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On the influence of volume currents and extended sources on neuromagnetic fields: A simulation study

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Abstract

The influence of volume currents on the magnetic field is an important question in magnetoencephalography since the spherical volume conductor is still widely used for source localization. In theory, the magnetic field of a radial dipole in a homogeneous sphere is zero. In realistic models of the head, the field is suppressed when compared with a tangential dipole. To determine the influence of the volume currents, this suppression ratio (magnetic field of the radial dipole divided by the field of the tangential dipole) needs to be quantified. Large-scale finite element method models of the human head and the rabbit head were constructed and the suppression ratio was computed. The computed suppression value of 0.28 in the rabbit head was similar to the previously measured experimental value. In the human head, an average suppression ratio of 0.19±0.07 was found for different regions and depths in the gray matter. It was found that the computed magnetic field of radial sources varied significantly with the conductivities of the surrounding tissues where the dipole was located. We also modeled the magnetic field of an epileptic interictal spike in a finite element model of the rabbit head with a single dipole and with extended sources of varying length (1–8 mm). The extended source models developed were based on invasive measurements of an interictal spike within the rabbit brain. The field patterns of the small (1–2 mm) extended sources were similar to a single dipolar source and begin to deviate significantly from a dipolar field for the larger extended sources (6–8 mm).

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References

  1. Polk, C., and E. Postow (eds.).CRC Handbook of Biological Effects of Electromagnetic Fields. CRC Press, Boca Raton, FL, 1986.

    Google Scholar 

  2. Baule, G., and R. McFee. Theory of magnetic detection of the heart's electrical activity.J. Appl. Phys. 36:2066–2073, 1965.

    Article  Google Scholar 

  3. Bertrand, O., M. Thevenet F. Perrin, and J. Pernier. Effects of skull holes on the scalp potential distribution evaluated with a finite element model. Proc. 14th Ann. Int. Conf. IEEE Eng. Med. and Biol. Soc., Lyon, 1992, pp. 42–45.

  4. Brodmann, K.Vergleichende Lokalisationslehre der Großhirnrinde. Leipzig: Barth, 1909.

    Google Scholar 

  5. Cohen, D., B. N. Cuffin, K. Yunokuchi, R. Maniewski, C. Purcell, G. R. Cosgrove, J. Ives, J. G. Kennedy, and D. L. Schomer. MEG versus EEG localization test using implanted sources in the human brain.Ann. Neurol. 28(6): 811–817, 1990.

    Article  PubMed  CAS  Google Scholar 

  6. Cuffin, B. N. Effects of local variations in skull and scalp thickness on EEG's and MEG's.IEEE Trans. Biomed. Eng. BME-40(1):42–48, 1993.

    Article  PubMed  CAS  Google Scholar 

  7. Eiselt, M., H. Wagner, and U. Zwiener. Conditions for a precise analysis of penicillin-induced spikes by currentsource-density. Proc. Hans Berger Symposium, Jena, 1993.

  8. Geddes, L. A., and L. E. Baker. The specific resistance of biological materials—a compendium of data for the biomedical engineer and physiologist.Med. Biol. Eng. 5:271–293, 1967.

    Article  PubMed  CAS  Google Scholar 

  9. Jorgenson, D. B., D. R. Haynor, G. H. Bardy, and Y. Kim. Computational studies of transthoracic and transvenous defibrillation in a detailed 3-D human thorax model.IEEE Trans. Biomed. Eng. 42:172–184, 1995.

    Article  PubMed  CAS  Google Scholar 

  10. Le, J., and A. Gevins. Method to reduce blur distortion from EEG's using a realistic head model.IEEE Trans. Biomed. Eng. BME-40(6):517–528, 1993.

    Article  PubMed  CAS  Google Scholar 

  11. Melcher, J. R., and D. Cohen. Dependence of the MEG on dipole orientation in the rabbit head.Electroenceph. Clin. Neurophysiol. 70(5):460–472, 1988.

    Article  PubMed  CAS  Google Scholar 

  12. Miller, Ch. E. and C. S. Henriquez. Finite element analysis of bioelectric phenomena.Crit. Rev. Biomed. Eng. 18(3): 207–233, 1990.

    PubMed  CAS  Google Scholar 

  13. Pethig, R. Dielectric properties of body tissues.Clin. Phys. Physiol. Meas. 8(Suppl. A), 1987.

  14. Potter, G. D.Sectional Anatomy and Tomography of the Head. Grune & Stratton, 1971.

  15. Reddy, G. N., and S. Saha. Electrical and dielectric properties of wet bone as a function of frequency.IEEE Trans. Biomed. Eng. BME-31(3):296–302, 1984.

    Article  PubMed  CAS  Google Scholar 

  16. Rush, S., J. A. Abildskov, and R. McFee. Resistivity of body tissues at low frequencies.Circ. Res. 12:40–50, 1963.

    PubMed  CAS  Google Scholar 

  17. Shek, J. W., G. Y. Wen, and H. M. Wisniewski.Atlas of the Rabbit Brain and Spinal Cord. Basel: Karger, 1986.

    Google Scholar 

  18. Yamamoto, T., and Y. Yamamoto. Electrical properties of the epidermal stratum corneum.Med. Biol. Eng. 14(2):151–158, 1976.

    Article  PubMed  CAS  Google Scholar 

  19. Yan, Y., P. L. Nunez, and R. T. Hart, Finite-element model of the human head: scalp potentials due to dipole sources.Med. Biol. Eng. Comput. 29:475–481, 1991.

    Article  PubMed  CAS  Google Scholar 

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Authors and Affiliations

  1. Biomagnetisches Zentrum, Friedrich-Schiller-Universität Jena, Jena, Germany

    Jens Haueisen

  2. Institut für Pathologische Physiologie, Friedrich-Schiller-Universität Jena, Jena, Germany

    Michael Eiselt

  3. Center for Bioengineering, University of Washington, 98195, Seattle, WA, USA

    Ceon Ramon

  4. Department of Electrical Engineering, University of Washington, 98195, Seattle, WA, USA

    Piotr Czapski

Authors
  1. Jens Haueisen
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  2. Ceon Ramon
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  3. Piotr Czapski
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  4. Michael Eiselt
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Haueisen, J., Ramon, C., Czapski, P. et al. On the influence of volume currents and extended sources on neuromagnetic fields: A simulation study. Ann Biomed Eng 23, 728–739 (1995). https://doi.org/10.1007/BF02584472

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  • DOI: https://doi.org/10.1007/BF02584472

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