Source localization using virtual magnetoencephalography helmets: A simulation study toward a prior-based tailored scheme

Magnetoencephalography (MEG) source estimation of brain electromagnetic fields is an ill-posed problem. A virtual MEG helmet (VMH), can be constructed by recording in different head positions and then transforming the multiple head-MEG coordinates into one head frame (i.e., as though the MEG helmet...

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Main Authors: Oshrit Arviv, Yuval Harpaz, Evgeny Tsizin, Tal Benoliel, Dana Ekstein, Mordekhay Medvedovsky
Format: Article
Language:English
Published: Frontiers Media S.A. 2022-09-01
Series:Frontiers in Neuroscience
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fnins.2022.947228/full
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author Oshrit Arviv
Oshrit Arviv
Yuval Harpaz
Evgeny Tsizin
Evgeny Tsizin
Tal Benoliel
Tal Benoliel
Dana Ekstein
Dana Ekstein
Mordekhay Medvedovsky
author_facet Oshrit Arviv
Oshrit Arviv
Yuval Harpaz
Evgeny Tsizin
Evgeny Tsizin
Tal Benoliel
Tal Benoliel
Dana Ekstein
Dana Ekstein
Mordekhay Medvedovsky
author_sort Oshrit Arviv
collection DOAJ
description Magnetoencephalography (MEG) source estimation of brain electromagnetic fields is an ill-posed problem. A virtual MEG helmet (VMH), can be constructed by recording in different head positions and then transforming the multiple head-MEG coordinates into one head frame (i.e., as though the MEG helmet was moving while the head remained static). The constructed VMH has sensors placed in various distances and angles, thus improving the spatial sampling of neuromagnetic fields. VMH has been previously shown to increase total information in comparison to a standard MEG helmet. The aim of this study was to examine whether VMH can improve source estimation accuracy. To this end, controlled simulations were carried out, in which the source characteristics are predefined. A series of VMHs were constructed by applying two or three translations and rotations to a standard 248 channel MEG array. In each simulation, the magnetic field generated by 1 to 5 dipoles was forward projected, alongside noise components. The results of this study showed that at low noise levels (e.g., averaged data of similar signals), VMHs can significantly improve the accuracy of source estimations, compared to the standard MEG array. Moreover, when utilizing a priori information, tailoring the constructed VMHs to specific sets of postulated neuronal sources can further improve the accuracy. This is shown to be a robust and stable method, even for proximate locations. Overall, VMH may add significant precision to MEG source estimation, for research and clinical benefits, such as in challenging epilepsy cases, aiding in surgical design.
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spelling doaj.art-f17821a50e0d4a198fed6694487998af2022-12-22T01:44:10ZengFrontiers Media S.A.Frontiers in Neuroscience1662-453X2022-09-011610.3389/fnins.2022.947228947228Source localization using virtual magnetoencephalography helmets: A simulation study toward a prior-based tailored schemeOshrit Arviv0Oshrit Arviv1Yuval Harpaz2Evgeny Tsizin3Evgeny Tsizin4Tal Benoliel5Tal Benoliel6Dana Ekstein7Dana Ekstein8Mordekhay Medvedovsky9Department of Neurology, Agnes Ginges Center of Human Neurogenetics, Hadassah Medical Center, Jerusalem, IsraelFaculty of Medicine, Hebrew University of Jerusalem, Jerusalem, IsraelThe Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, IsraelDepartment of Neurology, Agnes Ginges Center of Human Neurogenetics, Hadassah Medical Center, Jerusalem, IsraelThe Zandman-Slaner Graduate School of Engineering, Tel Aviv University, Tel Aviv, IsraelDepartment of Neurology, Agnes Ginges Center of Human Neurogenetics, Hadassah Medical Center, Jerusalem, IsraelFaculty of Medicine, Hebrew University of Jerusalem, Jerusalem, IsraelDepartment of Neurology, Agnes Ginges Center of Human Neurogenetics, Hadassah Medical Center, Jerusalem, IsraelFaculty of Medicine, Hebrew University of Jerusalem, Jerusalem, IsraelDepartment of Neurology, Agnes Ginges Center of Human Neurogenetics, Hadassah Medical Center, Jerusalem, IsraelMagnetoencephalography (MEG) source estimation of brain electromagnetic fields is an ill-posed problem. A virtual MEG helmet (VMH), can be constructed by recording in different head positions and then transforming the multiple head-MEG coordinates into one head frame (i.e., as though the MEG helmet was moving while the head remained static). The constructed VMH has sensors placed in various distances and angles, thus improving the spatial sampling of neuromagnetic fields. VMH has been previously shown to increase total information in comparison to a standard MEG helmet. The aim of this study was to examine whether VMH can improve source estimation accuracy. To this end, controlled simulations were carried out, in which the source characteristics are predefined. A series of VMHs were constructed by applying two or three translations and rotations to a standard 248 channel MEG array. In each simulation, the magnetic field generated by 1 to 5 dipoles was forward projected, alongside noise components. The results of this study showed that at low noise levels (e.g., averaged data of similar signals), VMHs can significantly improve the accuracy of source estimations, compared to the standard MEG array. Moreover, when utilizing a priori information, tailoring the constructed VMHs to specific sets of postulated neuronal sources can further improve the accuracy. This is shown to be a robust and stable method, even for proximate locations. Overall, VMH may add significant precision to MEG source estimation, for research and clinical benefits, such as in challenging epilepsy cases, aiding in surgical design.https://www.frontiersin.org/articles/10.3389/fnins.2022.947228/fullsource estimationsource localizationinverse problemequivalent current dipoledipole fitgain matrix
spellingShingle Oshrit Arviv
Oshrit Arviv
Yuval Harpaz
Evgeny Tsizin
Evgeny Tsizin
Tal Benoliel
Tal Benoliel
Dana Ekstein
Dana Ekstein
Mordekhay Medvedovsky
Source localization using virtual magnetoencephalography helmets: A simulation study toward a prior-based tailored scheme
Frontiers in Neuroscience
source estimation
source localization
inverse problem
equivalent current dipole
dipole fit
gain matrix
title Source localization using virtual magnetoencephalography helmets: A simulation study toward a prior-based tailored scheme
title_full Source localization using virtual magnetoencephalography helmets: A simulation study toward a prior-based tailored scheme
title_fullStr Source localization using virtual magnetoencephalography helmets: A simulation study toward a prior-based tailored scheme
title_full_unstemmed Source localization using virtual magnetoencephalography helmets: A simulation study toward a prior-based tailored scheme
title_short Source localization using virtual magnetoencephalography helmets: A simulation study toward a prior-based tailored scheme
title_sort source localization using virtual magnetoencephalography helmets a simulation study toward a prior based tailored scheme
topic source estimation
source localization
inverse problem
equivalent current dipole
dipole fit
gain matrix
url https://www.frontiersin.org/articles/10.3389/fnins.2022.947228/full
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