US-German Collaboration: Testing Muscle Synergies in a Neuromechanical Rat Model for Nominal and Perturbed Locomotion

本项目重点研究在运动过程中导致动态稳定性的神经和生物力学原理。通过更好地了解哺乳动物的脊髓回路，可以改进影响平衡和协调的神经疾病(如脊髓损伤、中风、帕金森氏症)的医疗和诊断。神经机械模型还将激励改进辅助外骨骼的机械系统和控制器的设计，以确保人类的稳定性和机动性。例如，这种神经模型可以有效地控制人的肌肉，同时控制外骨骼的马达和人的完整系统。从这项工作中衍生出的控制系统还可以为自主腿机器人提供更大的机动性和适应未知地形的移动。这个项目还将涉及神经生物学、动物学、机械工程学和系统控制交叉领域的国际合作和跨学科教育和培训。为了更好地了解哺乳动物神经系统如何处理多感觉反馈以动态控制后腿的多个自由度，研究人员将：1)使用同步双平面X射线摄像、测力板和肌电记录来测量在不同环境(不同速度和灵活性的跑步机，以及在有洞、陷门和变化的地面条件等意外干扰的衬底上)运行的大鼠的运动学、地面反作用力和肌肉激活；2)利用这些数据扩展大鼠的矢状面生物力学模型和基于电导的神经模型，以产生三维的后腿自立行走；以及3)通过探索不同的组织模型并测试这些模型适应扰动和维持行走行为的动态控制的能力，来研究协同肌群的控制机制。

This project focuses on the neural and biomechanical principles that result in dynamic stability during locomotion. Medical treatments and diagnosis for neurological conditions that affect balance and coordination (e.g. spinal cord injury, stroke, Parkinson's) can be improved with a better understanding of mammalian spinal cord circuits. Neuromechanical models will also inspire improvements to the design of mechanical systems and controllers for assistive exoskeletons for human stability and mobility. For example, such a neural model could be effective for controlling a person's muscles in tandem with control of an exoskeleton's motors and with the person's intact systems. Control systems derived from this work may also provide autonomous legged robots greater mobility and adaptability for movement in unknown terrain. This project will also involve international collaboration and interdisciplinary education and training at the intersection of neurobiology, zoology, mechanical engineering, and system control.To better understand how the mammalian nervous system processes multi-sensory feedback for dynamic control of the many degrees of freedom in the rear legs, the investigators will: 1) Use simultaneous two-plane X-ray videography, force plates and EMG recordings to measure the kinematics, ground reaction forces, and muscle activations of rats running in various environments (treadmills of different speeds and flexibility, and on substrates with unexpected disturbances such as holes, a trapdoor and a shifting ground condition); 2) Use these data to expand a sagittal plane biomechanical model and conductance-based neural model of the rat to produce self-supporting walking of the hind legs in three dimensions; and 3) Investigate mechanisms for control of synergistic muscle groups by exploring different organizational models and testing the capability of these models for adapting to perturbations and maintaining dynamic control of walking behavior.A companion project is being funded by the Federal Ministry of Education and Research, Germany (BMBF).