Source analysis of MEG activities during sleep (abstract)

S. Ueno, Keiji Iramina

研究成果: ジャーナルへの寄稿記事

抄録

The present study focuses on magnetic fields of the brain activities during sleep, in particular on K complexes, vertex waves, and sleep spindles in human subjects. We analyzed these waveforms based on both topographic EEG (electroencephalographic) maps and magnetic fields measurements, called MEGs (magnetoencephalograms). The components of magnetic fields perpendicular to the surface of the head were measured using a dc SQUID magnetometer with a second derivative gradiometer. In our computer simulation, the head is assumed to be a homogeneous spherical volume conductor, with electric sources of brain activity modeled as current dipoles. Comparison of computer simulations with the measured data, particularly the MEG, suggests that the source of K complexes can be modeled by two current dipoles. A source for the vertex wave is modeled by a single current dipole which orients along the body axis out of the head. By again measuring the simultaneous MEG and EEG signals, it is possible to uniquely determine the orientation of this dipole, particularly when it is tilted slightly off axis. In sleep stage 2, fast waves of magnetic fields consistently appeared, but EEG spindles appeared intermittently. The results suggest that there exist sources which are undetectable by electrical measurement but are detectable by magnetic field measurement. Such source can be described by a pair of opposing dipoles of which directions are oppositely oriented.

元の言語英語
ページ数1
ジャーナルJournal of Applied Physics
69
発行部数8
DOI
出版物ステータス出版済み - 4 15 1991

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sleep
dipoles
magnetic fields
spindles
brain
apexes
computerized simulation
gradiometers
magnetometers
electrical measurement
waveforms
conductors

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

これを引用

Source analysis of MEG activities during sleep (abstract). / Ueno, S.; Iramina, Keiji.

:: Journal of Applied Physics, 巻 69, 番号 8, 15.04.1991.

研究成果: ジャーナルへの寄稿記事

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