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/Subject (To achieve a deeper understanding of the brain, scientists, and clinicians use electroencephalography \(EEG\) and magnetoencephalography \(MEG\) inverse methods to reconstruct sources in the cortical sheet of the human brain. The influence of structural and electrical anisotropy in both the skull and the white matter on the EEG and MEG source reconstruction is not well understood. In this paper, we report on a study of the sensitivity to tissue anisotropy of the EEG/MEG forward problem for deep and superficial neocortical sources with differing orientation components in an anatomically accurate model of the human head. The goal of the study was to gain insight into the effect of anisotropy of skull and white matter conductivity through the visualization of field distributions, isopotential surfaces, and return current flow and through statistical error measures. One implicit premise of the study is that factors that affect the accuracy of the forward solution will have at least as strong an influence over solutions to the associated inverse problem. Major findings of the study include \(1\) anisotropic white matter conductivity causes return currents to flow in directions parallel to the white matter fiber tracts; \(2\) skull anisotropy has a smearing effect on the forward potential computation; and \(3\) the deeper a source lies and the more it is surrounded by anisotropic tissue, the larger the influence of this anisotropy on the resulting electric and magnetic fields. Therefore, for the EEG, the presence of tissue anisotropy both for the skull and white matter compartment substantially compromises the forward potential computation and as a consequence, the inverse source reconstruction. In contrast, for the MEG, only the anisotropy of the white matter compartment has a significant effect. Finally, return currents with high amplitudes were found in the highly conducting cerebrospinal fluid compartment, underscoring the need for accurate modeling of this space.)
/Author (C. H. Wolters and A. Anwander and X. Tricoche and D. Weinstein and M. A. Koch and R. S. MacLeod)
/Creator (LaTeX with hyperref package)
/Keywords (Anisotropy; Brain, physiology; Computer Simulation; Electric Conductivity; Electroencephalography; Finite Element Analysis; Humans; Magnetic Resonance Imaging; Magnetoencephalography; Models, Theoretical)
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/ModDate (D:20060407134653+02'00')
/Title (Influence of tissue conductivity anisotropy on EEG/MEG field and return current computation in a realistic head model: a simulation and visualization study using high-resolution finite element modeling.)
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To achieve a deeper understanding of the brain, scientists, and clinicians use electroencephalography (EEG) and magnetoencephalography (MEG) inverse methods to reconstruct sources in the cortical sheet of the human brain. The influence of structural and electrical anisotropy in both the skull and the white matter on the EEG and MEG source reconstruction is not well understood. In this paper, we report on a study of the sensitivity to tissue anisotropy of the EEG/MEG forward problem for deep and superficial neocortical sources with differing orientation components in an anatomically accurate model of the human head. The goal of the study was to gain insight into the effect of anisotropy of skull and white matter conductivity through the visualization of field distributions, isopotential surfaces, and return current flow and through statistical error measures. One implicit premise of the study is that factors that affect the accuracy of the forward solution will have at least as strong an influence over solutions to the associated inverse problem. Major findings of the study include (1) anisotropic white matter conductivity causes return currents to flow in directions parallel to the white matter fiber tracts; (2) skull anisotropy has a smearing effect on the forward potential computation; and (3) the deeper a source lies and the more it is surrounded by anisotropic tissue, the larger the influence of this anisotropy on the resulting electric and magnetic fields. Therefore, for the EEG, the presence of tissue anisotropy both for the skull and white matter compartment substantially compromises the forward potential computation and as a consequence, the inverse source reconstruction. In contrast, for the MEG, only the anisotropy of the white matter compartment has a significant effect. Finally, return currents with high amplitudes were found in the highly conducting cerebrospinal fluid compartment, underscoring the need for accurate modeling of this space.
C. H. Wolters
A. Anwander
X. Tricoche
D. Weinstein
M. A. Koch
R. S. MacLeod
10.1016/j.neuroimage.2005.10.014
Anisotropy; Brain
physiology; Computer Simulation; Electric Conductivity; Electroencephalography; Finite Element Analysis; Humans; Magnetic Resonance Imaging; Magnetoencephalography; Models
Theoretical
Influence of tissue conductivity anisotropy on EEG/MEG field and return current computation in a realistic head model: a simulation and visualization study using high-resolution finite element modeling.
2006-04
application/pdf
Article
C. H. Wolters
A. Anwander
X. Tricoche
D. Weinstein
M. A. Koch
R. S. MacLeod
Wolters_Neuroimage_preprint_2006
10.1016/j.neuroimage.2005.10.014
Wolters_Neuroimage_preprint_2006.pdf:Wolters_Neuroimage_preprint_2006.pdf:PDF
Westfälische Wilhelms-Universität Münster, Institut für Biomagnetismus und Biosignalanalyse, Malmedyweg 15, 48149 Münster, Germany. carsten.wolters@uni-muenster.de
Neuroimage
Anisotropy; Brain, physiology; Computer Simulation; Electric Conductivity; Electroencephalography; Finite Element Analysis; Humans; Magnetic Resonance Imaging; Magnetoencephalography; Models, Theoretical
eng
Apr
3
Alfred
813--826
2009.12.03
Influence of tissue conductivity anisotropy on EEG/MEG field and return current computation in a realistic head model: a simulation and visualization study using high-resolution finite element modeling.
http://dx.doi.org/10.1016/j.neuroimage.2005.10.014
30
2006
Article
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