Vision plays a central role in maintaining balance. When humans perceive their body as moving, they trigger counter movements. This results in body sway, which has typically been investigated by measuring the body's center of pressure (COP). Here, we aimed to induce visually evoked postural responses (VEPR) by simulating self-motion in virtual reality (VR) using a sinusoidally oscillating "moving room" paradigm. Ten healthy subjects participated in the experiment. Stimulation consisted of a 3D-cloud of random dots, presented through a VR headset, which oscillated sinusoidally in the anterior-posterior direction at different frequencies. We used a force platform to measure subjects' COP over time and quantified the resulting trajectory by wavelet analyses including inter-trial phase coherence (ITPC). Subjects exhibited significant coupling of their COP to the respective stimulus. Even when spectral analysis of postural sway showed only small responses in the expected frequency bands (power), ITPC revealed an almost constant strength of coupling to the stimulus within but also across subjects and presented frequencies. Remarkably, ITPC even revealed a strong phase coupling to stimulation at 1.5 Hz, which exceeds the frequency range that has generally been attributed to the coupling of human postural sway to an oscillatory visual scenery. These findings suggest phase-locking to be an essential feature of visuomotor control.

中文翻译：

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虚拟现实中视觉诱发的姿势反应的试验间阶段相干性。

视觉在保持平衡中起着核心作用。当人们感知到自己的身体在运动时，他们会触发反向运动。这会导致人体摇摆，通常通过测量人体的压力中心（COP）进行调查。在这里，我们旨在通过使用正弦振荡的“运动室”范例在虚拟现实（VR）中模拟自我运动来诱发视觉诱发的姿势反应（VEPR）。十名健康受试者参加了实验。刺激由通过VR头显呈现的随机点的3D云组成，这些头点在前后方向上以不同频率呈正弦振动。我们使用了一个测力平台来测量受试者在一段时间内的COP，并通过小波分析（包括试验间相干性（ITPC））来量化所得轨迹。受试者表现出其COP与各自刺激的显着耦合。即使姿势摇摆的频谱分析在预期的频带（功率）中仅显示出很小的响应，ITPC仍显示出与受试者内部以及所呈现频率之间的刺激耦合几乎恒定的强度。值得注意的是，ITPC甚至显示出与1.5 Hz刺激的强烈相位耦合，该频率超出了通常归因于人体姿势摇摆与振荡视觉风景耦合的频率范围。这些发现表明锁相是视觉运动控制的基本特征。ITPC揭示了与受试者内部以及各个受试者和所呈现频率之间的刺激耦合的几乎恒定的强度。值得注意的是，ITPC甚至显示出与1.5 Hz刺激的强相位耦合，该频率超出了通常归因于人类姿势摇摆与振荡视觉风景耦合的频率范围。这些发现表明锁相是视觉运动控制的基本特征。ITPC揭示了与受试者内部以及各个受试者和所呈现频率之间的刺激耦合的几乎恒定的强度。值得注意的是，ITPC甚至显示出与1.5 Hz刺激的强烈相位耦合，该频率超出了通常归因于人体姿势摇摆与振荡视觉风景耦合的频率范围。这些发现表明锁相是视觉运动控制的基本特征。