The electroencephalogram (EEG) reflecting brain activity may be characterised through brief periods of stable neural activity patterns that recur over time and are referred to as microstates. Microstates are related to a range of cognitive processes, and their analysis has become an increasingly popular tool for studying human brain function. While microstates have been extensively studied in humans, their presence and characteristics in animal models have yet to be as thoroughly investigated. This study aims to address this gap by detecting and characterising microstates in EEGs of rats collected using a superficial electrode system corresponding to homological areas of the human 10-20 system. Specifically, we demonstrate the presence of microstates in rats' EEGs, i.e., those that may be captured by the same metrics as in humans. We identified five microstate EEG maps in rats, explaining 71% of the variance in our dataset (N = 30). The explained variance, mean temporal coverage values (0.2), and average duration (0.26 s) are comparable to the human-derived EEG microstates. Via a source localisation technique, the cingulate cortex, precuneus, and insula were found to be associated with the microstates' temporal dynamics. Among the microstates that showed a broadband character, we also found those that showed an association with the theta and alpha bands. These findings have important implications for the use of microstates as a preclinical tool for investigating brain functions, detecting new biomarkers of brain diseases, and translating this knowledge to humans.

3rd Faculty of Medicine Charles University Prague Prague Czech Republic

Clinical Research Program National Institute of Mental Health Klecany Czech Republic

Dept of Biomedical Technology Faculty of Biomedical Engineering Czech Technical University Prague Kladno Czech Republic

Faculty of Electrical Engineering Czech Technical University Prague Prague Czech Republic

Institute of Biosciences Vilnius University Vilnius Lithuania

Institute of Computer Science Czech Academy of Sciences Prague Czech Republic

Psychedelic Research Centre National Institute of Mental Health Klecany Czech Republic

Sleep and Chronobiology Research Centre National Institute of Mental Health Klecany Czech Republic

Translational Health Research Institute Vilnius University Vilnius Lithuania

Zobrazit více v PubMed

Khanna A, Pascual-Leone A, Michel CM, Farzan F. Microstates in resting-state eeg: current status and future directions. Neurosci Biobehav Rev. 2015;49:105–13. 10.1016/j.neubiorev.2014.12.010. PubMed DOI PMC

Michel CM, Koenig T, Brandeis D, Gianotti LRR, Wackermann J. Electrical neuroimaging. Cambridge: Cambridge University Press, 2009. 10.1017/CBO9780511596889.

Tarailis P, Koenig T, Michel CM, et al. The functional aspects of resting eeg microstates: a systematic review. Brain Topogr. 2024;37:181–217. 10.1007/s10548-023-00958-9. PubMed DOI

Koenig T, Prichep L, Lehmann D, Sosa PV, Braeker E, Kleinlogel H, et al. Millisecond by millisecond, year by year: normative EEGg microstates and developmental stages. NeuroImage. 2002;16:41–48. 10.1006/nimg.2002.1070. PubMed DOI

Kleinert T, Nash K, Koenig T, et al. Normative intercorrelations between EEG microstate characteristics. Brain Topogr. 2024;37:265–9. 10.1007/s10548-023-00988-3. PubMed DOI PMC

Bressler SL, Kelso JA. Cortical coordination dynamics and cognition. Trends Cogn Sci. 2001;5:26–36. 10.1016/s1364-6613(00)01564-3. PubMed DOI

Michel CM, Koenig T. EEG microstates as a tool for studying the temporal dynamics of whole-brain neuronal networks: A review. NeuroImage. 2018;180:577–93. PubMed DOI

Britz J, Van De Ville D, Michel CM. Bold correlates of EEG topography reveal rapid resting-state network dynamics. NeuroImage. 2010;52:1162–70. 10.1016/j.neuroimage.2010.02.052. PubMed DOI

Bréchet L, Michel CM. EEG microstates in altered states of consciousness. Front Psychol. 2022;13:856697. 10.3389/fpsyg.2022.856697. PubMed DOI PMC

Zanesco AP, King BG, Skwara AC, Saron CD. Within and between-person correlates of the temporal dynamics of resting EEG microstates. NeuroImage. 2020;211:116631. 10.1016/j.neuroimage.2020.116631. PubMed DOI

Schiller B, Kleinert T, Teige-Mocigemba S. Temporal dynamics of resting EEG networks are associated with prosociality. Sci Rep. 2022;10:1–10. 10.1038/s41598-020-69999-5. DOI

Kleinert T, Nash K. Trait aggression is reflected by a lower temporal stability of eeg resting networks. Brain Topogr. 2024;37:514–23. 10.1007/s10548-022-00929-6. PubMed DOI PMC

Mégevand P, Quairiaux C, Lascano AL, Kiss JZ, M MC. A mouse model for studying large-scale neuronal networks using eeg mapping techniques. Neuroimage. 2008;42:591–602. 10.1016/j.neuroimage.2008.05.016. PubMed DOI

Mishra A, Marzban N, Cohen MX, Englitz B. Dynamics of neural microstates in the vta–striatal–prefrontal loop during novelty exploration in the rat. J Neurosci. 2021;41:6864–77. 10.1523/JNEUROSCI.2256-20.2021. PubMed DOI PMC

Salagean A, Pasc AM, Ardelean ER, Muresan RC, Moca VV, Dinsoreanu M, et al. Local field potential microstate analysis. IEEE Explore, 2022;221-7. 10.1109/ICCP56966.2022.10053960

Boyce R, Dard RF, Cossart R. Cortical neuronal assemblies coordinate with EEG microstate dynamics during resting wakefulness. Cell Rep. 2023;42:112053. 10.1016/j.celrep.2023.112053. PubMed DOI PMC

Milz P, Pascual-Marqui RD, Achermann P, Kochi K, Faber PL. The EEG microstate topography is predominantly determined by intracortical sources in the alpha band. Neuroimage. 2017;162:353–61. 10.1016/j.neuroimage.2017.08.058. PubMed DOI

Custo A, Van De Ville D, Wells W, Tomescu M, Brunet D, Michel C. EEG resting-state networks: microstates’ source localization. Brain Connect 2017;7:671–82. 10.1089/brain.2016.0476

Paxinos G, Watosn C The rat brain in stereotaxic coordinates. Amsterdam: Academic Press; 2014.

Vejmola Č, Tylš F, Piorecká V, Koudelka V, Kadeřábek L, Novák T, et al. Psilocin, LSD, mescaline, and DOB all induce broadband desynchronization of EEG and disconnection in rats with robust translational validity. Transl psychiatry. 2021;11:506. 10.1038/s41398-021-01603-4. PubMed DOI PMC

Delorme A, Makeig S. Eeglab: an open source toolbox for analysis of single-trial EEG dynamics including independent component analysis. J Neurosci Methods. 2004;134:9–21. 10.1016/j.jneumeth.2003.10.009. PubMed DOI

Pascual-Marqui RD, Michel CM, Lehmann D. Segmentation of brain electrical activity into microstates: model estimation and validation. IEEE Trans Biomed Eng. 1995;42:658–65. 10.1109/10.391164. PubMed DOI

Murray M, Brunet D, Michel C. Topographic erp analyses: a step-by-step tutorial review. Brain Topogr. 2008;20:249–64. 10.1007/s10548-008-0054-5. PubMed DOI

Brunet D, Murray MM, Michel CM. Spatiotemporal analysis of multichannel EEG: Cartool. Computational intelligence and neuroscience 2011 2011. 10.1155/2011/813870

Koenig T. MicrostateAnalysis (Version 1.2) [EEGLAB plugin]. 2018. Available from: https://sccn.ucsd.edu/eeglab/plugin_uploader/plugin_list_all.php

Poulsen A, Pedroni A, Langer N, Hansen L. Microstate EEGLAB toolbox: an introductory guide 2018. 10.1101/289850

Lehmann D, Faber PL, Galderisi S, Herrmann WM, Kinoshita T, Koukkou M, et al. EEG microstate duration and syntax in acute, medication-naive, first-episode schizophrenia: a multi-center study. Psychiatry Res: Neuroimaging. 2005;138:141–56. 10.1016/j.pscychresns.2004.05.007. DOI

Al Zoubi O, Mayeli A, Tsuchiyagaito A, Misaki M, Zotev V, Refai H, et al. EEG microstates temporal dynamics differentiate individuals with mood and anxiety disorders from healthy subjects. Front Hum Neurosci. 2019;13:56. 10.3389/fnhum.2019.00056. PubMed DOI PMC

Milz P, Faber PL, Lehmann D, Koenig T, Kochi K, Pascual-Marqui RD. The functional significance of EEG microstates—associations with modalities of thinking. Neuroimage. 2016;125:643–56. 10.1016/j.neuroimage.2015.08.023. PubMed DOI

Krzanowski WJ, Lai YT. A criterion for determining the number of groups in a data set using sum-of-squares clustering. Biometrics. 1988;44:23–34. 10.2307/2531893. DOI

Brodbeck V, Kuhn A, von Wegner F, Morzelewski A, Tagliazucchi E, Borisov S, et al. EEG microstates of wakefulness and NREM sleep. NeuroImage. 2012;62:2129–39. 10.1016/j.neuroimage.2012.05.060. PubMed DOI

von Wegner F, Knaut P, Laufs H. EEG microstate sequences from different clustering algorithms are information-theoretically invariant. Front Computational Neurosci. 2018;12:70. 10.3389/fncom.2018.00070. DOI

Günther W, Müller N, Trapp W, Haag C, Putz A, Straube A. Quantitative EEG analysis during motor function and music perception in tourette's syndrome. Eur Arch Psychiatry Clin Nuerosci. 1996;246:197–202. 10.1007/BF02188953. DOI

Jiricek S, Koudelka V, Lacik J, Vejmola C, Kuratko D, Wójcik DK, et al. Electrical Source Imaging in Freely Moving Rats: Evaluation of a 12-Electrode Cortical Electroencephalography System. Front Neuroinform. 2021;14:589228. 10.3389/fninf.2020.589228. PubMed DOI PMC

Pascual-Marqui, RD: Discrete, 3d distributed, linear imaging methods of electric neuronal activity part 1: exact, zero error localization. arXiv [Preprint]. 2007 0710.3341. Available from: 10.48550/arXiv.0710.3341

Oostenveld R, Fries P, Maris E, Schoffelen J-M. Fieldtrip: Open source software for advanced analysis of MEG, EEG, and invasive electrophysiological data. Computat Intell Neurosci. 2011;2011:156869. 10.1155/2011/156869. DOI

Pascual-Marqui RD, Lehmann D, Faber P, Milz P, Kochi K, Yoshimura M, et al. The resting microstate networks (RMN): cortical distributions, dynamics, and frequency specific information flow. arXiv [Preprint]. 2014 1411.1949. Available from: 10.48550/arXiv.1411.1949

Mishra A, Englitz B, Cohen MX. EEG microstates as a continuous phenomenon. Neuroimage. 2020;208:116454. 10.1016/j.neuroimage.2019.116454. PubMed DOI

Smith SM, Nichols TE. Threshold-free cluster enhancement: addressing problems of smoothing, threshold dependence and localisation in cluster inference. Neuroimage. 2009;44:83–98. 10.1016/j.neuroimage.2008.03.061. PubMed DOI

Valdés-Hernández PA, Sumiyoshi A, Nonaka H, Haga R, Aubert- Vásquez E. Ogawa, et al. An in vivo MRI template set for morphometry, tissue segmentation, and fMRI localization in rats. Front neuroinform. 2011;5:26. 10.3389/fninf.2011.00026. PubMed DOI PMC

Zhang K, Shi W, Wang C, Li Y, Liu Z, Liu T, et al. Reliability of EEG microstate analysis at different electrode densities during propofol-induced transitions of brain states. NeuroImage. 2021;231:117861. 10.1016/j.neuroimage.2021.117861. PubMed DOI

Murphy M, Stickgold R, Parr E, Callahan C, Wamsley E. Recurrence of task-related electroencephalographic activity during post-training quiet rest and sleep. Sci Rep. 2018;8:5398. 10.1038/s41598-018-23590-1. PubMed DOI PMC

Vellante F, Ferri F, Baroni G, Croce P, Migliorati D, Pettorruso M, et al. Euthymic bipolar disorder patients and EEG microstates: a neural signature of their abnormal self experience. J Affect Disord. 2020;272:326–34. 10.1016/j.jad.2020.03.175. PubMed DOI

Santarnecchi E, Khanna AR, Musaeus CS, et al. EEG microstate correlates of fluid intelligence and response to cognitive training. Brain Topogr. 2017;30:502–20. 10.1007/s10548-017-0565-z. PubMed DOI

Croce P, Zappasodi F, Capotosto P. Offline stimulation of human parietal cortex differently affects resting EEG microstates. Sci Rep. 2018;8:1–8. 10.1038/s41598-018-19698-z. PubMed DOI PMC

Croce P, Zappasodi F, Spadone S, Capotosto P. Magnetic stimulation selectively affects pre-stimulus EEG microstates. NeuroImage. 2018;176:239–45. 10.1016/j.neuroimage.2018.04.061. PubMed DOI

Zappasodi F, Perrucci M, Saggino A, Croce P, Mercuri P, Romanelli R, et al. EEG microstates distinguish between cognitive components of fluid reasoning. NeuroImage. 2019;189:560–73. 10.1016/j.neuroimage.2019.01.067. PubMed DOI

Gschwind M, Hardmeier M, Van De Ville D, Tomescu MI, Penner I-K, Naegelin Y, et al. Fluctuations of spontaneous EEG topographies predict disease state in relapsing-remitting multiple sclerosis. NeuroImage: Clin. 2016;12:466–77. 10.1016/j.nicl.2016.08.008. PubMed DOI PMC

Hatz F, Hardmeier M, Bousleiman H, Rüegg S, Schindler C, Fuhr P. Reliability of functional connectivity of electroencephalography applying microstate-segmented versus classical calculation of phase lag index. Brain Connect. 2016;6:461–9. 10.1089/brain.2015.0368. PubMed DOI

Zanesco AP. Normative temporal dynamics of resting EEG microstates. Brain Topogr. 2024;37:243–64. 10.1007/s10548-023-01004-4. PubMed DOI

Seitzman BA, Abell M, Bartley SC, Erickson MA, Bolbecker AR, Hetrick WP. Cognitive manipulation of brain electric microstates. Neuroimage. 2017;146:533–43. 10.1016/j.neuroimage.2016.10.002. PubMed DOI PMC

Férat V, Seeber M, Michel CM, Ros T. Beyond broadband: Towards a spectral decomposition of electroencephalography microstates. Hum Brain Mapp. 2022;43:3047–61. 10.1002/hbm.25834. PubMed DOI PMC

Krylova M, Alizadeh S, Izyurov I, Teckentrup V, Chang C, van der Meer J, et al. Evidence for modulation of EEG microstate sequence by vigilance level. NeuroImage. 2021;224:117393. 10.1016/j.neuroimage.2020.117393. PubMed DOI

Bréchet L, Brunet D, Birot G, Gruetter R, Michel CM, Jorge J. Capturing the spatiotemporal dynamics of self-generated, task-initiated thoughts with EEG and fMRI. Neuroimage. 2019;194:82–92. 10.1016/j.neuroimage.2019.03.029. PubMed DOI

da Cruz JR, Favrod O, Roinishvili M, Chkonia E, Brand A, Mohr C, et al. EEG microstates are a candidate endophenotype for schizophrenia. Nat Commun. 2020;11:3089. 10.1038/s41467-020-16914-1. PubMed DOI PMC

Li Y, Yuan S, Liu X, Tang Y, Wang Y, Zhang X. EEG microstates as markers of major depressive disorder: a resting-state study before and after antidepressant treatment. Prog Neuro-psychopharmacol Biol Psychiatry. 2022;116:110514. 10.1016/j.pnpbp.2022.110514. DOI

Berchio C, Kumar SS, Narzisi A, Fabbri-Destro M. EEG microstates in the study of attention-deficit hyperactivity disorder: a review of preliminary evidence. Psychophysiology. 2025;62:e14762. 10.1111/psyp.14762. PubMed DOI

Koenig T, Lehmann D, Merlo MC, Kochi K, Hell D, Koukkou M. A deviant EEG brain microstate in acute, neuroleptic-naive schizophrenics at rest. Eur Arch psychiatry Clin Neurosci. 1999;249:205–11. 10.1007/s004060050088. PubMed DOI

Jajcay N, Hlinka J. Towards a dynamical understanding of microstate analysis of M/EEG data. NeuroImage. 2023;281:120371. 10.1016/j.neuroimage.2023.120371. PubMed DOI

Pascual-Marqui RD, Kochi K, Kinoshita T On the relation between EEG microstates and cross-spectra. arXiv [Preprint]. 2022 2208.02540. Available from: 10.48550/arXiv.2208.02540

van den Heuvel MP, Sporns O. Network hubs in the human brain. Trends Cogn Sci. 2013;17:683–96. 10.1016/j.tics.2013.09.012. PubMed DOI

Hagmann P, Cammoun L, Gigandet X, Meuli R, Honey CJ, Van Wedeen J, et al. Mapping the structural core of human cerebral cortex. PLoS Biol. 2008;6:1479–93. 10.1371/journal.pbio.0060159. DOI

Collin G, Sporns O, Mandl RCW, Van Den Heuvel MP. Structural and functional aspects relating to cost and benefit of rich club organization in the human cerebral cortex. Cereb Cortex. 2014;24:2258–67. 10.1093/cercor/bht064. PubMed DOI PMC

Musso F, Brinkmeyer J, Mobascher A, Warbrick T, Winterer G. Spontaneous brain activity and EEG microstates. a novel EEG/fMRI analysis approach to explore resting-state networks. Neuroimage. 2010;52:1149–61. 10.1016/j.neuroimage.2010.01.093. PubMed DOI

Rajkumar R, Régio Brambilla C, Veselinović T, et al. Excitatory–inhibitory balance within EEG microstates and resting-state fMRI networks: assessed via simultaneous trimodal PET–MR–EEG imaging. Transl Psychiatry. 2021;11:60. 10.1038/s41398-020-01160-2. PubMed DOI PMC

Hallez H, Vanrumste B, Grech R, Muscat J, De Clercq W, Vergult A, et al. Review on solving the forward problem in EEG source analysis. J Neuroeng rehabil. 2007;4:1–29. 10.1186/1743-0003-4-46. PubMed DOI PMC