Mardi 7 octobre 2025 à 11h00 / Amphithéâtre F. Canac, LMA
Summary: A cochlear implant is a medical device that creates of sensation of sound by directly stimulating the auditory nerve electrically. These devices have provided a sense of hearing to millions of people with severe or profound deafness. At the same time, they have provided a unique case for auditory research to study the mechanisms of sound coding at the level of the auditory nerve, and how the human hearing system adapts to new inputs that are unlike anything it has ever encountered. In this presentation, I will describe two studies aiming at characterizing the changes that take place in the auditory system when an adult individual receives cochlear implant stimulation after a period of deafness. One study focuses on apparent changes in the loudness of the sensation provided by the electrical stimulation. Using a set of electrophysiological techniques that probe neural activity at successive stages of processing in the brain, we investigated how the loudness of electrical stimulation relates to neural gain. Our results suggest that steady-state neural responses are a good predictor of loudness variations between individuals, but within-individual perceptual variations occur over time that are independent of the brain responses we measured. A second study focuses on the ability of cochlear implant recipients to discriminate between different temporal and spatial patterns of electrical nerve stimulation, and on how this ability may change as they gain more experience listening with their device. These studies may help explain the wide variability of speech perception performances with implants and the variability of the associated “learning trajectories”, as well as orient rehabilitation strategies for those recipients making slower progress.
