1. Department of Psychiatry, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
2. Institute of Behavioral Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
3. Department of Psychiatry, Tainan Hospital, Ministry of Health and Welfare, Tainan, Taiwan
4. Neuroimaging Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA