Large-scale two-photon calcium imaging in freely moving mice

Area of Science:

• Neuroscience
• Biomedical Engineering
• Optical Imaging

Background:

• Calcium imaging is crucial for understanding neural circuit dynamics.
• Existing two-photon microscopy systems can be bulky and restrictive for freely moving subjects.
• High-throughput neural recordings are needed to map complex brain functions.

Purpose of the Study:

• To develop a miniaturized, lightweight two-photon microscope for in vivo calcium imaging.
• To enable high-resolution, multiplane imaging in freely moving mice without behavioral impairment.
• To increase the number of neurons that can be simultaneously recorded.

Main Methods:

• Development of a miniaturized two-photon microscope (MINI2P) weighing under 3g.
• Utilized an enlarged field of view and a micro-tunable lens for increased z-scanning range and speed.
• Employed flexible connection cables for unimpeded movement in various behavioral assays.

Main Results:

• Achieved stable, high-resolution, multiplane calcium imaging of over 1,000 neurons per session.
• Demonstrated no impediment to behavior in freely moving, unimplanted mice.
• Enabled recordings from over 10,000 neurons in the same animal through successive FOV imaging.
• Obtained large-scale data from visual cortex, medial entorhinal cortex, and hippocampus.

Conclusions:

• The MINI2P system facilitates large-scale neural population recordings in behaving animals.
• The technology reveals spatial tuning properties of neurons across different brain regions.
• This advancement supports in-depth investigation of neural circuits underlying complex behaviors.