Using a simulation approach, we propose a biophysically feasible mechanism describing how a multifunctional central pattern generator (CPG) can produce co-existing slow and fast rhythms of the patterned motor output. This mechanism suggests that the same core elemental CPG can produce either a locomotion or a paw shaking rhythm in mammals (cat). We built a Hodgkin–Huxley-style biophysical model that generates multistability of a locomotion-like regime and a paw shake-like regime. This model is constructed as a half-center oscillator (HCO), in which two inhibitory neurons (representing the respective neuronal populations in real CPGs) reciprocally inhibit each other. We propose that the locomotion rhythm and the paw shaking rhythm are controlled by two different slowly inactivating intrinsic ion currents. In our model, slowly inactivating low voltage-activated calcium current (ICaS) drives the locomotion-like regime, while slowly inactivating sodium current (INaS) drives the paw shakelike regime. We investigated whether asymmetric characteristics of these regimes could be reliably and separately controlled by asymmetric variation of the conductances of these two currents. We found that variation of the conductance of ICaS in only one neuron, while holding this conductance constant in the other neuron, produces asymmetric changes in bursting characteristics, including the burst duration and interburst interval of the locomotion-like regime without producing notable changes of the paw shake-like regime. We also found that similar variation of the conductance of INaS affects the bursting characteristics of both regimes, although the paw shake-like regime is affected more remarkably than the locomotion-like one.

中文翻译：

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多功能中央模式发生器中慢节奏和快节奏共存的不对称控制：模型研究

使用模拟方法，我们提出了一种生物物理学上可行的机制，描述了多功能中央模式发生器 (CPG) 如何产生共存的模式化运动输出的慢节奏和快节奏。这种机制表明，相同的核心元素 CPG 可以在哺乳动物（猫）中产生运动或爪子颤抖的节奏。我们建立了一个霍奇金 - 赫胥黎风格的生物物理模型，该模型产生了类似运动的机制和类似爪子的机制的多重稳定性。该模型构建为半中心振荡器 (HCO)，其中两个抑制性神经元（代表真实 CPG 中的相应神经元群）相互抑制。我们建议运动节律和爪子颤抖节律由两种不同的缓慢失活的固有离子流控制。在我们的模型中，缓慢失活低电压激活钙电流 (ICaS) 驱动类似运动的状态，而缓慢失活钠电流 (INAS) 驱动类似爪子抖动的状态。我们研究了这些机制的不对称特性是否可以通过这两种电流的电导的不对称变化可靠地单独控制。我们发现，只有一个神经元中 ICaS 的电导发生变化，而在另一个神经元中保持该电导不变，会产生爆发特性的不对称变化，包括类似运动状态的爆发持续时间和爆发间隔，而不会产生显着的爪子抖动般的政权。我们还发现 INaS 电导的类似变化会影响两种机制的爆裂特性，