Dynamic transformation of vestibular signals for orientation.
Dynamic transformation of vestibular signals for orientation.
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用于定向的前庭信号的动态转换。
DOI：
10.1007/s00221-012-3250-1
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发表时间：
2012
影响因子：
2
通讯作者：
Osler CJ
中科院分区：
文献类型：
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作者：
Osler CJ
相同的前庭传入反馈模式可能意味着失去平衡或身体方向的改变，这取决于最初的头部姿势。为了解决这种模糊性并产生适当的运动反应，CNS必须将前庭信息从以头部为中心的参考系转换为相关的运动坐标。但如果参考系是连续移动的呢？在这里，我们要问的是，在头部姿势的自愿变化过程中，这种神经转换过程是否会不断更新。前庭电刺激（GVS）被用来诱导头部滚动运动的感觉被蒙上眼睛的受试者在现场进行。当头部方向固定时，这会导致无意识的转动行为，在颈部屈曲时最大，在头部水平时最小，在颈部伸展时反向。受试者，然后被要求产生一个连续的自愿改变头俯仰，而GVS的应用。当颈部从完全屈曲到伸展时，旋转速度被连续调制，甚至反向，反映了在头部固定条件下观察到的模式。因此，一个相同的前庭输入导致运动输出，这是动态调制的头部俯仰的变化。然而，反应幅度显着降低，表明可能抑制前庭输入在自愿头部运动。尽管如此，这些结果表明，中枢神经系统不断重新解释前庭外传入占正在进行的自愿改变头部姿势。这可以解释为什么头部可以自由移动而不会失去平衡感和方向感。
The same pattern of vestibular afferent feedback may signify a loss of balance or a change in body orientation, depending upon the initial head posture. To resolve this ambiguity and generate an appropriate motor response, the CNS must transform vestibular information from a head-centred reference frame into relevant motor coordinates. But what if the reference frame is continuously moving? Here, we ask if this neural transformation process is continuously updated during a voluntary change in head posture. Galvanic vestibular stimulation (GVS) was used to induce a sensation of head roll motion in blindfolded subjects marching on the spot. When head orientation was fixed, this caused unconscious turning behaviour that was maximal during neck flexion, minimal with the head level and reversed direction with neck extension. Subjects were then asked to produce a continuous voluntary change in head pitch, while GVS was applied. As the neck moved from full flexion into extension, turn velocity was continuously modulated and even reversed direction, reflecting the pattern observed during the head-fixed condition. Hence, an identical vestibular input resulted in motor output which was dynamically modulated by changes in head pitch. However, response magnitude was significantly reduced, suggesting possible suppression of vestibular input during voluntary head movement. Nevertheless, these results show that the CNS continuously reinterprets vestibular exafference to account for ongoing voluntary changes in head posture. This may explain why the head can be moved freely without losing the sense of balance and orientation.