CRCNS US-German Research Proposal: An Experimental-Computational Approach to the Integration of Subtasks with a Spinal Reflex Model of Locomotion

两足站立的进化发展使双手从运动中解放出来，这被认为是人类和我们最亲近的亲戚之间的根本区别。但是两条腿的运动就不那么稳定了。工程设备通常通过具有较宽的支撑基础或将其大部分重量集中在较低的位置来解决稳定性问题。相比之下，人类的身体在进化过程中，大部分的质量集中在躯干的上部，这使得它天生不稳定，容易摔倒。这种“机械不稳定”的设计是由一个复杂的神经控制系统补充的，该系统可以主动稳定身体。然而，这种神经控制器如何解决保持直立姿态的复杂控制问题，同时避开障碍物和在不同地形上导航的细节，还没有得到很好的理解。目前缺乏知识是一系列相关领域的限制因素，从智能假肢装置的开发，到可以在复杂环境中导航的类人机器人，以及因神经系统疾病或损伤而行动不便的人的康复方法。该项目将使用实验和计算相结合的方法来确定人类在行走、绕过障碍物或调整速度时如何控制直立平衡。虽然对人类运动控制的研究已经建立了神经系统如何产生目标相关运动的基本原理，但尚不清楚不同的目标如何整合成一个同时处理所有任务的连贯模式。该项目将研究人类如何将行走时的平衡控制与功能性任务（如避开障碍物、调整速度和行走方向）结合起来。该项目的实验部分将使用前庭系统的电刺激来探测神经控制器如何对直立姿势的感知威胁做出反应，以及这些反应在步态周期的不同点上如何变化。虚拟现实将被用于从障碍中施加约束，并研究人类如何将这些功能性任务与平衡控制结合起来。这个项目的理论部分将建立一个神经种群调节平衡的场动力学模型，并建立运动装置的高维配置空间如何用于将多个低维任务整合到一个连贯的运动计划中的原则。这种神经控制的动态场模型将与人类运动的生物力学和脊柱神经生理学的现有模型相结合，以生成人类行走模式的预测模拟。利用相互信息的理论和实验实现运动、平衡、行走和避障的神经解释将为运动的神经生理基础提供一个功能框架。该功能框架将考虑到日常生活活动的各种需求，促进智能机器人和设备的发展，并说明运动稳定性如何随着年龄和神经系统疾病而恶化。伙伴项目由德国联邦教育和研究部（BMBF）资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The evolutionary development of bipedal stance, which freed the hands from locomotion, is considered a fundamental distinction between humans and our closest relatives. But two-legged locomotion is far less stable. Engineered devices frequently solve the stability problem by having a wide base of support, or concentrating the bulk of its weight lower down. In contrast, the human body has evolved with most of its mass concentrated higher up in the trunk, making it inherently unstable and prone to falls. This "mechanically unstable" design is complemented by a sophisticated neural control system that actively stabilizes the body. However, the details of how this neural controller solves the complex control problem of maintaining upright stance, while simultaneously avoiding obstacles and navigating varied terrain, are not well understood. This current lack of knowledge is a limiting factor in a range of related fields, from the development of intelligent prosthetic devices, to humanoid robots that can navigate complex environments, as well as rehabilitative methods for those with poor mobility due to neurological disease or injury. This project will use a combined experimental and computational approach to determine how humans control upright balance during walking, while navigating around obstacles or adjusting speed.While research in human motor control has established basic principles about how the nervous system generates goal-related movements, it is unknown how different goals are integrated into a coherent pattern that addresses all tasks simultaneously. This project will study how humans combine the control of balance during walking with functional tasks such as avoiding obstacles and modifying speed and walking direction. The experimental component of this project will use electric stimulation of the vestibular system to probe how the neural controller reacts to sensed threats to upright posture and how these responses change at different points of the gait cycle. Virtual reality will be used to impose constraints from obstacles and study how humans integrate such functional tasks with balance control. The theoretical component of this project will develop a model of the field dynamics of neural populations regulating balance and establish principles for how the high-dimensional configuration space of the motor apparatus can be used to integrate multiple low-dimensional tasks into a coherent movement plan. This dynamic field model of neural control will be combined with an existing model of the biomechanics and spinal neurophysiology of human locomotion to generate predictive simulations of human walking patterns. Achieving a neural account of locomotion, balance, stepping, and obstacle avoidance using mutually informative theory and experiment will provide a functional framework for the neurophysiological basis of locomotion. This functional framework will take into account the varied demands of daily life activities, foster development of intelligent robots and devices, and illustrate how stability of locomotion deteriorates with aging and neurological disease.Companion project is being funded by the Federal Ministry of Education and Research, Germany (BMBF).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.