Sevoflurane Alters Spatiotemporal Functional Connectivity Motifs That Link Resting-State Networks during Wakefulness.

Mohammadmehdi Kafashan,Ben J A Palanca,Shinung Ching

doi:10.3389/fncir.2016.00107

Mohammadmehdi Kafashan, Ben J A Palanca + Show 1 more

Open Access

https://doi.org/10.3389/fncir.2016.00107

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Abstract

Background: The spatiotemporal patterns of correlated neural activity during the transition from wakefulness to general anesthesia have not been fully characterized. Correlation analysis of blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI) allows segmentation of the brain into resting-state networks (RSNs), with functional connectivity referring to the covarying activity that suggests shared functional specialization. We quantified the persistence of these correlations following the induction of general anesthesia in healthy volunteers and assessed for a dynamic nature over time.Methods: We analyzed human fMRI data acquired at 0 and 1.2% vol sevoflurane. The covariance in the correlated activity among different brain regions was calculated over time using bounded Kalman filtering. These time series were then clustered into eight orthogonal motifs using a K-means algorithm, where the structure of correlated activity throughout the brain at any time is the weighted sum of all motifs.Results: Across time scales and under anesthesia, the reorganization of interactions between RSNs is related to the strength of dynamic connections between member pairs. The covariance of correlated activity between RSNs persists compared to that linking individual member pairs of different RSNs.Conclusions: Accounting for the spatiotemporal structure of correlated BOLD signals, anesthetic-induced loss of consciousness is mainly associated with the disruption of motifs with intermediate strength within and between members of different RSNs. In contrast, motifs with higher strength of connections, predominantly with regions-pairs from within-RSN interactions, are conserved among states of wakefulness and sevoflurane general anesthesia.

Highlights

The induction of general anesthesia incurs a dramatic change in phenotype compared to wakefulness
Extending on prior work (Kafashan et al, 2014), we studied how dynamic functional connectivity changes in subjects who underwent general anesthesia induced by the halogenated ether, sevoflurane
How similar, on average, is the correlation structure during wakefulness compared to that during sevoflurane general anesthesia. This analysis complemented our earlier analysis (Palanca et al, 2015) that suggested key alterations within the DMN and VAN. Using both a simple correlation (Figure 2) for quantifying similarity across average correlation matrices (0 and 1.2%), we observed a high degree of conservation of functional connectivity within resting-state networks (RSNs) regardless of arousal state

Summary

Introduction

The induction of general anesthesia incurs a dramatic change in phenotype compared to wakefulness. Each RSN encompasses brain regions of presumably shared functional specialization that demonstrate marked zero time lag correlation among surrogates of neural activity. This phenomenon of functional connectivity recapitulates the patterns of brain activation associated with particular stimulus or task. These findings evoke a complementary line of inquiring regarding which components of the functional neuroarchitecture underlying wakefulness remain preserved during the anesthetized state. Correlation analysis of blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI) allows segmentation of the brain into resting-state networks (RSNs), with functional connectivity referring to the covarying activity that suggests shared functional specialization. We quantified the persistence of these correlations following the induction of general anesthesia in healthy volunteers and assessed for a dynamic nature over time

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