Lu Jiani, Xie Haoyu, Chien Jung Hung
Department of Rehabilitation, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Department of Health and Rehabilitation Science, College of Allied Health Professions, University of Nebraska Medical Center, Omaha, NE, United States.
Front Hum Neurosci. 2022 Jun 27;16:896221. doi: 10.3389/fnhum.2022.896221. eCollection 2022.
The vestibular system is critical for human locomotion. Any deteriorated vestibular system leads to gait instability. In the past decades, these alternations in gait patterns have been majorly measured by the spatial-temporal gait parameters and respective variabilities. However, measuring gait characteristics cannot capture the full aspect of motor controls. Thus, to further understand the effects of deteriorated vestibular system on gait performance, additional measurement needs to be taken into consideration. This study proposed using the margin of stability (MOS) to identify the patterns of dynamic control under different types of mastoid vibrations in walking. This study hypothesized that (1) using the MOS method could facilitate the understanding of another aspect of motor control induced by different types of mastoid vibrations, and (2) applying the mastoid vibrations could induce the asymmetric MOS. Twenty healthy young adults were recruited. Two electromechanical vibrotactile transducers were placed on the bilateral mastoid process to apply different types of vestibular vibrations (bilateral, unilateral, and no vibration). A motion capture system with eight cameras was used to measure the MOSap (margin of stability in the anterior-posterior direction), MOSml (margin of stability in the medial-lateral direction), and respective variabilities. The results were in line with the hypotheses that both bilateral and unilateral mastoid vibrations significantly increased MOSap ( = 0.036, < 0.001), MOSml ( = 0.012, < 0.001), and respective variabilities = 0.001, < 0.001; = 0.001, < 0.01 when compared to the no vibration condition. Also, significantly larger MOSml ( = 0.001), MOSml variability ( < 0.023), MOSap ( < 0.001), and MOSap variability ( = 0.002) were observed under the unilateral vibration condition than that observed under the bilateral vibration condition. The above-mentioned result found that different types of mastoid vibrations affected the MOS differently, suggesting different patterns of control mechanisms under different sensory-conflicted situations. Besides, a significant difference between the dominant and non-dominant legs was observed in MOSml. Moreover, applying the unilateral mastoid vibrations induced a greater symmetric index of MOSml, suggesting that more active control in balance was needed in the medial-lateral than in the anterior-posterior direction.
前庭系统对人类运动至关重要。任何前庭系统的退化都会导致步态不稳。在过去几十年中，步态模式的这些变化主要通过时空步态参数及其各自的变异性来衡量。然而，测量步态特征并不能全面反映运动控制情况。因此，为了进一步了解退化的前庭系统对步态表现的影响，需要考虑额外的测量方法。本研究提出使用稳定裕度（MOS）来识别步行时不同类型乳突振动下的动态控制模式。本研究假设：（1）使用MOS方法有助于理解不同类型乳突振动引起的运动控制的另一个方面；（2）施加乳突振动会诱发不对称的MOS。招募了20名健康的年轻成年人。将两个机电式振动触觉换能器放置在双侧乳突上，以施加不同类型的前庭振动（双侧、单侧和无振动）。使用一个配备八个摄像头的运动捕捉系统来测量前后方向的稳定裕度（MOSap）、内外侧方向的稳定裕度（MOSml）及其各自的变异性。结果与假设一致，即与无振动条件相比，双侧和单侧乳突振动均显著增加了MOSap（P = 0.036，P < 0.001）、MOSml（P = 0.012，P < 0.001）及其各自的变异性（P = 0.001，P < 0.001；P = 0.001，P < 0.01）。此外，与双侧振动条件相比，单侧振动条件下观察到显著更大的MOSml（P = 0.001）、MOSml变异性（P < 0.023）、MOSap（P < 0.001）和MOSap变异性（P = 0.002）。上述结果表明，不同类型的乳突振动对MOS的影响不同，这表明在不同的感觉冲突情况下存在不同的控制机制模式。此外，在MOSml方面，优势腿和非优势腿之间存在显著差异。而且，施加单侧乳突振动会诱发更大的MOSml对称指数，这表明在内外侧方向上比在前后方向上需要更积极的平衡控制。
