3-photon targeted patching (3PTP) of neurons in mouse hippocampus in vivo excited at the 1700-nm window

Deep-brain targeted electrophysiological recording remains challenging due to the limited imaging depth of conventional optical approaches. Here, we develop a 1700-nm 3-photon targeted patching platform that integrates deep-brain 3-photon microscopy, a customized trans-suture cranial window, and dual-channel visualization of neurons and micropipettes. The platform enables real-time optical guidance and whole-cell recording of identified excitatory and inhibitory neurons in the mouse hippocampus at depths exceeding 1 mm. This approach overcomes the depth limitation of conventional 2-photon targeted patching and provides a versatile optical platform for functional interrogation of deep-brain neural circuits in vivo.