Mapping Auricular Vagus Nerve Circuitry

Study Overview
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Brief Summary
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This study will determine how vagus nerve stimulation affects human brain, stomach, and autonomic activity.

Detailed Description
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Scientific research into the basic mechanisms underlying neuromodulation is relatively recent and incomplete. The purpose of the proposed study is to determine how a form of neuromodulation, transcutaneous vagus nerve stimulation, which is non-invasive and non-painful, affects human brain and autonomic activity. We will accomplish this by integrating whole brain functional MRI (fMRI) methodologies with gastric MRI and physiological monitoring. This study will comprise 2 functional magnetic resonance imaging (fMRI) brain-gut scans and 2 behavioral visits consisting of a nutrient drink test, all while receiving the neuromodulation with varying parameters. Participants will also have their heart rate, breathing, and gastric activity monitored during all visits.

Official Title
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Auricular Vagal Nerve Stimulation for Gastric and Brain Outcomes

Conditions
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Healthy

Intervention / Treatment
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* Device: active auricular tVNS
* Device: inactive auricular tVNS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Right-handed Exclusion Criteria: Any condition contraindicating an fMRI brain scan Any neurological or psychiatric disorders Any pain syndromes

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 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
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: auricular tVNS<br>active and inactive auricular transcutaneous vagus nerve stimulation (tVNS) | Device: active auricular tVNS<br>* non-painful active auricular tVNS will be delivered to the left ear<br>Device: inactive auricular tVNS<br>* non-painful inactive auricular tVNS will be delivered to the left ear<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Brain activity during functional magnetic resonance imaging (fMRI) | Blood oxygen-level dependent (BOLD) signal change between active and inactive auricular tVNS | 1 hour | 
| Stomach activity during gastric magnetic resonance imaging (MRI) | Gastric accommodation and sensitivity change between active and inactive auricular tVNS | 30 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Electrogastrography (EGG) | We will use EGG to measure slow wave myoelectrical activity, as measured by EGG power/peak frequency. | 2 hours | 
| Electrocardiography (ECG) | We will use ECG to examine high frequency heart rate variability (HF-HRV), i.e. the R-peak of the QRS complex. | 2 hours | 
| Respiration | Respiration will be measured in beats per minute (bpm). | 2 hours | 
| Skin Conductance Levels (SCL) | SCL will be measured in volts per second. | 2 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Acupuncture, Magnetic Resonance Imaging, Functional, Brain Mapping, healthy volunteers, Neuromodulation, gastric MRI