Neural mechanisms underlying the adaptive plasticity of human locomotion

当我们走路时，我们不必考虑我们的腿正在做的详细运动。我们要考虑的是我们要去哪里，要多快。之所以如此，是因为我们的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有效的，因为它减少了我们必须投入到步行中的注意力。但是，当步行运动必须改变时，例如疾病，受伤或新的环境需求（例如在船上行走或将来在火星上行走），我们不能总是适应新的情况。有时培训会有所帮助，有时效率低下。为了适应，神经系统必须重新组织它在行走过程中指挥肌肉的方式，这种现象称为运动可塑性。目前，我们无法预测可塑性何时发生。了解运动可塑性是如何发生的，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，那么这一点非常重要。本研究计划提出了一种研究运动可塑性的原创方法。使用一种简单而有效的方法（通过机器人靴子向腿部施加外力行走），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年内解决关于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)运动可塑性的范围/限度是什么？以及3）如果提供训练，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，这是目前对运动知之甚少的一个方面。这里获得的结果将在基础科学和健康应用中产生重大影响。

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.