Dimitre G Ouzounov, Tianyu Wang, et al. record spontaneous activity from up to 150 neurons in the hippocampal stratum pyramidale at ~1-mm depth within an intact mouse brain.
Using three-photon microscopy at 1,300-nm excitation, the authors of a recently published Nature Methods paper, demonstrated that functional imaging of GCaMP6s-labeled neurons can be achieved beyond the depth of two-photon microscopy. The method creates opportunities for noninvasive recording of neuronal activity with high spatial and temporal resolution deep within scattering brain tissues.