PROPRIOCEPTIVE, VISUAL AND VESTIBULAR THRESHOLDS FOR THE PERCEPTION OF SWAY DURING STANDING IN HUMANS
PROPRIOCEPTIVE, VISUAL AND VESTIBULAR THRESHOLDS FOR THE PERCEPTION OF SWAY DURING STANDING IN HUMANS
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DOI：
10.1113/jphysiol.1994.sp020240
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发表时间：
1994-07-01
影响因子：
5.5
通讯作者：
MCCLOSKEY, DI
中科院分区：
文献类型：
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作者：
FITZPATRICK, R;MCCLOSKEY, DI
1.对五名正常站立受试者测定了由轻微扰动引起的姿势摇摆的感知阈值。在这种情况下，我们将“感知”理解为“能够提供主观报告”。当可用的感觉输入仅限于前庭、视觉和本体感受系统中的一个或一对时，确定了相当于摇摆速度和幅度的运动感知阈值。为了单独检查前庭输入，排除视觉，并移动整个身体，使脚踝处于固定位置。为了单独检查视觉输入，身体保持静止，并在受试者周围移动一个“房间”，以模拟站立时发生的相对视野运动。为了限制来自腿部的本体感觉的可用感觉输入，受试者保持静止，并使用脚踝平衡相当于他们自己身体的负荷。在这种情况下，扰动被应用于“等效身体”，这些只能从由此产生的脚踝运动中感知。在相同的姿势下，也确定了感知踝关节运动的支撑点，但腿部肌肉不承受负荷。站立时感知摇摆的阈值非常小，通常在0.001 rad s（-1）的速度下为0.003 rad，当摇摆的平均速度增加到0.003 rad s（-1）时，甚至可以感知到更小的运动。前后摇摆的感知阈值无差异。在站立时闭眼并不影响感知摇摆的阈值。当感觉输入仅限于腿部的本体感觉时，被动踝关节运动的感知阈值相当于站立期间所有感觉输入可用的摇摆感知阈值。当腿部肌肉放松时，感知踝关节运动的阈值增加了约两倍。在低速运动时，视觉运动阈值高于本体感觉阈值，而在高速运动时，两者无差异.本体感受阈值和视觉阈值都足够小，以允许感知受试者以放松的方式正常站立时记录的摇摆。相比之下，前庭阈值比视觉或本体感受阈值大一个数量级，并且高于正常站立期间记录的最大摇摆运动。当一个以上的感官模态可用于感知时，受试者的表现水平相当于具有更大敏锐度的感官模态。这些研究结果表明，在正常的站立，本体感受输入的腿提供了最敏感的方式感知姿势摇摆。在正常摇摆速度范围内的较高而非较低速度下，视觉输入提供了类似的感知摇摆的敏感手段。然而，在前庭机制可以提供关于身体摇摆的感知信息之前，需要大的姿势干扰，并且本研究表明，前庭系统在正常站立期间对摇摆的感知中不起作用。
1. Thresholds for the perception of postural sway induced by gentle perturbations were determined for five normal standing subjects. In this context we understand 'perception' to mean 'able to give a subjective report'. The thresholds for the perception of movements that were equivalent to sway in velocity and amplitude were determined when the available sensory input was limited to only one, or a pair, of the vestibular, visual, and proprioceptive systems. To examine vestibular inputs alone, vision was excluded and the whole body was moved with the ankles in a fixed position. To examine visual inputs alone, the body was kept stationary and a 'room' was moved around the subjects to simulate the relative visual-field movement that occurs during standing. To limit the available sensory input to proprioception from the legs, subjects were held stationary and balanced a load that was equivalent to their own body using their ankles. In this situation, perturbations were applied to the 'equivalent body' and these could only be perceived from the resulting ankle movements. Thresholds for perceiving ankle movements were also determined in the same posture, but with the leg muscles bearing no load.2. The thresholds for the perception of sway during standing were very small, typically 0.003 rad at a velocity of 0.001 rad s(-1), and even smaller movements were perceived as the mean velocity of the sway increased up to 0.003 rad s(-1). No difference was found between the thresholds for perceiving forward sway and backward sway. Eye closure during standing did not affect the threshold for perceiving sway.3. When sensory input was limited to proprioception from the legs, the thresholds for the perception of passive ankle movements were equivalent to the thresholds for the perception of sway during standing with all sensory inputs available. When the leg muscles were relaxed, the thresholds for perceiving ankle movements increased approximately twofold.4. The visual thresholds for perceiving movement were higher than the proprioceptive thresholds at slower velocities of movement, but there was no difference at higher velocities.5. Both the proprioceptive and visual thresholds were sufficiently small to allow perception of the sway that was recorded when the subjects stood normally in a relaxed manner. In contrast, the vestibular thresholds were an order of magnitude greater than the visual or proprioceptive thresholds and above the largest sway movements that were recorded during normal standing.6. When more than one sensory modality was available for perception, subjects performed at a level that was equivalent to the sensory modality that had the greater acuity.7. These findings indicate that, during normal standing, proprioceptive inputs from the legs provide the most sensitive means of perceiving postural sway. At higher, but not lower, velocities within the range of velocities of normal sway, visual inputs provided similarly sensitive means of perceiving sway. However, large disturbances of posture would be required before vestibular mechanisms could provide perceptual information about body sway, and the present study indicates that the vestibular system plays no part in the perception of sway during normal standing.