Noradrenaline and acetylcholine shape functional connectivity organization of NREM substages: An empirical and simulation study
Fernando Lehue, Carlos Coronel-Oliveros, Vicente Medel, Thomas Liebe, Jörn Kaufmann, Sebastián Orellana, Diego Becerra, Enzo Tagliazucchi, Patricio Orio
Abstract
Sleep onset is characterized by a departure from arousal, and can be separated into well-differentiated stages: NREM (which encompasses three substages: N1, N2 and N3) and REM (Rapid Eye Movement). Awake brain dynamics are maintained by various wake-promoting mechanisms, particularly the neuromodulators Acetylcholine (ACh) and Noradrenaline (NA), whose levels naturally decrease during the transition to sleep.
Introduction
Sleep is a natural state of reduced consciousness, where the brain transits between different functional states naturally driven by neuromodulatory systems [1]. Transitions between different stages of sleep constitute a naturalistic way to understand the neurochemical mechanisms behind states of consciousness.
Materials and method
EEG-fMRI acquisition and preprocessing
The dataset comprises EEG, EMG and fMRI recordings acquired from 71 participants [9]. All subjects were scanned during the evening and instructed to close their eyes and lie still and relaxed.
Results
We used fMRI data previously obtained in [9]. Recordings were obtained from 71 individuals, simultaneously with polysomnography measures from which sleep stages were labeled in each fMRI volume. As is common during a normal night’s sleep, there are regular jumps between epochs of different sleep stages.
Discussion
Summary
In this work, we analyzed empirical FC of individuals in NREM sleep stages, and fitted FC using a whole-brain model that includes ACh and NA neuromodulatory influences. From the analysis of the fluctuations of empirical FCs, our results suggest a decrease in NA modulation during N2, and a joint decrease of ACh and NA modulation in N3. At the same time, they do not show changes in LC and BF FC between W and N1. The in-silico testing of our empirically-derived hypotheses of NREM modulation then suggests a role of ACh in the transition from W to N1, and a role of NA in the transition from N1 to N2 and N3 (see parameters in Fig 3 and FC matrices in Fig 4).
Acknowledgments
F.L. is supported by Beca de Doctorado Nacional N° 21220708 (Agencia Nacional de Investigación y Desarrollo ANID, Chile). V.M. is supported by FONDECYT Exploración 13240170 and FONDECYT de Iniciación 11251578 (ANID, Chile). T.L. is supported by a German Research Foundation Grant (D.F.G.) Projektnummer 41466077, 526259959. J.K. received no specific funding for this work.
Citation: Lehue F, Coronel-Oliveros C, Medel V, Liebe T, Kaufmann J, Orellana S, et al. (2025) Noradrenaline and acetylcholine shape functional connectivity organization of NREM substages: An empirical and simulation study. PLoS Comput Biol 21(10): e1012852. https://doi.org/10.1371/journal.pcbi.1012852
Editor: Hugues Berry, Inria, FRANCE
Received: February 3, 2025; Accepted: October 14, 2025; Published: October 28, 2025
Copyright: © 2025 Lehue et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: fMRI data has been previously published in Tagliazucchi et al., 2012 (10.1016/j.neuroimage.2012.06.036) and is availabe at https://zenodo.org/records/16755776 Structural connectome (kindly provided by Dr. Gustavo Deco (Deco et al., 2018, 10.1016/j.cub.2018.07.083)) and Python codes to reproduce analysis and Figures are available at https://github.com/vandal-uv/NREMmodFC.
Funding: F.L. is supported by Beca de Doctorado Nacional N° 21220708 (Agencia Nacional de Investigación y Desarrollo ANID, Chile). V.M. is supported by FONDECYT Exploración 13240170 and FONDECYT de Iniciación 11251578 (ANID, Chile). T.L. is supported by a German Research Foundation Grant (D.F.G.) Projektnummer 41466077, 526259959. J.K. received no specific funding for this work. S.O. is supported by Beca de Doctorado Nacional N°21241572 (ANID, Chile). D.B is supported by Beca de Doctorado Nacional N°21210914 (ANID, Chile). E.T is supported by FONDECYT Exploración 13240170 and FONDECYT Regular 1220995 (ANID, Chile). P.O. is supported by FONDECYT Regular 1241469 (ANID, Chile) Fondecyt Exploración 13240170, and the Advanced Center for Electrical and Electronic Engineering (AFB240002 ANID, Chile).The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
