Neural stimulation method could lessen damage from implanted devices

Neural stimulation can be therapeutic for neurological disorders, however the device implanted to facilitate this can deteriorate in time and scar the neural tissue. Now researchers at Pittsburgh University have come up with a way of achieving neural stimulation using a light activated untethered electrode which they hope will contribute towards diminishing such damage.

Takashi Kozai, an assistant professor of bioengineering at the university’s Swanson School of Engineering, said: “Typically with neural stimulation, in order to maintain the connection between mind and machine, there is a transcutaneous cable from the implanted electrode inside of the brain to a controller outside of the body. Movement of the brain or this tether leads to inflammation, scarring, and other negative side effects. We hope to reduce some of the damage by replacing this large cable with long wavelength light and an ultra-small, untethered electrode. When the photoelectric effect contaminated our electrophysiological recording while imaging with a near-infrared laser, we were a little surprised. It turned out that the original equation had to be modified in order to explain this outcome. We tried numerous strategies to eliminate this photoelectric artefact but were unsuccessful in each attempt, so we turned the bug into a feature. What we didn’t expect to see was that this photoelectric method of stimulation allows us to stimulate a different and more discrete population of neurons than could be achieved with electrical stimulation. This gives researchers another tool in their toolbox to explore neural circuits in the nervous system. We’ve had numerous critics who did not have faith in the mathematical modifications that were made to Einstein’s original photoelectric equation, but we believed in the approach and even filed a patent application. This is a testament to Kaylene’s hard work and diligence to take a theory and turn it into a well-controlled validation of the technology.”

Kaylene Stocking, a senior bioengineering and computer engineering student, said: “Our group decided to use this feature of the photoelectric effect to our advantage in neural stimulation. We used the change in electrical potential with a near-infrared laser to activate an untethered electrode in the brain. We discovered that photostimulation is effective. Temperature increases were not significant, which lowers the chance of heat damage, and activated cells were closer to the electrode than in electrical stimulation under similar conditions, which indicates increased spatial precision.”