1. a Multimodal Integration Research Group , Human Technology Research Institute , National Institute of Advanced Industrial Scienceand Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8566, Japan
2. b Laboratory of Cellular Cybernetics , GraduateSchool of Information Science and Technology , Hokkaido University Kita 14, Nishi 9, Kita-ku, Sapporo, Hokkaido, 060–0814, Japan