半側空間無視の病態生理 Pathophysiology of unilateral spatial neglect

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著者

    • 後藤 純信 Goto Yoshinobu
    • 国際医療福祉大学福岡リハビリテーション学部作業療法学科 Department of Occupational Therapy, Faculty of Rehabilitation, International University of Health and Welfare
    • 山崎 貴男 Yamasaki Takao
    • 九州 大学大学院医学研究院臨床神経生理 Department of Clinical Neurophysiology, Graduate School of Medical Sciences, Kyushu University

抄録

半側空間無視(Unilateral spatial neglect : USN)の発症メカニズムに注意障害説や表 象障害説などがある。近年のUSN の研究では、行動無視検査(Behavioral Inattention Test, BIT)による評価のみならず探索眼球運動(Exploratory EyeMovements, EEMs)などの生理学 的評価を行うことで、USN の病態生理を客観的に検討する試みがなされている。しかし、未 だ脳内視覚情報処理機能とUSN の病態生理との関連性を解明するまでには至っていない。 本研究では、USN 群、左片麻痺でUSN を合併していない群、右片麻痺群および健常者での脳 内視覚情報処理機能の違いを、心理物理学的評価とEEMsの変化を基に比較検討し、USN で の視覚情報処理の病態生理を明らかにすることを目的とした。その結果、EEMsではUSN 群 で健常者群と比べ有意に左側の注視点数や総移動距離が減少し平均注視時間の延長が認めら れた。また、右片麻痺群でも右側を無視する傾向を認めた。さらに、USN 群ではEEMs と BIT行動性無視検査に有意な相関を認めた。但し、USN 群では注意喚起前後でのEEMsの変 化はわずかであった。本研究のように、心理物理学的評価法にEEMsなどの脳生理学的アプ ローチを加えることで、より客観的にUSN の病態生理の本質にせまることができると考え られる。

Unilateral spatial neglect(USN)is a disorder that results mainly from rightward bias of spatial attention and is accompanied with some general disorders such as motivational dysfunction. USN may fail to respond to stimuli in left hemispace and show a lot of problems in activities of daily living. Although many studies attempt to clarify the pathophysiology of USN, it is still unknown the relationship between anatomical brain dysfunction and pathophysiology of USN. A major challenge for pathophysiological study of USN in neurological patients is that brain lesions vary tremendously in extent and location between individuals. In our study, patients of left hemiplegia with USN, patients of left hemiplegia without USN, patients of right hemiplegia without USN and age-matched healthy volunteers were recruited for recording exploratory eye movements(EEMs)on the visual search task. The patients of USN were diagnosed by the behavioral inattention test(BIT)score above 24. At the results, left hemiplegia with USN patients only searched their right side during EEM recording. The mean gazing time of left hemiplegia with USN patients was significantly longer than that of other subjects. In addition, the total number of gazing points of left hemiplegia with USN patients was significantly smaller than that of healthy volunteers. Interestingly, the patients of right hemiplegia without USN tended to search their left side. The relationship between EEM data and BIT score was significantly correlated. These results suggested that visual input from the right part of an object was projected to the left visual cortex. The damaged right hemisphere utilized this input via corpus callosum and constructed a totalized image of the object. This tendency to construct a totalized image suppressed the visuospatial ability of the left hemisphere. Such interactions between right and left hemispheres might play an important role in USN. Furthermore, it is useful for analyzing the pathophysiology of USN to use this kind of neurophysiological approach.

収録刊行物

  • 認知神経科学

    認知神経科学 13(1), 71-78, 2011

    認知神経科学会

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