The patient is instructed to take low residue diet 2 days prior to barostat. On the day before barostat, bowel preparation is performed by ingestion of 4 liters of polyethylene glycol solution in 2 divided doses. After a 12-hour fast, the participant is positioned in supine position on MRI table. A barostat bag is inserted into the rectum. The barostat device is connected to the barostat catheter using a low compliance PVC tubing. The participant will remain alone in MRI cubicle during the whole experiment but a speaker and microphone system allows communication with the investigator. He/she is also provided a squeeze bulb to signify pain. Repeated squeezing of the bulb signifies request for termination of procedure.