Characterization of Gastric Evoked Potentials

Study Overview
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Brief Summary
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This is an exploratory study that will determine and standardize how best to record gastric evoked potentials (GEPs) elicited by a non-invasive method of brain stimulation (Transcranial Magnetic Stimulation, TMS), by optimizing the TMS parameters and cortical sites necessary to evoke GEPs.

Detailed Description
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The overall goal of this exploratory study is to determine the optimal conditions to elicit gastric evoked potentials (GEPs) with Transcranial Magnetic Stimulation (TMS). Aim 1: Determine the optimal stimulation parameters and the optimal location for eliciting GEPs in cortical motor areas. Aim 2: Determine whether various modes of repetitive TMS (rTMS) neuromodulation targeted to GEP hotspots shape gastric motor responses to a water load. The investigators will record some clinical, demographic, and autonomic data (i.e. EKG) in our enrolled subjects. Secondary analyses will use these variables as covariates to investigate any systematic impact on the measures from Aims 1 and 2.

Official Title
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Characterization of Gastric Evoked Potentials

Conditions
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Healthy

Intervention / Treatment
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* Procedure: Transcranial Magnetic Stimulation, TMS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: - Exclusion Criteria: psychosis or altered cognitive status history of head injury, metal in the skull, stroke, or a history of seizures, loss of consciousness or syncope implantable devices, such as a pacemaker or nerve stimulator current use of antiepileptic medications or current use of the following medications or substances which are known to lower the seizure threshold: Clozapine (Clozaril), Chlorpromazine (Thorazine), amphetamines or methamphetamine, Ecstasy, Ketamine, Angel Dust/PCP, cocaine, or 3 or more alcoholic drinks per day pregnancy BMI > 30 history of bariatric surgery such as sleeve gastrectomy or Roux-en-Y gastric bypass diabetes suffering from a neurodegenerative disorder.

Ages Eligible for Study
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Minimum Age: 21 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: All participants<br>All participants | Procedure: Transcranial Magnetic Stimulation, TMS<br>* The best location for evoking an electromyographic (EMG) response of the first dorsal interosseus (FDI) muscle in the dominant hand and the minimum stimulation intensity required to evoke a certain EMG response amplitude (Motor Threshold, MT) are used as reference to determine the best location and stimulation parameters to evoke GEPs. After identification of the GEP hot-spot, a water load test is administered to determine whether satiety shapes GEP responses. In subsequent study visits, the water load test is preceded by application of neuromodulatory repetitive TMS (rTMS), targeted to the GEP hotspot.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in GEP hotspot location | Stimulation location evoking the largest GEP response, relative to FDI hotspot location | Multiple study sessions spanning up to 12 months | 
| Change in optimal stimulation parameters at GEP hotspot | Stimulation pattern (single pulses or brief bursts) and strength relative to MT for FDI | Multiple study sessions spanning up to 12 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Effect of satiety | Change in GEP amplitude after water load test | Multiple study sessions spanning up to 12 months | 
| Effect of neuromodulation | Change in GEP amplitude when water load test is preceded by rTMS | Multiple study sessions spanning up to 12 months |