Researchers Unveil Fiber-Optic Device to Control Brain Neurons

A groundbreaking advancement in brain research has emerged from a team at Washington University in St. Louis, where researchers have developed a novel fiber-optic device capable of controlling thousands of neurons simultaneously. Known as the PRIME (Panoramically Reconfigurable IlluMinativE) fiber, this innovative technology promises to transform the field of neuroscience by enabling multi-site optical stimulation through a single, hair-thin implant.

The device combines fiber-based techniques with optogenetics, allowing for unprecedented control over deep-brain stimulation. According to Song Hu, a professor of biomedical engineering at the McKelvey School of Engineering, “By combining fiber-based techniques with optogenetics, we can achieve deep-brain stimulation at unprecedented scale.” This advancement could pave the way for more detailed understandings of complex brain circuits, which require stimulation at numerous points across the brain.

Traditional fiber-optic systems are limited, with a single fiber able to deliver light to only one specific location. This presents a significant challenge for neuroscientists who study intricate brain networks. Adding multiple fibers would be too invasive, making the development of a single fiber that can direct light into thousands of pathways essential. The PRIME fiber achieves this by utilizing ultrafast-laser 3D microfabrication to inscribe thousands of tiny light emitters into a fiber that is as thin as a human hair.

The research team included Shuo Yang, a postdoctoral researcher who led the PRIME technology’s development. “We’re carving very small light emitters into very small pieces,” Yang commented. “Very small, meaning tiny mirrors that are 1/100th the size of a human hair.” This innovative approach allows the PRIME fiber to connect light to neurons across different regions of the brain.

Testing the technology involved validating its neural modulation capabilities in freely behaving animal models. Co-first author Keran Yang, along with postdoctoral senior scientist Quentin Chevy, demonstrated the device’s utility by driving activity in specific subregions of the superior colliculus, a brain area vital for sensorimotor transformation. By varying the light patterns, they could systematically induce behaviors such as freezing or escape responses in the subjects.

“This kind of tool lets us ask questions that were impossible before,” Keran Yang noted. The ability to precisely shape light in both space and time opens new avenues for researchers to explore how different brain circuits interact and the relationship between neural activity patterns and behavior. Adam Kepecs, a professor of neuroscience and psychiatry at WashU Medicine, emphasized the significance of this breakthrough. “This device significantly expands what’s possible in experimentally linking distributed neural activity to perception and action,” he stated.

Looking to the future, the research team aims to enhance the PRIME fiber into a bidirectional interface that combines optogenetics with photometry. This would allow simultaneous stimulation and recording of brain activity, further enriching the research landscape. “This is just the start of an exciting journey,” Hu remarked, expressing the team’s ambition to develop a wireless and wearable version of PRIME. Such advancements would significantly reduce the invasiveness of the tool, allowing for more natural data collection from subjects that are not tethered by wires.

The findings of this research were published in the journal Nature Neuroscience in 2025, marking a significant milestone in the intersection of neurotechnology and optical engineering. The implications of the PRIME fiber extend beyond mere research capabilities, potentially influencing treatment strategies for various neurological conditions in the future.

For more information, refer to the article by Shuo Yang et al, titled “Laser-engineered PRIME fiber for panoramic reconfigurable control of neural activity,” published in Nature Neuroscience.