1. Laboratory of Central Nervous System Studies, National Institute of Neurological and Communicative Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.
2. Department of Molecular Biology, Scripps Clinic and Research Foundation, La Jolla, CA 92037.
3. Department of Basic and Clinical Research, Scripps Clinic and Research Foundation, La Jolla, CA 92037.