Altered regional connectivity reflecting effects of different anaesthesia protocols in the mouse brain.
Studies in mice using resting-state functional magnetic resonance imaging (rs-fMRI) have provided opportunities to investigate the effects of pharmacological manipulations on brain function and map the phenotypes of mouse models of human brain disorders. Mouse rs-fMRI is typically performed under anaesthesia, which induces both regional suppression of brain activity and disruption of large-scale neural networks. Previous comparative studies using rodents investigating various drug effects on long-distance functional connectivity (FC) have reported agent-specific FC patterns, however, effects of regional suppression are sparsely explored. Here we examined changes in regional connectivity under six different anaesthesia conditions using mouse rs-fMRI with the goal of refining the framework of understanding the brain activation under anaesthesia at a local level. Regional homogeneity (ReHo) was used to map local synchronization in the brain, followed by analysis of several brain areas based on ReHo maps. The results revealed high local coherence in most brain areas. The primary somatosensory cortex and caudate-putamen showed agent-specific properties. Lower local coherence in the cingulate cortex was observed under medetomidine, particularly when compared to the combination of medetomidine and isoflurane. The thalamus was associated with retained local coherence across anaesthetic levels and multiple nuclei. These results show that anaesthesia induced by the investigated anaesthetics through different molecular targets promote agent-specific regional connectivity. In addition, ReHo is a data-driven method with minimum user interaction, easy to use and fast to compute. Given that examination of the brain at a local level is widely applied in human rs-fMRI studies, our results show its sensitivity to extract information on varied neuronal activity under six different regimens relevant to mouse functional imaging. These results, therefore, will inform future rs-fMRI studies on mice and the type of anaesthetic agent used, and will help to bridge observations between this burgeoning research field and ongoing human research across analytical scales.
Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia.
Tong
T
Wu
Molecular Imaging and Functional Pharmacology, Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland; Singapore BioImaging Consortium, Agency for Science, Technology and Research, Singapore.
Joanes
J
Grandjean
The Centre for Advanced Imaging, The University of Queensland, Brisbane, Queensland, Australia.
Simone C
SC
Bosshard
Molecular Imaging and Functional Pharmacology, Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.
Markus
M
Rudin
The Centre for Advanced Imaging, The University of Queensland, Brisbane, Queensland, Australia.
David
D
Reutens
Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia; Brainnetome Centre, Institute of Automation, Chinese Academy of Sciences, Beijing, China; Key Laboratory for NeuroInformation of the Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 625014, China.
Tianzi
T
Jiang
D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects*; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D007091:Image Processing, Computer-Assisted; D007530:Isoflurane / Q000494:pharmacology; D008279:Magnetic Resonance Imaging; D020926:Medetomidine / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D009434:Neural Pathways / Q000187:drug effects*; D015742:Propofol / Q000494:pharmacology; D012146:Rest; D014520:Urethane / Q000494:pharmacology
D000777:Anesthetics; D014520:Urethane; D007530:Isoflurane; D020926:Medetomidine; D015742:Propofol
Anaesthesia; Mouse; Regional homogeneity; Resting state fMRI