Brain, Behavior and Endocrine Effects of Transcutaneous Vagus Nerve Stimulation

Study Overview
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Brief Summary
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The main aim of the study is to investigate whether the transcutaneous vagus nerve stimulation(tVNS) promotes oxytocin release and the potential biomarkers of tVNS based on eye-tracking data

Detailed Description
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A randomized, single-blinded, sham-controlled, within-subject, crossover design will be employed in this study. In a randomized order, a total of 54 healthy subjects will receive transcutaneous vagus nerve stimulation via tragus and sham stimulation vis earlobe in the left ear (interval between these two stimulations will be 1 week). Eye-tracking and behavioral data will be collected before and after 30 minutes of stimulation, saliva samples will be collected before and after 30 minutes of stimulation, and the end of the experiment. Some personal traits will be assessed using different kinds of questionnaires, such as the Autism Spectrum Quotient(ASQ), Social Responsiveness Scale(SRS), State-Trait Anxiety Inventory (STAI), Beck's Depression Inventory(BDI), and Toronto Alexithymia Scale (TAS-20).

Official Title
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Transcutaneous Vagus Nerve Stimulation Promotes Oxytocin Release and Increases Fixations on Nose

Conditions
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Healthy

Intervention / Treatment
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* Device: Vagus nerve stimulation via tragus
* Device: Sham stimulation via earlobe


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy subjects without past or current psychiatric or neurological disorders Exclusion Criteria: history of head injury; pregnant, menstruating, taking oral contraceptives; medical or psychiatric illness.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 28 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Tragus then earlobe stimulation<br> | Device: Vagus nerve stimulation via tragus<br>* The device will send stimulus intensity around 0.5mA via tragus in the left ear (based on participants' subjective report), delivered with a pulse width of 0.25 ms at 25 Hz. Stimulation will be active for 30 seconds, followed by a break of 30 seconds.<br>Device: Sham stimulation via earlobe<br>* The device will send stimulus intensity around 0.5mA via earlobe in the left ear (based on participants' subjective report), delivered with a pulse width of 0.25 ms at 25 Hz. Stimulation will be active for 30 seconds, followed by a break of 30 seconds.<br>|
| Experimental: Earlobe then tragus stimulation<br> | Device: Vagus nerve stimulation via tragus<br>* The device will send stimulus intensity around 0.5mA via tragus in the left ear (based on participants' subjective report), delivered with a pulse width of 0.25 ms at 25 Hz. Stimulation will be active for 30 seconds, followed by a break of 30 seconds.<br>Device: Sham stimulation via earlobe<br>* The device will send stimulus intensity around 0.5mA via earlobe in the left ear (based on participants' subjective report), delivered with a pulse width of 0.25 ms at 25 Hz. Stimulation will be active for 30 seconds, followed by a break of 30 seconds.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Oxytocin release | Investigating the oxytocin release after vagus nerve stimulation via tragus based on saliva samples | After 30 min tragus stimulation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The relationship between oxytocin concentration and personal traits | Analyzing the correlation between saliva oxytocin concentration and scores on different personal traits | through study completion, an average of half an year | 
| Pupil size | Investigating whether vagus nerve stimulation via tragus will increase pupil diameter | After 30 min tragus stimulation | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Transcutaneous vagus nerve stimulation, Oxytocin release, Eye-tracking