Neuron phase shift adaptive to time delay in locomotor control
Neuron phase shift adaptive to time delay in locomotor control
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DOI：
10.1016/j.apm.2007.12.011
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发表时间：
2009-02
影响因子：
5
通讯作者：
Kunishige Ohgane;Shin-ichiro Ei;H. Mahara
中科院分区：
文献类型：
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作者：
Kunishige Ohgane;Shin-ichiro Ei;H. Mahara
基于神经生理学证据，理论研究已经表明，步行可以通过中央模式发生器（CPG）和身体的振荡的相互夹带来产生。然而，它也已被证明，在感觉运动回路的时间延迟不稳定的相互夹带，并在失败的步行结果。最近，已经报道，如果（a）用生理上忠实的神经元模型代替用于构造CPG的神经元模型，（Bonhoop-Van der Pol型）和（B）身体的机械阻抗（肌肉粘弹性）取决于两条腿之间的角度来控制，CPG活动和身体运动之间的相位关系可以根据环路延迟灵活地锁定，因此，可以稳定相互夹带。也就是说，运动控制自适应环路延迟可以出现从CPG和身体之间的耦合。在这里，我们称这种机制为灵活相位锁定。本文构造了一个耦合振子系统作为步行系统的简化模型，从理论上研究了柔性锁相的机理，并对简化模型进行了分析。分析表明，CPG与人体耦合系统的渐近稳定极限环和传入与传出耦合系数的符号差是其基本机制.
Based on neurophysiological evidence, theoretical studies have shown that walking can be generated by mutual entrainment of oscillations of a central pattern generator (CPG) and a body. However, it has also been shown that the time delay in the sensorimotor loop destabilizes mutual entrainment, and results in the failure to walk. Recently, it has been reported that if (a) the neuron model used to construct the CPG is replaced by physiologically faithful neuron model (Bonhoeffer–Van der Pol type) and (b) the mechanical impedance of the body (muscle viscoelasticity) is controlled depending on the angle between two legs, the phase relationship between CPG activity and body motion could be flexibly locked according to the loop delay and, therefore, mutual entrainment can be stabilized. That is, locomotor control adaptive to the loop delay can emerge from the coupling between CPG and body. Here, we call this mechanism flexible-phase locking. In this paper, we construct a system of coupled oscillators as a simplified model of a walking system to theoretically investigate the mechanism of flexible-phase locking, and to analyze the simplified model. The analysis suggests that the following are required as the essential mechanism: (i) an asymptotically stable limit cycle of the coupling system of CPG and body and (ii) a sign difference between afferent and efferent coupling coefficients.