Thursday January 6^th, 2022, from 3:00 to 4:00 p.m.

Université de Montréal, Pavilion Marie-Victorin, Room D-427 

The recording of the lecture is available: here

Post-lingual deafness-induced plasticity and consequences on auditory rehabilitation outcome

Abstract: Similarly to certain brain injuries, post-lingual deafness imposes central reorganization to adapt to the loss of easy and instinctive oral communication. Occurring in mature brains, plasticity cops with not so available brain resources such as those encountered in developing brains. Using fMRI in post-lingual deaf adults and matched normal hearing controls, we address the question of late deafness-induced reorganization by exploring phonological processing from written material and relate the different adopted strategies to speech recognition scores obtained after cochlear implantation (CI). During easy to more difficult written rhyming tasks, the involvement of right temporal areas during deafness prior to CI is a consistent marker of poor speech outcome after auditory rehabilitation. The recruitment of these right areas, not usually involved in phonological processing but in paralinguistic processing, is a marker of the central reorganization some subjects develop to palliate the difficulties of losing oral communication. Depending on the skills of audio-visual fusion, two neurobiological profiles emerge: i) some subjects are able to maintain a left hemispheric dominance anchored to oral interactions through left audio-visual loops, maintained by lip-reading. They will later become proficient CI users, ii) some subjects, less balanced, will develop a greater reliance on visual inputs, based on a functional interaction between early visual cortex and the right superior temporal areas. This greater right involvement favors and speeds up written processing, easing social interactions when lip-reading is impossible. This shift in hemispheric dominance, leaving the visual cortex less available for left audio-visual interactions, seems a reliable predictor of poorer CI outcome.

Bio: Dr. Diane Lazard is an ENT surgeon and a Neuroscientist, leading a research team at the Hearing Institute (Institut Pasteur) in Paris.  She defended her PhD at École Normale Supérieure and undertook several postdocs at the Bionics Institute, Melbourne, Australia, at École Normale Supérieure, Paris, France, and at the Institute of Neurosciences, Montpellier, France.

Her main basic research topic is cortical plasticity induced by deafness, and its links to cochlear implantation outcome. She is currently pursuing her work on deciphering language processing variability in deafness. She also practices surgical and teaching activities at the Institut Arthur Vernes, a non-profit surgical centre in Paris.

She plans to collaborate with Dr. Lehmann on McGill Cochlear Implant project.