The ventral hippocampus (vHPC) is a critical hub in networks that process emotional information. While recent studies have indicated that ventral CA1 (vCA1) projection neurons are functionally dissociable, the basic principles of how the inputs and outputs of vCA1 are organized remain unclear. Here, we used viral and sequencing approaches to define the logic of the extended vCA1 circuit. Using high-throughput sequencing of genetically barcoded neurons (MAPseq) to map the axonal projections of thousands of vCA1 neurons, we identify a population of neurons that simultaneously broadcast information to multiple areas known to regulate the stress axis and approach–avoidance behavior. Through molecular profiling and viral input–output tracing of vCA1 projection neurons, we show how neurons with distinct projection targets may differ in their inputs and transcriptional signatures. These studies reveal new organizational principles of vCA1 that may underlie its functional heterogeneity.

腹侧海马体 (vHPC) 是处理情绪信息的网络中的关键枢纽。虽然最近的研究表明腹侧 CA1 (vCA1) 投射神经元在功能上是可分离的，但 vCA1 输入和输出如何组织的基本原理仍不清楚。在这里，我们使用病毒和测序方法来定义扩展 vCA1 电路的逻辑。利用基因条形码神经元的高通量测序 (MAPseq) 来绘制数千个 vCA1 神经元的轴突投影图，我们确定了一组神经元，它们同时向多个已知调节压力轴和接近回避行为的区域广播信息。通过 vCA1 投射神经元的分子分析和病毒输入输出追踪，我们展示了具有不同投射目标的神经元在输入和转录特征方面可能存在的差异。这些研究揭示了 vCA1 的新组织原则，这可能是其功能异质性的基础。