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

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.

Abnormal dynamic functional connectivity is linked to recovery after acute ischemic stroke

“…This circumstance can lead to potential confounds—that, on the other hand, can be alleviated when contrasting patient subgroups with conceivably more similar risk profiles. Furthermore, our dataset is comparable in size with prior dynamic functional connectivity studies in the first few days after stroke (Hu et al, 2018: 19 patients; Bonkhoff, Espinoza, et al, 2020: 31 patients; Bonkhoff, Rehme, et al, 2020: 54 patients). Notably, one of our main findings, that is, favored transiently increased segregation in case of a high stroke severity, is well in line with previous reports of increased transition likelihood to segregated states in case of severe motor impairments (Bonkhoff, Espinoza, et al, 2020).…”

Dynamic functional connectivity analysis reveals transiently increased segregation in patients with severe stroke

“…It is unique in its approach of assessing acute alterations in dynamic connectivity exclusively within strata of variably affected stroke patients, without the direct comparison to a healthy control group. Furthermore, it is comparable in size with prior dynamic functional connectivity studies in the first few days after stroke ( 59 : 19 patients; 18 : 31 patients). Notably, one of our main findings, i.e.…”

An imbalance between functional segregation and integration in patients with pontine stroke: A dynamic functional network connectivity study

“…The other possible reason is that the enrolled patients were at different infarction stages. Differences in regional temporal variability among the acute, subacute, and chronic stages have been reported in stroke patients using dynamic network analysis( Hu et al, 2018 ). Future studies will need to investigate whether there are different organizational structures of dFNC among PS patients with infarction stages.…”