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A vast neural tracing effort by a team of Janelia scientists has upped the number of fully-traced neurons in the mouse brain by a factor of 10. Researchers can now download and browse the data in three dimensions. Inside the mouse brain, individual neurons zigzag across hemispheres, embroider branching patterns and, researchers have now discovered, can even spool out spindly fibers up to 45 centimeters long. Scientists can see and explore these wandering neural traces in 3-D in the most detailed map of mouse brain wiring yet created. The map reconstructs the shape and position of more than 300 of the 70 million neurons in the mouse brain. Previous efforts to trace the path of individual neurons had topped out in the dozens. The selectively-labeled neurons were mapped in an iterative process with two-photon microscopy. The brain is sliced in 200-micron sections and a few dozen neurons are labeled at a time and imaged. Each brain imaged yields about 50 terabytes of data, each containing mapped neurons which can be browsed via the NeuronBrowser application at https://ml-neuronbrowser.janelia.org/. Researchers interested in the complete raw data set should contact Janelia to discuss obtaining it via hardware transfer.贾内利亚研究所（Janelia）的科研团队开展的大规模神经示踪研究，使小鼠大脑中已完整示踪的神经元数量增长至原有水平的10倍。如今研究人员可下载并三维浏览该数据集。在小鼠大脑内，单个神经元在大脑半球间蜿蜒穿行，织就如刺绣般精巧的分支结构；研究团队最新发现，它们甚至能延伸出长达45厘米的纤细纤维。科学家们可在这一迄今最精细的小鼠大脑连接图谱中，以三维形式观察并探索这些蜿蜒的神经示踪轨迹。该图谱重构了小鼠大脑7000万个神经元中超过300个的形态与位置；此前的单神经元示踪研究最多仅能完成数十个神经元的示踪。本次研究中，经选择性标记的神经元通过双光子显微镜（two-photon microscopy）以迭代流程完成成像绘制：研究中将大脑切割为200微米的薄片，每次标记并成像数十个神经元。每枚成像的大脑可产生约50太字节的数据，其中包含已完成绘制的神经元，研究人员可通过NeuronBrowser应用程序（访问地址：https://ml-neuronbrowser.janelia.org/）进行浏览。若有研究人员需要完整的原始数据集，可联系贾内利亚研究所协商通过硬件传输方式获取。