Altered Frontal Lobe Network Function in Temporal Lobe Epilepsy Revealed by Graph Theory Analysis (P1.279)

Objective: To identify aberrant brain network function in people with temporal lobe epilepsy (TLE) using graph theory analysis of resting-state fMRI (rsfMRI) data. Background: Although usually classified as a focal epilepsy, TLE is increasingly viewed as a process that involves large-scale networks of the brain. Graph theory provides a method of quantifying functional network properties that may be difficult to identify or characterize using standard connectivity approaches. Design/Methods: Forty minutes of rsfMRI data were collected from 50 people with TLE and 40 healthy controls as part of the NINDS-funded Epilepsy Connectome Project. Connectivity matrices of z-score activity correlation values between 379 cortical and subcortical nodes defined by the Glasser parcellation were made for each participant. Matrices were thresholded to retain the strongest 6% of connections in addition to each matrix’ minimum spanning tree (the minimal connections required to include all nodes in the network). Graph theory measures assessing network integration, i.e. pagerank and closeness centrality, and network segregation, i.e. modularity, were compared between groups using t-tests, with Bonferroni correction (p Results: Compared to controls, TLE patients showed significantly lower pagerank values in several frontal opercular nodes (right FOP1, right FOP4, left FOP1, right MI), and lower modularity values in several prefrontal nodes (left a9–46v, right 11l, right d32, right 46). TLE patients showed greater closeness centrality in left medial motor region 5m compared to controls. Conclusions: Lower pageranks in the TLE opercular network indicate reduced influence of these nodes on network function. Lower modularity in the TLE prefrontal network indicates a reduced organization of this region into sub-networks. These alterations could underlie the reported executive and working memory deficits observed in some people with TLE. Study Supported by: American Academy of Neurology Medical Student Summer Research Scholarship NINDS U01 NS093650 Disclosure: Dr. Iyer has nothing to disclose. Dr. Mathis has nothing to disclose. Dr. Ustine has nothing to disclose. Dr. Nair has nothing to disclose. Dr. Rozman has nothing to disclose. Dr. McMillan has nothing to disclose. Dr. Kraegel has nothing to disclose. Dr. Almane has nothing to disclose. Dr. Forseth has nothing to disclose. Dr. Hwang has nothing to disclose. Dr. Nencka has nothing to disclose. Dr. Birn has nothing to disclose. Dr. Ward has nothing to disclose. Dr. Prabhakaran has nothing to disclose. Dr. Maganti has nothing to disclose. Dr. Conant has nothing to disclose. Dr. Hermann has nothing to disclose. Dr. Humphries has nothing to disclose. Dr. DeYoe has nothing to disclose. Dr. Raghavan has nothing to disclose. Dr. Meyerand has nothing to disclose. Dr. Binder has nothing to disclose.