Control of human standing posture

我的NSERC资助的研究项目研究大脑如何控制肌肉力量和运动，特别是在疲劳和姿势控制的条件下，通过运动单元行为的研究。 运动单位是大脑发出的命令在肌肉中产生力量的手段。 保持直立是人类活动的基础。 站立平衡对于防止老年人福尔斯摔倒的破坏性后果至关重要。 小腿肌肉对于站立平衡是必不可少的，以前所有的小腿肌肉都被认为在站立时均匀地激活。 传统上，肌肉激活是用放置在肌肉中的两个表面电极或细线电极来测量的，但这些技术从局限于相对较小的肌肉区域（mm至cm）的运动单元收集信息。 我们将使用一种创新的方法来研究占据小腿肌肉不同区域的运动单位群体。 这是通过使用放置在整个肌肉上的20-24个非常小的电极（称为HDS-EMG）的网格来实现的。 使用这项新技术，我们将研究肌肉对平衡干扰的反应是否存在重要的区域差异。 我们将通过在受试者的臀部施加载荷来制造平衡障碍。 将在不同方向上施加不同大小的负载（使小腿肌肉疲劳和不疲劳），以根据平衡障碍的特征确定小腿肌肉是否在特定区域被激活。 将年轻健康受试者与老年受试者进行比较，以确定区域激活是否用于微调对老年人可能缺乏的平衡障碍的姿势反应。 最后，我们将探讨大脑区域的激活与肌肉中局部活动区域的关系，以确定大脑是否会影响平衡障碍期间肌肉激活的模式。 这些知识将促进我们对人体姿势控制的理解，并提供对老年人福尔斯跌倒的见解。

My NSERC-funded research program examines how the brain controls muscle force and movement, particularly under conditions of fatigue and postural control, through the study of motor unit behaviour. The motor unit is the means for the commands from the brain to create forces in the muscle. Maintenance of upright standing is fundamental to human mobility. Standing balance is of utmost importance to prevent the devastating consequences of falls in the aged. The calf muscles are essential for standing balance and previously all the calf muscles were thought to be activated uniformly in standing. Traditionally, muscle activation is measured with two surface electrodes or fine-wire electrodes placed in the muscle but these techniques collect information from motor units confined to a relatively small muscle region (mm to cm). We will use an innovative way of studying populations of motor units occupying different regions of the calf muscles. This is achieved by using grids of 20-24 very small electrodes (called HDS-EMG) placed over the entire muscle. Using this novel technology, we will examine whether there are important regional differences in how the muscles must react to balance disturbances. We will create balance disturbances by applying loads at the subjects' hips. Loads of varying magnitude will be applied in different directions (with and without fatiguing the calf muscles) to determine if the calf muscles are activated in specific regions based on the characteristics of the balance disturbance. Young healthy subjects will be compared to elderly subjects to determine if the regional activation serves to fine tune the postural response to the balance disturbance which may be lacking in the elderly. Finally, we will explore the relationship of activation of areas of the brain with areas of localized activity in the muscle to determine if the brain influences the pattern of muscle activation during balance disturbances. This knowledge will advance our understanding of human postural control and provide insight on falls in the elderly.