School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada.
Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada.
J Neurophysiol. 2024 Aug 1;132(2):454-460. doi: 10.1152/jn.00075.2024. Epub 2024 Jul 3.
The relative contributions of proprioceptive, vestibular, and visual sensory cues to balance control change depending on their availability and reliability. This sensory reweighting is classically supported by nonlinear sway responses to increasing visual surround and/or surface tilt amplitudes. However, recent evidence indicates that visual cues are reweighted based on visual tilt velocity rather than tilt amplitude. Therefore, we designed a study to specifically test the hypothesized velocity dependence of reweighting while expanding on earlier findings for visual reweighting by testing proprioceptive reweighting for standing balance on a tilting surface. Twenty healthy young adults stood with their eyes closed on a toes-up/-down tilting platform. We designed four pseudorandom tilt sequences with either a slow (S) or a fast (F) tilt velocity and different peak-to-peak amplitudes. We used model-based interpretations of measured sway characteristics to estimate the proprioceptive sensory weight () within each trial. In addition, root-mean-square values of measured body center of mass sway amplitude (RMS) and velocity (RMSv) were calculated for each tilt sequence. , RMS, and RMSv values varied depending on the stimulus velocity, exhibiting large effects (all Cohen's >1.10). In contrast, we observed no significant differences across stimulus amplitudes for (Cohen's : 0.02-0.16) and, compared with the differences in velocity, there were much smaller changes in RMS and RMSv values (Cohen's : 0.05-0.91). These results confirmed the hypothesized velocity, rather than amplitude, dependence of sensory reweighting. This novel study examined the velocity dependence of sensory reweighting for human balance control using support surface tilt stimuli with independently varied amplitude and velocity. Estimates of the proprioceptive contribution to standing balance, derived from model-based interpretations of sway characteristics, showed greater sensitivity to changes in surface tilt velocity than surface tilt amplitude. These results support a velocity-based mechanism underlying sensory reweighting for human balance control.
本体感、前庭和视觉感觉线索对平衡控制的相对贡献取决于它们的可用性和可靠性。这种感觉重新加权通常由非线性摇摆反应来支持，即增加视觉环境和/或表面倾斜幅度。然而，最近的证据表明，视觉线索是根据视觉倾斜速度而不是倾斜幅度进行重新加权的。因此，我们设计了一项研究来专门测试重新加权的假设速度依赖性，同时通过测试在倾斜表面上站立平衡的本体感觉重新加权来扩展早期的视觉重新加权发现。二十名健康的年轻人闭着眼睛站在一个脚趾向上/向下倾斜的平台上。我们设计了四个伪随机倾斜序列，具有慢（S）或快（F）倾斜速度和不同的峰峰值。我们使用测量摇摆特征的基于模型的解释来估计每个试验中的本体感觉权重（）。此外，还为每个倾斜序列计算了测量身体质心摇摆幅度（RMS）和速度（RMSv）的均方根值。值、RMS 和 RMSv 值取决于刺激速度，表现出较大的影响（所有 Cohen's >1.10）。相比之下，我们没有观察到刺激幅度对 （Cohen's：0.02-0.16）和 有显著差异，与速度差异相比，RMS 和 RMSv 值的变化要小得多（Cohen's：0.05-0.91）。这些结果证实了感觉重新加权的假设速度依赖性，而不是振幅依赖性。这项新研究使用具有独立变化幅度和速度的支撑表面倾斜刺激，检查了人类平衡控制的感觉重新加权的速度依赖性。从摇摆特征的基于模型的解释中得出的对站立平衡的本体感觉贡献的估计值对表面倾斜速度的变化比表面倾斜幅度更敏感。这些结果支持了人类平衡控制中感觉重新加权的基于速度的机制。
