| dc.description.abstract | Sleep is an important physiological rhythm for many creatures, not only associated with physical regulation but also associated with mental reorganization. It has been proven that sleep correlates with lots of cognitive functions such as the emotion regulation, memory consolidation and attention. Previous sleep studies were typically conducted using electroencephalography (EEG), targeting on the changes of specific frequency bands or certain sleep stage; however, dynamic changes was rarely reported across all frequency bands and sleep stages. Therefore, to reveal the dynamicity within sleeping brain, we first investigate the sleeping EEG power and connectivity across frequency bands and non-rapid-eye-movement (NREM) sleep stages using simultaneous EEG-fMRI. Our second goal is to observe the impact of slow wave sleep (SWS) on brain activity and connectivity. Our results indicated spectral and regional disparities in EEG power and connectivity analysis across sleep stages. For example, the delta band showed increasing power along with deep sleep stages, meanwhile the delta connectivity pattern converted from waking longitudinal connection into a transverse connection during sleep. Secondly, the low-frequency bands did not show significant SWS effect on awakening in both power and transverse connectivity, but presented strong changes in longitudinal connectivity, which implied that slow wave sleep modulates the brain longitudinal connectivity. Furthermore, it should be noted that both EEG and fMRI presented a dissimilar mismatch between the spectral power and functional connectivity across sleep stages. Conclusively, this study indicate that during NREM sleep, EEG frequency bands had their own dynamic features in both power and connectivity, and lack of slow wave sleep might affect the consecutive functional connectivity upon awakening. | en_US |