ÉTUDE DU LIEN ENTRE LE SOMMEIL ET LA RÉACTIVITÉ DU LOCUS COERULEUS ÉVALUÉE VIA UNE TÂCHE AUDITIVE DE TYPE ODDBALL EN IRM À TRÈS HAUTE RÉSOLUTION

Abstract

Sleeping is a fundamental behavior that occupies almost a third of our lives. Its physiological importance is therefore easily understood. Scientific evidence of the role of quality sleep for healthy cognitive aging is accumulating. Many studies have shown the association between sleep dysfunction and Alzheimer's disease (AD). Interestingly, a significant aspect of AD is that its primary pathophysiological sign is detected post-mortem before the age of 35 years in the locus coeruleus (LC) which is a small brainstem nucleus essential for sleep regulation. Thus, there are some reasons to establish early associations between sleep and AD via the LC. However, the link between variability in sleep quality and variability in LC characteristics remains poorly understood in humans. Therefore, it seems appropriate to first study the link between sleep and LC characteristics such as its reactivity. In this context, we postulate that a greater LC reactivity during wakefulness is associated with a better sleep, during youth as well as throughout the aging process. To test this hypothesis, young (18-29 years, n = 13) and older subjects (53-69 years, n = 14) were recruited. On the one hand, we worked with electroencephalography to characterize sleep, on the other hand, we used ultra-high field MRI (7 Tesla) to assess LC reactivity. The aim of this thesis was to highlight a link between sleep and LC reactivity during an auditory oddball task. Our results suggested for the first time in humans, a link which seems to change over the life course. Thus, in the youth, sleep seems to be more stable when the LC is more reactive, at least when this reactivity is assessed via an auditory oddball task.