Instrumentation for biomagnetism

Duret, D.; Karp, P.

doi:10.1007/bf02455917

Cited by 8 publications

(2 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In general, an adequate base line for an axial gradiometer is 1 -2 times the typical distance to the source. This provides sufhcient far-Geld rejection without severe attenuation of the signal (Vrba et al , 1982;Duret and Karp, 1983). One should note, however, that noise from nearby sources, such as the Dewar, cannot be avoided with gradiometric techniques.…”

Section: Gradiometersmentioning

confidence: 99%

See 1 more Smart Citation

Magnetoencephalography—theory, instrumentation, and applications to noninvasive studies of the working human brain

et al. 1993

View full text Add to dashboard Cite

Magnetoencephalography(MEG) is a noninvasive technique for investigating neuronal activity in the living human brairi. The time resolution of the method is better than 1 ms and the spatial discrimination is, under favorable circumstances, 2 -3 mm for sources in the cerebral cortex. In MEG studies, the weak 10 fT -1 pT magnetic fields produced by electric currents fiowing in neurons are measured with multichannel SQUID {superconducting quantum interference device) gradiometers. The sites in the cerebral cortex that are activated by a stimulus can be found from the detected magnetic-field distribution, provided that appropriate assumptions about the source render the solution of the inverse problem unique. Many interesting properties of the working human brain can be studied, including spontaneous activity and signal processing following external stimuli. For clinical purposes, determination of the locations of epileptic foci is of interest. The authors begiri with a general introduction and a short discussion of the neural basis of MEG. The mathematical theory of the method is then explained in detail, followed by a thorough description of MEG instrumentation, data analysis, and practical construction of multi-SQUID devices. Finally, several MEG experiments performed in the authors laboratory are described, covering studies of evoked responses and of spontaneous activity in both healthy and diseased brains. Many MEG studies by other groups are discussed briefiy as well.

show abstract

Section: Gradiometersmentioning

confidence: 99%

“…In wire-wound gradiometers, an initial imbalance of a few percent is typical. It can be reduced by changing the effective areas of the coils with movable superconducting pieces (Aittoniemi et al , 1978;Duret and Karp, 1983). Three tabs are needed to adjust the x, y, and z components separately.…”

Section: Gradiometersmentioning

confidence: 99%