You may have heard of the condition synesthesia, which describes the cross-wiring of the brain’s senses that can lead to people hearing colors, seeing sounds, and assorted other unusual phenomena. Researchers at Germany’s University Medical Center Göttingen have demonstrated a useful variation on this idea: A technique that involves using flashes of light to restore hearing. As researcher Dr. Marcus Jeschke told Digital Trends, it allows subjects — in this case, gerbils — to “actually hear light.”
Their demonstration involved injecting the ears’ cochlea with a virus that genetically codes the cells to be sensitive to light. The researchers then implanted optical fibers to deliver light to the neurons. It proved effective, and the researchers were able to show that the animals experienced light from these optical fibers as sound. Going forward, they hope that this technique could be used to make superior cochlear implants for humans.
“Hearing loss is a big problem for many people,” Jeschke said. “It’s also a problem that pretty much all of us will face during our lifetime. As you get older, you hear less and less well. You may end up hearing so poorly that you need a hearing aid or an implanted hearing system. What we’ve been doing is trying to come up with a way to make cochlear implants work better, and we’ve done that by using light to stimulate the auditory nerve neurons, thereby providing patients with a much finer frequency resolution. That means more sound information channels.”
This higher-resolution sound is important for future cochlear implants since current models can often make hearing sounds in certain contexts difficult — for instance, conversation in a crowded room. Right now, the research is still in its embryonic stages, and Jeschke noted that there is much more to be done before this can be applied to humans in the form of clinical trials.
“There are two main next steps for us,” he said. “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.”
A paper describing the work was recently published in the journal Science Translational Medicine.