Brain-body interactions during bipedalism

两足行走，包括直立站立、步态开始和步态，是人类物种最重要的成就之一，也是大多数日常生活活动的核心。今天，我们对两足动物运动控制的理解主要来自动物研究，强调脊髓中枢模式发生器的关键作用。然而，人类的两足行走是由皮层和脊髓网络之间复杂的动态相互作用造成的，其中皮层机制占主导地位。皮层振荡是运动任务中脑神经生理学的一个显著特征，在大脑功能中通过远程神经网络之间的同步交换信息起着重要作用。有趣的是，皮质振荡也与生物力学运动输出同步。事实上，在体力活动和摄动姿势任务期间，运动区域的皮层振荡和运动运动学以及肌肉协同作用之间存在显著的一致性。因此，皮质振荡直接介导人体运动的神经表征。本研究计划的长期目标是评估动态自然运动过程中皮质振荡和运动输出之间的耦合。为了实现这一目标，短期目标是开展一系列研究，采用一种结合神经科学和生物力学的创新方法来研究两足行走时的脑-体耦合。主要，我们将研究在直立，步态和步态开始期间的皮质运动学和皮质协同一致性。我们假设脑-体相互作用在两足行走的控制中起着关键作用，并期望：1)直立和步态时，感觉运动皮层θ带振荡分别与压力中心和质量中心运动（皮质运动学相干）表现出显著的一致性；2)初级运动皮层伽马带振荡分别在步态和步态启动过程中与肌肉协同（皮质协同相干）表现出显著的相干性；3)运动任务需求增加的实验条件会影响皮质-生物力学一致性的大小。参与者将配备脑电图帽、肌电图电极和反射性皮肤标记。反作用力将使用力平台或仪器跑步机记录。参与者将在正常和干扰的实验条件下站立、行走和开始行走，以增加运动任务的需求。神经影像学和生物力学的结合在加拿大是独一无二的。我们的神经生物力学方法将促进对两足动物皮层振荡机制的发现，并加速运动辅助设备创新技术的发展：脑机接口、动力神经假体和机器人外骨骼前馈控制。

Bipedalism, which includes standing upright, gait initiation, and gait, is one of the most important achievements of the Human species and is central to most daily-living activities. Today, our comprehension of motor control during bipedalism mostly comes from animal studies highlighting a key role of spinal cord central pattern generators. However, human bipedalism results from complex dynamic interactions between cortical and spinal networks with a dominance of cortical mechanisms. Cortical oscillations represent a salient feature of brain neurophysiology during motor tasks and play a major role in brain functions to exchange information between remote neural networks through their synchronization. Interestingly, cortical oscillations also synchronize with biomechanical movement outputs. Indeed, significant coherence has been evidenced between cortical oscillations from motor areas and movement kinematics as well as muscle synergies during manual activities and perturbation postural task, respectively. Consequently, cortical oscillations directly mediate neural representations of human motion. The long-term objective of this research program is to evaluate the coupling between cortical oscillations and movement outputs during dynamic natural motor actions. To achieve this objective, the short-term goals are to conduct a series of studies employing an innovative approach that combines neuroscience and biomechanics to investigate brain-body coupling during bipedalism. Mainly, we will investigate corticokinematic and corticosynergy coherence during standing upright, gait, and gait initiation. We hypothesize that brain-body interactions have a key role for the control of bipedalism and expect that: 1) sensorimotor cortex theta-band oscillations will show significant coherence with center of pressure and center of mass kinematics (corticokinematic coherence) during standing upright and gait, respectively; 2) primary motor cortex gamma-band oscillations will show significant coherence with muscle synergies (corticosynergy coherence) during gait and gait initiation, respectively; 3) experimental conditions requiring increased motor task demands will affect the magnitude of cortico-biomechanical coherence. Participants will be equipped with an electroencephalographic cap, electromyographic electrodes, and reflective skin markers. Reaction forces will be recorded using force platforms or an instrumented treadmill. Participants will stand upright, walk, and initiate walk under normal and perturbed experimental conditions to increase the demand of motor tasks. The combination of neuroimaging and biomechanics is unique in Canada. Our neuro-biomechanical approach will foster discoveries on cortical oscillatory mechanisms underlying bipedalism and hasten the development of innovative technologies for movement assistive devices: brain computer interfaces, powered neuro-prostheses, and feed-forward controls for robotic exoskeletons.