Miniscope Imaging of Nucleus Accumbens Neural Activity in Freely Behaving Rats: Virus Injection, Gradient Index Lens...

Area of Science:

• Neuroscience
• Surgical Techniques
• Behavioral Science

Background:

• In vivo calcium imaging using miniscopes in freely moving rats offers real-time insights into neural mechanisms of behavior.
• Gradient index (GRIN) lenses are essential for relaying neural activity from deep brain structures.
• Detailed surgical and long-term imaging protocols for rats are less common than for mice, despite rats' suitability for complex behavioral studies.

Purpose of the Study:

• To present a robotic surgical protocol for simultaneous virus injection and GRIN lens implantation in the rat nucleus accumbens core.
• To detail methods for achieving high-quality, long-term neural recordings (months) in rats using miniscopes.
• To introduce protective strategies for miniscopes to ensure consistent imaging and minimize animal stress.

Main Methods:

• Robotic surgery for same-day virus injection and GRIN lens implantation into the rat nucleus accumbens core.
• Direct lens insertion technique without tissue aspiration.
• Daily recording strategies to minimize tissue damage and preserve image quality.
• Custom fabrication of protective miniscope cones and cable management.

Main Results:

• Successful GRIN lens implantation enabling image retention for months.
• Consistent, high-quality neural recordings from deep brain structures in freely moving rats.
• Elimination of repeated anesthesia and maintenance of a stable focal plane through protective strategies.

Conclusions:

• The presented robotic surgical protocol facilitates robust, long-term in vivo calcium imaging in rats.
• This methodology enhances the study of neural correlates of complex behaviors in a rodent model better suited for human-relevant research.
• Protective strategies improve experimental consistency and animal welfare by reducing stress and anesthesia exposure.