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Effects of Forward Model Errors on EEG Source Localization
Subject-specific four-layer boundary element method (BEM) electrical forward head models for four participants, generated from magnetic resonance (MR) head images using NFT (www.sccn.ucsd.edu/wiki/NFT), were used to simulate electroencephalographic (EEG) scalp potentials at 256 recorded electrode po...
Autores principales: | , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Springer US
2013
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3683142/ https://www.ncbi.nlm.nih.gov/pubmed/23355112 http://dx.doi.org/10.1007/s10548-012-0274-6 |
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author | Akalin Acar, Zeynep Makeig, Scott |
author_facet | Akalin Acar, Zeynep Makeig, Scott |
author_sort | Akalin Acar, Zeynep |
collection | PubMed |
description | Subject-specific four-layer boundary element method (BEM) electrical forward head models for four participants, generated from magnetic resonance (MR) head images using NFT (www.sccn.ucsd.edu/wiki/NFT), were used to simulate electroencephalographic (EEG) scalp potentials at 256 recorded electrode positions produced by single current dipoles of a 3-D grid in brain space. Locations of these dipoles were then estimated using gradient descent within five template head models fit to the electrode positions. These were: a spherical model, three-layer and four-layer BEM head models based on the Montreal Neurological Institute (MNI) template head image, and these BEM models warped to the recorded electrode positions. Smallest localization errors (4.1–6.2 mm, medians) were obtained using the electrode-position warped four-layer BEM models, with largest localization errors (~20 mm) for most basal brain locations. When we increased the brain-to-skull conductivity ratio assumed in the template model scalp projections from the simulated value (25:1) to a higher value (80:1) used in earlier studies, the estimated dipole locations moved outwards (12.4 mm, median). We also investigated the effects of errors in co-registering the electrode positions, of reducing electrode counts, and of adding a fifth, isotropic white matter layer to one individual head model. Results show that when individual subject MR head images are not available to construct subject-specific head models, accurate EEG source localization should employ a four- or five-layer BEM template head model incorporating an accurate skull conductivity estimate and warped to 64 or more accurately 3-D measured and co-registered electrode positions. |
format | Online Article Text |
id | pubmed-3683142 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2013 |
publisher | Springer US |
record_format | MEDLINE/PubMed |
spelling | pubmed-36831422013-06-19 Effects of Forward Model Errors on EEG Source Localization Akalin Acar, Zeynep Makeig, Scott Brain Topogr Original Paper Subject-specific four-layer boundary element method (BEM) electrical forward head models for four participants, generated from magnetic resonance (MR) head images using NFT (www.sccn.ucsd.edu/wiki/NFT), were used to simulate electroencephalographic (EEG) scalp potentials at 256 recorded electrode positions produced by single current dipoles of a 3-D grid in brain space. Locations of these dipoles were then estimated using gradient descent within five template head models fit to the electrode positions. These were: a spherical model, three-layer and four-layer BEM head models based on the Montreal Neurological Institute (MNI) template head image, and these BEM models warped to the recorded electrode positions. Smallest localization errors (4.1–6.2 mm, medians) were obtained using the electrode-position warped four-layer BEM models, with largest localization errors (~20 mm) for most basal brain locations. When we increased the brain-to-skull conductivity ratio assumed in the template model scalp projections from the simulated value (25:1) to a higher value (80:1) used in earlier studies, the estimated dipole locations moved outwards (12.4 mm, median). We also investigated the effects of errors in co-registering the electrode positions, of reducing electrode counts, and of adding a fifth, isotropic white matter layer to one individual head model. Results show that when individual subject MR head images are not available to construct subject-specific head models, accurate EEG source localization should employ a four- or five-layer BEM template head model incorporating an accurate skull conductivity estimate and warped to 64 or more accurately 3-D measured and co-registered electrode positions. Springer US 2013-01-26 2013-07 /pmc/articles/PMC3683142/ /pubmed/23355112 http://dx.doi.org/10.1007/s10548-012-0274-6 Text en © Springer Science+Business Media New York 2013 |
spellingShingle | Original Paper Akalin Acar, Zeynep Makeig, Scott Effects of Forward Model Errors on EEG Source Localization |
title | Effects of Forward Model Errors on EEG Source Localization |
title_full | Effects of Forward Model Errors on EEG Source Localization |
title_fullStr | Effects of Forward Model Errors on EEG Source Localization |
title_full_unstemmed | Effects of Forward Model Errors on EEG Source Localization |
title_short | Effects of Forward Model Errors on EEG Source Localization |
title_sort | effects of forward model errors on eeg source localization |
topic | Original Paper |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3683142/ https://www.ncbi.nlm.nih.gov/pubmed/23355112 http://dx.doi.org/10.1007/s10548-012-0274-6 |
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