Open-source, high performance miniature 2-photon microscopy systems for freely behaving animals.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Optical Imaging

Background:

• Calcium imaging is crucial for understanding neural circuit dynamics.
• Miniaturized microscopes are needed for in vivo recordings in deep brain structures.
• Existing technologies face limitations in light collection efficiency and field of view.

Purpose of the Study:

• To introduce the UCLA 2P Miniscope, an open-source miniature 2-photon microscope.
• To demonstrate its capability for recording calcium dynamics in deep neural structures and dendrites.
• To provide open access to the design and building instructions.

Main Methods:

• Developed a miniature 2-photon microscope utilizing two on-board silicon-based photon detectors.
• Achieved a 445µm × 380µm field of view with electronic focusing over a 150µm range.
• Tested the system by recording calcium dynamics in hippocampus place cells, retrosplenial cortex dendrites, and deep dentate granule cells.

Main Results:

• The UCLA 2P Miniscope demonstrated effective calcium imaging in deep brain regions.
• Achieved approximately 4-fold greater light collection compared to fiber bundle approaches.
• Successfully recorded neural activity from neurons over 620µm deep during open field behavior.

Conclusions:

• The UCLA 2P Miniscope is a powerful, open-source tool for advanced in vivo calcium imaging.
• Its design facilitates recordings from deep neural structures and dendrites with high resolution.
• Open-source availability promotes wider adoption and further development in neuroscience research.