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

ObjectiveThis 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. MethodsA 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. ResultsFrom 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. ConclusionsThe 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 epilepsys 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.