[Magnetoencephalography, a new function diagnostic method].

Abstract

Recording of MEG is possible by the existence of magnetic fields caused by flowing electric currents. The magnetic field produced by neurons is at least one million times weaker than the steady earth field or other disturbing fields. The application and the current development of the SQUID technology operating by superconduction makes registration possible even in an unshielded envirement. The MEG has the following advantages compared with the EEG: The MEG has no artifacts of electrodes and eye movements as the EEG does. Reference electrodes are not needed thus no artifacts of these occur. Therefore recording of the steady magnetic field of the brain can be done. The localization of neuronal sources is more distinct and circumscript in the MEG than in the EEG. For several reasons not all components of the MEG are found in the EEG and vice versa. MEG and EEG is a meaningful combination. The MEG allows also to record and localize sources in the deep of the brain, i.e. beneath the cortex. A three dimensional functional realtime measurement is possible. In the future the MEG technique allows a lot of possibilities not only in the research but also in the dayly functional diagnosis.