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Gamma amplitude-envelope correlations are strongly elevated within hyperexcitable networks in focal epilepsy. Sci Rep 2024 Jul 31;14(1):17736

Date

08/01/2024

Pubmed ID

39085280

Pubmed Central ID

PMC11291981

DOI

10.1038/s41598-024-67120-8

Scopus ID

2-s2.0-85200293097 (requires institutional sign-in at Scopus site)

Abstract

Methods to quantify cortical hyperexcitability are of enormous interest for mapping epileptic networks in patients with focal epilepsy. We hypothesize that, in the resting state, cortical hyperexcitability increases firing-rate correlations between neuronal populations within seizure onset zones (SOZs). This hypothesis predicts that in the gamma frequency band (40-200 Hz), amplitude envelope correlations (AECs), a relatively straightforward measure of functional connectivity, should be elevated within SOZs compared to other areas. To test this prediction, we analyzed archived samples of interictal electrocorticographic (ECoG) signals recorded from patients who became seizure-free after surgery targeting SOZs identified by multiday intracranial recordings. We show that in the gamma band, AECs between nodes within SOZs are markedly elevated relative to those elsewhere. AEC-based node strength, eigencentrality, and clustering coefficient are also robustly increased within the SOZ with maxima in the low-gamma band (permutation test Z-scores > 8) and yield moderate discriminability of the SOZ using ROC analysis (maximal mean AUC ~ 0.73). By contrast to AECs, phase locking values (PLVs), a measure of narrow-band phase coupling across sites, and PLV-based graph metrics discriminate the seizure onset nodes weakly. Our results suggest that gamma band AECs may provide a clinically useful marker of cortical hyperexcitability in focal epilepsy.

Author List

Raghavan M, Pilet J, Carlson C, Anderson CT, Mueller W, Lew S, Ustine C, Shah-Basak P, Youssofzadeh V, Beardsley SA

Authors

Scott Beardsley PhD Associate Professor in the Biomedical Engineering department at Marquette University
Chad Carlson MD Professor in the Neurology department at Medical College of Wisconsin
Sean Lew MD Chief, Professor in the Neurosurgery department at Medical College of Wisconsin
Wade M. Mueller MD Professor in the Neurosurgery department at Medical College of Wisconsin
Manoj Raghavan MD, PhD Professor in the Neurology department at Medical College of Wisconsin
Priyanka P. Shah PhD Assistant Professor in the Neurology department at Medical College of Wisconsin
Vahab Youssofzadeh PhD Assistant Professor in the Neurology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Adolescent
Adult
Brain Mapping
Electrocorticography
Electroencephalography
Epilepsies, Partial
Female
Gamma Rhythm
Humans
Male
Nerve Net
Young Adult