1. National Center for Nervous, Mental, and Muscular Disorders, 2620 Ogawa-Higashi, Kodaira, Tokyo 187, Japan
2. Department of Neurology, Chiba University School of Medicine, 1-8-1 lnohana, Chiba 280, Japan
3. Department of Biological Chemistry, Faculty of Pharmaceutical Sciences, Kyoto University, Kyoto 606, Japan