Experiencing light as sound

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Scientists at Germany’s University Medical Center Göttingen have developed a technique that involves using flashes of light to restore hearing. They tested an optical cochlear implant that uses light for spatially and temporally precise stimulation of the auditory nerve in deaf adult gerbils.

Lead researcher on the project, Dr. Marcus Jeschke, was interviewed by the technology information website Digital Trends, for their Emerging tech column. According to Jeschke, the study showed that the test gerbils were actually able to hear light. The technique is known as optogenetic cochlear stimulation.

The technique involved virus-mediated expression of a light-sensitive protein in the cochlear neurons, enabling the cells to become sensitive to light. The next step was to implant optical fibers to deliver light to the neurons.

Results showed that light stimulation, in the gerbil model, generated auditory responses and cued avoidance behavior. The authors say this indicates partial restoration of auditory function. They believe that the data show that optogenetic cochlear stimulation can be effective, suggesting that the technique might be used to develop cochlear implants with improved restorative capabilities.

“There are two main next steps for us,” Jeschke told Digital Trends. “The first is to understand much better how the auditory system is activated by this light stimulation in the cochlea. We need to know how, if at all, it differs from normal auditory stimulation. The second is to transfer this beyond rodent models. There’s a big step in going from a rodent to a human model. We need to find a step in between, where we look at a nervous system and an immune system that is much closer to that of a human.”

Source: Wrobel C, et al. Optogenetic stimulation of cochlear neurons activates the auditory pathway and restores auditory-driven behavior in deaf adult gerbils. Science Translational Medicine. 2018 Jul 11;10(449); Digital Trends/Emerging tech.

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