1 Center for Information and Neural Networks (CiNet), Advanced ICT Research Institute, National Institute of Information and Communications Technology, Suita, 565-0871, Japan; Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan. Electronic address: ikimura-osk@umin.ac.jp.
2 Department of Human Neurophysiology, Fukushima Medical University, Fukushima, 960-1295, Japan.
3 Center for Information and Neural Networks (CiNet), Advanced ICT Research Institute, National Institute of Information and Communications Technology, Suita, 565-0871, Japan; Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan.
4 Center for Information and Neural Networks (CiNet), Advanced ICT Research Institute, National Institute of Information and Communications Technology, Suita, 565-0871, Japan; Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan; Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, 113-8656, Japan. Electronic address: kaoru_amano@ipc.i.u-tokyo.ac.jp.