Disrupted Neuroscynchrony in Aging

Aging, a natural degenerative process of human physiology, gradually deteriorates our daily cognitive performance and sleep efficiency. Facing the global trend of aged society, the preventive medicine and early diagnosis of brain aging was one of the major targets in the global policy of Healthy Ageing. Therefore, following the call of Brain Initiative and the Human Brain Project, the resting-state functional connectivity (RSFC) has been widely applied to neurodegenerative investigations on brain integrity. However, it is noteworthy that previous investigations generally assumed the time-invariance of RSFC. In reality, accumulating researches addressed that RSFC changes dynamically between different times of a day. For example, Peltier et al. (2005) observed the reduction of sensorimotor RSFC following motor fatigue in healthy control. Khan et al. (2014) reported the default-mode network connectivity varied across different times of a day in clinical patients. These studies suggest that the circadian neurosynchrony indeed exists, and the disruption of circadian rhythms can further accelerate the aging process. To RSFC investigations based on large-cohort database, ignoring the circadian neurophysiology may lead to erroneous statements on the target of neurodegeneration. Here we propose a novel concept that the circadian neurosynchrony may shift in phase or weaken in amplitude between different age groups, affecting the sleep efficiency and cognitive performances. Therefore, in this proposal, we will target on examining the age effect on circadian neurophysiology among multiple brain networks.