1. Center for the Study of Itch, Washington University School of Medicine Pain Center, St. Louis, MO 63110, USA
2. Departments of Anesthesiology, Washington University School of Medicine Pain Center, St. Louis, MO 63110, USA
3. Departments of Psychiatry, Washington University School of Medicine Pain Center, St. Louis, MO 63110, USA
4. Departments of Developmental Biology, Washington University School of Medicine Pain Center, St. Louis, MO 63110, USA