Optimizing transcutaneous auricular Vagus Nerve Stimulation: Applications for Extinction Learning
Animal research has shown that vagus nerve stimulation (VNS) can greatly facilitate extinction learning - the laboratory analogue of exposure therapy for trauma-related disorders. A novel non-invasive variant of this technique, transcutaneous auricular VNS (taVNS), activates the auricular branch of vagus nerve via electrical stimulation of the outer ear. Because taVNS is easy and cheap to implement, its potential use as an add-on for exposure therapy is feasible and promising. Unfortunately, findings on effects of taVNS on extinction learning in humans have been inconsistent. A potential explanation is that current taVNS protocols fail to optimally increase afferent vagal activity. Little is currently known about which stimulation parameters should be used to optimize treatment efficacy of taVNS. The proposed project will test two ways in which taVNS can be optimized, by systematically testing parameter-specific modulation of noradrenergic activity, and by synchronizing the timing of taVNS with naturally occurring fluctuations in vagal activity along the respiratory cycle. The optimized taVNS protocol will then be compared to conventional taVNS and sham stimulation in a fear extinction study. The results from this project could provide important indications for the clinical applicability of taVNS as an add-on for exposure therapy. More generally, this project will strongly benefit the emerging field of taVNS in the context of a myriad of psychiatric and neurological disorders.