Pan-cortical cellular imaging in freely behaving mice using a miniaturized micro-camera array microscope (mini-MCAM)

Understanding how circuits in the brain simultaneously coordinate their activity to mediate complex ethologically relevant behaviors requires recording neural activities from distributed populations of neurons in freely behaving animals. Current miniaturized imaging microscopes are typically limited to imaging a relatively small field of view (FOV), precluding the measurement of neural activities across multiple brain regions. Here, we present a miniaturized micro-camera array microscope (mini-MCAM) that consists of four fluorescence imaging micro-cameras, each capable of capturing neural activity across a 4.5 millimeter × 2.55 millimeter FOV. Cumulatively, the mini-MCAM images over a 30-square millimeter area of sparsely expressed GCaMP6s neurons that were distributed throughout the dorsal cortex, in regions including the primary and secondary motor, somatosensory, visual, retrosplenial, and association cortices across both hemispheres. We demonstrate cortex-wide cellular resolution in vivo calcium (Ca²⁺) imaging using the mini-MCAM in both head-fixed and freely behaving mice.