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Thesis defense : Célise HALDIN

Thesis defence

On 6 March 2023

Neurocognitive and linguistic reorganization of language and speech in post-stroke aphasia. An interdisciplinary approach

The language disorders that characterize post-stroke aphasia interfere with patients’ communication abilities, with multiple impacts on daily life. There is considerable variability in the initial severity of language disorders, as well as the degree of speech and language recovery among patients. Moreover, the effectiveness of classical speech therapy methods decreases after a few months of application. In addition, socio-economic and medical factors are known to influence the management of patients in the chronic phase. Therefore, there are two essential steps towards advancing the treatment of patients with post-stroke aphasia. First, there is a need for a more thorough understanding of the neurocognitive mechanisms and factors influencing language representation and neuroplasticity in patients with post-stroke disorders. Second, new methods and programs for speech and language rehabilitation in patients with disorders following a brain injury need to be developed on the basis of these novel findings and adapted to long-term management.Following these requirements and in line with current theoretical models of speech production, the two main goals of this thesis are (i) to better understand the alteration of speech and language mechanisms in relation to other cognitive processes and the reorganization of the underlying brain networks and (ii) to propose new perspectives for speech and language rehabilitation. Specifically, we propose a new rehabilitation method based on technology that provides a realistic visual illustration of lingual and labial articulatory dynamics (the Ultraspeech-player software). We assume that adding visual information could improve the multisensory phonological representations on which motor planning and programming rely during speech production. This visual information could thus contribute to the reorganization of language networks and to the compensation of deficits observed in post-stroke non-fluent aphasia. Beyond developing a new method, we highlight the interest of applying rehabilitation programs combining at least two methods to increase the efficiency and speed of speech and language recovery.In the first part of this work, we focus on the role of determinants of initial severity and recovery of language and speech in patients with post-stroke aphasia. We show the importance of intensive rehabilitation in patients with severe aphasia following a frontal injury involving the inferior frontal gyrus. In addition, we argue that reinforcing phonological mechanisms through audio-visual training of speech would allow for optimal anatomo-functional reorganization of language networks.In the second part, we propose to supplement classical language and speech therapy with visually augmented rehabilitation (the Ultraspeech-player software). Our results suggest that this new rehabilitation program strengthens phonological representations and contributes to reorganizing language networks in patients with post-stroke aphasia.Taken together, the results of this thesis allow us to propose an experimental protocol that evaluates, at the group level, the efficiency of the augmented rehabilitation at the language, cognitive and cerebral levels. More precisely, in future studies, we aim to demonstrate in patients with non-fluent aphasia: (i) the effectiveness of visually augmented rehabilitation, compared to conventional speech therapy, and (ii) the effectiveness of a rehabilitation program combining several methods, compared to a single method. By including a control group of age-matched healthy participants, we will also provide new evidence of the effects of aging on cognitive mechanisms and the reorganization of speech and language brain networks.

Composition du jury :

François-Xavier ALARIO - Directeur de Recherche, CNRS, Délégation Provence Alpes - Rapporteur
Arnaud SAJ - Professeur Adjoint, Université de Montréal - Rapporteur
Sylvie MORITZ-GASSER - Maître de Conférences, Université de Montpellier - Examinatrice
Olivier DETANTE - Professeur des Universités, Praticien Hospitalier, Université Grenoble Alpes - Examinateur
Monica BACIU - Professeure des Universités, Université Grenoble Alpes - Directrice de thèse
Hélène LŒVENBRUCK - Directrice de Recherche, CNRS, Délégation Alpes - Co-Directrice de thèse

Read the thesis


On 6 March 2023



01/10/2019 - 31/03/2023

Submitted on 20 November 2023

Updated on 20 November 2023