Hyperactivations frontales en mémoire de travail dans le trouble cognitif léger
Recent studies have shown greater task-related activation in individuals with mild cognitive impairment (MCI) compared to healthy older adults. It has been suggested that these hyperactivations reflect compensatory processes of brain plasticity in the early phase of Alzheimer’s disease (AD). Functional compensation processes could emerge in response to a loss of structural integrity in brain regions typically required for the task. In this masters dissertation, I examined this hypothesis in MCI using a working memory task that incorporated a parametrical variation of difficulty level as well as functional and structural magnetic resonance imaging (MRI). Multiple regression analyses were used to identify areas of the brain in MCI in which functional activation varied as a function of neural injury as measured by hippocampal volume. Parameter estimates from these areas were then extracted and used for further correlational analyses with performance and structural volumes. Results indicate that MCI participants with high neural injury hyperactivated a subset of regions in the right frontal lobe. Furthermore, the level of activation was negatively correlated with the volume of frontal and parietal regions. These results indicate the presence of compensatory hyperactivations associated with a working memory task in persons with MCI.
Hyperactivation Analyses multimodales Alzheimer’s disease Mild cognitive impairment Executive functions Compensatory mechanisms Magnetic resonance imaging Multimodal analyses