This research study is being done to gather information about how to do further clinical studies using AZD3355 as an add-on treatment to proton pump inhibitors (PPI).

Inclusion Criteria:

• Subject able to read and write US english and able to use electronic devices
• Subjects who have experienced GERD symptoms for at least six months
• Subjects currently taking a prescription or over-the-counter PPI medications for GERD
• Body Mass Index (BMI) 18.5-35.0, inclusive

Exclusion Criteria:

• Subjects that have not experienced any GERD symptoms improvement at all after PPI treatment
• Subjects who have any of the following conditions or diseases- Heart disease, Angina, Seizure disorders such as epilepsy, Congestive Heart Failure (CHF), Liver disease such as Cirrhosis or Hepatitis, Kidney disease, Lung disease or lung cancer, Cancer
• Prior surgery of the upper Gastrointestinal (GI) tract