1. Centre for Digestive DiseasesBlizard InstituteWingate Institute of NeurogastroenterologyBarts and the London School of Medicine & DentistryQueen Mary University of London London E1 2AJ UK
2. University Hospitals of North Midlands Stoke on Trent Staffordshire ST4 6QG UK
3. Department of NeuroimagingInstitute of PsychiatryKing's College London London SE5 8AF UK
4. Medical Research Council Spatial Disorientation GroupDepartment of MedicineImperial College London London SW7 2BX UK
5. Department of Medical SciencesUppsala University Box 256 751 05 Uppsala Sweden
6. Division of Biomedical SciencesSt George's University of London London SW17 0RE UK