Neocortical areas communicate through extensive axonal projections, but the logic of information transfer remains poorly understood, because the projections of individual neurons have not been systematically characterized. It is not known whether individual neurons send projections only to single cortical areas or distribute signals across multiple targets. Here we determine the projection patterns of 591 individual neurons in the mouse primary visual cortex using whole-brain fluorescence-based axonal tracing and high-throughput DNA sequencing of genetically barcoded neurons (MAPseq). Projections were highly diverse and divergent, collectively targeting at least 18 cortical and subcortical areas. Most neurons targeted multiple cortical areas, often in non-random combinations, suggesting that sub-classes of intracortical projection neurons exist. Our results indicate that the dominant mode of intracortical information transfer is not based on ‘one neuron–one target area’ mapping. Instead, signals carried by individual cortical neurons are shared across subsets of target areas, and thus concurrently contribute to multiple functional pathways.

中文翻译：

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视觉皮层单细胞投影的逻辑

新皮质区域通过广泛的轴突投射进行交流，但信息传递的逻辑仍然知之甚少，因为尚未系统地表征单个神经元的投射。目前尚不清楚单个神经元是仅向单个皮层区域发送投影还是将信号分布在多个目标上。在这里，我们使用基于全脑荧光的轴突追踪和基因条形码神经元 (MAPseq) 的高通量 DNA 测序来确定小鼠初级视觉皮层中 591 个单个神经元的投影模式。预测是高度多样化和发散的，共同针对至少 18 个皮质和皮质下区域。大多数神经元针对多个皮层区域，通常是非随机组合，这表明存在皮层内投射神经元的亚类。我们的结果表明，皮质内信息传输的主要模式不是基于“一个神经元-一个目标区域”的映射。相反，单个皮层神经元携带的信号在目标区域的子集之间共享，因此同时有助于多个功能通路。