Introduction: The study of motor responses induced by electrical vestibular stimulation (EVS) may help clarify the role of the vestibular system in postural control. Although back muscles have an important role in postural control, their EVS-induced motor responses were rarely studied. Moreover, etthe effects of EVS parameters, head position and vision on EVS-induced back muscles responses remain little explored. Objectives: To explore the effects of EVS parameters, head position, and vision on lumbar erector spinae muscles EVS-induced responses. Design: Exploratory, cross-soectional study Materials and methods: Ten healthy participants were recruited. Three head positions (right, left and no head rotation), 4 intensities (2, 3, 4, 5 mA) and 4 EVS durations (5, 20, 100, 200 ms) were tested in sitting position with eyes open or closed. EVS usually induced a body sway toward the anode (placed on the right mastoid). EMG activity of the right lumbar erector spinae was recorded. Variables of interest were amplitude, occurrence, and latency of the EVS-induced modulation of the EMG activity. Results: The short-latency response was inhibitory and the medium-latency response was excitatory. Increased EVS current intensity augmented the occurrence and the amplitude of the short- and medium-latency responses (more inhibition and more excitation, respectively). EVS duration influenced the medium-latency response differently depending on the position of the head. Right head rotation produced larger responses amplitude and occurrence than left head rotation. Opposite head rotation (left vs. right) did not induce a reversal of the short- and medium-latency responses (i.e., the inhibition did not become an excitation), as typically reported in lower legs muscles. The eyes open condition did not modulate muscle responses. Conclusions: Modulation of EVS parameters (current intensity and duration of EVS) affects the amplitude and occurrence of the lumbar erector spinae responses. In contrast, vision did not influence the responses, suggesting its minimal contribution to vestibulomotor control in sitting. The lack of response reversal in sagittal plane may reflect the biomechanical role of lumbar erector spinae to fine-tune the lumbar lordosis during the induced body sway instead. This hypothesis remains to be further tested.

中文翻译：

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坐着的参与者前庭电刺激引起的腰竖脊肌的运动反应

介绍：对前庭电刺激 (EVS) 诱发的运动反应的研究可能有助于阐明前庭系统在姿势控制中的作用。尽管背部肌肉在姿势控制中具有重要作用，但很少研究它们的 EVS 引起的运动反应。此外，EVS 参数、头部位置和视力对 EVS 诱导的背部肌肉反应的影响仍然很少被探索。目的：探讨 EVS 参数、头部位置和视力对腰椎竖脊肌 EVS 诱导反应的影响。设计：探索性、跨部门研究 材料和方法：招募了 10 名健康参与者。在睁眼或闭眼的坐姿下测试了三种头部位置（右、左和无头部旋转）、4 种强度（2、3、4、5 mA）和 4 种 EVS 持续时间（5、20、100、200 毫秒）。EVS 通常会导致身体向阳极（放置在右侧乳突上）摆动。记录右腰竖脊肌的肌电图活动。感兴趣的变量是 EVS 诱导的 EMG 活动调制的幅度、发生和潜伏期。结果：短延迟反应为抑制性，中延迟反应为兴奋性。增加的 EVS 电流强度增加了短和中延迟反应的发生和幅度（分别为更多的抑制和更多的兴奋）。EVS 持续时间对中等延迟响应的影响取决于头部的位置。右头部旋转产生比左头部旋转更大的反应幅度和发生率。相反的头部旋转（左与右）不会引起短和中延迟反应的逆转（即，抑制没有变成兴奋），正如在小腿肌肉中通常报道的那样。睁眼状态不会调节肌肉反应。结论：EVS 参数（EVS 的电流强度和持续时间）的调节影响腰部竖脊肌反应的幅度和发生。相比之下，视觉不影响反应，这表明它对坐着时的前庭运动控制的贡献很小。矢状面缺乏反应逆转可能反映了腰椎竖脊肌在诱导身体摆动期间微调腰椎前凸的生物力学作用。这个假设还有待进一步检验。EVS 参数（EVS 的电流强度和持续时间）的调制影响腰部竖脊肌反应的幅度和发生。相比之下，视觉不影响反应，这表明它对坐着时的前庭运动控制的贡献很小。矢状面缺乏反应逆转可能反映了腰椎竖脊肌在诱导身体摆动期间微调腰椎前凸的生物力学作用。这个假设还有待进一步检验。EVS 参数（EVS 的电流强度和持续时间）的调制影响腰部竖脊肌反应的幅度和发生。相比之下，视觉不影响反应，这表明它对坐着时的前庭运动控制的贡献很小。矢状面缺乏反应逆转可能反映了腰椎竖脊肌在诱导身体摆动期间微调腰椎前凸的生物力学作用。这个假设还有待进一步检验。矢状面缺乏反应逆转可能反映了腰椎竖脊肌在诱导身体摆动期间微调腰椎前凸的生物力学作用。这个假设还有待进一步检验。矢状面缺乏反应逆转可能反映了腰椎竖脊肌在诱导身体摆动期间微调腰椎前凸的生物力学作用。这个假设还有待进一步检验。