Dynamic Network Analysis Reveals Altered Temporal Variability in Brain Regions after Stroke: A Longitudinal Resting-State fMRI Study.

Jianping Hu,Yifei Weng,Rongfeng Qi,Qiang Xu,Guangming Lu,Fang Yang,Xiaoxue Liu,Juan Du,Zhiqiang Zhang,Xi-Jian Dai,Fanyong Zeng

doi:10.1155/2018/9394156

Abstract

Recent fMRI studies have demonstrated that resting-state functional connectivity (FC) is of nonstationarity. Temporal variability of FC reflects the dynamic nature of brain activity. Exploring temporal variability of FC offers a new approach to investigate reorganization and integration of brain networks after stroke. Here, we examined longitudinal alterations of FC temporal variability in brain networks after stroke. Nineteen stroke patients underwent resting fMRI scans across the acute stage (within-one-week after stroke), subacute stage (within-two-weeks after stroke), and early chronic stage (3-4 months after stroke). Nineteen age- and sex-matched healthy individuals were enrolled. Compared with the controls, stroke patients exhibited reduced regional temporal variability during the acute stages, which was recovered at the following two stages. Compared with the acute stage, the subacute stage exhibited increased temporal variability in the primary motor, auditory, and visual cortices. Across the three stages, the temporal variability in the ipsilesional precentral gyrus (PreCG) was increased first and then reduced. Increased temporal variability in the ipsilesional PreCG from the acute stage to the subacute stage was correlated with motor recovery from the acute stage to the early chronic stage. Our results demonstrated that temporal variability of brain network might be a potential tool for evaluating and predicting motor recovery after stroke.

Highlights

Functional connectivity (FC) and functional connectomics based on resting-state functional magnetic resonance imaging have proven to be powerful tools for investigating the brain function in both physiological and disease states [1,2,3]
We investigated the longitudinal alteration in temporal variability of resting-state functional networks in stroke patients with motor function impairment
Our findings showed that (1) compared with healthy controls, stroke patients at the acute stage demonstrated extensively reduced temporal variability in several brain regions such as primary sensorimotor, auditory, visual cortices, and default mode network (DMN)

Summary

Introduction

Functional connectivity (FC) and functional connectomics based on resting-state functional magnetic resonance imaging (rs-fMRI) have proven to be powerful tools for investigating the brain function in both physiological and disease states [1,2,3]. Most of the studies on resting-state brain networks were based upon the assumption that the strength of FC is constant over scan session [4]. Merging evidence suggests that the FC of the resting-state brain network is not static and presents temporal variability even within a session [5,6,7]. A novel approach introduced by Zhang et al could measure the temporal variability of functional architecture in a specific region, which is different from the conventional dynamic FC method which only measures the interregional property of FC variability [11]. The temporal variability of the particular brain region might reflect its dynamic reconfiguration into distinct functional regions

Methods

Results

Conclusion