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Normative brain mapping of interictal intracranial EEG to localize epileptogenic tissue

Lookup NU author(s): Dr Peter TaylorORCiD, Christoforos Papasavvas, Tom Owen, Dr Gabrielle SchroederORCiD, Dr Yujiang WangORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2022 The Author(s) (2022). Published by Oxford University Press on behalf of the Guarantors of Brain. The identification of abnormal electrographic activity is important in a wide range of neurological disorders, including epilepsy for localizing epileptogenic tissue. However, this identification may be challenging during non-seizure (interictal) periods, especially if abnormalities are subtle compared to the repertoire of possible healthy brain dynamics. Here, we investigate if such interictal abnormalities become more salient by quantitatively accounting for the range of healthy brain dynamics in a location-specific manner. To this end, we constructed a normative map of brain dynamics, in terms of relative band power, from interictal intracranial recordings from 234 participants (21598 electrode contacts). We then compared interictal recordings from 62 patients with epilepsy to the normative map to identify abnormal regions. We proposed that if the most abnormal regions were spared by surgery, then patients would be more likely to experience continued seizures postoperatively. We first confirmed that the spatial variations of band power in the normative map across brain regions were consistent with healthy variations reported in the literature. Second, when accounting for the normative variations, regions that were spared by surgery were more abnormal than those resected only in patients with persistent postoperative seizures (t = -3.6, P = 0.0003), confirming our hypothesis. Third, we found that this effect discriminated patient outcomes (area under curve 0.75 P = 0.0003). Normative mapping is a well-established practice in neuroscientific research. Our study suggests that this approach is feasible to detect interictal abnormalities in intracranial EEG, and of potential clinical value to identify pathological tissue in epilepsy. Finally, we make our normative intracranial map publicly available to facilitate future investigations in epilepsy and beyond.

Publication metadata

Author(s): Taylor PN, Papasavvas CA, Owen TW, Schroeder GM, Hutchings FE, Chowdhury FA, Diehl B, Duncan JS, McEvoy AW, Miserocchi A, De Tisi J, Vos SB, Walker MC, Wang Y

Publication type: Article

Publication status: Published

Journal: Brain

Year: 2022

Volume: 145

Issue: 3

Pages: 939-949

Print publication date: 10/03/2022

Online publication date: 24/01/2022

Acceptance date: 02/09/2021

Date deposited: 25/05/2022

ISSN (print): 0006-8950

ISSN (electronic): 1460-2156

Publisher: Oxford University Press


DOI: 10.1093/brain/awab380

PubMed id: 35075485


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Funder referenceFunder name
208940/Z/17/ZWellcome Trust
NIH National Institute of Neurological Disorders and Stroke U01-NS090407 (Center for SUDEP Research)