1. Department of Neurology, University of California, San Francisco, California, USA
2. Department of Anesthesiology, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, Korea
3. Department of Pain Medicine, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, Korea
4. Departments of Anesthesiology, Sanggye Paik Hospital, Inje University, School of Medicine, Seoul, Korea
5. Department of Physiology, College of Medicine, Hallym University, Chun Cheon, Korea