Do neurons guide light within the brain

A provocative research effort at the University of Rochester is exploring whether neurons might serve not only as conduits for electrical impulses but also as channels for light transmission. This work could significantly reshape prevailing models of how the brain communicates internally.

With a three-year, $1.5 million grant from the John Templeton Foundation, researchers from Rochester's Institute of Optics have launched a study to test the hypothesis that axons-the elongated structures projecting from neurons-could conduct light, akin to optical fibers.

"There are scientific papers offering indications that light transport could happen in neuron axons, but there's still not clear experimental evidence," said Pablo Postigo, lead investigator and professor at the Institute of Optics. "Scientists have shown that there is ultra-weak photon emission in the brain, but no one understands why the light is there."

If this light-based communication proves real, the discovery could pave new paths for treating neurological disorders and redefine how clinicians approach brain healing and regeneration. However, the technical challenges are formidable. Axons are extremely narrow-less than two microns in diameter-necessitating ultra-precise nanophotonic instrumentation.

"A neuron's axon is less than two microns wide, so if you want to measure the optical properties, you need to use nanophotonic techniques," Postigo explained. "If there is light transmission, it may happen with very tiny amounts of light, even a single photon at a time."

To pursue this, Postigo will create nanophotonic probes capable of optically interfacing with live neurons. Collaborating with Michel Telias, an assistant professor of ophthalmology and neuroscience and a researcher at the Center for Visual Science, the team aims to inject light into axons and measure any emerging photons.

By tracking both the wavelength and intensity of any light that traverses the axons, the researchers hope to determine whether light can be purposefully transmitted within neural tissue.

Research Report:Photons detected in the active nerve by photographic technique