Massachusetts Institute of Technology, Cambridge, MA, USA.
J Neuroeng Rehabil. 2012 Aug 3;9:53. doi: 10.1186/1743-0003-9-53.
Multi-axis vibrotactile feedback has been shown to significantly reduce the root-mean-square (RMS) sway, elliptical fits to sway trajectory area, and the time spent outside of the no feedback zone in individuals with vestibular deficits during continuous multidirectional support surface perturbations. The purpose of this study was to examine the effect of multidirectional vibrotactile biofeedback on postural stability during discrete multidirectional support surface perturbations.
The vibrotactile biofeedback device mapped tilt estimates onto the torso using a 3-row by 16-column tactor array. The number of columns displayed was varied to determine the effect of spatial resolution upon subject response. Torso kinematics and center of pressure data were measured in six subjects with vestibular deficits. Transient and steady state postural responses with and without feedback were characterized in response to eight perturbation directions. Four feedback conditions in addition to the tactors off (no feedback) configuration were evaluated. Postural response data captured by both a force plate and an inertial measurement unit worn on the torso were partitioned into three distinct phases: ballistic, recovery, and steady state.
The results suggest that feedback has minimal effects during the ballistic phase (body's outbound trajectory in response to the perturbation), and the greatest effects during the recovery (return toward baseline) and steady state (post-recovery) phases. Specifically, feedback significantly decreases the time required for the body tilt to return to baseline values and significantly increases the velocity of the body's return to baseline values. Furthermore, feedback significantly decreases root mean square roll and pitch sway and significantly increases the amount of time spent in the no feedback zone. All four feedback conditions produced comparable performance improvements. Incidences of delayed and uncontrolled responses were significantly reduced with feedback while erroneous (sham) feedback resulted in poorer performance when compared with the no feedback condition.
The results show that among the displays evaluated in this study, no one tactor column configuration was optimal for standing tasks involving discrete surface perturbations. Feedback produced larger effects on body tilt versus center of pressure parameters. Furthermore, the subjects' performance worsened when erroneous feedback was provided, suggesting that vibrotactile stimulation applied to the torso is actively processed and acted upon rather than being responsible for simply triggering a stiffening response.
多轴振动触觉反馈已被证明可显著降低前庭功能障碍个体在连续多向支撑面扰动期间的均方根（RMS）摆动、摆动轨迹面积的椭圆拟合以及在无反馈区域外的时间。本研究的目的是研究多向振动触觉生物反馈对离散多向支撑面扰动期间姿势稳定性的影响。
振动触觉生物反馈设备使用 3 行 16 列的传感器阵列将倾斜估计映射到躯干上。显示的列数有所变化，以确定空间分辨率对受试者反应的影响。使用六名前庭功能障碍患者测量躯干运动学和中心压力数据。在有和没有反馈的情况下，分别对八个扰动方向的瞬态和稳态姿势反应进行了特征描述。除了关闭传感器（无反馈）配置之外，还评估了四种反馈条件。通过力板和穿在躯干上的惯性测量单元捕获的姿势反应数据被分为三个不同的阶段：弹道、恢复和稳态。
结果表明，反馈在弹道阶段（身体对扰动的向外运动）的影响最小，在恢复阶段（向基线的返回）和稳态阶段（恢复后）的影响最大。具体来说，反馈显著减少了身体倾斜恢复到基线值所需的时间，并显著增加了身体返回基线值的速度。此外，反馈还显著减少了 RMS 滚动和俯仰摆动，并显著增加了无反馈区域的时间。所有四种反馈条件都产生了类似的性能改进。与无反馈条件相比，反馈显著减少了延迟和失控反应的发生率，而错误（虚假）反馈则导致性能下降。
结果表明，在所评估的显示中，没有一种传感器列配置对于涉及离散表面扰动的站立任务是最佳的。反馈对身体倾斜的影响大于对中心压力参数的影响。此外，当提供错误的反馈时，受试者的表现会恶化，这表明应用于躯干的振动触觉刺激是被主动处理和作用的，而不是仅仅触发僵硬反应。
