Connections between neurons can be mapped by acquiring and analysing electron microscopic brain images. In recent years, this approach has been applied to chunks of brains to reconstruct local connectivity maps that are highly informative^1,2,3,4,5,6, but nevertheless inadequate for understanding brain function more globally. Here we present a neuronal wiring diagram of a whole brain containing 5 × 10⁷ chemical synapses⁷ between 139,255 neurons reconstructed from an adult female Drosophila melanogaster^8,9. The resource also incorporates annotations of cell classes and types, nerves, hemilineages and predictions of neurotransmitter identities^10,11,12. Data products are available for download, programmatic access and interactive browsing and have been made interoperable with other fly data resources. We derive a projectome—a map of projections between regions—from the connectome and report on tracing of synaptic pathways and the analysis of information flow from inputs (sensory and ascending neurons) to outputs (motor, endocrine and descending neurons) across both hemispheres and between the central brain and the optic lobes. Tracing from a subset of photoreceptors to descending motor pathways illustrates how structure can uncover putative circuit mechanisms underlying sensorimotor behaviours. The technologies and open ecosystem reported here set the stage for future large-scale connectome projects in other species.

可以通过获取和分析电子显微镜脑图像来绘制神经元之间的连接。近年来，这种方法已被应用于大脑块，以重建局部连接图，这些图谱具有高度信息量^1,2,3,4,5,6，但仍然不足以更全面地了解大脑功能。在这里，我们展示了一个全脑的神经元布线图，其中包含 5 × 10⁷ 个化学突触⁷，从成年雌性黑腹果蝇重建的 139,255 个神经元 ^8,9。该资源还包含细胞类别和类型、神经、半系和神经递质身份预测的注释^10,11,12。数据产品可供下载、编程访问和交互式浏览，并且已与其他 fly 数据资源互操作。我们从连接组中得出一个投影组——区域之间的投影图——并报告了突触通路的追踪和从输入（感觉和上升神经元）到输出（运动、内分泌和下降神经元）的信息流分析跨两个半球以及中枢脑和视叶之间。从光感受器子集到下行运动通路的追踪说明了结构如何揭示感觉运动行为背后的假定电路机制。这里报告的技术和开放生态系统为未来其他物种的大规模连接组项目奠定了基础。