Correlation Between Global Network Betweenness Properties And Local Attention Networks In Patients With Refractory Epilepsy

Objective Using resting-state functional magnetic resonance imaging(rs-f MRI),the changes of brain network in patients with refractory epilepsy were studied.By means of graph theory,the alteration of global and local brain networks in patients with refractory epilepsy was explored.The possible mechanism of pathophysiological changes in patients with refractory epilepsy was investigated from the perspective of brain network.(1)To explore the alteration of betweenness and the abnormal brain connectivity in patients with refractory epilepsy by means of graph theory.(2)The aims of this study were to assess functional and causal connectivities of the attention networks and default mode network using rs-f MRI.Methods(1)Two groups ofresting-state f MRI data was collected from 20 cases of refractory epilepsy patients and 20 healthy controls recruited at the same period.The data preprocessing was performed by the network construction module based on the Gretna software under the Mat Lab platform.The Betweenness value of the brain networkswere obtained through the network analysis module.Statistical tests were used to find brain regions with significant differences.The functional connections in the brain regions were obtained by extracting the above-mentioned significant brain regions into regions of interest(ROI).Finally,the obtained FC values were subjected to a two-sample t-test to obtain a significant connection.(2)Resting-state f MRI data were gathered from 19 patients with refractory epilepsy(mixed localization and aetiologies)and 21 healthy people.The f MRI data were analyzed by group independent component analysis(ICA)f MRI toolbox to extract default mode network(DMN),ventral attention network(VAN)and dorsal attention network(DAN).The components of the selected networks were compared between patients and healthy controls to explore the change in functional connectivity(FC).Granger causality analysis was performed by taking the aforementioned significant brain areas as regions of interest(ROIs)to calculate autoregression coefficients of each pair of ROIs.Comparisons were done to find the significantly different causal connectivity when FC was changed between patients and healthy controls.Results(1)Compared with normal people,the Betweenness value of right olfactory cortex and right triangular of inferior frontal gyrus of patients with epilepsy showed increased(P<0.05).The Betweenness value of right superior temporal gyrus,left orbital part of superior frontal gyrus,right dorsolateral superior frontal gyrus,left anterior cingulate gyrus,and right inferior temporal gyrus were all decreased(all P<0.05).Compared with normal people,the functional connection between the superior temporal gyrus and the triangle of inferior frontal gyrus was lower in patients with refractory epilepsy,and no significant changes were found in the functional connectivity of the other mediators.(2)In DAN,the FC values of the bilateral frontal eye field(FEF)and left intraparietal sulcus(IPS)were decreased.In VAN,the FC values of the double-side ventral prefrontal cortex(v PFC)and the temporoparietal junction(TPJ)were reduced.As for DMN,the FC values of the bilateral medial prefrontal cortices(m PFC)were decreased whereas those for the bilateral precuneus(PCUN)were increased.Granger causal connectivity values were correlated: causal influence was decreased significantly from the left IPS(in DAN)to the double side of the v PFC but remained the same for the right FEF(in DAN)to the right TPJ.The value was decreased from the left PCUN(in DMN)to the right TPJ and FEF,and the causal flow from the right PCUN to the right TPJ and bilateral v PFC was also significantly inhibited(p<0.05).Conclusions(1)In the resting state,the Betweenness of global network in patients with refractory epilepsy represented significant changes,and the FC value ofthe abnormal brain regions of Betweenness in the brain networks also changed significantly.This is probably the brain network foundation that causes brain damage,especially the attention networks.(2)Frequent seizures in patients with refractory epilepsy may damage the cortex and disturb DAN,VAN,and DMN,leading to functional and causal connectivity alteration.In addition,epileptic activity may disrupt network interactions and further influence information communication.