1. Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
2. Department of Clinical Medicine, University of Bergen, Bergen, Norway
3. National Center for Functional Gastrointestinal Disorders, Department of Medicine, Haukeland University Hospital, Bergen, Norway
4. Department of Biomedicine, University of Bergen, Bergen, Norway
5. Mohn Medical and Visualization Center, Department of Radiology, Haukeland University Hospital, Bergen, Norway