The exquisite intricacies of neural circuits are fundamental to an animal’s diverse and complex repertoire of sensory and motor functions. The ability to precisely map neural circuits and to selectively manipulate neural activity is critical to understanding brain function and has, therefore been a long-standing goal for neuroscientists. The recent development of optogenetic tools, combined with transgenic mouse lines, has endowed us with unprecedented spatiotemporal precision in circuit analysis. These advances greatly expand the scope of tractable experimental investigations. Here, in the first half of the review, we will present applications of optogenetics in identifying connectivity between different local neuronal cell types and of long-range projections with both in vitro and in vivo methods. We will then discuss how these tools can be used to reveal the functional roles of these cell-type specific connections in governing sensory information processing, and learning and memory in the visual cortex, somatosensory cortex, and motor cortex. Finally, we will discuss the prospect of new optogenetic tools and how their application can further advance modern neuroscience. In summary, this review serves as a primer to exemplify how optogenetics can be used in sophisticated modern circuit analyses at the levels of synapses, cells, network connectivity and behaviors.

神经回路的精致错综复杂是动物的多种多样的感觉和运动功能的基础。精确映射神经回路和选择性操纵神经活动的能力对于理解脑功能至关重要，因此一直是神经科学家的长期目标。光遗传学工具的最新发展与转基因小鼠品系相结合，使我们在电路分析中具有空前的时空精度。这些进步极大地扩展了易于实验研究的范围。在本文的上半部分，我们将介绍光遗传学在识别不同局部神经元细胞类型之间的连通性以及两者的远距离预测中的应用体外 和 体内方法。然后，我们将讨论如何使用这些工具来揭示这些细胞类型特定连接在控制感觉信息处理以及视觉皮层，体感皮层和运动皮层的学习和记忆中的功能作用。最后，我们将讨论新的光遗传学工具的前景以及它们的应用如何进一步促进现代神经科学。总而言之，本篇综述作为引言来举例说明光遗传学如何在突触，细胞，网络连接性和行为水平上用于复杂的现代电路分析。