The aim of this year's lecture was to take stock of the molecular mechanisms of hearing, by examining how, twenty-five years after its inception, the genetic approach to the functioning of the auditory system, i.e. the study of hereditary deafness, continues to be a remarkably effective lever for gaining knowledge of these mechanisms.
We began this series of lectures with a brief review of the knowledge acquired in the early 1990s, when the molecular deciphering of cochlear physiology was initiated. A great deal of previous research, involving both physicists and biologists, had led to a detailed model of cochlear function, accounting for a large number of its physiological and biophysical properties, and in particular its auditory transduction function performed by sensory hair cells. This model is still widely used today. However, it lacked a major facet: an understanding of the molecular mechanisms involved, starting with the identification of the proteins involved. It was the genetic approach that gradually made it possible to fill this gap, bringing the field of hearing into the "molecular era". We have outlined the emergence of this approach, and the major advances it has enabled, leading to an understanding of cochlear physiology in molecular terms. We then illustrated what can be expected of this approach today, based on a small number of recent studies from our laboratory and others.
Most of the data obtained to date concern the cochlea, the mammalian auditory sensory organ. Nevertheless, the molecular deciphering of the mechanisms of central sound processing (in the various relays of the auditory pathways from the cochlear nucleus to the auditory cortex) has already begun, also based on a genetic strategy; it promises to be the major development in the field in the years to come. The seminars that followed the lectures were part of this approach. They focused on the functioning of the auditory cortex. The plasticity of this system, which is called upon by all methods of auditory rehabilitation for deafness, both existing and in development, was the main common theme of these seminars.