Vagus Nerve Stimulation for Pain

The goal of this clinical trial is to learn whether stimulating a nerve in the neck changes how much pain people feel. It also looks at whether this stimulation changes brain activity. The study is being done in healthy adults ages 18 to 70.

The nerve being studied is called the vagus nerve. It runs through the neck and connects to parts of the brain that handle pain. In this study, the nerve is stimulated from outside the body using a small device placed on the skin. There is no surgery, and nothing is implanted.

The main questions it aims to answer are: (1) Does stimulating the vagus nerve lower the pain people feel during a cold water test? (2) Does stimulating the vagus nerve change the electrical activity in the brain?

Researchers will compare pain ratings and brain activity under three conditions in the same person: no stimulation, real stimulation over the vagus nerve, and sham stimulation placed nearby on the neck. Sham stimulation feels similar but is not aimed at the nerve.

Participants will: (1) Come to one visit that lasts about 90 minutes, with no follow-up visits, (2) Wear a cap that records the brain's natural electrical signals for the whole visit, (3) Place both hands in cold water, about 39 degrees Fahrenheit, up to three times for up to 2 minutes each time, (4) Rate their pain after each cold water test, (5) Wear a stimulation device on the neck during two of the three cold water tests, (6) Not be told which of those two is the real stimulation until the visit is over.