Abstract
Spontaneous brain activity exhibits a highly structured modular organization that varies across individuals and reconfigures over time. Although it has been proposed that brain organization is shaped by an economic trade-off between minimizing costs and facilitating efficient information transfer, it remains untested whether modular variability and its changes during unconscious conditions might be constrained by the economy of brain organization. We acquired functional MRI and FDG-PET in rats under three different levels of consciousness induced by propofol administration. We examined alterations in brain modular variability during loss of consciousness from mild sedation to deep anesthesia. We also investigated the relationships between modular variability with glucose metabolism and functional connectivity strength as well as their alterations during unconsciousness. We observed that modular variability increased during loss of consciousness. Critically, across-individual modular variability is oppositely associated with functional connectivity strength and cerebral metabolism, and with deepening dosage of anesthesia, becoming increasingly dependent on basal metabolism over functional connectivity. These results suggested that, propofol-induced unconsciousness may lead to brain modular reorganization, which are putatively shaped by re-negotiations between energetic resources and communication efficiency.
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Data availability
The data that support the findings of this study are available upon reasonable request from the authors.
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Code for data cleaning and analysis will be updated as part of the replication package once the paper has been conditionally accepted.
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Acknowledgements
This work was supported by the National Natural Science Foundation of China (https://www.nsfc.gov.cn/, grant numbers 82072000 and 81671769 to [XL]); and National Natural Science Foundation of China (https://www.nsfc.gov.cn/, grant number 82171261 to [JZ]).
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SL conducted the experiments and data analysis; SL and XL designed the experiments and wrote the paper; CL performed the experiments and data acquisition; ZL helped data preprocessing; PR helped data curation; XL and JZ revised the paper and supervised the work.
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Li, S., Chen, Y., Ren, P. et al. Alterations in rat brain modular organization during unconsciousness are dependent on communication efficiency and metabolic cost. Brain Struct Funct 228, 2115–2124 (2023). https://doi.org/10.1007/s00429-023-02708-w
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DOI: https://doi.org/10.1007/s00429-023-02708-w