Unveiling visuomotor control of bipedal stance, step by step
Unveiling visuomotor control of bipedal stance, step by step
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逐步揭示双足站立的视觉运动控制
DOI：
10.1113/jp272597
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Masani K
中科院分区：
文献类型：
--
作者：
Masani K
你正坐在车站的火车上。你旁边的另一列火车开始行驶。你可能会有一种错觉，以为自己正在移动。如果你当时站着，你的身体可能会因为这种错觉而倾斜。 Day 等人（2016）在本期《生理学杂志》上的一项研究揭示，这种对视野运动的姿势反应不是一个简单的反应，而是源于控制双足站立平衡的不同视觉运动通路的一系列两种反应。这一发现进一步证明了我们的大脑在调节姿势平衡时非常重视视觉形态——尽管它提供的信息不明确。视觉对姿势的影响非常大。大脑手头有三个主要的感觉信息来源，即视觉系统、前庭系统和体感系统。虽然所有可用的感官信息都被集成以控制姿势，但每个来源的贡献都根据给定情况灵活加权。在这些感觉系统中，我们的大脑在稳定人体时非常重视视觉信息。例如，当我们站在一个墙壁开始振动的房间里时，即使其他两个感觉源向大脑报告我们身体的静止状态，我们的身体也会随着墙壁的振动而开始振动。这种所谓的移动房间范式标志着三个感觉系统中视觉形态的独特性：也就是说，虽然其他两个系统被设计为始终报告任何形式的自我运动，但视觉系统不一定这样做。事实上，视觉场景中记录的运动可以与自身运动、外部物体的运动或两者相关联。因此，为了有效地使用视觉信息来控制姿势，大脑需要从视觉场景中记录的运动中提取有关自身运动的可靠信息。尽管存在这种背景要求，视觉在姿势控制中仍发挥着关键作用——大概是因为它是唯一可以评估头部相对于环境的方向的方式。在这一研究领域中，Day 等人（2016）通过应用离散视野运动而不是大多数相关研究中使用的连续振荡运动，将我们的理解向前推进了一步。令人惊讶且值得注意的是，利用离散视野运动的范例在该研究领域是新颖的。虽然本研究中发现的两种姿势反应可能也作为短暂现象出现在连续视野运动期间，但 Day 等人。能够用他们的方法隔离他们。他们发现在对离散视野运动的姿势反应中存在两个连续的组成部分：早期反应的潜伏期约为 0.19 秒，而晚期反应的潜伏期长得惊人，约为 0.7 秒。一方面，早期反应量化了对诱发视野运动的初始快速反应和基于进一步感觉信息的补偿反应。当视野运动更快时，这种早期反应更小，因为大脑可以更快地排除自我运动的存在。另一方面，在施加离散视野运动期间，后期反应继续使身体偏离垂直方向。戴等人。推测后期反应是由大脑对重力方向的错误估计引起的。这种解释借鉴了 Dichgans 等人 (1972)
You are sitting on a train at a station. Another train beside you starts moving. You may have an illusion that you are moving instead. If you are standing at that time, your body may tilt due to this illusion. A study by Day et al.(2016) in this issue of The Journal of Physiology unveils that this postural response to visual-field motion is not one simple reaction, but a series of two reactions stemming from different visuomotor pathways controlling bipedal standing balance. This finding further demonstrates the large emphasis our brain puts on the visual modality when regulating postural balance–and this in spite of the ambiguous information it provides. Vision is a very strong influencer of posture. The brain has three primary sources of sensory information at hand, ie the visual, vestibular and somatosensory systems. While all available sensory information is integrated for controlling posture, the contribution of each source is flexibly weighted dependent on a given situation. Among these sensory systems, our brain puts strong emphasis on visual information when stabilizing the human body. For example, when we stand in a room whose walls start oscillating, our bodies will start to oscillate following the walls’ oscillations even if the other two sensory sources report our bodies’ motionlessness to the brain. This so-called moving room paradigm signifies the uniqueness of the visual modality among the three sensory systems: that is, while the other two systems are designed to always report on any form of self-motion, the visual system does not necessarily do so. In fact, motion registered in the visual scene can be associated with self-motion, motion of external objects, or both. Thus, to effectively use visual information in controlling posture, the brain needs to extract reliable information on self-motion from the registered motion in the visual scene. In spite of this contextual requirement, vision plays a critical role in postural control–presumably due to the fact that it is the only modality that can evaluate head orientation with respect to the environment.Within this research domain, Day et al.(2016) moved our understanding one step forward by applying a discrete visual-field motion instead of a continuous oscillatory one that has been used in the majority of related studies. It is surprising and noteworthy that the paradigm of exploiting a discrete visual-field motion is novel in this research area. While the two postural responses found in this study are presumably also present during continuous visual-field motion as a transient phenomenon, Day et al. were able to isolate them with their approach. They discovered the existence of two consecutive components in the postural response to discrete visual-field motion: the early-phase response occurs with a latency of about 0.19 s, and the late-phase response with a surprisingly long latency of about 0.7 s. On the one hand, the early-phase response quantifies both the initial, fast reaction to the induced visual-field motion and the compensatory reaction based on further sensory information. This early-phase response is smaller when the visual-field motion is faster as the brain can more quickly rule out the presence of self-motion. On the other hand, the latephase response continues to deviate the body away from vertical during the applied discrete visual-field motion. Day et al. speculate that the late-phase response is caused by the brain’s erroneous estimate of gravity direction. This interpretation borrows from Dichgans et al.(1972) who
影响因子：
56.9
作者：
DICHGANS, J;HELD, R;YOUNG, LR
通讯作者：
YOUNG, LR