Mathematical Informatics Laboratory, Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Japan.|Mathematical Informatics Laboratory, Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Japan.|Department of Neurosurgery, Yamaguchi University Graduate School of Medicine, Ube, Japan.|Department of Physiology, Yamaguchi University Graduate School of Medicine, Ube, Japan.|Organization for Innovation and Excellence, Kumamoto University, Kumamoto, Japan.|Department of Neurosurgery, Yamaguchi University Graduate School of Medicine, Ube, Japan.|Mathematical Informatics Laboratory, Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Japan.