Department of Neurophysics, University of Marburg, Marburg, Germany; Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus-Liebig-University, Gießen, Germany.
Department of Neurophysics, University of Marburg, Marburg, Germany; Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus-Liebig-University, Gießen, Germany.
Gait Posture. 2021 May;86:132-138. doi: 10.1016/j.gaitpost.2021.03.010. Epub 2021 Mar 8.
It has been shown that humans adapt their postural sway to oscillatory, visually simulated self-motion. However, little is still known about the way individual body segments contribute to this adjustment of body sway and how this contribution varies with different environmental conditions.
How do the centre of pressure (COP) and individual body segments phase-lock to a sinusoidal visual drive depending on the frequency of stimulation?
In this study, we introduce phase coupling as a method for assessing full body motion in response to visual stimuli presented in virtual reality (VR). 12 participants (mean age: 31 ± 9 years) stood inside a virtual tunnel which oscillated sinusoidally in the anterior-posterior direction at a frequency of 0.2 Hz, 0.8 Hz or 1.2 Hz. Primary outcome measures were the trajectories of their COP as well as of 25 body segments obtained by a motion tracking system.
Subjects significantly coupled the phase of their COP and body segments to the visual drive. Our analysis yielded significant phase coupling of the COP to the stimulus for all tested frequencies. The phase coupling of body segments revealed a shift in postural response as a function of frequency. At the low frequency of 0.2 Hz, we found strong and significant phase coupling homogeneously distributed across the body. At the higher frequencies of 0.8 Hz and 1.2 Hz, however, overall phase coupling became weaker and was centred around the lower torso and hip segments.
Information on how the visual percept of self-motion affects balance control is crucial for understanding visuomotor processing in health and disease. Our setup and methods constitute a reliable tool for assessing perturbed balance control, which can be utilized in future clinical trials.
已经证明，人类会根据视觉模拟的自身运动的摆动来调整姿势。然而，对于个体身体部位如何有助于调整身体摆动以及这种贡献如何随不同的环境条件而变化，我们仍然知之甚少。
根据刺激的频率，人体重心（COP）和各个身体部位如何与正弦视觉驱动同步锁定？
在这项研究中，我们引入了相位耦合作为一种评估人体对虚拟现实（VR）中呈现的视觉刺激做出反应的整体运动的方法。12 名参与者（平均年龄：31±9 岁）站在一个虚拟隧道内，该隧道以 0.2 Hz、0.8 Hz 或 1.2 Hz 的频率在前后方向上进行正弦摆动。主要的测量指标是他们的 COP 轨迹以及由运动跟踪系统获得的 25 个身体部位的轨迹。
受试者显著地将 COP 和身体部位的相位与视觉驱动相耦合。我们的分析得出，COP 与测试的所有频率的刺激都存在显著的相位耦合。身体部位的相位耦合揭示了一种随频率变化的姿势反应的转变。在 0.2 Hz 的低频下，我们发现了全身均匀分布的强而显著的 COP 相位耦合。然而，在 0.8 Hz 和 1.2 Hz 的较高频率下，整体相位耦合变得较弱，并且集中在较低的躯干和臀部部位。
了解自身运动的视觉感知如何影响平衡控制对于理解健康和疾病中的视动处理至关重要。我们的设置和方法构成了评估平衡控制失调的可靠工具，可用于未来的临床试验。
