Non-invasive Vagal Nerve Stimulation in Opioid Use Disorders UH3

Participants will receive stimulation of the vagus nerve with the non-invasive transcutaneous cervical Vagal Nerve Stimulation (tcVNS), which does not require surgery or implantation, and electrically stimulates the vagus nerve as it passes through the neck, dampening the sympathetic nervous system and modulating brain regions to a single side of the neck with the GammaCore device. Participants will be trained on self-stimulation and from days 1-7 patients undergo four times daily self-stimulation with tcVNS first for two minutes on one side, followed by a one-minute pause, then two minutes on the same side. The intensity of the stimulus (i.e. the current amplitude) will be adjusted by the user, to the maximum tolerable level without causing excessive pain \[typically 10-30 V and 60milliamperes (mA) (peak)\], with an alternating current (AC) signal consisting of five 5 kilohertz (kHz) pulses 200 microseconds in duration, repeating at a rate of 25 Hz (about once every 40 milliseconds).

Participants will have the same procedures as with the tcVNS but will instead receive a device that appears identical to the active tcVNS device in look, weight, visual and audible feedback, and also in user controls. The Sham device looks and sounds like an active device but does not deliver an electric current.

\[F-18\]Fallypride is a radioactive material. Each patient will have two \[F-18\]Fallypride PET scans. For each scan \[F-18\]Fallypride will be injected as an intravenous bolus. The radiation dose to body organs in this study is well within the Food and Drug Administration (FDA) national guidelines for radiation exposure for human research studies and less than the total amount that is permitted for research studies in one year.