1. Division of Advanced Science and Technology, Japan Advanced Institute of Science and Technology, Nomi 923-1292, Japan
2. Department of Brain & Neurosciences, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-0057, Japan
3. Department of Computer Science and Engineering, University of Colorado Denver, Denver, CO 80204, USA
4. Division of Health Sciences, Komatsu University, Komatsu 923-0961, Japan
5. Department of Clinical Engineering, Kanagawa Institute of Technology, Atsugi 243-0292, Japan
6. Swartz Center for Computational Neuroscience, Institute for Neural Computation, University of California San Diego, La Jolla, CA 92093, USA
7. Department of Clinical Engineering, Komatsu University, Komatsu 923-0961, Japan