[A 4.7 T static magnetic field has no effect on the electric activity of the brain in cats].

The effect of increasing static magnetic field strength up to 4.7 Tesla on the electrical function of the cat brain was studied by EEG frequency analysis and recording of somatosensory evoked potentials. While the latencies of the peaks P6 and P10 of the somatosensory evoked potentials were stable during the time course of the experiment, EEG intensity, EEG frequency index and the P10/N15 amplitude showed substantial fluctuations. EEG intensity varied between 67 and 156%, and EEG frequency index between 65 and 140% of the mean value averaged over the whole length of the experiment. The P10/N15 amplitude even varied between 16 and 186% of the mean amplitude. Despite these variations none of the variables correlated with the strength of the magnetic field. The observed changes are therefore interpreted as spontaneous fluctuations of vigilance and not as effects of the static magnetic field.