Auricular vagus nerve stimulation facilitates contextual fear extinction via insular-mPFC pathway without affecting reconsolidation
Cervical vagus nerve stimulation (VNS) suppresses conditioned fear in rodents and may serve as an adjunct to exposure-based therapy for anxiety disorders. Non-invasive auricular VNS reduces conditioned fear also in humans, although the underlying mechanisms remain unclear. Using a contextual fear conditioning paradigm, in which brief re-exposure induces reconsolidation and prolonged re-exposure…
Auricular vagus nerve stimulation (VNS) shows promise as a new approach for treating anxiety disorders by enhancing the process of fear extinction in mice. This technique involves non-invasive stimulation of the ear, which reduces conditioned fear responses specifically during prolonged re-exposure to a previously feared situation.
The underlying mechanism appears to involve increased activity in the posterior insular cortex (pIC) and associated pathways to the medial prefrontal cortex (mPFC). These brain regions are known to play key roles in regulating fear responses.
Researchers found that auricular VNS during the later stages of prolonged re-exposure not only reduced freezing behavior but also strengthened the connections between the pIC and mPFC. Optogenetic experiments confirmed that activating this pathway directly mimicked the fear-extinction effects of VNS, while inhibiting it blocked these effects.
These findings suggest that vagus nerve stimulation may offer a novel way to engage the insular-prefrontal circuitry, facilitating the process of learning to extinguish fear memories without interfering with memory reconsolidation. Further study is needed to explore the potential of this approach in humans with anxiety disorders.
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