Evaluation of changes in oxyhemoglobin during Shiritori task in elderly subjects including those with Alzheimer's diseaseEvaluation of changes in oxyhemoglobin during Shiritori task in elderly subjects including those with Alzheimer's disease アルツハイマー型認知症を含む老年者のしりとり課題施行中の酸素化ヘモグロビン変動の検討