Resting state fMRI reveals pervasive thalamic hyperactivity and default mode network hypoactivity in epilepsy: Systematic review and meta-analysis

Objective This coordinate-based meta-analysis incorporates studies employing local metrics like amplitude of low frequency fluctuation (ALFF) and regional homogeneity (ReHo), and studies utilizing independent component analysis (ICA) to probe the default mode network (DMN) in epilepsy. Methods A comprehensive literature search was conducted in PubMed, Embase, and Web of Science to identify relevant studies published up to July 2022. We included all studies that compared RS-fMRI local activity in epileptic patients and healthy controls. Results From 644 identified studies, 54 were included in the meta-analyses. Our analysis revealed a consistent increase in local activity in the right mediodorsal thalamus (MDT), bilateral medial temporal lobe, and bilateral sensorimotor cortex. Conversely, a notable decrease in local activity was observed within the DMN regions, including the posterior cingulate cortex (PCC)/precuneus, medial prefrontal cortex, and bilateral inferior parietal lobule. Furthermore, a significant negative correlation between abnormal activity in the right MDT and PCC was identified through our meta-correlation analysis. Conclusions The findings from our study provide compelling evidence of increased local activity in the mediodorsal thalamus and decreased activity in the default mode network in epilepsy. These observations could potentially advance our understanding of epilepsy’s neural underpinnings and guide targeted intervention strategies. What is already known on this topic? Epilepsy involves abnormal brain activity, recurrent seizures, and possible thalamic and DMN involvement. What this study adds? This study reveals consistent thalamic hyperactivity, DMN hypoactivity in various epilepsy types, and a significant negative correlation between these activities. How this study might affect research, practice, and/or policy? Decreased DMN activity and increased thalamus activity could clarify epilepsy pathogenesis and suggest precise, targeted interventions. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by the National Natural Science Foundation of China (NSFC): 81520108016, 82071537 and Key Medical Discipline of Hangzhou. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors