The electrical conductivity of human cerebrospinal fluid at body temperature

doi:10.1109/10.554770

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The electrical conductivity of human cerebrospinal fluid at body temperature

Journal Article•DOI•

The electrical conductivity of human cerebrospinal fluid at body temperature

S.B. Baumann¹, D.R. Wozny¹, Shawn K. Kelly¹, F.M. Meno¹•Institutions (1)

University of Pittsburgh¹

01 Mar 1997-IEEE Transactions on Biomedical Engineering (IEEE)-Vol. 44, Iss: 3, pp 220-223

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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Abstract: The electrical conductivity of human cerebrospinal fluid (CSF) from seven patients was measured at both room temperature (25/spl deg/C) and body temperature (37/spl deg/C). Across the frequency range of 10 Hz-10 kHz, room temperature conductivity was 1.45 S/m, but body temperature conductivity was 1.79 S/m, approximately 23% higher. 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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Journal Article•DOI•

Gyri-precise head model of transcranial direct current stimulation: Improved spatial focality using a ring electrode versus conventional rectangular pad

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Abhishek Datta¹, Varun Bansal¹, Julian Diaz¹, Jinal Patel¹, Davide Reato¹, Marom Bikson¹ - Show less +2 more•Institutions (1)

City University of New York¹

01 Oct 2009-Brain Stimulation

TL;DR: It is shown that electric fields may be clustered at distinct gyri/sulci sites because of details in tissue architecture/conductivity, notably cerebrospinal fluid (CSF).

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1,071 citations

Cites background from "The electrical conductivity of huma..."

...465.(29-36) The muscle, fatty tissue, eyes, and blood vessel compartments were assigned the conductivity of scalp tissue....
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Journal Article•DOI•

Conductivity tensor mapping of the human brain using diffusion tensor MRI

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David S. Tuch¹, Van J. Wedeen, Anders M. Dale, John S. George, John W. Belliveau - Show less +1 more•Institutions (1)

Harvard University¹

25 Sep 2001-Proceedings of the National Academy of Sciences of the United States of America

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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Abstract: Knowledge of the electrical conductivity properties of excitable tissues is essential for relating the electromagnetic fields generated by the tissue to the underlying electrophysiological currents. Efforts to characterize these endogenous currents from measurements of the associated electromagnetic fields would significantly benefit from the ability to measure the electrical conductivity properties of the tissue noninvasively. Here, using an effective medium approach, we show how the electrical conductivity tensor of tissue can be quantitatively inferred from the water selfdiffusion tensor as measured by diffusion tensor magnetic resonance imaging. The effective medium model indicates a strong linear relationship between the conductivity and diffusion tensor eigenvalues (respectively, s and d) in agreement with theoretical bounds and experimental measurements presented here (syd ’ 0.844 6 0.0545 Szsymm3, r2 5 0.945). The extension to other biological transport phenomena is also discussed.

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510 citations

Journal Article•DOI•

Extracellular Total Electrolyte Concentration Imaging for Electrical Brain Stimulation (EBS).

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Saurav Z. K. Sajib¹, Mun Bae Lee², Hyung Joong Kim¹, Eung Je Woo¹, Oh In Kwon² - Show less +1 more•Institutions (2)

Kyung Hee University¹, Konkuk University²

10 Jan 2018-Scientific Reports

TL;DR: A fast non-iterative technique to visualize the total extracellular electrolyte concentration (EEC), which is a fundamental component of the conductivity, is presented.

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Abstract: Techniques for electrical brain stimulation (EBS), in which weak electrical stimulation is applied to the brain, have been extensively studied in various therapeutic brain functional applications. The extracellular fluid in the brain is a complex electrolyte that is composed of different types of ions, such as sodium (Na+), potassium (K+), and calcium (Ca+). Abnormal levels of electrolytes can cause a variety of pathological disorders. In this paper, we present a novel technique to visualize the total electrolyte concentration in the extracellular compartment of biological tissues. The electrical conductivity of biological tissues can be expressed as a product of the concentration and the mobility of the ions. Magnetic resonance electrical impedance tomography (MREIT) investigates the electrical properties in a region of interest (ROI) at low frequencies (below 1 kHz) by injecting currents into the brain region. Combining with diffusion tensor MRI (DT-MRI), we analyze the relation between the concentration of ions and the electrical properties extracted from the magnetic flux density measurements using the MREIT technique. By measuring the magnetic flux density induced by EBS, we propose a fast non-iterative technique to visualize the total extracellular electrolyte concentration (EEC), which is a fundamental component of the conductivity. The proposed technique directly recovers the total EEC distribution associated with the water transport mobility tensor.

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494 citations

Journal Article•DOI•

Review on solving the forward problem in EEG source analysis

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Hans Hallez¹, Bart Vanrumste², Bart Vanrumste³, Roberta Grech⁴, Joseph Muscat⁴, Wim De Clercq², Anneleen Vergult², Yves D'Asseler¹, Kenneth P. Camilleri⁴, Simon G. Fabri⁴, Sabine Van Huffel², Ignace Lemahieu¹ - Show less +8 more•Institutions (4)

Ghent University¹, Katholieke Universiteit Leuven², Katholieke Hogeschool Kempen³, University of Malta⁴

30 Nov 2007-Journal of Neuroengineering and Rehabilitation

TL;DR: This review article focuses on different aspects of solving the forward problem of electroencephalogram source localization and introduces the use of reciprocity to speed up the forward calculations.

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Abstract: Background The aim of electroencephalogram (EEG) source localization is to find the brain areas responsible for EEG waves of interest. It consists of solving forward and inverse problems. The forward problem is solved by starting from a given electrical source and calculating the potentials at the electrodes. These evaluations are necessary to solve the inverse problem which is defined as finding brain sources which are responsible for the measured potentials at the EEG electrodes.

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472 citations

Journal Article•DOI•

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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Carsten H. Wolters¹, Alfred Anwander², Xavier Tricoche³, David M. Weinstein³, Martin Koch⁴, Rob S. MacLeod⁵, Rob S. MacLeod³ - Show less +3 more•Institutions (5)

University of Münster¹, Max Planck Society², Scientific Computing and Imaging Institute³, University of Hamburg⁴, University of Utah⁵

15 Apr 2006-NeuroImage

TL;DR: 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 is reported on.

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440 citations

Cites background from "The electrical conductivity of huma..."

...…and assigned the following conductivities for the isotropic reference model (Geddes and Baker, 1967; Rush and Driscoll, 1968; Haueisen, 1996; Baumann et al., 1997): skin = 0.33 S/m, skull = 0.0042 S/m (skull to skin conductivity ratio of approximately 1:80), CSF = 1.79 S/m, gray matter =…...
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...…the different tissues within the head with special attention to the poorly conducting human skull and the highly ARTICLE IN PRESS C.H. Wolters et al. / NeuroImage xx (2005) xxx–xxx 3 conductive CSF (Hämäläinen and Sarvas, 1987; Cuffin, 1996; Roth et al., 1993; Huiskamp et al., 1999; Ramon et…...
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...Using a Line Integral Convolution (LIC) technique (Cabral and Leedom, 1993), we computed the return ARTICLE IN PRESS C.H. Wolters et al. / NeuroImage xx (2005) xxx–xxx 7 current directly over the surface of the head and on coronal slices through the head....
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...To construct a realistic volume conductor model requires segmentation of the different tissues within the head with special attention to the poorly conducting human skull and the highly ARTICLE IN PRESS C.H. Wolters et al. / NeuroImage xx (2005) xxx–xxx 3 conductive CSF (Hämäläinen and Sarvas, 1987; Cuffin, 1996; Roth et al., 1993; Huiskamp et al., 1999; Ramon et al., 2004)....
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...ARTICLE IN PRESS C.H. Wolters et al. / NeuroImage xx (2005) xxx–xxx 11 For a superficial tangentially oriented source in the somatosensory cortex, our results concerning the influence of skull anisotropy on the EEG potential distribution are in agreement with the observations of others (Marin et al., 1998; van den Broek et al., 1998)....
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References

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Journal Article•DOI•

The specific resistance of biological material—A compendium of data for the biomedical engineer and physiologist

[...]

L. A. Geddes¹, L. E. Baker¹•Institutions (1)

Baylor University¹

01 May 1967-Medical & Biological Engineering & Computing

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.

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Abstract: 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. Where possible, the conditions of measurement are given.

...read moreread less

1,645 citations

Journal Article•DOI•

Realistic conductivity geometry model of the human head for interpretation of neuromagnetic data

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Matti Hämäläinen¹, Jukka Sarvas¹•Institutions (1)

Helsinki University of Technology¹

01 Feb 1989-IEEE Transactions on Biomedical Engineering

TL;DR: A method to handle the numerical difficulties caused by the presence of poorly conducting skull is presented and it is shown numerically that for the computation of B produced by cerebral current sources, it is sufficient to consider a brain-shaped homogeneous conductor only.

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Abstract: The computational and practical aspects of a realistically shaped multilayer model for the conductivity geometry of the human head are discussed. A method to handle the numerical difficulties caused by the presence of poorly conducting skull is presented. Using the method, both the potential on the surface of the head and the magnetic field outside the head can be computed accurately. The procedure is tested with the multilayer sphere model, for which analytical expressions are available. The method is then applied to a realistically shaped head model, and it is shown numerically that for the computation of B produced by cerebral current sources, it is sufficient to consider a brain-shaped homogeneous conductor only, since the secondary currents on the outer interfaces give only a negligible contribution to the magnetic field outside the head. Comparisons with the sphere model are included to pinpoint areas where the homogeneous conductor model provides essential improvements in the calculation of the magnetic field outside the head. >

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1,033 citations

"The electrical conductivity of huma..." refers background in this paper

...However, this model is inaccurate for many sources, particularly for deeper dipoles [6] or for dipoles located in the anterior portion of the brain or near the flat sides of the head [7]....
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Journal Article•DOI•

The cerebrospinal fluid

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H. Houston Merritt, Frank Fremont-Smith

01 Apr 1938-The American Journal of the Medical Sciences

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Charles Polk

31 Aug 1986

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.

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Abstract: The objective of this book is to 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. In reviewing the vast amount of experimental data which have been obtained in recent years, the authors tried to select those results that are, in their opinion, of major importance and of lasting value. In discussing mechanisms of interaction of electromagnetic fields with living matter they have tried to differentiate between what is clearly established, what is suggested by available evidence without being convincingly proven, and what is conjecture at the present time.

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836 citations

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Electrodes and the measurement of bioelectric events

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L. A. Geddes

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329 citations

"The electrical conductivity of huma..." refers methods in this paper

...Both the current-injection and voltage-sensing electrodes are blackened using Kohlraush solution at a current density dependent upon electrode surface area [18]....
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