title: Association between resting-state brain functional connectivity and muscle sympathetic burst incidence.
abstract: The insula (IC) and cingulate are key components of the central autonomic network and central nodes of the salience network (SN), a set of spatially distinct but temporally correlated brain regions identified with resting-state (task free) functional MRI (rsMRI). To examine the SN's involvement in sympathetic outflow, we tested the hypothesis that individual differences in intrinsic connectivity of the SN correlate positively with resting postganglionic muscle sympathetic nerve activity (MSNA) burst incidence (BI) in subjects without and with obstructive sleep apnea (OSA). Overnight polysomnography, 5-min rsMRI, and fibular MSNA recording were performed in 36 subjects (mean age 57 yr; 10 women, 26 men). Independent component analysis (ICA) of the entire cohort identified the SN as including bilateral IC, pregenual anterior cingulate cortex (pgACC), midcingulate cortex (MCC), and the temporoparietal junction (TPJ). There was a positive correlation between BI and the apnea-hypopnea index (AHI) (P < 0.001), but dual-regression analysis identified no differences in SN functional connectivity between subjects with no or mild OSA (n = 17) and moderate or severe (n = 19) OSA. Correlation analysis relating BI to the strength of connectivity within the SN revealed large (i.e., spatial extent) and strong correlations for the left IC (P < 0.001), right pgACC/MCC (P < 0.006), left TPJ (P < 0.004), thalamus (P < 0.035), and cerebellum (P < 0.013). Indexes of sleep apnea were unrelated to BI and the strength of SN connectivity. There were no relationships between BI and default or sensorimotor network connectivity. This study links connectivity within the SN to MSNA, demonstrating several of its nodes to be key sympathoexcitatory regions.
authors.affiliation: University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Toronto, Ontario, Canada; john.floras@utoronto.ca.
authors.forename: Keri S
authors.initials: KS
authors.lastname: Taylor
authors.affiliation: Department of Psychiatry, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts; and.
authors.forename: Aaron
authors.initials: A
authors.lastname: Kucyi
authors.affiliation: University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Toronto, Ontario, Canada;
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Millar
authors.affiliation: University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Toronto, Ontario, Canada;
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Murai
authors.affiliation: University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Toronto, Ontario, Canada; School of Health and Human Performance, Faculty of Health Professions, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Derek S
authors.initials: DS
authors.lastname: Kimmerly
authors.affiliation: University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Toronto, Ontario, Canada;
authors.forename: Beverley L
authors.initials: BL
authors.lastname: Morris
authors.affiliation: University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Toronto, Ontario, Canada;
authors.forename: T Douglas
authors.initials: TD
authors.lastname: Bradley
authors.affiliation: University Health Network and Mount Sinai Hospital Department of Medicine, University of Toronto, Toronto, Ontario, Canada;
authors.forename: John S
authors.initials: JS
authors.lastname: Floras
mesh_terms: D016022:Case-Control Studies; D002531:Cerebellum / Q000502:physiology; D002540:Cerebral Cortex / Q000502:physiology* / Q000503:physiopathology; D063132:Connectome; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000502:physiology*; D013788:Thalamus / Q000502:physiology
keywords: microneurography; obstructive sleep apnea; resting-state magnetic resonance imaging; salience network; sympathetic nervous system