The understanding of brain computations requires methods that read out neural activity
on different spatial and temporal scales. Following signal propagation and integration
across a neuron and recording the concerted activity of hundreds of neurons pose distinct
challenges, and the design of imaging systems has been mostly focused on tackling
one of the two operations. We developed a high-resolution, acousto-optic two-photon
microscope with continuous three-dimensional (3D) trajectory and random-access scanning
modes that reaches near-cubic-millimeter scan range and can be adapted to imaging
different spatial scales. We performed 3D calcium imaging of action potential backpropagation
and dendritic spike forward propagation at sub-millisecond temporal resolution in
mouse brain slices. We also performed volumetric random-access scanning calcium imaging
of spontaneous and visual stimulation-evoked activity in hundreds of neurons of the
mouse visual cortex in vivo. These experiments demonstrate the subcellular and network-scale
imaging capabilities of our system.
