Dual-color volumetric imaging of neural activity of cortical columns in vivo (Conference Presentation)

Abstract

High-speed volumetric imaging of neural activity at cellular resolution is important to capture the emergent functional properties of neural circuits. While two-photon calcium imaging provides a power tool to study population activity in vivo, conventional two-photon microscopes only image two-dimensional planes. Expanding it to three-dimensions while maintaining a high spatiotemporal resolution appears necessary. Here, we developed a novel two-photon microscope with dual-color laser excitation that can image neural activity in a 3D volume with high spatiotemporal resolution. We use 920 nm and 1064 nm lasers to image, at the same time, neurons labeled with GCaMP6 in mice cortical layer 2/3, and with jRGECO in layer 5, respectively. An electrically tunable lens or a spatial light modulator was implemented in the beam path to enable fast sequential or simultaneous imaging of different focal planes. Using this beam multiplexing strategy, we image the neuronal activity of cortical circuits at high speed in primary visual cortex from awake mice (from layer 1 to 5 at 10 vol/s). We analyze the orientation tuning properties of cells in cortical columns, as well as the spatial structures of visually-evoked neuronal ensembles. Furthermore, we demonstrate fast volumetric calcium imaging of layer 1 apical dendrites and layer 2/3 somata in local V1 circuits, as well as long-range projections from PFC and layer 2/3 somata in V1.