[Effect of hypnosis and suggestion on the EEG-powerspectrum in the preparatory interval (author's transl)].

Fourier-analysis of the EEG (P4 02, P3 O1, CZ A1) in the stimulation period (1 sec) before acoustic stimulation showed significant differences between hypnosis and waking. Diminished power was found in the slower spectrum (0-3 and 4-7 c/sec) over the right hemisphere (P4O2) during hypnosis. Increased power was found in the alpha-spectrum (8-13 c/sec) over the Vertex (CZA1) during suggestion. We interpreted this effect as inhibition of exteroceptive perception during suggestion. Powerspectrum was averaged over 30 stimulation periods before acoustic stimulation with identic tones (sinus of 500 c/sec, 70 dB, duration 40 msec, stimulus interval 3--10 sec). The combination of experimental conditions (Hypnosis/Waking and Suggestions) were given in a balanced order to control seriel effects. We examined 12 persons in a repeated measurement design.