The goal of this study is to determine whether stimulation of the brain-stomach connection can influence stomach activity in healthy adults and in individuals suffering from chronic nausea. The main questions it aims to answer are:

• What are the best brain sites to influence the stomach?
• What are the effects of different stimulation patterns on stomach activity?
• Does the stimulation affect the sensation of nausea in participants suffering from chronic nausea?

Researchers will use a non-invasive method of brain stimulation called Transcranial Magnetic Stimulation (TMS) and will record stomach responses with skin electrodes on the abdomen.

Participants will:

• Visit the clinic at least once, and for up to 9 times more over the course of several months.
• Receive TMS while sitting in a chair similar to a dentist's chair.
• Drink water or consume a test meal during each study visit.

This study will use cutaneous recordings of stomach activity (electrogastrogram, EGG) and non-invasive brain stimulation with Transcranial Magnetic Stimulation (TMS) to

1. map descending cerebral cortical-to-stomach circuitry via gastric motor-evoked potentials (GMEPs),
2. use repetitive TMS (rTMS) applied to GMEP hotspots to modulate the stomach response to a satiety task (water load or nutrient drink/meal),
3. assess differences in topography and function of cortical-to-stomach circuitry between healthy subjects and subjects suffering from chronic nausea vomiting syndrome (CNVS).

Some clinical, demographic, and autonomic data (i.e. EKG) will be recorded and used as covariates to investigate any systematic impact on the outcome measures.

Inclusion Criteria:

• Adults between ages 21-60 years old, with and without CNVS diagnosis per self-report.

Exclusion Criteria:

• body mass index (BMI) > 30
• pregnancy or intention to become pregnant
• past or present chemotherapy
• diagnosis of gastric (stomach) cancer
• any kind of gastric (stomach) surgery
• current use of GLP-1 receptor agonists (e.g. Ozempic, Trulicity)
• medications which significantly lower seizure thresholds (e.g. bupropion (Wellbutrin), fluoxetine (Prozac), or tramadol (Ultram))
• implantable devices, such as a pacemakers or nerve stimulators
• history of head injury that required hospitalization, metal in the skull, or neurologic disease such as stroke, history of seizures or history of syncope (fainting or passing out)
• neurodegenerative disease (Multiple Sclerosis, Parkinson's or Alzheimer's Disease)
• ongoing psychosis or altered cognitive status status (e.g. hearing sounds or seeing visions that are not there, or feeling confused or suffering from memory lapses)
• history of cardiovascular (i.e., heart attack), pulmonary (i.e., need for supplemental oxygen), or endocrine disease (e.g. diabetes)
• current enrollment in another study using Transcranial Magnetic Stimulation (TMS)
• current use of drugs such as amphetamines, methamphetamine, Ecstasy, Ketamine, Angel Dust/PCP, cocaine, or drinking 3 or more alcoholic drinks per day
• For healthy subjects only: chronic history of gastrointestinal symptoms (e.g., nausea, indigestion, bloating, abdominal pain)
• For CNVS subjects only: diagnosis of gastric motility disorder (e.g. gastroparesis/slow stomach emptying) or history of bowel obstruction (i.e., chronic partial small bowel obstruction)

Final analytic de-identified datasets will be deposited in the SPARC data repository.

Datasets will be deposited within 2 years of study completion for as long as the SPARC repository is active.

The SPARC repository is publicly accessible.