Background
Fearful experiences can produce long-lasting and debilitating memories. Extinction
of conditioned fear requires consolidation of new memories that compete with fearful
associations. In human subjects, as well as rats, posttraining stimulation of the
vagus nerve enhances memory consolidation. Subjects with posttraumatic stress disorder
show impaired extinction of conditioned fear. The objective of this study was to determine
whether vagus nerve stimulation (VNS) can enhance the consolidation of extinction
of conditioned fear.
Methods
Male Sprague-Dawley rats were trained on an auditory fear conditioning task followed
by 1 to 10 days of extinction training. Treatment with vagus nerve or sham stimulation
was administered concurrently with exposure to the fear conditioned stimulus. Another
group was given VNS and extinction training but the VNS was not paired with exposure
to conditioned cues. Retention of fear conditioning was tested 24 hours after each
treatment.
Results
Vagus nerve stimulation paired with exposure to conditioned cues enhanced the extinction
of conditioned fear. After a single extinction trial, rats given VNS stimulation demonstrated
a significantly lower level of freezing, compared with that of sham control rats.
When extinction trials were extended to 10 days, paired VNS accelerated extinction
of the conditioned response.
Conclusions
Extinction paired with VNS is more rapid than extinction paired with sham stimulation.
As it is currently approved by the Federal Food and Drug Administration for depression
and seizure prevention, VNS is a readily available and promising adjunct to exposure
therapy for the treatment of severe anxiety disorders.
Key Words
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Article info
Publication history
Published online: December 14, 2012
Accepted:
October 12,
2012
Received in revised form:
October 12,
2012
Received:
August 10,
2012
Identification
Copyright
Published by Elsevier Inc.
ScienceDirect
Access this article on ScienceDirectLinked Article
- Fear and Anxiety Take a Double Hit From Vagal Nerve StimulationBiological PsychiatryVol. 73Issue 11
- PreviewAt the forefront of translational research to combat anxiety disorders is the idea of developing neuroscience-based adjuncts to traditional exposure-based treatment such as cognitive/behavioral therapy. The core concept of exposure therapy is Pavlovian extinction, in which an anxiety-triggering stimulus is repeatedly presented so that that the patient learns that the stimulus predicts no negative consequences. This new association acts to inhibit the anxiety normally provoked by the stimulus. On its own, such exposure is quite effective, but it has some limitations.
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