Motor control of an insect leg during level and incline walking
Motor control of an insect leg during level and incline walking
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DOI：
10.1242/jeb.188748
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发表时间：
2019-04-01
影响因子：
2.8
通讯作者：
Schmitz, Josef
中科院分区：
文献类型：
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作者：
Dallmann, Chris J.;Duerr, Volker;Schmitz, Josef
在行走过程中，腿部运动系统必须不断地适应机械条件的变化，例如地面的倾斜度。为了理解潜在的控制，重要的是要知道腿部肌肉活动的变化如何与腿部运动学（运动）和腿部动力学（力，扭矩）相关。在这里，我们研究了这些参数在后腿的棍子昆虫（Carausius morosus）在水平和上坡/下坡（+/- 45度）行走，使用组合的肌电图，三维运动捕捉和地面反作用力测量。我们发现，一些运动学参数，包括腿关节角度和身体高度不同的步行条件。然而，运动学与动力学相比变化不大：在上坡行走期间，胸髋关节（腿前伸/回缩）和股骨胫骨关节（腿屈曲/伸展）处的水平腿力和扭矩往往更强，而在下坡行走期间，其符号相反。在胸髋关节，不同的机械需求通过调整拮抗肌活动的时间和幅度来满足。调整主要发生在腿触地后的前半站姿。当昆虫从水平行走过渡到倾斜行走时，肌肉活动的特征性调整发生在腿在倾斜上的第一步，但不是在预期中。总之，这些研究结果表明，竹节虫调整腿部肌肉活动的一步一步的基础上，以保持类似的运动模式下不同的机械需求。潜在的控制可能主要依赖于来自腿部本体感受器的反馈信号腿部位置和运动。
During walking, the leg motor system must continually adjust to changes in mechanical conditions, such as the inclination of the ground. To understand the underlying control, it is important to know how changes in leg muscle activity relate to leg kinematics (movements) and leg dynamics (forces, torques). Here, we studied these parameters in hindlegs of stick insects (Carausius morosus) during level and uphill/downhill (+/- 45 deg) walking, using a combination of electromyography, 3D motion capture and ground reaction force measurements. We find that some kinematic parameters including leg joint angles and body height vary across walking conditions. However, kinematics vary little compared with dynamics: horizontal leg forces and torques at the thorax-coxa joint (leg protraction/retraction) and femur-tibia joint (leg flexion/extension) tend to be stronger during uphill walking and are reversed in sign during downhill walking. At the thorax-coxa joint, the different mechanical demands are met by adjustments in the timing and magnitude of antagonistic muscle activity. Adjustments occur primarily in the first half of stance after the touch-down of the leg. When insects transition from level to incline walking, the characteristic adjustments in muscle activity occur with the first step of the leg on the incline, but not in anticipation. Together, these findings indicate that stick insects adjust leg muscle activity on a step-by-step basis so as to maintain a similar kinematic pattern under different mechanical demands. The underlying control might rely primarily on feedback from leg proprioceptors signaling leg position and movement.