Localization of brain electric sources in patients with focal epilepsy.
Autor(a) principal: | |
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Data de Publicação: | 1996 |
Outros Autores: | , , , , , |
Tipo de documento: | Artigo |
Idioma: | por |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | https://www.actamedicaportuguesa.com/revista/index.php/amp/article/view/2604 |
Resumo: | In this paper we discuss a non-invasive method to localize neural electrical sources using EEG data. In this method, the human head is modelled by a set of four concentric spheres with different conductivities which represent the scalp, the skull, the CSF and the brain or by three triangulated surfaces which approximate the exact head shape (in this model we do not consider the CSF layer) using NMR images. In this case the computer effort is very high, since the calculations imply thousands of equations. Therefore, the number of research groups working with this improved model, in the world, is very small. In both models, we assume that the neural source is a current dipole. This makes the model suitable for cases where the active brain areas are limited and localized. We discuss some error factors associated with the method, as the geometry of the head, the conductivity of the different layers and the number of electrodes used in the EEG measurements. Comparing the more realistic head model, with the spherical one we often have differences of 1-2 cm. However, we can reach even more pronounced differences in the frontal areas. Concerning the skull conductivity, we realized that it could introduce errors of 1-2 cm. We observed that at least 50 electrodes should be used only since 21 electrodes could imply errors of about 0.5 cm. The method was applied, both in the spherical version and the realistic one, to clinical cases of focal epileptic patients. The results are discussed in terms of the other clinical information available and they are coherent with the remaining clinical data. |
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Localization of brain electric sources in patients with focal epilepsy.Localização de fontes eléctricas cerebrais em doentes com epilepsia focal.In this paper we discuss a non-invasive method to localize neural electrical sources using EEG data. In this method, the human head is modelled by a set of four concentric spheres with different conductivities which represent the scalp, the skull, the CSF and the brain or by three triangulated surfaces which approximate the exact head shape (in this model we do not consider the CSF layer) using NMR images. In this case the computer effort is very high, since the calculations imply thousands of equations. Therefore, the number of research groups working with this improved model, in the world, is very small. In both models, we assume that the neural source is a current dipole. This makes the model suitable for cases where the active brain areas are limited and localized. We discuss some error factors associated with the method, as the geometry of the head, the conductivity of the different layers and the number of electrodes used in the EEG measurements. Comparing the more realistic head model, with the spherical one we often have differences of 1-2 cm. However, we can reach even more pronounced differences in the frontal areas. Concerning the skull conductivity, we realized that it could introduce errors of 1-2 cm. We observed that at least 50 electrodes should be used only since 21 electrodes could imply errors of about 0.5 cm. The method was applied, both in the spherical version and the realistic one, to clinical cases of focal epileptic patients. The results are discussed in terms of the other clinical information available and they are coherent with the remaining clinical data.In this paper we discuss a non-invasive method to localize neural electrical sources using EEG data. In this method, the human head is modelled by a set of four concentric spheres with different conductivities which represent the scalp, the skull, the CSF and the brain or by three triangulated surfaces which approximate the exact head shape (in this model we do not consider the CSF layer) using NMR images. In this case the computer effort is very high, since the calculations imply thousands of equations. Therefore, the number of research groups working with this improved model, in the world, is very small. In both models, we assume that the neural source is a current dipole. This makes the model suitable for cases where the active brain areas are limited and localized. We discuss some error factors associated with the method, as the geometry of the head, the conductivity of the different layers and the number of electrodes used in the EEG measurements. Comparing the more realistic head model, with the spherical one we often have differences of 1-2 cm. However, we can reach even more pronounced differences in the frontal areas. Concerning the skull conductivity, we realized that it could introduce errors of 1-2 cm. We observed that at least 50 electrodes should be used only since 21 electrodes could imply errors of about 0.5 cm. The method was applied, both in the spherical version and the realistic one, to clinical cases of focal epileptic patients. The results are discussed in terms of the other clinical information available and they are coherent with the remaining clinical data.Ordem dos Médicos1996-09-30info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttps://www.actamedicaportuguesa.com/revista/index.php/amp/article/view/2604oai:ojs.www.actamedicaportuguesa.com:article/2604Acta Médica Portuguesa; Vol. 9 No. 7-9 (1996): Julho-Setembro; 219-27Acta Médica Portuguesa; Vol. 9 N.º 7-9 (1996): Julho-Setembro; 219-271646-07580870-399Xreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAPporhttps://www.actamedicaportuguesa.com/revista/index.php/amp/article/view/2604https://www.actamedicaportuguesa.com/revista/index.php/amp/article/view/2604/2016Silva, COostendorp, TDucla-Soares, EForeid, J PPimentel, TBotelho, M JAlmeida, Ainfo:eu-repo/semantics/openAccess2022-12-20T11:00:49Zoai:ojs.www.actamedicaportuguesa.com:article/2604Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T16:17:51.100101Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse |
dc.title.none.fl_str_mv |
Localization of brain electric sources in patients with focal epilepsy. Localização de fontes eléctricas cerebrais em doentes com epilepsia focal. |
title |
Localization of brain electric sources in patients with focal epilepsy. |
spellingShingle |
Localization of brain electric sources in patients with focal epilepsy. Silva, C |
title_short |
Localization of brain electric sources in patients with focal epilepsy. |
title_full |
Localization of brain electric sources in patients with focal epilepsy. |
title_fullStr |
Localization of brain electric sources in patients with focal epilepsy. |
title_full_unstemmed |
Localization of brain electric sources in patients with focal epilepsy. |
title_sort |
Localization of brain electric sources in patients with focal epilepsy. |
author |
Silva, C |
author_facet |
Silva, C Oostendorp, T Ducla-Soares, E Foreid, J P Pimentel, T Botelho, M J Almeida, A |
author_role |
author |
author2 |
Oostendorp, T Ducla-Soares, E Foreid, J P Pimentel, T Botelho, M J Almeida, A |
author2_role |
author author author author author author |
dc.contributor.author.fl_str_mv |
Silva, C Oostendorp, T Ducla-Soares, E Foreid, J P Pimentel, T Botelho, M J Almeida, A |
description |
In this paper we discuss a non-invasive method to localize neural electrical sources using EEG data. In this method, the human head is modelled by a set of four concentric spheres with different conductivities which represent the scalp, the skull, the CSF and the brain or by three triangulated surfaces which approximate the exact head shape (in this model we do not consider the CSF layer) using NMR images. In this case the computer effort is very high, since the calculations imply thousands of equations. Therefore, the number of research groups working with this improved model, in the world, is very small. In both models, we assume that the neural source is a current dipole. This makes the model suitable for cases where the active brain areas are limited and localized. We discuss some error factors associated with the method, as the geometry of the head, the conductivity of the different layers and the number of electrodes used in the EEG measurements. Comparing the more realistic head model, with the spherical one we often have differences of 1-2 cm. However, we can reach even more pronounced differences in the frontal areas. Concerning the skull conductivity, we realized that it could introduce errors of 1-2 cm. We observed that at least 50 electrodes should be used only since 21 electrodes could imply errors of about 0.5 cm. The method was applied, both in the spherical version and the realistic one, to clinical cases of focal epileptic patients. The results are discussed in terms of the other clinical information available and they are coherent with the remaining clinical data. |
publishDate |
1996 |
dc.date.none.fl_str_mv |
1996-09-30 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
https://www.actamedicaportuguesa.com/revista/index.php/amp/article/view/2604 oai:ojs.www.actamedicaportuguesa.com:article/2604 |
url |
https://www.actamedicaportuguesa.com/revista/index.php/amp/article/view/2604 |
identifier_str_mv |
oai:ojs.www.actamedicaportuguesa.com:article/2604 |
dc.language.iso.fl_str_mv |
por |
language |
por |
dc.relation.none.fl_str_mv |
https://www.actamedicaportuguesa.com/revista/index.php/amp/article/view/2604 https://www.actamedicaportuguesa.com/revista/index.php/amp/article/view/2604/2016 |
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info:eu-repo/semantics/openAccess |
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openAccess |
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application/pdf |
dc.publisher.none.fl_str_mv |
Ordem dos Médicos |
publisher.none.fl_str_mv |
Ordem dos Médicos |
dc.source.none.fl_str_mv |
Acta Médica Portuguesa; Vol. 9 No. 7-9 (1996): Julho-Setembro; 219-27 Acta Médica Portuguesa; Vol. 9 N.º 7-9 (1996): Julho-Setembro; 219-27 1646-0758 0870-399X reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação instacron:RCAAP |
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Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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RCAAP |
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RCAAP |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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