Presented in part at the International Society for Magnetic Resonance in Medicine meeting in Glasgow, Scotland, April 21–27, 2001, and the International Congress on Schizophrenia Research, Whistler, B.C., Canada, April 28–May 5, 2001. Received Jan. 18, 2002; revision received May 15, 2002; accepted May 22, 2002. From the Department of Nuclear Medicine and Magnetic Resonance, St. Joseph’s Health Care, London, Ont., Canada; the Laboratory for Functional Magnetic Resonance Research, John P. Robarts Research Institute, London, Ont., Canada; the Department of Psychiatry and Department of Psychology, University of Western Ontario, London; and King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia. Address reprint requests to Dr. Williamson, Department of Psychiatry, University Campus, London Health Sciences Centre, 339 Windermere Rd., London, ON Canada N6A 5A5; firstname.lastname@example.org (e-mail). Supported in part by grant MT-12078 from the Canadian Institutes of Health Research.