1. Departments of Physiology and Pharmacology (R.L.G., I.H., C.C.N., J.M.C., M.V., S.M.H.), Robert C. Byrd Health Sciences Center, Morgantown, West Virginia 26506
2. Neurobiology and Anatomy (H.J.B.), Robert C. Byrd Health Sciences Center, Morgantown, West Virginia 26506
3. Department of Anatomy and Cell Biology (M.N.L.), Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada N6A 5C1