Molkov Yaroslav I, Yu Guoning, Ausborn Jessica, Bouvier Julien, Danner Simon M, Rybak Ilya A
Department of Mathematics and Statistics, Georgia State University, Atlanta, GA 30303, USA.
Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA.
R Soc Open Sci. 2024 Aug 21;11(8):240207. doi: 10.1098/rsos.240207. eCollection 2024 Aug.
Locomotion is a complex process involving specific interactions between the central neural controller and the mechanical components of the system. The basic rhythmic activity generated by locomotor circuits in the spinal cord defines rhythmic limb movements and their central coordination. The operation of these circuits is modulated by sensory feedback from the limbs providing information about the state of the limbs and the body. However, the specific role and contribution of central interactions and sensory feedback in the control of locomotor gait and posture remain poorly understood. We use biomechanical data on quadrupedal locomotion in mice and recent findings on the organization of neural interactions within the spinal locomotor circuitry to create and analyse a tractable mathematical model of mouse locomotion. The model includes a simplified mechanical model of the mouse body with four limbs and a central controller composed of four rhythm generators, each operating as a state machine controlling the state of one limb. Feedback signals characterize the load and extension of each limb as well as postural stability (balance). We systematically investigate and compare several model versions and compare their behaviour to existing experimental data on mouse locomotion. Our results highlight the specific roles of sensory feedback and some central propriospinal interactions between circuits controlling fore and hind limbs for speed-dependent gait expression. Our models suggest that postural imbalance feedback may be critically involved in the control of swing-to-stance transitions in each limb and the stabilization of walking direction.
运动是一个复杂的过程，涉及中枢神经控制器与系统机械部件之间的特定相互作用。脊髓中运动回路产生的基本节律活动定义了节律性肢体运动及其中枢协调。这些回路的运作受到来自肢体的感觉反馈的调节，这些反馈提供了有关肢体和身体状态的信息。然而，中枢相互作用和感觉反馈在控制运动步态和姿势方面的具体作用和贡献仍知之甚少。我们利用小鼠四足运动的生物力学数据以及脊髓运动回路中神经相互作用组织的最新研究结果，创建并分析了一个易于处理的小鼠运动数学模型。该模型包括一个具有四肢的小鼠身体简化机械模型和一个由四个节律发生器组成的中央控制器，每个节律发生器作为一个状态机控制一个肢体的状态。反馈信号表征每个肢体的负荷和伸展以及姿势稳定性（平衡）。我们系统地研究和比较了几个模型版本，并将它们的行为与现有的小鼠运动实验数据进行比较。我们的结果突出了感觉反馈以及控制前肢和后肢的回路之间一些中枢脊髓固有相互作用在速度依赖性步态表达中的具体作用。我们的模型表明，姿势不平衡反馈可能在控制每个肢体的摆动到站立过渡以及行走方向的稳定中起关键作用。
