AI 中文总结
本研究通过自下而上重建海蛞蝓游泳CPG的四细胞模型，揭示网络爆发层级涌现机制：从细胞内在动力学到条件性HCO爆发，再到完整网络中由交叉兴奋、抑制和电耦合协同产生的稳健节律，并提供可实验检验的预测。
AI 中文摘要
一个神经回路如何在其组成神经元均不能内源性地爆发时，仍能节律性地爆发？我们通过自下而上的重建来回答这个问题，该重建基于海蛞蝓\ extit{Dendronotus iris}的游泳中枢模式发生器（CPG）建模的4细胞神经回路。我们首先绘制了游泳中间神经元（SiN）模型神经元的内在状态区，并表明缓慢的相互抑制可以在由紧张性放电或静息细胞组装成的半中心振荡器（HCO）中产生反相爆发。慢-快相空间解构将该成对节律解释为一种释放机制。接着我们进行CPG参数化，其中细胞1和2为静息态，而细胞3和4为紧张性放电细胞，但其孤立的HCO只能表现出紧张性放电或抑制。因此，爆发既不出现在细胞水平，也不出现在HCO水平。它仅在两个模块组装成完整的4细胞网络后才出现，在该网络中，交叉兴奋、交叉抑制和整流电耦合共同作用以支持稳健的网络节律生成。基于事件的符号编码和GPU并行参数扫描表明，这种高阶集体状态占据扩展的参数域而非单一调谐点，并量化了网络相互作用如何重塑这些域以及每次爆发的尖峰数。符号扫描识别出健康的活动状态区（周期序列）和转变边界；Lempel-Ziv复杂度被用作非周期符号输出的描述符，而非混沌或动力学不稳定性的证明。我们的结果建立了节律生成的层级结构——从内在细胞动力学，经由条件性HCO爆发，到仅在完全组装的4细胞CPG中才出现的爆发——并为扰动其化学和电耦合提供了实验上可检验的预测。
英文摘要
How can a neural circuit rhythmically burst when none of its constituent neurons can endogenously do so? We address this question through a bottom-up reconstruction of a 4-cell neural circuit modeled after the swim central pattern generator (CPG) of the sea slug \textit{Dendronotus iris}. We first map the intrinsic regimes of a swim interneuron (SiN) model neuron and show that slow mutual inhibition can generate anti-phase bursting in a half-center oscillator (HCO) assembled from tonic-spiking or quiescent cells. A slow--fast phase-space deconstruction explains this pairwise rhythm as a release mechanism. We then move on to CPG parametrization, in which cells 1 and 2 are quiescent, while cells 3 and 4 are tonic spikers but their isolated HCO can only exhibit tonic spiking or suppression. Bursting therefore does not arise at either the cellular or HCO level. It appears only after the two modules are assembled into the complete 4-cell network, where cross excitation, cross inhibition, and rectified electrical coupling act together to support a robust network rhythm-generation. Event-based symbolic encoding and GPU-parallel parameter sweeps show that this higher-order collective state occupies extended parameter domains rather than a single tuned point, and they quantify how the network interactions reshape those domains and the spike counts per burst. Symbolic sweeps identify the healthy range of activity regimes (periodic sequences) and transition boundaries; Lempel--Ziv complexity is used as a descriptor of aperiodic symbolic output rather than as proof of chaos or dynamical instability. Our results establish a hierarchy of rhythm generation---from intrinsic cell dynamics, through conditional HCO bursting, to bursting that emerges only in the fully assembled 4-cell CPG---and provide experimentally accessible predictions for perturbing its chemical and electrical couplings.
