Background

For individuals who never achieve independent standing, rehabilitation is focused on trunk posture and balance control. Visual biofeedback has the potential to augment sitting balance training, however previous work in this area has been limited to standing.

Research question

To what extent do different types of visual biofeedback influence trunk sway in sitting?

Methods

Twelve healthy young adults sat on an articulating bench. During ‘sway referencing’ trials, the bench tilted up and down in proportion to trunk sway in the frontal plane. This paradigm increased difficulty of the balance task and required participants to rely on visual and vestibular cues. Participants were provided different visual biofeedback through a rotating needle-gage display. Trials lasted 165 s, were ordered randomly, and included either direct feedback (needle rotated in proportion to body sway), inverted feedback (needle rotated in the opposite direction of sway), time delayed feedback (0.5 s), random feedback, eyes closed, or control (eyes open with screen off). To explore the impact of inherent stability, trials were repeated with and without external trunk support.

Results

Body sway depended on feedback type. Specifically, direct and inverted feedback reduced root-mean-squared (RMS) sway the most, time delayed feedback had a smaller effect, and random visual feedback increased participants’ RMS sway compared to control. Frequency domain analyses demonstrated direct and inverted visual feedback reduced sway amplitude at the lower frequencies while having minimal effect on (or increasing) sway amplitude at higher frequencies.

Significance

This study extends previous work by showing that visual biofeedback can have powerful effects on sitting balance, even with external support. Results from the different types of feedback conditions further our understanding of how the brain interprets visual biofeedback. Frequency-based results were similar to previous studies using different modalities and suggest participants interpret biofeedback through sensory addition as opposed to sensory substitution.

中文翻译：

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视觉生物反馈和固有稳定性对躯干姿势控制的影响。

背景

对于从未获得独立站立能力的个人，康复的重点是躯干姿势和平衡控制。视觉生物反馈有可能增强坐姿平衡训练，但是该领域以前的工作仅限于站立。

研究问题

不同类型的视觉生物反馈在多大程度上影响着坐姿的摇摆？

方法

十二个健康的年轻成年人坐在铰接的长凳上。在“摇摆参考”试验中，工作台与额叶躯干在额面上的摇摆成比例地上下倾斜。这种范例增加了平衡任务的难度，并要求参与者依靠视觉和前庭提示。通过旋转的针规显示器为参与者提供了不同的视觉生物反馈。试验持续165 s，随机排序，包括直接反馈（与身体摇摆成正比地旋转针），反向反馈（与摇摆相反的方向对针旋转），延时反馈（0.5 s），随机反馈，闭眼或控制（眼睛睁开，屏幕关闭）。为了探索固有稳定性的影响，在有或没有外部后备箱支撑的情况下重复进行试验。

结果

身体摇摆取决于反馈类型。具体而言，与对照相比，直接和反向反馈最大程度地减少了均方根（RMS）摇摆，延时反馈的影响较小，而随机视觉反馈则增加了参与者的RMS摇摆。频域分析表明，直接和反向视觉反馈可降低较低频率下的摇摆幅度，而对较高频率下的摇摆幅度影响最小（或增加）。

意义

这项研究通过显示视觉生物反馈即使在外部支撑下也可以对坐姿平衡产生强大影响，从而扩展了以前的工作。来自不同类型反馈条件的结果进一步加深了我们对大脑如何解释视觉生物反馈的理解。基于频率的结果与以前使用不同方式的研究相似，建议参与者通过感觉增加而不是感觉替代来解释生物反馈。