1. Department of Materials Physics and Chemistry, Graduate School of Engineering, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan, Mitsubishi Kagaku Institute for Life Sciences, Minamiohtani 11, Machida, Tokyo 194-0031, and Laboratory of Cellular Neurobiology, School of Life Science, Tokyo University of Pharmacy and Life Science, Horinouchi 1432-1, Hachiouji, Tokyo 192-0355