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。

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.