1. Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
2. Neuropathology Laboratory, Departments of Pathology and Neurology, Baltimore, Maryland 21205
3. Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
4. Departments of Pharmacology and Experimental Therapy, Psychiatry, and Neuroscience, Baltimore, Maryland 21205