Hearing does not only take place in the ear

Deafness is one of the most common congenital diseases of the sensory organs in newborns. Cochlear implants can compensate for hearing loss in a good two thirds of those affected. However, the hearing prostheses do not help a third. Oldenburg scientists are on the trail of this phenomenon. Hearing does not only take place in the ear - the acoustic information that the ear picks up must be passed on to the brain and processed in the central nervous part of the auditory system, the auditory pathway, before it is perceived there. Scientists led by neurogeneticists Dr Tina Schlüter and Prof. Dr Hans Gerd Nothwang from the University of Oldenburg have succeeded in substantiating the hypothesis that the same genes play an important role in the development and function of the ear as in the development of the auditory pathway. The researchers have published their results from animal experiments in the current issue of the scientific journal Human Molecular Genetics. The work focussed on a new class of biomolecules known as microRNAs. "MicroRNAs are important for regulating the translation of genetic information into vital proteins. In this way, they influence how an organism develops," says Schlüter. MicroRNA-96 is of great importance for hearing. Individual changes, so-called point mutations, in this microRNA lead to hereditary hearing loss in the inner ear of humans and mice. During her doctorate as part of the "Molecular Basis of Sensory Biology" research training group, Schlüter and colleagues from Hanover, Munich, London and Tel Aviv specifically investigated the auditory pathway in mice with such a mutation in microRNA-96. The researchers found numerous changes in the structure and function of nerve cells in the brains of the mice. The cells were smaller and worked differently than usual - they had not developed as well overall. These changes could not be observed in deaf mice that did not have such a mutation. "I am convinced that other deafness genes are also associated with changes in both the ear and the auditory pathway, as only a few deafness genes in the auditory pathway have been specifically analysed to date," says Schlüter. With this work, they were also able to show for the first time that microRNAs play an important role in the correct development of the auditory pathway. Nothwang, one of the leading scientists in the "Hearing4all" cluster of excellence, has been analysing deafness genes in mice with his neurogenetics research group for several years. This basic biomedical research is yielding important results for the treatment of hearing loss in humans. "We are thus making an important contribution to being able to take better rehabilitation measures in the future," says Nothwang, who is also Dean of School V - School of Medicine and Health Sciences.