回転加速度耐性獲得と自己受容器
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概要
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A blindfolded chicken is placed without any restriction on a perch made on a rotatory chair and is rotated 100 times in 200 seconds to both directions every day for 4 weeks. At first the chicken is unable to adapt itself to this rotatory motion i.e. the head, trunk, wings and tail move violently with each rotatory motion and finally it falls off the perch to the floor. However, with the daily repetition of this rotatory motion the chicken becomes capable of adapting itself smoo-thly to the dynamic motion after 2-4 weeks; i.e. the original unstable postures of the head, trunk, wings and tail are countermanded by new stable postures which just are the mirror image of the postures at the beginning. Fukuda et al could demonstrate that these new postures resulted from establishment of a labyrinthine reflex of a higher order, which enables the chicken to adapt the dynamic motion, therefore Fukuda named this process "Training" and this result "Trainining effect". In Fukuda's investigation, a blindfolded chic- ken was placed without restriction in any way on a perch. Therefore, not only the vestibular la- byrinths but also the proprioceptive organs should have been stimulated by rotatory motion. In order to know how the proprioceptive organs par- ticipate in the establishment of the training effect (a labyrinthine reflex of a higher order), the head, neck, trunk, wings and tail were restricted separa- tely or combinedly in the following various ways and the chicken was trained for 4 weeks by rota-ting it in each direction 10 times daily for periods of 6 minutes respectively using the so-called li- minal rotation, that is, acceleration of 3° per second to a maximum speed of 180° per second. The groups of chickens which were subjected to various types of restraint during the training are arranged below in the order of the facility with which the training was accomplished.1. Blindfolded chickens which were placed on a perch without restriction in any way.2. Blindfolded chickens of which the trunk and wings were fixed with i plaster cast and which were placed on a perch made in a box.3. Blindfolded chickens of which the trunk and wings were fixed with a plaster cast and which were placed in a box without any perch.4. Blindfolded chickens of which the head, trunk and wings were fixed with a plaster cast and which were placed on a perch made in a box.5. Blindfolded chickens of which the head, trunk and wings were fixed with a plaster cast and which were placed in a box without any perch.The results show that the training effect is gained by virtue of the vestibular7 labyrinths and the proprioceptive organs distributing in the whole body. Therefore, the author believes that the training for the air and space flight should be performed in this way; i.e. not only the vestibular labyrinths but the proprioceptive organs of the whole body should be trained simultaeneously.Even a trained chicken cannot maintain a good equilibrating posture during rotatory motion and falls to the floor, after a lapse of a month's untrained interval. However, it soon recovers its good equilibrating function through repetition of rotation for a few days or for a week.