Yao Mingchen, Nagamori Akira, Azim Eiman, Sharpee Tatyana, Goulding Martyn, Golomb David, Gatto Graziana
Computational Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA.
Department of Physics, UCSD, La Jolla, CA, USA.
bioRxiv. 2025 Jan 8:2025.01.08.631866. doi: 10.1101/2025.01.08.631866.
Rhythmic motor behaviors are generated by neural networks termed central pattern generators (CPGs). Although locomotor CPGs have been extensively characterized, it remains unknown how the neuronal populations composing them interact to generate adaptive rhythms. We explored the non-linear cooperation dynamics among the three main populations of ipsilaterally projecting spinal CPG neurons - V1, V2a, V2b neurons - in scratch reflex rhythmogenesis. Ablation of all three neuronal subtypes reduced the oscillation frequency. Activation of excitatory V2a neurons enhanced the oscillation frequency, while activating inhibitory V1 neurons caused atonia. These findings required the development of a novel neuromechanical model that consists of flexor and extensor modules coupled via inhibition, in which rhythm in each module is generated by self-bursting excitatory populations and accelerated by intra-module inhibition. Inter-module inhibition coordinates the phases of flexor and extensor activity and slows the oscillations, while facilitation mechanisms in excitatory neurons explain the V2a activation-driven increase in frequency.
节律性运动行为由称为中枢模式发生器（CPG）的神经网络产生。尽管对运动CPG进行了广泛的表征，但构成它们的神经元群体如何相互作用以产生适应性节律仍不清楚。我们探讨了同侧投射脊髓CPG神经元的三个主要群体——V1、V2a、V2b神经元——在搔抓反射节律发生中的非线性合作动力学。消融所有三种神经元亚型会降低振荡频率。兴奋性V2a神经元的激活会提高振荡频率，而激活抑制性V1神经元会导致肌张力缺失。这些发现需要开发一种新型神经力学模型，该模型由通过抑制耦合的屈肌和伸肌模块组成，其中每个模块的节律由自发放电的兴奋性群体产生，并由模块内抑制加速。模块间抑制协调屈肌和伸肌活动的相位并减缓振荡，而兴奋性神经元中的易化机制解释了V2a激活驱动的频率增加。
