Fiber-optic fluorescence microscopy for functional brain imaging in awake, mobile mice

Fiber-optic based optical imaging is an emerging technique for studying brain activity in live animals. Here, we introduce a novel fluorescence fiber-optic microendoscopy approach to minimal invasively detect neural activities in a live mouse brain. The system uses a flexible endoscopic probe composed of a multi-core coherent fiber-bundle terminated with an approximately 1500-micron working distance objective lens. The fiber-optic neural interface is mounted on a 4-mm(2) cranial window enabling visualization of glial calcium transients from the same brain region for weeks. We evaluated the system performance through in vivo imaging of GCaMP3 fluorescence in transgenic head-restrained mice during locomotion.