Kilohertz two-photon fluorescence microscopy imaging of neural activity in vivo

Understanding information processing in the brain requires monitoring neuronal activity at high spatiotemporal resolution. Using an ultrafast two-photon fluorescence microscope empowered by all-optical laser scanning, we imaged neuronal activity in vivo at up to 3,000 frames per second and submicrometer spatial resolution. This imaging method enabled monitoring of both supra- and subthreshold electrical activity down to 345 μm below the brain surface in head-fixed awake mice. High-speed two-photon laser scanning microscopy using a passive laser scanner based on free-space angular-chirp-enhanced delay achieves frame rates suitable for voltage imaging in vivo in the mouse brain.