1. Department of Physiology, School of Medicine, Hiroshima University, 1‐2‐3 Kasumi, Minami‐ku, Hiroshima, 734‐8551, Japan
2. Department of Clinical Engineering, Hiroshima International University, Faculty of Health Sciences, 555‐36 Gakuendai, Kurose‐cho, Kamo‐Gun, Hiroshima, 724‐0695, Japan