On the exterior magnetic field and silent sources in magnetoencephalography

Autor: George Dassios, Fotini Kariotou
Jazyk: angličtina
Rok vydání: 2004
Předmět:
Zdroj: Abstract and Applied Analysis, Vol 2004, Iss 4, Pp 307-314 (2004)
Druh dokumentu: article
ISSN: 1085-3375
1687-0409
10853375
DOI: 10.1155/S1085337504306032
Popis: Two main results are included in this paper. The first one deals with the leading asymptotic term of the magnetic field outside any conductive medium. In accord with physical reality, it is proved mathematically that the leading approximation is a quadrupole term which means that the conductive brain tissue weakens the intensity of the magnetic field outside the head. The second one concerns the orientation of the silent sources when the geometry of the brain model is not a sphere but an ellipsoid which provides the best possible mathematical approximation of the human brain. It is shown that what characterizes a dipole source as silent is not the collinearity of the dipole moment with its position vector, but the fact that the dipole moment lives in the Gaussian image space at the point where the position vector meets the surface of the ellipsoid. The appropriate representation for the spheroidal case is also included.
Databáze: Directory of Open Access Journals
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