The Effect of Source Extension on the Location and Components of the Equivalent Dipole

  • J. C. de Munck
  • H. Spekreijse
Conference paper


Evoked potentials and Electroencephalograms can be used to determine the location of brain activity and the direction of the polarity. For this purpose mathematical models are used in which the various regions in the head with different conductivity are represented by generalized forms like spheres and spheroids. In most models the source is described by a mathematical point dipole. Since there exists a one-to-one correspondence between visual field and area 17 of the visual cortex, in many evoked potential experiments with visual stimuli the size of the stimulus field is chosen as small as possible in order to activate only a small part of the cortex. In this way a point dipole is imitated at the cost of a lower signal-to-noise ratio.


Potential Distribution Forward Problem Separation Angle Source Extension Point Dipole 
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  1. Ary JP, Klein SA, Fender DH (1981) Location of sources of evoked potentials: correction for skull and scalp thicknesses. IEEE Trans Biomed Eng 28:447–452PubMedCrossRefGoogle Scholar
  2. Cuffin BN (1985) A comparison of moving dipole inverse solutions using EEG’s and MEG’s. IEEE Trans Biomed Eng 32:905–910PubMedCrossRefGoogle Scholar
  3. De Munck JC, Van Dijk BW, Spekreijse H (1988) An analytic method to determine the effect of source modelling errors on the apparent location and direction of biological sources. J Appl Phys 63 (3): 944–956CrossRefGoogle Scholar
  4. Rudy Y, Plonsey R (1979) The eccentric spheres model as the basis for a study of the role of geometry and inhomogeneities in electrocardiography. IEEE Trans Biomed Eng 26:392–399PubMedCrossRefGoogle Scholar
  5. Van Oosterom A (1978) Cardiac potential distributions. Thesis, University of AmsterdamGoogle Scholar
  6. Yeh GCK, Martinek J (1959) Multipole representation of an eccentric dipole and an eccentric double layer. Bull Math Biophys 21:33–60CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1989

Authors and Affiliations

  • J. C. de Munck
  • H. Spekreijse
    • 1
  1. 1.The Netherlands Ophthalmic Research InstituteAmsterdamThe Netherlands

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