Authors :
Presenting Author: F. Kathryn King, PhD – UT Arlington
Brianna McCullough, BS – Cook Children’s Health Care System
M. Scott Perry, MD – Cook Children’s Physician Network
Christos Papadelis, PhD – Cook Children’s Health Care System
Crystal Cooper, PhD – UT Arlington
Rationale:
Emerging evidence suggests that epilepsy stems from preexisting brain network dysfunction, which may predispose the brain to developing this disorder. However, there is a need to investigate network functioning in young and newly diagnosed epilepsy patients to assess whether connectivity deficits exist prior to long-term seizure exposure. Most research relies on resting-state fMRI, highlighting the need for high-temporal-resolution methods to examine effective connectivity during cognitively demanding tasks. This study aims to investigate task-based effective connectivity during emotional conflict processing in adolescents with epilepsy using magnetoencephalography (MEG).
Methods:
Our sample of 28 adolescents with epilepsy and 25 controls, (10-20 years old) performed an Emotional Face-Word Stroop task while undergoing MEG recording (Fig. 1). Effective connectivity was evaluated using Granger causality and graph theory analysis was implemented to compute global efficiency and path length, and node-level strength, degree, and betweenness for nodes of the Default Mode, Salience, Frontoparietal Control, and Somatomotor networks across nine overlapping 200 ms time windows spanning 1-1000 ms post-stimulus. These metrics were compared between groups using MANOVAs for each time window (Bonferroni corrected), followed by post-hoc t-tests for each node (FDR corrected).
Results:
While controls showed normative connectivity dynamics according to task demands, those with epilepsy exhibited relatively static connectivity across time (Fig. 2). Specifically, controls exhibited high early (~first 0.5s) effective connectivity centrality predominantly in regions of the Default Mode and Salience networks, which was significantly lower in the epilepsy group from 0.2-0.4 s (ps< .05). This was followed by a reduction in this connectivity in controls, while those with epilepsy maintained a static level, resulting in late (0.5-0.7s) significant hyperconnectivity in a region of the Salience Network (p< .05). As expected, controls exhibited low early (~first 0.5s) effective connectivity centrality in regions of the Frontoparietal Control network that increased later in time (~0.5-1.0s); this connectivity was relatively static in the epilepsy group, with significantly higher early centrality in nodes of this network (0.2-0.4s, ps< .05). Furthermore, the epilepsy group exhibited significantly lower early global efficiency and higher average lambda than controls (0-0.2s, ps< .05).