Summary
This paper describes a uniform method for calculating the interpolation of scalp EEG potential distribution, the current source density (CSD), the cortical potential distribution (cortical mapping) and the CSD of the cortical potential distribution. It will be shown that interpolation and deblurring methods such as CSD or cortical mapping are not independent of the inverse problem in potential theory. Not only the resolution but also the accuracy of these techniques, especially those of deblurring, depend greatly on the spatial sampling rate (i.e., the number of electrodes). Using examples from simulated and real (64 channels) data it can be shown that the application of more than 100 EEG channels is not only favourable but necessary to guarantee a reasonable accuracy in the calculations of CSD or cortical mapping. Likewise, it can be shown that using more than 250 electrodes does not improve the resolution.
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References
Alcaini, M., Giard, M.H., Thevenet, M. and Pernier, J. Dissociation of two frontal components in the N1 wave of the human auditory evoked response Psychophysiol., 1994, 31: 611–615.
Böhmer K. Spline-Funktionen. B.G. Teubner Stuttgart, 1974.
Braun C., Lutzenberger W., Miltner W., Elbert T. Can subcortical structures generate potentials large in amplitude? In: Brunia, C.H.M., Gaillard, A.W.K., Kok, A., eds. Psychophysiological Brain Research, Vol.1. Tilburg, Tilburg University Press, 1990, pp. 31–35.
Cuffin, B.N. and Cohen, D. Comparison of the magnetoencephalogram and electroencephalogram. Electroenceph. clin. Neurophysiol., 1979, 47:132–146.
Freeden, W. On Spherical Spline Interpolation and Approximation. Math. Meth. in the Appl. Sciences, 1981, 3: 551–575.
Gevins, A., Jian, L., Brickett, P., Reutter, B., and Desmond, J. Seeing through the skull: advanced EEGs accurately measure cortical activity from the scalp. Brain Topography, 1991, 4:125–132
Gevins, A., Jian, L., Martin, N.K., Brickett, P., Desmond, J., and Reutter, B. High resolution EEG: 124-channel recording spatial deblurring and MRI integration methods. Electroencph. Clin. Neurophysiol., 1994, 90: 337–358.
Giard, M.H., Perrin, F., Echallier, J.F., Thevenet, M., Froment, J.C. and Pernier, J. Dissociation of temporal and frontal components in the human auditory N1 wave: a scalp current density and dipole model analysis. Electroenceph. clin. Neurophysiol., 1994, 92: 238–252.
Gonzalez, S., Grave de Peralta, R., Lütkenhöner B., Menninghaus, E., and Hoke, M. A strategy for the soultion of the inverse problem using simultaneous EEG and MEG measurements. In Hoke, M., Okada, Y., Erné, S.N., Romani, G.L. (eds.): Advances in Biomagnetism'91: Clinical Aspects. Elsevier, Amsterdam, 1991: 99–100.
Nuñez, P.L., Silberstein, R.B., Cadusch, P.J., and Wijensinghe, R.S. Comparison of high resolution methods having different theoretical bases. Brain Topography, 1993, 5(4): 361–364.
Nuñez, P.L., Silberstein, R.B., Cadusch, P.J., Wijensinghe, R.S., Westdorp, A.F., and Srinivasan, R. A theoretical and experimental study of high resolution EEG based on surface Laplacians and cortical imaging. Electroenceph. Clin. Neurophysiol., 1994, 90: 40–57.
Perrin, F., Bertrand, O., and Pernier, J. Scalp current density mapping: value and estemationnfrom potential data. IEEE Transactions on Biomedical Engineering, 1987, 34(4): 283–289.
Perrin, F., Pernier, J., Bertrand, O., and Echallier, J.F. Spherical splines for potential and current density mapping. Electroenc. Clin. Neurophys., 1989, 72: 184–187.
Sakatow, P.S. Lehrbuch der höheren GeodÄsie. VEB Verlag Technik Berlin, 1957.
Schoenberg, I.J. On trigonometric spline interpolation. J. Math. Mech. 13, 1964: 795–825.
Wahba, G. Spline Interpolation and Smoothing on the Sphere, SIAM, J. Sci. Stat. Comput, 1991, 2(1): 5–16.
Yamashita, Y. Theoretical studies on the inverse problem in electrocardiography and the uniqueness of the solution. IEEE Trans. Biomed. Eng. 1982, 29: 719–724.78.
Yamashita, Y. and Takahashi T. Use of the finite element method to determine epicardial from body surface potentials under a realistic torso model. IEEE Trans. Biomed. Eng. 1984, 31: 611–621.
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This study was supported by grants from the Deutsche Forschungsgemeinschaft to Thomas Elbert and Brigitte Rockstroh. The authors would like to thank Dr. Dorothy Charbonnier.
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Junghöfer, M., Elbert, T., Leiderer, P. et al. Mapping EEG-potentials on the surface of the brain: A strategy for uncovering cortical sources. Brain Topogr 9, 203–217 (1997). https://doi.org/10.1007/BF01190389
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DOI: https://doi.org/10.1007/BF01190389