Two Brain Network Measures Reveal Shared and Distinct Patterns in Focal Epilepsy

Focal epilepsy affects distributed brain systems rather than a single lesion site, but capturing patient-specific network organization in a clinically meaningful way has remained difficult. A new study published in Nature Communications on 25 October 2026 addresses this gap using resting-state functional MRI to estimate overlapping, individualized brain networks and to derive two complementary measures of network architecture in people with epilepsy.

The first measure, termed network correspondence, indexes system integrity by assessing how strongly an individual’s networks match canonical brain systems. The second, k-hubness, indexes cross-system integration by quantifying multi-network participation, reflecting how brain regions act as hubs connecting different systems. The researchers applied these axes to a presurgical cohort of 305 patients with focal epilepsy and 224 healthy participants, and then validated the findings in an independent cohort of 903 patients spanning focal, common generalized, and childhood epilepsy syndromes, alongside 666 healthy participants.

The two axes revealed distinct patterns of alteration. Disruption of network correspondence was broadly shared across different forms of focal epilepsy, suggesting a common signature of impaired system integrity. In contrast, k-hubness alterations showed lateralized and syndrome-dependent redistributions of cross-system integration, meaning that changes in how brain regions participate across multiple networks varied according to the side of the brain involved and the specific epilepsy syndrome.

Although the two measures shared variance, the study reported modest preferential associations with different clinical domains: network correspondence related to cognition, while k-hubness related to epilepsy clinical features. According to the authors, these measures together characterize both common and heterogeneous alterations in individualized brain system organization, linking complementary aspects of network topology to cognitive and clinical variation. The work, led by Qirui Zhang, Joseph I. Tracy, and colleagues, remains an accepted manuscript shared early for faster access and is subject to further edits before the final version of record.

Subject of Research: Individualized brain network integrity and integration measures in focal epilepsy

Article Title: Complementary axes of functional system integrity and integration with divergent clinical correlates characterize focal epilepsy

Article References: Zhang, Q., Dascal, A., Javidi, S. S., Ankeeta, A., Sperling, M. R., Zhang, Z., & Tracy, J. I. (2026). Complementary axes of functional system integrity and integration with divergent clinical correlates characterize focal epilepsy. Nature Communications. https://doi.org/10.1038/s41467-026-79018-2

Image Credits: AI Generated

DOI: 10.1038/s41467-026-79018-2

Keywords: focal epilepsy, resting-state fMRI, brain networks, network correspondence, k-hubness, system integrity, cross-system integration, presurgical cohort, cognition, epilepsy syndromes, Complementary, axes