Visual and Vestibular Inputs Affect Muscle Synergies Responsible for Body Extension and Stabilization in Sit-to-Stand Motion
Visual and Vestibular Inputs Affect Muscle Synergies Responsible for Body Extension and Stabilization in Sit-to-Stand Motion
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DOI：
10.3389/fnins.2018.01042
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发表时间：
2019-01-15
影响因子：
4.3
通讯作者：
Asama, Hajime
中科院分区：
文献类型：
--
作者：
Yoshida, Kazunori;An, Qi;Asama, Hajime
坐立运动是日常生活中常见的运动，了解坐立运动的机理具有重要意义。我们以前的研究表明，四个肌肉协同作用可以表征坐立运动，他们有特定的角色，如上身屈曲，从椅子上站起来，身体伸展和姿势稳定。这些协同作用的时变权重被改变以实现自适应运动。然而，感觉输入和肌肉协同作用的激活之间的关系并不完全清楚。在本文中，我们的目的是澄清前庭和视觉输入如何影响坐立运动中的肌肉协同作用。为了解决这个问题，我们进行了如下实验。肌肉活动，身体运动学和地面反作用力进行了测量，坐站运动在三种不同的条件下：控制，视觉干扰，前庭干扰条件。在控制条件下，参与者站立，不受任何干预。在视觉干扰条件下，受试者戴上凸透镜眼镜，在暗室中进行从坐到站的运动。在前庭障碍条件下，进行冷热试验。使用非负矩阵分解计算这三种条件下的肌肉协同作用。我们研究了在每种条件下是否采用相同的四种肌肉协同作用，并确定了随时间变化的系数的变化。这些实验是在7名健康的年轻参与者身上进行的。结果发现，四个肌肉协同作用可以解释在坐到站的动作在三个条件下的肌肉活动。然而，有显着差异的时变权重系数。当视觉输入受到干扰时，肌肉协同作用的幅度较大，主要在坐立运动的最后姿势稳定阶段激活。在前庭干扰条件下，观察到更长的激活协同作用，扩展整个身体，并导致姿势稳定。结果表明，在人类坐到站的运动，视觉输入有较少的贡献，改变或正确的肌肉协同激活，直到最后一个阶段。另一方面，臀部离开后肌肉协同作用的持续时间延长，以适应前庭干扰下垂直感下降的不稳定状态。
The sit-to-stand motion is a common movement in daily life and understanding the mechanism of the sit-to-stand motion is important. Our previous study shows that four muscle synergies can characterize the sit-to-stand motion, and they have specific roles, such as upper body flexion, rising from a chair, body extension, and posture stabilization. The time-varying weight of these synergies are changed to achieve adaptive movement. However, the relationship between sensory input and the activation of the muscle synergies is not completely understood. In this paper, we aim to clarify how vestibular and visual inputs affect the muscle synergy in sit-to-stand motion. To address this, we conducted experiments as follows. Muscle activity, body kinematics, and ground reaction force were measured for the sit-to-stand motion under three different conditions: control, visual-disturbance, and vestibular-disturbance conditions. Under the control condition, the participants stood without any intervention. Under the visual-disturbance condition, the participants wore convex lens glasses and performed the sit-to-stand motion in a dark room. Under the vestibular-disturbance condition, a caloric test was performed. Muscle synergies were calculated for these three conditions using non-negative matrix factorization. We examined whether the same four muscle synergies were employed under each condition, and the changes in the time-varying coefficients were determined. These experiments were conducted on seven healthy, young participants. It was found that four muscle synergies could explain the muscle activity in the sit-to-stand motion under the three conditions. However, there were significant differences in the time-varying weight coefficients. When the visual input was disturbed, a larger amplitude was found for the muscle synergy that activated mostly in the final posture stabilization phase of the sit-to-stand motion. Under vestibular-disturbance condition, a longer activation was observed for the synergies that extended the entire body and led to posture stabilization. The results implied that during human sit-to-stand motion, visual input has less contribution to alter or correct activation of muscle synergies until the last phase. On the other hand, duration of muscle synergies after the buttocks leave are prolonged in order to adapt to the unstable condition in which sense of verticality is decreased under vestibular-disturbance.