Influence of expectation on postural disturbance evoked by proprioceptive stimulation
Influence of expectation on postural disturbance evoked by proprioceptive stimulation
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DOI：
10.1007/s00221-007-1079-9
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发表时间：
2008-01-01
影响因子：
2
通讯作者：
Guerraz, Michel
中科院分区：
文献类型：
--
作者：
Caudron, Sebastien;Boy, Frederic;Guerraz, Michel
最近的实验表明，平衡控制的前庭通道从根本上不同于视觉通道。然而，如果受试者意识到即将到来的干扰可能是由外部因素而不是自我运动引起的，则对视觉干扰的反应可以被抑制，关于前庭系统不能做出类似的假设。本实验研究了本体感受扰动（跟腱以90 Hz振动2.2 s）引起的姿势反应是否是自动的且不受预期影响（类似于前庭反应）或认知可穿透（类似于视觉反应）。受试者（n = 12）站在测力平台上，同时由受试者本人（自触发条件）或实验者提供刺激。对于后一种情况，刺激是在没有警告（不可预测的条件）或在一个固定的时间间隔（500毫秒）后，听觉提示（precue条件）。结果表明，向后CoP位移引起的振动延迟约500 ms相比，在预期和自触发条件下的意外条件。然而，一旦启动，与非预期条件相比，在自触发条件下向后位移的速度更高。在2.2 s的振动周期后，该向后CoP位移的幅度在三种实验条件下相似。因此，虽然预期似乎延迟了主体向后身体摇摆的到来，但它似乎无法衡量本体感受刺激的影响。这表明，由参与姿势控制的不同感觉通道提供的传入对高水平过程（如期望）并不敏感。
Recent experiments have shown that the vestibular channel of balance control differs fundamentally from the visual channel. Whereas the response to a visual perturbation can be suppressed if the subject has awareness that an upcoming disturbance is likely to be caused by an external agent rather than by self-motion, a similar assumption cannot be made concerning the vestibular system. The present experiment investigated whether postural responses evoked by a proprioceptive perturbation (vibration of the Achilles' tendon at 90 Hz for 2.2 s) are either automatic and immune to expectation (similarly to vestibular responses) or cognitively penetrable (similarly to visual responses). Subjects (n = 12) stood on a force platform while stimuli were delivered either by the subject himself (self-triggered condition) or by the experimenter. For the latter condition, the stimulus was delivered either without warning (unpredictable condition) or at a fixed interval (500 ms) following an auditory cue (precue condition). Results showed that the backward CoP displacement induced by vibration was delayed by approximately 500 ms in the expected and self-triggered conditions compared to the unexpected condition. However, once initiated, the velocity of the backward displacement was higher in the self-triggered condition as compared to the unexpected condition. After a period of 2.2 s of vibration, the amplitude of this backward CoP displacement was similar in the three experimental conditions. Therefore, although expectation appears to delay the upcoming of the main backward body sway, it does not appear to be able to weight the impact of the proprioceptive stimulation. This suggested that afferents provided by the different sensory channels involved in postural control are not similarly susceptible to high level processes such as expectation.