhanced processing of threat signals may occur in the absence of awareness. Specifically, our data indicate that subliminally induced amygdala activation may be detected, even when adopting a trial-based approach that is sensitive to transient fluctuations in perceptual sensitivity. Thus, our results further corroborate the concept of a neural module centered on the amygdala that may be automatically

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Archival ReportVigilance for Threat Interacts with Amygdala Responses to Subliminal Threat Cues in Specific Phobia

Background

Methods

Results

Conclusions

Section snippets

Subjects

Behavioral Data

Discussion

Neurosci Lett

Biol Psychiatry

Biol Psychiatry

Curr Opin Neurobiol

Neuroimage

Neuroimage

Trends Cogn Sci

Behav Ther

Behav Res Ther

Neuropsychologia

Neuroimage

Neuroimage

Neuroimage

Neuroimage

Biol Psychiatry

Neuroimage

J Anxiety Disord

Neuroscience

Trends Cogn Sci

Recent trends in the study of specific phobias

Curr Opin Psychiatry

Agoraphobia, simple phobia, and social phobia in the National Comorbidity Survey

Arch Gen Psychiatry

The Emotional Brain

Archival Report
Vigilance for Threat Interacts with Amygdala Responses to Subliminal Threat Cues in Specific Phobia