1Department of Neural Regenerative Medicine, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, Sapporo, Japan.
2Department of Neural Regenerative Medicine, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, Sapporo, Japan - msasaki@sapmed.ac.jp.
3Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, USA.
4Center for Neuroscience and Regeneration Research, VA Connecticut Healthcare System, West Haven, Connecticut, USA.
5Department of Neurosurgery, Sapporo Medical University School of Medicine, Sapporo, Japan.