Crossley Michael, Simon Anna, Marathe Shashidhara, Rau Christoph, Roth Arnd, Marra Vincenzo, Staras Kevin
Department of Neuroscience, University of Sussex, Brighton BN1 9QG, United Kingdom.
Wolfson Institute for Biomedical Research, University College London, London WC1E 6BT, United Kingdom.
Proc Natl Acad Sci U S A. 2025 Mar 4;122(9):e2422706122. doi: 10.1073/pnas.2422706122. Epub 2025 Feb 27.
Molluscan brains are composed of morphologically consistent and functionally interrogable neurons, offering rich opportunities for understanding how neural circuits drive behavior. Nonetheless, detailed component-level CNS maps are often lacking, total neuron numbers are unknown, and organizational principles remain poorly defined, limiting a full and systematic characterization of circuit operation. Here, we establish an accessible, generalizable approach, harnessing synchrotron X-ray tomography, to rapidly determine the three-dimensional structure of the multimillimeter-scale CNS of . Focusing on the feeding ganglia, we generate a full neuron-level reconstruction, revealing key design principles and revising cell count estimates upward threefold. Our atlas uncovers the superficial but also nonsuperficial ganglionic architecture, reveals the cell organization in normally hidden regions-ganglionic "dark sides"-and details features of single-neuron morphology, together guiding targeted follow-up functional investigation based on intracellular recordings. Using this approach, we identify three pivotal neuron classes: a command-like food-signaling cell type, a feeding central pattern generator interneuron, and a unique behavior-specific motoneuron, together significantly advancing understanding of the function of this classical control circuit. Combining our morphological and electrophysiological data, we also establish a functional CNS atlas in as a shared and scalable resource for the research community. Our approach enables the rapid construction of cell atlases in large-scale nervous systems, with key relevance to functional circuit interrogation in a diverse range of model organisms.
软体动物的大脑由形态一致且功能可探究的神经元组成，为理解神经回路如何驱动行为提供了丰富的机会。然而，详细的组件级中枢神经系统图谱往往缺失，神经元总数未知，组织原则仍定义不清，这限制了对回路运作的全面和系统的表征。在此，我们建立了一种可获取、可推广的方法，利用同步加速器X射线断层扫描技术，快速确定多毫米尺度的中枢神经系统的三维结构。以摄食神经节为重点，我们生成了完整的神经元水平重建图，揭示了关键的设计原则，并将细胞计数估计值向上修正了三倍。我们的图谱揭示了浅表和非浅表的神经节结构，揭示了通常隐藏区域——神经节的“暗面”——的细胞组织，并详细描述了单个神经元形态的特征，共同指导基于细胞内记录的有针对性的后续功能研究。使用这种方法，我们确定了三类关键神经元：一种类似指令的食物信号细胞类型、一种摄食中枢模式发生器中间神经元和一种独特的行为特异性运动神经元，共同显著推进了对这个经典控制回路功能的理解。结合我们的形态学和电生理数据，我们还在[具体物种]中建立了一个功能性中枢神经系统图谱，作为研究界共享且可扩展的资源。我们的方法能够在大规模神经系统中快速构建细胞图谱，这与多种模式生物中功能回路的研究密切相关。
