Elices Irene, Varona Pablo
Grupo de Neurocomputación Biológica, Departamento de Ingeniería Informática, Escuela Politécnica Superior, Universidad Autónoma de Madrid Madrid, Spain.
Front Comput Neurosci. 2017 Feb 16;11:9. doi: 10.3389/fncom.2017.00009. eCollection 2017.
Central Pattern Generator (CPG) circuits are neural networks that generate rhythmic motor patterns. These circuits are typically built of half-center oscillator subcircuits with reciprocally inhibitory connections. Another common property in many CPGs is the remarkable rich spiking-bursting dynamics of their constituent cells, which balance robustness and flexibility to generate their joint coordinated rhythms. In this paper, we use conductance-based models and realistic connection topologies inspired by the crustacean pyloric CPG to address the study of asymmetry factors shaping CPG bursting rhythms. In particular, we assess the role of asymmetric maximal synaptic conductances, time constants and gap-junction connectivity to establish the regularity of half-center oscillator based CPGs. We map and characterize the synaptic parameter space that lead to regular and irregular bursting activity in these networks. The analysis indicates that asymmetric configurations display robust regular rhythms and that large regions of both regular and irregular but coordinated rhythms exist as a function of the asymmetry in the circuit. Our results show that asymmetry both in the maximal conductances and in the temporal dynamics of mutually inhibitory neurons can synergistically contribute to shape wide regimes of regular spiking-bursting activity in CPGs. Finally, we discuss how a closed-loop protocol driven by a regularity goal can be used to find and characterize regular regimes when there is not time to perform an exhaustive search, as in most experimental studies.
中枢模式发生器（CPG）电路是产生节律性运动模式的神经网络。这些电路通常由具有相互抑制连接的半中心振荡器子电路构成。许多CPG的另一个共同特性是其组成细胞具有显著丰富的峰电位 - 爆发动力学，这种动力学平衡了稳健性和灵活性以产生联合协调节律。在本文中，我们使用基于电导的模型和受甲壳类动物幽门CPG启发的真实连接拓扑结构来研究塑造CPG爆发节律的不对称因素。具体而言，我们评估不对称最大突触电导、时间常数和缝隙连接连通性在建立基于半中心振荡器的CPG规律性方面的作用。我们绘制并表征了导致这些网络中规则和不规则爆发活动的突触参数空间。分析表明，不对称配置显示出稳健的规则节律，并且规则和不规则但协调的节律的大片区域作为电路不对称性的函数而存在。我们的结果表明，最大电导和相互抑制神经元的时间动态中的不对称都可以协同作用，以塑造CPG中广泛的规则峰电位 - 爆发活动模式。最后，我们讨论了在没有时间进行详尽搜索的情况下，如在大多数实验研究中，如何使用由规律性目标驱动的闭环协议来找到并表征规则模式。
