Cross-Scale Dynamicity of Entropy and Connectivity in the Sleeping Brain

Yi Chia Kung, Chia Wei Li, Fan Chi Hsiao, Pei Jung Tsai, Shuo Chen, Ming Kang Li, Hsin Chien Lee, Chun Yen Chang, Changwei W. Wu*, Ching Po Lin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Introduction: The concept of local sleep refers to the phenomenon of local brain activity that modifies neural networks during unresponsive global sleep. Such network rewiring may differ across spatial scales; however, the global and local alterations in brain systems remain elusive in human sleep. Materials and Methods: We examined cross-scale changes of brain networks in sleep. Functional magnetic resonance imaging data were acquired from 28 healthy participants during nocturnal sleep. We adopted both metrics of connectivity (functional connectivity [FC] and regional homogeneity [ReHo]) and complexity (multiscale entropy) to explore the global and local functionality of the neural assembly across nonrapid eye movement sleep stages. Results: Long-range FC decreased with sleep depth, whereas local ReHo peaked at the N2 stage and reached its lowest level at the N3 stage. Entropy exhibited a general decline at the local scale (Scale 1) as sleep deepened, whereas the coarse-scale entropy (Scale 3) was consistent across stages. Discussion: The negative correlation between Scale-1 entropy and ReHo reflects the enhanced signal regularity and synchronization in sleep, identifying the information exchange at the local scale. The N2 stage showed a distinctive pattern toward local information processing with scrambled long-distance information exchange, indicating a specific time window for network reorganization. Collectively, the multidimensional metrics indicated an imbalanced global-local relationship among brain functional networks across sleep-wake stages.

Original languageEnglish
Pages (from-to)835-845
Number of pages11
JournalBrain Connectivity
Issue number9
Publication statusPublished - 2022 Nov


  • functional connectivity
  • functional magnetic resonance imaging
  • local sleep
  • multiscale entropy
  • regional homogeneity
  • sleep

ASJC Scopus subject areas

  • General Neuroscience


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