1Department of Neurosurgery, Sapporo Medical University School of Medicine, Sapporo Hokkaido, Japan.
2Department of Neural Regenerative Medicine, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, Sapporo Hokkaido, Japan.
3Department of Molecular Medicine, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, Sapporo Hokkaido, Japan.
4Department of Public Health, Sapporo Medical University School of Medicine, Sapporo Hokkaido, Japan.