Emilie, C. 1, 2, 3 , Perrone-Bertolotti, M. 1, 3 , Jouvenel, L. 1, 3 , Moreaud, O. 1, 4 , Toescu, E. 5 & Baciu, M. 1, 3
1 Laboratoire de Psychologie et Neurocognition, UMR CNRS 5105 Université Pierre Mendès-France, Grenoble
2 Structure Fédérative de Recherche N°1, RMN Biomédicale et Neurosciences, Unité IRM 3T, CHU Grenoble, France
3 Structure Fédérative de Recherche « Santé et Société», Université Pierre Mendès-France, Grenoble, France
4 Service de Neurologie, CHU Grenoble, France
5 Clinical and Experimental Medicine, School: Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT
The evolution of our knowledge of normal aging and its evolution now allow the development of strategies to prevent cognitive decline, knowing that dementia increases with age. In this study, we aim at highlighting cerebral correlates of language plasticity in old adults without cognitive impairment by using 2 neuroimaging methods: (i) resting state fMRI (RS-fMRI) in which the magnitude of deactivated regions underlines task-negative network (TNN) and (ii) fMRI of language task activations in which the magnitude of activated regions underlines task-positive network (TPN). 7 young adult volunteers and 7 old adults without cognitive impairment performed categorization tasks (Living) on words and images, respectively. These tasks were used to explore TPN. Moreover, they performed RS-fMRI (participants were instructed to fixate a cross in the middle of the screen during 7 min) in order to explore TNN. Our major result is that older people without cognitive impairment show (when compared to young adults) altered deactivations (decrease) of several TNN regions and higher levels of activation (reduced hemispheric asymmetry) within TPN regions, and particularly in bilateral prefrontal and temporal regions, during language tasks. Reduced asymmetry is congruent with the HAROLD model and compensation mechanism could explain altered links between TPN and TNN.