On the Centrality of the Focus in Human Epileptic Brain Networks

TL;DR

This study investigates the dynamic role of the epileptic focus within brain networks, revealing that its importance fluctuates over time rather than remaining consistently central, challenging previous assumptions about its role as a network hub.

Contribution

The paper introduces a time-resolved analysis of node importance in epileptic brain networks, highlighting the variability of the epileptic focus’s role over time.

Findings

Epileptic focus is not always the most important node.

Node importance varies significantly over time.

Previous assumptions of the focus as a consistent hub are challenged.

Abstract

There is increasing evidence for specific cortical and subcortical large-scale human epileptic networks to be involved in the generation, spread, and termination of not only primary generalized but also focal onset seizures. The complex dynamics of such networks has been studied with methods of analysis from graph theory. In addition to investigating network-specific characteristics, recent studies aim to determine the functional role of single nodes---such as the epileptic focus---in epileptic brain networks and their relationship to ictogenesis. Utilizing the concept of betweenness centrality to assess the importance of network nodes, previous studies reported the epileptic focus to be of highest importance prior to seizures, which would support the notion of a network hub that facilitates seizure activity. We performed a time-resolved analysis of various aspects of node importance in epileptic brain networks derived from long-term, multi-channel, intracranial electroencephalographic recordings from an epilepsy patient. Our preliminary findings indicate that the epileptic focus is not consistently the most important network node, but node importance may drastically vary over time.