# Multi-Graph Assessment of Temporal and Extratemporal Lobe Epilepsy in Resting-State fMRI
## 4 Discussion
### Brain Reorganization  
In the comparison of global topological features, the healthy control group presents statistical differences with the TLE group only in the Pearson correlation graphs. Our analysis revealed lower values of global assortativity, global efficiency, and mean clustering coefficient values in TLE patients compared to healthy controls, particularly at density levels exceeding 25%. Although the reduction of global efficiency observed in TLE patients is supported by similar studies [23; 24; 25; 26; 27; 28], it is worth mentioning that other researchers report contradictory findings [31; 53]. In a similar manner, TLE patients display lower mean clustering coefficient values, with some studies reporting comparable results [24; 26; 27; 28; 31; 53], while others suggest a higher global clustering coefficient for patients with focal epilepsy compared to controls [25]. Figure 7: Overall hub probability within the brain sectors. The bottom and top edges of each box indicate the 25 th and 75 th percentiles, while the red line indicates the median value. The whiskers extend to the most extreme values, whereas outliers are presented with a circle. Significant differences (\(p<0.05\)) are presented with the asterisk (*) symbol. This could be related to the fact that there are methodological differences between those studies, such as the definition of the ROIs with different atlases, and the threshold methods applied [54]. For instance, [PERSON] et al. [31] applied automated anatomical labeling (AAL) and temporal correlations and asserted that individuals with temporal lobe epilepsy (TLE) exhibit functional networks characterized by higher global efficiency and lower clustering coefficient compared to healthy controls. However, most of the studies report similar results to our analysis, where TLE patients present lower global integration (reduced efficiency) and segregation (reduced mean clustering coefficient) in their graphs compared to the controls. Interestingly, those topological features have been related to cognitive deficits observed in chronic epilepsy [28]. The ETLE group presents increased mean clustering coefficient compared to the control group in the undirected graphs of Pearson correlation and MI, at different density levels (40-45% in the MI and 5% in the Pearson correlation graph). Previous studies report similar changes in children with frontal lobe epilepsy, where patients presented efficient communication within specific clusters of ROIs but limited connection between the clusters [55]. Since half of our cohort in the ETLE group are patients with frontal lobe epilepsy, no generalization can be made in all extratemporal lobe epilepsies, but further investigation should be performed with bigger cohorts. We find no difference in the global efficiency of the ETLE groups compared to controls. In line with our results, [PERSON] et al. [56] employed a brain mask consisting of 278 nodes and a Pearson correlation method, reporting no difference in the path length but increased segregation in patients with ETLE compared to controls. We find statistical differences in the brain topological features of the TLE and ETLE group that may include useful information regarding the organization of the epileptic network in the two types of epilepsy. TLE patients exhibit more disassortative graphs compared to ETLE in lower density levels of the MI graphs (5-10%) and in almost all the density levels of the Granger causality graphs. Further, the TLE group exhibits a greater number of components in relation to the other two groups at density levels exceeding 40%. This could be due to network edges present in the TLE graphs with weak connectivity strength although acting as bridges. In the undirected graphs of Pearson correlation, at 30-35% density level, ETLE graphs show topological characteristics more aligned with small-world architecture (higher clustering coefficients and global efficiency) in comparison to the TLE group.