Cortical excitability signatures for the degree of sleepiness in human
Sleep is essential in maintaining physiological homeostasis in the brain. While the underlying mechanism is not fully understood, a 'synaptic homeostasis' theory has been proposed that synapses continue to strengthen during awake, and undergo downscaling during sleep. This theory predicts that brain excitability increases with sleepiness. Here, we collected transcranial magnetic stimulation (TMS) measurements in 38 subjects in a 34-hour program, and decoded the relationship between cortical excitability and self-report sleepiness using advanced statistical methods. By utilizing a combination of partial least squares (PLS) regression and mixed-effect models, we identified a robust pattern of excitability changes, which can quantitatively predict the degree of sleepiness. Moreover, we found that synaptic strengthen occurred in both excitatory and inhibitory connections after sleep deprivation. In sum, our study provides supportive evidence for the synaptic homeostasis theory in human sleep and clarifies the process of synaptic strength modulation during sleepiness.
All data generated or analysed during this study are included in the manuscript and supporting files.
Article and author information
National Key Research and Development Program of China (2018YFC2001700)
- Yi Wu
the Key Projects of Shanghai Science and Technology on Biomedicine (18411962300)
- Rui-Ping Hu
Shanghai Health and Family Planning Commission project (201840225)
- Yu-Lian Zhu
Shanghai Municipal Key Clinical Specialty (s.shslczdzk02702)
- Yi Wu
the Key Projects of Shanghai Science and Technology on Biomedicine (20412420200)
- Yi Wu
Natural Science Foundation of China grant (32071010)
- Zhe Zhang
Shanghai Pujiang Program (20PJ1415000)
- Zhe Zhang
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Human subjects: 1. That informed consent, and consent to publish, was obtained2. This study was designed as a prospective self-controlled study. The Ethics Committee of Huashan Hospital approved the study (2017-410) and was registered on the Chinese Clinical Trial Registry (ChiCTR1800016771).
- Laura Dugué, Université de Paris, France
- Received: November 22, 2020
- Accepted: July 26, 2021
- Accepted Manuscript published: July 27, 2021 (version 1)
- Version of Record published: August 18, 2021 (version 2)
© 2021, Chia et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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