ABSTRACT
Sleep is a highly stereotyped and reproducible phenomenon, requiring robust spatial and temporal coordination of neural activity. Understanding how the brain coordinates across local and long-range neural activity upon the transition to sleep is necessary as a foundation for research on the physiological functions subserved by sleep and pathologic phenomena associated with the sleep transition. In this study, we quantified whole brain network changes during the transition from wake to non-rapid eye movement (NREM) sleep using magnetoencephalography imaging in healthy subjects. In addition, we performed computational modeling to infer excitatory and inhibitory properties of local neural activity. Local and long-range neural synchrony in wake and light NREM sleep stages revealed that the transition to sleep is encoded in spatially and temporally specific patterns of regional neural activity. Patterns of information flow demonstrated that the mesial frontal regions receive hierarchically organized inputs from broad cortical regions in NREM as compared to wakefulness. Finally, biophysical neural mass modeling revealed that sleep onset was accompanied by a spatially heterogeneous change in cortical excitation-to-inhibition, highlighting a cortically-based homeostatic process with the transition to sleep. Together, these findings provide clear evidence for the structured corticocortical modulation in sleep-wake behavior and demonstrate the orchestration of local and long-range, frequency-specific cortical interactions that are fundamental to sleep onset.
Competing Interest Statement
The authors have declared no competing interest.
Abbreviations
- Amyg
- amygdala
- CG
- cingulate gyrus
- FC
- functional connectivity
- FuG
- fusiform gyrus
- Hipp
- hippocampus
- IFG
- inferior frontal gyrus
- IPL
- inferior parietal lobule
- INS
- insula
- ITG
- inferior temporal gyrus
- IQR
- interquartile range
- LOcC
- lateral occipital cortex
- MEG
- magnetoencephalography
- MFG
- middle frontal gyrus
- MTG
- middle temporal gyrus
- MVOcC
- medioventral occipital cortex
- NREM
- non-rapid eye movement
- N1
- stage 1 sleep (NREM)
- N2
- stage 2 sleep (NREM)
- OrG
- orbital frontal gyrus
- PCL
- paracentral lobule
- Pcun
- precuneus
- PhG
- parahippocampal gyrus
- PoG
- postcentral gyrus
- PrG
- precentral gyrus
- pSTS
- posterior superior temporal sulcus
- ROI
- region of interest
- SFG
- superior frontal gyrus
- SPL
- superior parietal lobule
- STG
- superior temporal gyrus
- W
- wake