Revolution in the hearing system: Göttingen researchers develop light implants!

Revolution in the hearing system: Göttingen researchers develop light implants!

The Göttingen Cluster of Excellence “Multiscale Bioimaging” (MBExC) and the Else Kröner Fresenius Center for Optogenetic Therapies (EKFZ OT) have specialized in the development of an innovative hearing prosthesis. Their goal is to give deaf and hard of hearing people access to natural hearing pleasure through a novel method known as “hearing with light.” Current cochlear implants (eCIs) in particular often have the problem that they make the sound perceived as artificial and distorted. This is particularly true for voices, while the perception of music is often perceived as foreign. We are therefore working on a combination of gene therapy and medical technology that promises to significantly improve the sound experience.

Current research uses optogenetics to make the nerve cells in the cochlea sensitive to light. Light signals sent by an optical cochlear implant (oCI) are intended to stimulate these nerve cells and produce a more fine-grained, more natural sound compared to the electrical stimulation used in conventional eiCIs. The project receives over one million euros from the “SPRUNG” project of the state of Lower Saxony and the Volkswagen Foundation and has the support of MBExC to make the transition from basic research to clinical application. The long-term goal of this development is to return the world of fine sounds, clear voices and complex musical experiences to the hearing impaired.

The challenges of conventional cochlear implants

According to the WHO, around 430 million people worldwide suffer from hearing loss. This number could rise to nearly 700 million by 2050 as the need for hearing rehabilitation grows. Cochlear implants are intended to convert auditory signals into neuronal impulses in order to circumvent the disturbed sound coding in the cochlea. Otonal implants, which have existed since the 1970s, are already used by over 700,000 hearing-impaired patients. Despite their ability to understand speech in quiet environments, users often struggle with background noise and emotion in their voice.

Most of these implants use electrical stimulation that results in a large lateral spread, meaning that often too many neurons are stimulated at the same time, limiting frequency and volume discrimination. The number of independent channels in these implants is typically less than ten, further compromising the sound encoding quality.

Optogenetics as a key technology

The team around Prof. Dr. med. Tobias Moser has identified optogenetics as a key technology. This innovative technology makes it possible to introduce light-sensitive proteins, so-called channelrhodopsins, into the nerve cells. The feasibility of this method has already been shown in tests in animal models. Now further development for humans is imminent. A planned 64-channel optical CI should be able to make speech understandable even in noisy environments and reproduce melodies clearly. A first clinical trial may start in 2026, but significant research is needed before then.

In addition, research on innovative micro-LED cochlear implants is being advanced to enable optical stimulation in the inner ear. The aim is to develop cochlear implants with up to 100 light sources that are suitable for human use. Functional studies should examine sound coding with optical implants in comparison to natural hearing.