Brain functional connectivity in individuals with psychogenic nonepileptic seizures (PNES): An application of graph theory

•The graph theory has the potential to be utilized to examine the underlying mechanisms in psychogenic nonepileptic seizures (PNES).•There is an imbalancement of functional connectivity (FC) in cognitive and emotion processing in patients with PNES.•Hyper-connectivity is detected in cognitive regions, whereas hypo-connectivity is observed in emotion processing regions. To determine brain functional connectivity (FC), based on the graph theory, in individuals with psychogenic nonepileptic seizures (PNES), in order to better understand the mechanisms underlying this disease. Twenty-three patients with PNES and twenty-five healthy control subjects were examined. Alterations in FC within the whole brain were examined using resting-state functional magnetic resonance imaging (MRI). We calculated measures of the nodal degree, a major feature of the graph theory, for all the cortical and subcortical regions in the brain. Pearson correlation was performed to determine the relationship between nodal degree in abnormal brain regions and patient characteristics. The nodal degrees in the right caudate (CAU), left orbital part of the left inferior frontal gyrus (ORBinf), and right paracentral lobule (PCL) were significantly greater (i.e. hyper-connectivity) in individuals with PNES than in healthy control subjects. On the other hand, a lesser nodal degree (i.e. hypo-connectivity) was detected in several other brain regions including the left and right insula (INS), as well as the right putamen (PUT), and right middle occipital gyrus (MOG). Our findings suggest that the FC of several major brain regions can be altered in individuals with PNES. Areas with hypo-connectivity may be involved in emotion processing (e.g., INS) and movement regulation (e.g., PUT), whereas areas with hyper-connectivity may play a role in the inhibition of unwanted movements and cognitive processes (e.g., CAU).