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Random Dipoles as a Model for Spontaneous EEG- and MEG-Activity

  • J. C. De Munck
  • P. C. M. Vijn
  • H. Spekreijse

Abstract

A serious obstacle for the interpretation of evoked electromagnetic fields is the presence of noise in the data. The background EEG is considered as the major origin of noise for evoked potentials. Also for evoked magnetic fields (EMF) the spontaneous brain activity is an important factor (Knuutila and Hämäläinen, 1987). When the statistical properties of this noise are known, confidence limits of estimated (dipole) parameters can be calculated (Sarvas, 1987) and noise filters can be designed to improve the signal to noise ratio. For this purpose we studied the spontaneous brain activity and formulated a mathematical model, which predicts the statistics of the electromagnetic field of the brain. Since the model gives the spatial covariance matrix in analytic form, this matrix needs not to be estimated every time an EMF is recorded.

Keywords

Volume Conductor Electrode Distance Spontaneous Brain Activity Spatial Covariance Matrix Stochastic Magnetic Induction 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. J.C. De Munck, 1988, The potential distribution in a layered anisotropic spheroidal volume conductor, J. Appl. Phys. 64(2), pp. 464–470.CrossRefGoogle Scholar
  2. J.C. De Munck, 1989, A mathematical and physical interpretation of the electromagnetic field of the brain, PhD-thesis University of Amsterdam, Amsterdam.Google Scholar
  3. J. Knuutila and M.S. Hämämäinen, 1987, Characterization of brain noise using a high sensitivity 7-channel magnetometer, Biomagnetism’87, Tokyo University Press, pp. 186–189.Google Scholar
  4. J. Sarvas, 1987, Basic mathematical and electromagnetic concepts of the biomagnetic inverse problem, Phys. Med. Biol. 32(1), pp. 11–22.PubMedCrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1989

Authors and Affiliations

  • J. C. De Munck
    • 1
  • P. C. M. Vijn
    • 1
  • H. Spekreijse
    • 1
  1. 1.The Laboratory of Medical PhysicsThe Netherlands Ophthalmic Research InstituteAmsterdam, ZOThe Netherlands

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