The insular cortex (IC) plays key roles in emotional and regulatory brain functions and is affected across psychiatric diseases. However, the brain-wide connections of the mouse IC have not been comprehensively mapped. Here, we traced the whole-brain inputs and outputs of the mouse IC across its rostro-caudal extent. We employed cell-type-specific monosynaptic rabies virus tracings to characterize afferent connections onto either excitatory or inhibitory IC neurons, and adeno-associated viral tracings to label excitatory efferent axons. While the connectivity between the IC and other cortical regions was highly bidirectional, the IC connectivity with subcortical structures was often unidirectional, revealing prominent cortical-to-subcortical or subcortical-to-cortical pathways. The posterior and medial IC exhibited resembling connectivity patterns, while the anterior IC connectivity was distinct, suggesting two major functional compartments. Our results provide insights into the anatomical architecture of the mouse IC and thus a structural basis to guide investigations into its complex functions.

中文翻译：

---

小鼠岛叶皮层的全脑连接图

岛叶皮层 (IC) 在情绪和调节大脑功能中起着关键作用，并且会受到各种精神疾病的影响。然而，小鼠 IC 的全脑连接尚未被全面映射。在这里，我们追踪了鼠标 IC 在其 rostro-caudal 范围内的全脑输入和输出。我们采用细胞类型特异性单突触狂犬病病毒追踪来表征兴奋性或抑制性 IC 神经元的传入连接，并使用腺相关病毒追踪来标记兴奋性传出轴突。虽然 IC 和其他皮质区域之间的连接是高度双向的，但 IC 与皮质下结构的连接通常是单向的，揭示了突出的皮质到皮质下或皮质下到皮质的通路。后部和内侧 IC 表现出类似的连接模式，而前 IC 连接是不同的，表明有两个主要的功能区室。我们的结果提供了对鼠标 IC 解剖结构的深入了解，从而为指导对其复杂功能的研究提供了结构基础。