SIAM Journal on Applied Dynamical Systems, Volume 20, Issue 2, Page 1022-1052, January 2021.
Understanding principles of neurolocomotion requires the synthesis of neural activity, sensory feedback, and biomechanics. The nematode C. elegans is an ideal model organism for studying locomotion in an integrated neuromechanical setting because its neural circuit has a well-characterized modular structure and its undulatory forward swimming gait adapts to the surrounding fluid with a shorter wavelength in higher viscosity environments. This adaptive behavior emerges from the neural modules interacting through a combination of mechanical forces, neuronal coupling, and sensory feedback mechanisms. However, the relative contributions of these coupling modes to gait adaptation are not understood. Here, an integrated neuromechanical model of C. elegans forward locomotion is developed and analyzed. The model consists of repeated neuromechanical modules that are coupled through the mechanics of the body, short-range proprioception, and gap-junctions. The model captures the experimentally observed gait adaptation over a wide range of mechanical parameters, provided that the muscle response to input from the nervous system is faster than the body response to changes in internal and external forces. The modularity of the model allows the use of the theory of weakly coupled oscillators to identify the relative roles of body mechanics, gap-junctional coupling, and proprioceptive coupling in coordinating the undulatory gait. The analysis shows that the wavelength of body undulations is set by the relative strengths of these three coupling forms. In a low-viscosity fluid environment, the competition between gap-junctions and proprioception produces a long wavelength undulation, which is only achieved in the model with sufficiently strong gap-junctional coupling. The experimentally observed decrease in wavelength in response to increasing fluid viscosity is the result of an increase in the relative strength of mechanical coupling, which promotes a short wavelength.

中文翻译：

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线虫步态适应的神经力学机制：神经和机械耦合的相对作​​用

SIAM Journal on Applied Dynamical Systems，第 20 卷，第 2 期，第 1022-1052 页，2021 年 1 月。
理解神经运动的原理需要综合神经活动、感觉反馈和生物力学。线虫 C. elegans 是在综合神经机械环境中研究运动的理想模式生物，因为它的神经回路具有特征明确的模块化结构，其波动的向前游动步态适应周围流体，在较高粘度的环境中具有较短的波长。这种适应性行为源于通过机械力、神经元耦合和感觉反馈机制的组合相互作用的神经模块。然而，这些耦合模式对步态适应的相对贡献尚不清楚。在这里，开发和分析了线虫向前运动的综合神经力学模型。该模型由重复的神经机械模块组成，这些模块通过身体力学、短程本体感觉和间隙连接耦合。如果肌肉对神经系统输入的反应快于身体对内力和外力变化的反应，则该模型捕获了实验观察到的步态适应在广泛的机械参数范围内。该模型的模块化允许使用弱耦合振荡器的理论来确定身体力学、间隙连接耦合和本体感受耦合在协调波动步态方面的相对作用。分析表明，身体波动的波长是由这三种耦合形式的相对强度决定的。在低粘度流体环境中，间隙连接和本体感觉之间的竞争产生了长波长的波动，这只有在间隙连接耦合足够强的模型中才能实现。实验观察到的波长随着流体粘度的增加而减小是机械耦合的相对强度增加的结果，这促进了短波长。