High-speed two-photon fluorescence microscopy for neural activity imaging

Two-photon fluorescence microscopy (2PFM) enables activity measurements with calcium indicators deep in the scattering brain with subcellular resolution. However, imaging membrane voltage changes, the most direct measure of neural activity, is more challenging due to its millisecond dynamics. Using a passive optical module based on free-space angular chirp-enhanced delay (FACED), we developed an ultrafast 2PFM system that enabled neural activity imaging in vivo at up to 3,000 frames per second and sub-micron spatial resolution. We have further engineered our system to attain faster imaging rates over 10× larger fields of view. I will discuss our recent results using FACED 2PFM for population imaging of calcium and voltage activity in vivo.