title: Do static magnetic fields of NMR influence biological signals?
abstract: When measuring auditory evoked potentials on test persons we found that an early signal, measurable between the mastoid and vertex electrodes and possibly caused by capacitive or/and inductive coupling from the electrodynamic headphone, was phase-shifted when the person was exposed to a static 0.35 T field. This shift only slowly (greater than 15 min) returned to zero after termination of the magnetic exposure. Using a circuit stimulating the EEG measurement we now show that this shift is caused by a change in the total capacity of the electrode impedances. Therefore, the magnetically induced shift may be explained by changes in electric capacities of the magnetically exposed biological system.
mesh_terms: D005072:Evoked Potentials, Auditory; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008280:Magnetics