1 Department of Computer Science and Electrical Engineering, University of Maryland, Baltimore County, MD, United States; Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health (NIH), Baltimore, MD, United States.
2 Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health (NIH), Baltimore, MD, United States; Tianjin Medical University, Tianjin, People's Republic of China.
3 Department of Computer Science and Electrical Engineering, University of Maryland, Baltimore County, MD, United States.
4 Department of Psychiatry, University of Maryland School of Medicine and Maryland Psychiatric Research Center, Baltimore, MD, United States.
5 Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health (NIH), Baltimore, MD, United States.
6 Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health (NIH), Baltimore, MD, United States. Electronic address: luha@mail.nih.gov.