1. Department of Molecular Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan;
2. Department of Pharmacology,
3. Department of Biomedical Sciences, Hokkaido University Graduate School of Veterinary Medicine, Sapporo 060-0818, Japan
4. Neurosciences Program,
5. Biomedical Sciences Program, School of Medicine, University of California, San Diego, La Jolla, California 92093-0636;
6. Molecular Neuroscience, Merck Research Laboratories, San Diego, California 91212; and