Abstract
Thalamic neurons discharge tonically during wakefulness and rapid-eye-movement (REM) sleep, but switch to burst firing during non-REM (NREM) sleep. It has been hypothesized that NREM thalamic bursts do not serve as a cortical “wake-up” signal due to their periodic and synchronized nature. Here, we analyze the simultaneously recorded polysomnographic signals, field potentials, and spiking activity of neurons in the ventral anterior and centromedian thalamic nuclei of two female non-human primates during naturally occurring vigilance states. These nuclei receive GABAergic output from the basal ganglia, with discharge rate decreasing during NREM sleep. Despite this reduction in inhibitory input, NREM bursting increases significantly as reported for glutamate-driven thalamic nuclei. The NREM bursts are neither periodic nor tightly synchronized. However, delta and sleep-spindle EEG activity and thalamic field potentials time-locked to burst onset during NREM sleep markedly differ from those observed during wakefulness and REM sleep. These results suggest that the basal ganglia modulate, rather than drive, their thalamic targets. Additionally, unique state-dependent thalamocortical dynamics, rather than the periodicity or tight synchrony of the thalamic bursts, are sufficient to account for why NREM thalamic bursts do not awaken the cortex.
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All data supporting the findings of this study are available within the paper as a Supplementary Data. Other data will be available from the corresponding authors upon reasonable request.
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We provided the code related to the figures of this paper as a Supplementary File. MATLAB code will also be available from the corresponding authors upon reasonable request. Please note that the code used in this study was developed by the researchers for data analysis and visualization. It is intended for research purposes and may not meet professional coding standards.
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Acknowledgements
The authors would like to thank Uri Werner-Reiss, PhD, for his valuable support with the surgical procedures and all aspects of monkey care, Tamar Ravins Yaish, DMD, and the HUJI-ELSC animal facility team for their assistance. We thank Ad Aertsen for the fruitful discussion of correlation analysis and the association index, and Andy Horn, Jackie Schiller, Pnina Rapel, Aric Agmon, and Yuval Nir for their discussions and comments on early versions of the manuscript. We acknowledge the use of large language model (LLM) tools for linguistic editing to improve the clarity and grammar of this manuscript; no scientific content was generated by these tools. This study is supported by grants from the ISF Breakthrough Research program (Grant No.: 1738/22) and the Collaborative Research Center TRR295, Germany (Project number 424778381) to HB.
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J.G. and H.B. conceived the research and designed the experiments. Z.I., D.W., and A.R. performed the surgical procedure. X.L. and J.G. supported the surgical procedure. They also performed the experiments, including electrophysiological and behavioral recordings, analyzed the data, and conducted the statistical analysis. X.L., J.G., and H.B. prepared the figures and wrote the manuscript. H.B. supervised the work. All authors read and approved the final manuscript.
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Liu, X., Guang, J., Israel, Z. et al. Entrained cortical delta–spindle activity, not periodic synchrony, prevents arousal by NREM thalamic bursts. Commun Biol (2026). https://doi.org/10.1038/s42003-026-09565-3
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DOI: https://doi.org/10.1038/s42003-026-09565-3
