Department of Physical Therapy, Faculty of Medical Science, Fukuoka International University of Health and Welfare, Fukuoka, Japan.
Department of Intelligent Mechanical Systems Engineering, Kochi University of Technology, Kochi, Japan.
Gait Posture. 2024 Jan;107:177-181. doi: 10.1016/j.gaitpost.2023.09.014. Epub 2023 Oct 6.
The ability to stand with eyes closed on a sinusoidal translational moving platform may be affected by spatial orientation owing to vestibular input information. Moreover, changes in the frequency of the moving platform may affect the sensory reweighting through somatosensory and vestibular sensations. However, it is unclear whether noisy galvanic vestibular stimulation (nGVS), which activates vestibular-related brain regions, affects the stability of individuals standing on a platform moving at different frequencies.
Do vestibular stimulation by nGVS and changes in the frequency of translationally moving platforms affect the standing stability of individuals?
Thirty-one healthy young adult participants were provided both sham and nGVS interventions while they maintained a static standing position, with their eyes closed, on an anterior-posterior sinusoidal translation platform. The nGVS was adapted to an optimal intensity below the perceptual threshold (frequency band: 100-640 Hz), and the sham stimulus was adapted to 0 µA. The participants were randomly assessed for postural stability at 0.2, 0.6, and 1.2 Hz moving platform frequencies for 80 s each under both stimulus conditions. Postural stability was calculated as the root mean square (RMS) sway from head accelerations in the anteroposterior (AP) and mediolateral (ML) directions for 50 s between 20 and 70 s during the 80 s period, measured using an inertial sensor placed on the external occipital ridge.
nGVS significantly reduced the RMS sway of head acceleration in the AP direction compared with sham stimulation. Furthermore, nGVS significantly reduced RMS sway in the ML direction compared with sham stimulation at a 1.2 Hz moving platform oscillation.
These findings suggest that postural adjustment by the vestibular system influences head stability on a moving platform at specific sinusoidal translation frequencies, suggesting that nGVS may reduce head sway.
由于前庭输入信息，闭眼站在正弦平移运动平台上的能力可能会受到空间定向的影响。此外，运动平台频率的变化可能会通过躯体感觉和前庭感觉来影响感觉权重的重新分配。然而，尚不清楚激活与前庭相关的大脑区域的噪声电前庭刺激（nGVS）是否会影响在不同频率的平台上运动的个体的站立稳定性。
nGVS 刺激和翻译运动平台频率的变化是否会影响个体的站立稳定性？
31 名健康的年轻成年参与者在闭眼、静态站立的情况下，分别接受假刺激和 nGVS 干预，站在前后正弦平移平台上。nGVS 适应于低于感知阈值的最佳强度（频带：100-640 Hz），而假刺激适应于 0 µA。在两种刺激条件下，参与者在 0.2、0.6 和 1.2 Hz 运动平台频率下随机评估 80 s 的姿势稳定性，每个频率下 80 s 中分别评估 80 s。在 80 s 期间，从头部加速度在前后（AP）和左右（ML）方向上的 RMS 摆动计算姿势稳定性，在 20 到 70 s 之间使用放置在外部枕骨嵴上的惯性传感器测量 50 s。
与假刺激相比，nGVS 显著降低了 AP 方向上头部加速度的 RMS 摆动。此外，与假刺激相比，nGVS 在 1.2 Hz 运动平台振动时，ML 方向的 RMS 摆动也显著降低。
这些发现表明，前庭系统的姿势调整会影响特定正弦平移频率下运动平台上头部的稳定性，表明 nGVS 可能会减少头部摆动。
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