Animal nervous system organization is crucial for all body functions and its disruption can lead to severe cognitive and behavioural impairment¹. This organization relies on features across scales—from the localization of synapses at the nanoscale, through neurons, which possess intricate neuronal morphologies that underpin circuit organization, to stereotyped connections between different regions of the brain². The sheer complexity of this organ means that the feat of reconstructing and modelling the structure of a complete nervous system that is integrated across all of these scales has yet to be achieved. Here we present a complete structure–function model of the main neuropil in the nematode Caenorhabditis elegans—the nerve ring—which we derive by integrating the volumetric reconstructions from two animals with corresponding³ synaptic and gap-junctional connectomes. Whereas previously the nerve ring was considered to be a densely packed tract of neural processes, we uncover internal organization and show how local neighbourhoods spatially constrain and support the synaptic connectome. We find that the C. elegans connectome is not invariant, but that a precisely wired core circuit is embedded in a background of variable connectivity, and identify a candidate reference connectome for the core circuit. Using this reference, we propose a modular network architecture of the C. elegans brain that supports sensory computation and integration, sensorimotor convergence and brain-wide coordination. These findings reveal scalable and robust features of brain organization that may be universal across phyla.

动物神经系统组织对所有身体功能都至关重要，其破坏可导致严重的认知和行为障碍¹。这种组织依赖于跨尺度的特征——从纳米尺度的突触定位到神经元，这些神经元具有支撑电路组织的复杂神经元形态，再到大脑不同区域之间的刻板连接²。这个器官的绝对复杂性意味着重建和建模一个完整的神经系统的结构并整合到所有这些尺度上的壮举尚未实现。在这里，我们提出了线虫秀丽隐杆线虫主要神经细胞的完整结构 - 功能模型——神经环——我们通过将两只动物的体积重建与相应的^{3 个}突触和间隙连接连接体相结合而得到。虽然以前神经环被认为是密集的神经过程，但我们揭示了内部组织并展示了局部邻域如何在空间上限制和支持突触连接组。我们发现C. elegans连接组不是一成不变的，而是在可变连接的背景中嵌入了一个精确连接的核心电路，并确定了核心电路的候选参考连接组。使用这个参考，我们提出了C. elegans的模块化网络架构支持感觉计算和整合、感觉运动收敛和全脑协调的大脑。这些发现揭示了大脑组织的可扩展和强大的特征，这些特征可能在整个门中都是普遍的。