1. Laboratory for Cell Function and Dynamics, Advanced Technology Development Center, Brain Science Institute, The Institute of Physical and Chemical Science (RIKEN), 2-1 Hirosawa, Wako-city, Saitama, 351-0198, Japan, and Brain Science Research Division, Brain Science and Life Technology Research Foundation, 1-28-12 Narimasu, Itabashi, Tokyo, 175-0094, Japan