Voxel-wise functional connectivity of the default mode network in epilepsies: a systematic review and meta-analysis.

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.