1. Department of Otorhinolaryngology—Head and Neck Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
2. Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
3. Monell Chemical Senses Center, Philadelphia, PA 19104, USA.
4. Philadelphia Veterans Affairs Medical Center Surgical Service, Philadelphia, PA 19104, USA.