Presented in part at the 10th annual scientific meeting of the International Society for Magnetic Resonance in Medicine, Honolulu, May 18–24, 2002. Received Oct. 29, 2002; revision received May 27, 2003; accepted May 29, 2003. 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 the Department of Psychology, University of Western Ontario, London, Ont., Canada; 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, Ont., Canada N6A 5A5; firstname.lastname@example.org. Supported by a grant from the Canadian Institutes of Health Research (MT-12078).