Abstract
We present a large field of view (FOV) open-source miniature microscope (MiniLFOV) designed to extend the capabilities of the UCLA Miniscope platform to large-scale, single cell resolution neural imaging in freely behaving large rodents and head-fixed mice. This system is capable of multiple imaging configurations, including deep brain imaging using implanted optical probes and cortical imaging through cranial windows. The MiniLFOV interfaces with existing open-source UCLA Miniscope DAQ hardware and software, can achieve single cell resolution imaging across a 3.6 × 2.7 mm field of view at 23 frames per second, has an electrically adjustable working distance of up to 3.5 mm±150 µm using an onboard electrowetting lens, incorporates an absolute head-orientation sensor, and weighs under 14 grams. The MiniLFOV provides a 30-fold larger FOV and yields 20-fold better sensitivity than Miniscope V3, and a 12-fold larger FOV with 2-fold better sensitivity than Miniscope V4. Power and data transmission are handled through a single, flexible coaxial cable down to 0.3 mm in diameter facilitating naturalistic behavior. We validated the MiniLFOV in freely behaving rats by simultaneously imaging >1000 GCaMP7s expressing neurons in the CA1 layer of the hippocampus and in head-fixed mice by simultaneously imaging ∼2000 neurons in the mouse dorsal cortex through a 4 × 4 mm cranial window. For freely behaving experiments, the MiniLFOV supports optional wire-free operation using a 3.5 g wire-free data acquisition expansion board which enables close to 1-hour of wire-free recording with a 400 mAh (7.5 g) on-board single-cell lithium-polymer battery and expands wire-free imaging techniques to larger animal models. We expect this new open-source implementation of the UCLA Miniscope platform will enable researchers to address novel hypotheses concerning brain function in freely behaving animals.
Competing Interest Statement
The authors have declared no competing interest.
