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Extent of cortical generators visible on the scalp: Effect of a subdural grid

von Ellenrieder, Nicolas, Beltrachini, Leandro ORCID:, Muravchik, Carlos H. and Gotman, Jean 2014. Extent of cortical generators visible on the scalp: Effect of a subdural grid. NeuroImage 101 , pp. 787-795. 10.1016/j.neuroimage.2014.08.009

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The effect of the non-conducting substrate of a subdural grid on the scalp electric potential distribution is studied through simulations. Using a detailed head model and the finite element method we show that the governing physics equations predict an important attenuation in the scalp potential for generators located under the grid, and an amplification for generators located under holes in the skull filled with conductive media. These effects are spatially localized and do not cancel each other. A 4 × 8 cm grid can produce attenuations of 2 to 3 times, and an 8 × 8 cm grid attenuation of up to 8 times. As a consequence, when there is no subdural grid, generators of 4 to 8 cm2 produce scalp potentials of the same maximum amplitude as generators of 10 to 20 cm2 under the center of a subdural grid. This means that the minimum cortical extents necessary to produce visible scalp activity determined from simultaneous scalp and subdural recordings can be overestimations.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Cardiff University Brain Research Imaging Centre (CUBRIC)
Subjects: Q Science > QC Physics
Uncontrolled Keywords: Electrocorticography; Subdural grid; Scalp EEG; Finite element method
Publisher: Elsevier
ISSN: 1053-8119
Date of First Compliant Deposit: 6 July 2017
Date of Acceptance: 4 August 2014
Last Modified: 03 Nov 2022 15:24

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