Journal ArticleDOI
Influence of tissue resistivities on neuromagnetic fields and electric potentials studied with a finite element model of the head
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TLDR
The aim of this paper is to examine the influence of tissue resistivity changes on the neuromagnetic field and the electric scalp potential, using a high-resolution finite element method of the human head with 13 different tissue types.Abstract:
Modeling in magnetoencephalography (MEG) and electroencephalography (EEG) requires knowledge of the in vivo tissue resistivities of the head. The aim of this paper is to examine the influence of tissue resistivity changes on the neuromagnetic field and the electric scalp potential. A high-resolution finite element method (FEM) model (452162 elements, 2-mm resolution) of the human head with 13 different tissue types is employed for this purpose. Our main finding was that the magnetic fields are sensitive to changes in the tissue resistivity in the vicinity of the source. In comparison, the electric surface potentials are sensitive to changes in the tissue resistivity in the vicinity of the source and in the vicinity of the position of the electrodes. The magnitude (strength) of magnetic fields and electric surface potentials is strongly influenced by tissue resistivity changes, while the topography is not as strongly influenced. Therefore, an accurate modeling of magnetic field and electric potential strength requires accurate knowledge of tissue resistivities, while for source localization procedures this knowledge might not be a necessity.read more
Citations
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Gyri-precise head model of transcranial direct current stimulation: Improved spatial focality using a ring electrode versus conventional rectangular pad
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Conductivity tensor mapping of the human brain using diffusion tensor MRI
TL;DR: The effective medium model indicates a strong linear relationship between the conductivity and diffusion tensor eigenvalues (respectively, σ and d) in agreement with theoretical bounds and experimental measurements presented here.
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The electrical conductivity of human cerebrospinal fluid at body temperature
TL;DR: Modelers of electrical sources in the human brain have underestimated human CSF conductivity by as much as 44% for nearly two decades, and this should be corrected to increase the accuracy of source localization models.
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Immediate neurophysiological effects of transcranial electrical stimulation.
Anli Liu,Mihály Vöröslakos,Greg Kronberg,Simon Henin,Matthew R. Krause,Yu Huang,Alexander Opitz,Ashesh D. Mehta,Christopher C. Pack,Bart Krekelberg,Antal Berényi,Lucas C. Parra,Lucia Melloni,Lucia Melloni,Orrin Devinsky,György Buzsáki +15 more
TL;DR: While it remains unclear how typical TES protocols affect neural activity, it is proposed that validated models of current flow should inform study design and artifacts should be carefully excluded during signal recording and analysis.
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The influence of brain tissue anisotropy on human EEG and MEG.
Jens Haueisen,David S. Tuch,Ceon Ramon,P.H. Schimpf,Van J. Wedeen,John S. George,John W. Belliveau +6 more
TL;DR: It is expected that inclusion of tissue anisotropy information will improve source estimation procedures and find a major influence on the amplitude of EEG and MEG due to the change in conductivity and the inclusion of anisotropic volume conduction.
References
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Journal ArticleDOI
MR diffusion tensor spectroscopy and imaging.
TL;DR: Once Deff is estimated from a series of NMR pulsed-gradient, spin-echo experiments, a tissue's three orthotropic axes can be determined and the effective diffusivities along these orthotropic directions are the eigenvalues of Deff.
Journal ArticleDOI
The specific resistance of biological material—A compendium of data for the biomedical engineer and physiologist
L. A. Geddes,L. E. Baker +1 more
TL;DR: The paper traces the history of, and tabulates determinations of the electrical resistivity of blood, other body fluids, cardiac muscle, skeletal muscle, lung, kidney, liver, spleen, pancreas, nervous tissue, fat, bone, and other miscellaneous tissues.
Book
CRC Handbook of Biological Effects of Electromagnetic Fields
TL;DR: In this paper, the authors present in a concise manner what is actually known at the present time about biological effects of time invariant, low frequency and radio frequency (including microwave) electric and magnetic fields.
Journal ArticleDOI
Ion diffusion modified by tortuosity and volume fraction in the extracellular microenvironment of the rat cerebellum.
Charles Nicholson,J.M. Phillips +1 more
TL;DR: The conclusions confirm that the laws of macroscopic diffusion are closely obeyed in the cerebellum for small ions in the extracellular space, provided that volume fraction and tortuosity are explicitly taken into account.
Journal ArticleDOI
Current distribution in the brain from surface electrodes.
Stanley Rush,Daniel A. Driscoll +1 more
TL;DR: It is apparent that the amount and distribution of current entering the brain is of great consequence, yet the literature discloses no systematic mathematical or experimental method for predicting current flow.
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