Voxel-wise Functional Connectivity of the Default Mode Network in Epilepsies: A Systematic Review and Meta-Analysis

Abstract

Background: Default mode network (DMN) is recognized to be involved in generation and propagation of epileptic activities in various epilepsies. Converging evidence has suggested disturbed functional connectivity (FC) in epilepsies, which was inferred to be related to underlying pathological mechanisms. However, abnormal changes of FC in DMN revealed by different studies are controversial, which obscures the role of DMN in distinct epilepsies. Objective: The present work aims to investigate the voxel-wise FC in DMN across epilepsies. Methods: A systematic review was conducted on 22 published articles before October 2020 indexed in PubMed and Web of Science. A meta-analysis with a random-effect model was performed using the effect-size signed differential mapping approach. Subgroup analyses were performed in three groups: idiopathic generalized epilepsy (IGE), mixed temporal lobe epilepsy (TLE), and mixed focal epilepsy (FE) with different foci. Results: The meta-analysis suggested common decreased FC in mesial prefrontal cortices across different epilepsies. Additional decreased FC in posterior DMN was observed in IGE. The TLE showed decreased FC in temporal lobe regions and increased FC in dorsal posterior cingulate cortex. Interestingly, an opposite finding in ventral and dorsal middle frontal gyrus was observed in TLE. The FE demonstrated increased FC in cuneus. Conclusion: The current findings revealed both common and specific alterations of FC in DMN across different epilepsies, highlighting the contribution of these dysfunctions to epileptic activities and cognitive behaviors in patients. Furthermore, the current study provided powerful evidence to support DMN as a potential candidate for effective intervention in epilepsy.

Functional and structural networks decoupling in generalized tonic–clonic seizures and its reorganization by drugs

“…In line with a previous study, 34,35 we observed higher connectivity between the DMN and other functional networks and within the DMN in patients than in HCs. The DMN is thought to be associated with the generation of epileptic discharges, 36 and the widespread enhancement of connections in patients may be a byproduct of the rapid transmission of electrical signals through the brain during a discharge. 37,38 When we compared the treated patients with the HC group, we showed higher functional and structural connections between the DMN and FPN in the patients.…”

Abnormal brain functional network dynamics in sleep‐related hypermotor epilepsy

“…Resting‐state functional magnetic resonance imaging (rs‐fMRI) is the most common method to explore functional connectivity by calculating the Pearson correlation coefficient between time series, which characterizes the synergistic activity in the brain. It has been widely used to explore the influence and mechanism of the epileptic network 9–11 . There are many studies of epilepsy that have found abnormal functional connectivity (FC) in multiple brain regions or networks, such as the basal ganglia, cerebral cortex, and default mode network 7,12–14 .…”

“…It has been widely used to explore the influence and mechanism of the epileptic network. [9][10][11] There are many studies of epilepsy that have found abnormal functional connectivity (FC) in multiple brain regions or networks, such as the basal ganglia, cerebral cortex, and default mode network. 7,[12][13][14] In general, all these abovementioned studies assumed that functional connectivity is stationary during the scanning process, but in fact, the brain connectivity is highly dynamic in the resting state.…”

Functional and Structural Networks Decoupling in GTCS and Its Reorganization by Drugs

“…Recently, the network-level weighted correlation probability(NWCP) was proposed to achieve the multimodal fusion of neuroimages on the network level in our previous study(Sisi Jiang et al, 2021).…”

“…The fusion of multimodal provides an effective instrument to integrate the advantage of different neuroimages(Sisi Jiang et al, 2021;Qin et al, 2021). The fusion on the network-level might be adaptive for the disorders of the brain network(SisiJiang et al, 2021). Our previous study proposed the NWCP focused on the static and dynamic functional connections[18], which would re ect the coupling between structural and functional connectivity.…”