Presentation: 2025 ND EPSCoR Annual conference 

October 21, 2025, NDSU Memorial Union, Fargo, North Dakota

Commutator-assisted fiber bundle imaging system for neural and behavioral recording in freely behaving animals

Exploration of neural mechanisms underlying complex behaviors in neuroscience experiments requires the recording and/or modulation of neural activity in naturalistic contexts. Miniaturized optical imaging systems and genetically encoded indicators have become widely used tools for studying brain circuit dynamics during naturalistic behaviors in various animal models. Besides wide-field miniature microscopes and single optical fiber-based systems, fiber bundle-based imaging systems, utilizing either single-photon or two-photon light sources, have also been developed to optically record or modulate the activity of neurons and glial cells in freely behaving mice. They enable structured illumination for single-cell optogenetic modulation while limited in freely behaving animals due to tether twisting caused by restricted rotation. Custom commutators and electrical-tether-based solutions either complicate image processing or are incompatible with fiber bundles. We describe a compact fiber bundle imaging and optogenetic modulation system that dynamically adjusts the position of the entire optical assembly in response to the animal’s movements, including translation and rotation. It incorporates torque sensing with a Hall sensor at the proximal end of the fiber bundle, coupled with a motorized rotary stage to rotate the optical system accordingly. A slip ring is used to provide power and enable rotation, while imaging data are managed by an onboard microcomputer integrated with the optical assembly and have sufficient throughput unlike transmitting high-bandwidth data through the slip ring. This system complements existing miniaturized optical imaging tools and offers a new paradigm for experiments requiring imaging and modulation of neural activity in freely behaving animals.