scholarly journals The role of nonlinearity in computing graph-theoretical properties of resting-state functional magnetic resonance imaging brain networks

2011 ◽  
Vol 21 (1) ◽  
pp. 013119 ◽  
Author(s):  
D. Hartman ◽  
J. Hlinka ◽  
M. Paluš ◽  
D. Mantini ◽  
M. Corbetta
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Resting State ◽  
Brain Networks ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging

scholarly journals Dexmedetomidine Disrupts the Local and Global Efficiencies of Large-scale Brain Networks

2017 ◽  
Vol 126 (3) ◽  
pp. 419-430 ◽  
Author(s):  
Javeria A. Hashmi ◽  
Marco L. Loggia ◽  
Sheraz Khan ◽  
Lei Gao ◽  
Jieun Kim ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Connectivity ◽  
Functional Magnetic Resonance Imaging ◽  
Resting State ◽  
Degree Distribution ◽  
Brain Networks ◽  
Resting State Networks ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging

Abstract Background A clear understanding of the neural basis of consciousness is fundamental to research in clinical and basic neuroscience disciplines and anesthesia. Recently, decreased efficiency of information integration was suggested as a core network feature of propofol-induced unconsciousness. However, it is unclear whether this finding can be generalized to dexmedetomidine, which has a different molecular target. Methods Dexmedetomidine was administered as a 1-μg/kg bolus over 10 min, followed by a 0.7-μg · kg−1 · h−1 infusion to healthy human volunteers (age range, 18 to 36 yr; n = 15). Resting-state functional magnetic resonance imaging data were acquired during baseline, dexmedetomidine-induced altered arousal, and recovery states. Zero-lag correlations between resting-state functional magnetic resonance imaging signals extracted from 131 brain parcellations were used to construct weighted brain networks. Network efficiency, degree distribution, and node strength were computed using graph analysis. Parcellated brain regions were also mapped to known resting-state networks to study functional connectivity changes. Results Dexmedetomidine significantly reduced the local and global efficiencies of graph theory–derived networks. Dexmedetomidine also reduced the average brain connectivity strength without impairing the degree distribution. Functional connectivity within and between all resting-state networks was modulated by dexmedetomidine. Conclusions Dexmedetomidine is associated with a significant drop in the capacity for efficient information transmission at both the local and global levels. These changes result from reductions in the strength of connectivity and also manifest as reduced within and between resting-state network connectivity. These findings strengthen the hypothesis that conscious processing relies on an efficient system of information transfer in the brain.

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