On the exterior magnetic field and silent sources in magnetoencephalography
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 brai...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Hindawi Limited
2004-01-01
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| Series: | Abstract and Applied Analysis |
| Online Access: | http://dx.doi.org/10.1155/S1085337504306032 |
| Summary: | 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. |
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| ISSN: | 1085-3375 1687-0409 |