# Disrupted modular and hub topology in right temporal lobe epilepsy: a multimodal MRI network analysis

## TL;DR

This study finds that right temporal lobe epilepsy disrupts brain network structure and function, leading to changes in connectivity and brain tissue.

## Contribution

The study reveals novel disruptions in modular and hub topology in right temporal lobe epilepsy using multimodal MRI.

## Key findings

- rTLE patients showed reduced modularity and small-world index compared to healthy controls.
- Increased modular interactions were observed between the SMA and ITG in rTLE patients.
- Structural changes included reduced FA and cortical thinning in key brain regions.

## Abstract

Right temporal lobe epilepsy (rTLE) is associated with disruptions in functional brain networks and structural connectivity, yet underlying mechanisms remain unclear. This study investigated the alterations in modular interactions, connector hub (CH) topology, and related structural changes in rTLE patients. It included 30 rTLE patients and 30 matched healthy controls (HCs), all of whom underwent resting-state functional MRI (rs-fMRI), diffusion-weighted imaging (DWI), and volumetric MRI (vMRI). Functional networks were analyzed by assessing modular interactions, functional connectivity (FC), and CH topological properties. White matter microstructural differences were examined using tract-based spatial statistics (TBSS), while cortical morphometry was evaluated in key CH regions. Compared with HCs, rTLE patients showed reduced modularity (Q), small-world index (σ), and clustering coefficient (γ), along with enhanced modular interactions, particularly between the supplementary motor area (SMA) and inferior temporal gyrus (ITG). CHs exhibited increased participation coefficient (PC), within-module degree z-score (WMD), and local efficiency. Structural analyses revealed reduced fractional anisotropy (FA) and increased radial diffusivity (RD) in the corpus callosum, as well as cortical thinning in the ITG and SMA. We confirmed that rTLE is characterized by disrupted modular architecture and CH topology, leading to network reorganization and associated structural abnormalities. These findings offer new insights into rTLE pathophysiology.