Computer simulation of stepping in the hind legs of the cat: An examination of mechanisms regulating the stance-to-swing transition
Computer simulation of stepping in the hind legs of the cat: An examination of mechanisms regulating the stance-to-swing transition
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DOI：
10.1152/jn.00065.2005
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发表时间：
2005-12-01
影响因子：
2.5
通讯作者：
Pearson, K
中科院分区：
文献类型：
--
作者：
Ekeberg, O;Pearson, K
对行走猫的生理学研究表明，两条感觉信号与后腿终止站立有关：一条与腿的卸载有关，另一条与臀部伸展有关。为了研究这两种信号的相对重要性，我们开发了猫后腿的三维计算机模拟，其中摆动到站立转换的时间由与踝关节伸肌力量、髋关节角度或两者结合相关的信号控制。即使在每条腿的控制器之间没有直接耦合的情况下，使用踝关节力和髋关节位置信号的组合或单独使用踝关节力信号也很容易获得稳定的步进。单独使用髋关节位置信号时，不发生稳定行走。通过相互抑制耦合两个控制器恢复了稳定性，但它并没有恢复两条后腿行走的正确时间。在摆动阶段施加的小扰动改变了对侧腿的运动，当包括踝关节力信号时，对侧腿的运动倾向于保持交替行走，但当单独使用髋关节位置信号时，对侧腿的协调倾向于改变交替行走。我们得出的结论是，后腿的协调行走严重依赖于来自每条腿的负荷敏感信号，并且由这些信号介导的腿之间的机械联系在建立交替步态中起着重要作用。
Physiological studies in walking cats have indicated that two sensory signals are involved in terminating stance in the hind legs: one related to unloading of the leg and the other to hip extension. To study the relative importance of these two signals, we developed a three- dimensional computer simulation of the cat hind legs in which the timing of the swing- to- stance transition was controlled by signals related to the force in ankle extensor muscles, the angle at the hip joint, or a combination of both. Even in the absence of direct coupling between the controllers for each leg, stable stepping was easily obtained using either a combination of ankle force and hip position signals or the ankle force signal alone. Stable walking did not occur when the hip position signal was used alone. Coupling the two controllers by mutual inhibition restored stability, but it did not restore the correct timing of stepping of the two hind legs. Small perturbations applied during the swing phase altered the movement of the contralateral leg in a manner that tended to maintain alternating stepping when the ankle force signal was included but tended to shift coordination away from alternating when the hip position signal was used alone. We conclude that coordination of stepping of the hind legs depends critically on load- sensitive signals from each leg and that mechanical linkages between the legs, mediated by these signals, play a significant role in establishing the alternating gait.