Inclusion Criteria:

Healthy Persons:

• Patients 18 years of age or older with no symptoms of GERD

Patients:

• Patients 18 years of age or older with symptoms of GERD
• Upper gastrointestinal endoscopy within the past 6 months and a prior diagnostic pH impedance study showing predominantly upright reflux

Exclusion Criteria:

Patients; Items indicated with an asterisk (*) are also exclusion criteria for healthy persons

• Patient who fulfil ROME IV Criteria for rumination disorder²°
• Clinical evidence of significant cardiovascular, respiratory, renal, hepatic, gastrointestinal, hematological, neurological (e.g., spinal cord injuries, dementia, multiple sclerosis, Parkinson's disease), psychiatric or other disease that may interfere with the objectives of the study and/or pose safety concerns.*
• Any prior gastric or esophageal surgery and significant intestinal or colonic resection*
• Hiatal hernia measuring 3 cm or larger as assessed by endoscopic or radiological studies
• Prior history of Los Angeles Grade C or D esophagitis, or esophageal stricture.
• Current use opioid analgesics or anticholinergic drugs.* We will permit low doses of tricyclic antidepressants, nortriptyline (up to 50 mg/day) or amitriptyline (up to 25 mg/day) provided they were commenced 3 months prior to the screening period, calcium channel or adrenergic1 antagonists
• Current use of proton pump inhibitors
• Known significant esophageal motor disorder (ie achalasia, aperistalsis, functional obstruction, jackhammer, distal esophageal spasm)*
• Inability to read due to: blindness, cognitive dysfunction, or English language illiteracy *
• Pregnant and lactating females *

Healthy Persons in addition to those marked with an Asterisk (*) above

• Ongoing use of Proton Pump Inhibitors ( PPIs) or a history consistent with GE reflux for 3 months or longer duration in past.
• Prior history of Los Angeles Grade B-D esophagitis
• Prior history of GERD on the basis of pH testing