1. Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
2. Department of Physiology, School of Medicine, Fukuoka University, 7-45-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan
3. ERATO Innovative Molecular Technology for Neuroscience Project, Japan Science and Technology Agency (JST), Kyoto 615-8530, Japan