During fictive locomotion cat lumbar motoneurons exhibit changes in membrane proprieties including a decrease in voltage threshold (V_th), afterhyperpolarization (AHP) and input resistance (R_in) and an increase in non-linear membrane property. The impact of these changes on the motoneuron recruitment remains unknown. Using modeling approach we investigated the channel mechanism regulating the motoneuron recruitment. Three types of motoneuron pools including slow (S), fatigue-resistant (FR) and fast-fatigable (FF) motoneurons were constructed based on the membrane proprieties of cat lumbar motoneurons. The transient sodium (NaT), persistent sodium (NaP), delayed-rectifier potassium [K(DR)], Ca²⁺-dependent K⁺ [K(AHP)] and L-type calcium (Ca_L) channels were included in the models. Simulation results showed that (1) Strengthening synaptic inputs increased the number of recruitments in all three types of motoneurons following the size principle. (2) Increasing NaT or NaP or decreasing K(DR) or K(AHP) lowered rheobase of spike generation thus increased recruitment of motoneuron pools. (3) Decreasing R_in reduced recruitment in all three types of motoneurons. (4) The FF-type motoneuron pool, followed by FR- and S-type, were the most sensitive to increase of synaptic inputs, reduction of R_in, upregulation of NaT and NaP, and downregulation of K(DR) and K(AHP). (5) Increasing Ca_L enhanced overall discharge rate of motoneuron pools with little effect on the recruitment. Simulation results suggested that modulation of ionic channels altered the output of motoneuron pools with either modulating the number of recruited motoneurons or regulating the overall discharge rate of motoneuron pools. Multiple channels contributed to the recruitment of motoneurons with interaction of excitatory and inhibitory synaptic inputs during walking.

在虚拟运动期间，猫腰部运动神经元表现出膜特性的变化，包括电压阈值 ( V _th )、后超极化 (AHP) 和输入电阻 ( R _in ) 的降低以及非线性膜特性的增加。这些变化对运动神经元募集的影响仍然未知。我们使用建模方法研究了调节运动神经元募集的通道机制。基于猫腰运动神经元的膜特性，构建了慢 (S)、抗疲劳 (FR) 和易疲劳 (FF) 三种运动神经元池。瞬时钠（NaT）、持久性钠（NaP）、延迟整流钾 [ K(DR)]、Ca ²⁺依赖的 K ⁺ [ K(AHP) ] 和 L 型钙 ( Ca _L ) 通道都包含在模型中。模拟结果表明：（1）加强突触输入增加了所有三种运动神经元遵循大小原则的招募数量。(2) 增加NaT 或 NaP或减少K(DR ) 或K(AHP)降低了尖峰生成的变基，从而增加了运动神经元池的募集。(3) 减少R _in减少所有三种运动神经元的招募。(4) FF 型运动神经元池，其次是 FR 型和 S 型，对突触输入增加、R _in减少、NaT和NaP上调以及K(DR ) 和K(层次分析法）。（5）增加的Ca_大号提高运动神经元池的整体放电率，对募集的影响很小。模拟结果表明，离子通道的调节通过调节募集的运动神经元的数量或调节运动神经元池的整体放电率来改变运动神经元池的输出。多个通道有助于运动神经元的募集，在步行过程中兴奋性和抑制性突触输入的相互作用。