1. Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
2. Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
3. Department of Anesthesiology, E-Da Hospital, School of Medicine, I-Shou University, Kaohsiung, Taiwan
4. Department of Neurobiology, Duke University Medical Center, Durham, NC, USA