1. Department of Electrical and Electronic Engineering, Hokkaido University of Science, Hokkaido 006-8585, Japan
2. Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan
3. Department of Electrical and Electronic Engineering, Tokyo Denki University, Tokyo 120-8551, Japan
4. Department of Human Intelligence Systems, Kyushu Institute of Technology, Kitakyushu 808-0196, Japan
5. International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo, Tokyo 113-0033, Japan