1. Department of Neurosurgery, Faculty of Medicine, University of Tsukuba, Japan
2. Department of Cardiology, Faculty of Medicine, University of Tsukuba: 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
3. Department of Rehabilitation, University of Tsukuba Hospital, Japan
4. Department of Cardiology, Kamisu Clinical Education and Training Center, University of Tsukuba Hospital, Japan
5. Center for Cybernics Research, University of Tsukuba, Japan