Neural mechanisms underlying the adaptive plasticity of human locomotion

当我们走路的时候，我们不需要去想我们的腿在做什么具体的动作。我们所要担心的是我们想要去哪里以及速度有多快。这可能是因为我们神经系统的一部分自主运作为我们产生了详细的行走运动。这样的运动控制器在日常生活中是快速和高效的，因为它减少了我们必须专注于行走的注意力。然而，当行走动作必须改变时，例如在疾病、受伤或新的环境需求之后（例如在船上行走，或者将来在火星上行走），我们不能总是适应新的情况。培训有时会有帮助，有时效率低下。为了适应，神经系统必须重新组织它在行走时指挥肌肉的方式，这种现象被称为运动可塑性。目前，我们还没有办法预测可塑性何时会发生。了解运动可塑性是如何发生的是非常重要的，如果我们希望有一天能够有效地训练宇航员在火星上安全行走，以及有行走问题的人恢复他们的行动能力。本研究项目提出了一种新颖的方法来研究运动可塑性。使用一种简单而有效的方法（通过机器人靴子在腿部施加外力的情况下行走），我们可以在实验室中重现适应行走所需的所有条件。将这种适应方法与现代运动学和神经生理学测试相结合，我们将在未来5年内解决神经系统在适应过程中如何重组的3个基本问题：1)适应所需的重要反馈信号是什么？2)运动可塑性的程度/极限是什么？3)如果进行训练，对神经系统的长期影响是什么？这是一个重要的研究项目，开启了对运动可塑性机制的研究，这是目前人们对运动的一个知之甚少的方面。这里获得的成果将对基础科学和卫生应用产生重大影响。

When we walk, we do not have to think about the detailed movements that our legs are making. All we have to worry about is where we want to go and how fast. It can be so because part of our nervous system that operates autonomously generates the detailed walking movement for us. Such a movement controller is fast and efficient in every day life, as it reduces the amount of attention we have to dedicate to walking.However, when walking movements have to be changed, such as after disease, injury or new environmental needs (for example walking on a boat or, in the future, on Mars), we can't always adapt to the new situation. Sometimes training will help, and sometimes it is inefficient. To adapt, the nervous system must reorganize the way it commands muscles during walking, a phenomenon called locomotor plasticity. At the moment, we have no way to predict when plasticity will occur or not. Understanding how locomotor plasticity occurs is extremely important if we want one day to be able to train effectively astronauts to walk safely on Mars, and people with walking problems to recover their mobility.The present research program proposes an original way to study locomotor plasticity. Using a simple and effective means (walking with an external force applied to the leg by a robotic boot), we can reproduce in the laboratory all the conditions required to adapt walking. Combining this method of adaptation to modern kinematic and neurophysiological testing, we will, over the next 5 years, address 3 fundamental questions on how the nervous system is reorganized during adaptation: 1) what are the important feedback signals needed to adapt? 2) what is the extent/limit of locomotor plasticity? and 3) if training is provided, what are the long-term effects on the nervous system?This is an important research program that opens the study of mechanisms of locomotor plasticity, an aspect of locomotion that is poorly understood at the moment. Results obtained here will have a major impact both in basic science and health applications.