• Citer

Multimodal functional mapping of language and associated control processes

par Dumitrescu, Alexandru Mihai
Président du jury Colin, Cécile
Promoteur De Tiege, Xavier
Co-Promoteur Urbain, Charline
Publication Non publié, 2024-09-10

Thèse de doctorat

• Accès en ligne
• Détails
• Contenu
• Statistiques

Résumé :

This PhD dissertation aims to characterize the spatial and temporal signatures of neural processes related to language control, providing valuable temporal information to the current static picture of the neural underpinnings of language control during challenging production tasks. Additionally, it strengthens the link between oscillatory cortical activity in specific frequency bands and the existing functional magnetic resonance imaging (fMRI) literature on lexical-semantic control.To achieve this fundamental goal, while bringing together the strengths of a multimodal neuroimaging approach combining magnetoencephalography (MEG) and fMRI, we first explored the oscillatory brain dynamics underlying language control processes (Study 1). Functional brain activity was recorded using MEG and fMRI in native French healthy adults during silent verb generation (VGEN) and picture naming (PN) tasks upon confrontation with pictures requiring low or high lexical-semantic control processes. We showed that language control processes critically rely on a complex sequence of early and late brain synchronization (ERS/ERD) processes involving fronto-temporo-parietal brain regions, with the prefrontal areas particularly involved at early stages.Further, we investigated the neural dynamics associated with verbal fluency tasks (VFT) and the differences between phonologic fluency task (PFT) and semantic fluency task (SFT) (Study 2) using MEG and fMRI. Through fMRI, we demonstrated that PFT, compared with SFT, relies on a left-dominant fronto-temporo-parietal network involved in lexical-semantic control processes, presumably due to the predominance of switching processes in this task. Conversely, SFT specifically engaged nodes of the semantic representation network which aligns with the predominance of clustering processes in that task. MEG identified beta-band power suppression at the left operculum during VFT with no significant difference between PFT and SFT, suggesting that it could reflect similar neural processes associated with the covert word production during the VFT. In conclusion, by combining advanced imaging techniques, this PhD dissertation offers valuable insights into the complex processes of language control and brain function. These findings provide a robust foundation for future clinical applications, particularly in the neuromagnetic preoperative language mapping for neurosurgical patients.