Novel device for exploratory imaging enables about 1,000 times more access to brain tissue

Key research finding: Science is examining the brain’s neural activity for applications ranging from innovative therapies for brain-related injuries and disease to computational learning architectures for artificial intelligence and deep neural networks.

A research team has developed a tool that lets researchers see more of a live mouse’s brain, to make discoveries that can advance research into the neural circuit mechanisms that form the underlying behavior of the human brain. The tool overcomes the drawback of traditional brain probes — the small amount of tissue they can access, which limits their ability to image neurons of interest. 

The innovation is to insert an imaging probe with side-viewing capabilities into a previously inserted optically matched channel — an ultrathin-wall glass capillary — to convert deep brain imaging into endoscopic imaging. The operator can freely rotate the probe to image different brain regions, getting a 360-degree view for imaging along the entire length of the inserted probe. This large-volume imaging enables an increase of about 1,000 times in tissue access volume, compared with what is available for imaging at the tip of typical miniature imaging probes.

The system, called COMPACT — Clear Optically Matched Panoramic Access Channel Technique — advances the use of high-resolution optical imaging in a living brain to investigate the function and adaptability of neural circuits underpinning behavior. The long-term goal is to transform the study and understanding of deep mammalian brain functions via close collaboration with neuroscientists.

Purdue professor, title: Meng Cui, assistant professor, Elmore Family School of Electrical and Computer Engineering, College of Engineering, and Department of Biological Sciences, College of Science. Expertise in communications, network, signal and image processing, and optics — applied to using imaging technology to study the mammalian brain, in order to understand the neural circuit underpinnings of behavior and advance the development of brain-machine interfaces. 

Journal name: Nature Methods. 

Funding: National Institutes of Health. 1U01NS118302, 1U01NS094341 and 1UF1NS107689. 

OTC/Patent information if relevant: In March 2020, the Purdue Research Foundation’s Office of Technology Commercialization filed a utility patent for the COMPACT-based deep brain neurophotonic interface (Inventor: Meng Cui; U.S. Application No: 16/833,550), which covered the concept, design and implementation of COMPACT.

Brief summary of methods: The researchers developed a motorized capillary insertion procedure and computer-controlled actuator to insert an ultrathin-wall glass capillary and probing device. They inserted an imaging GRIN (GRadient INdex) lens probe to focus inside the brain tissue and transmit an optical signal. The innovation in methodology is to overturn the convention of directly inserting the lens into the brain — rather, the researchers first put in a clear, optically matched channel, then insert an imaging probe into that channel. This isolated the imaging probe from the tissue for free rotation and a complete, panoramic view of neurons around the channel.

Media contact: Kayla Wiles, 765-494-2432, wiles5@purdue.edu 

Source: Meng Cui, mengcui@purdue.edu