EEG SPECTRAL-ANALYSIS DURING HYPNOTIC INDUCTION, HYPNOTIC DREAM AND AGE REGRESSION

EEG was recorded monopolarly at frontal (F3, F4), central (C3, C4) and posterior (in the middle of O1-P3-T5 and O2-P4-T6 triangles) derivati ons during the hypnotic induction of the Stanford Hypnotic Clinical Sc ale (SHCS) and during performance following suggestions of hypnotic dr eam and age-regression as expressed in the before-mentioned scale. 10 low-hypnotizable and 9 highly-hypnotizable and right-handed female stu dents participated in one experimental session. Evaluations were Fast- Fourier spectral analyses during the following conditions: waking-rest in eyes-open and eyes-closed condition; early, middle, and late phase s of hypnotic induction; rest-hypnosis in eyes closed condition; hypno tic dream and age regression. After spectral analysis of 0 to 44 Hz, t he mean spectral amplitude estimates across seven Hz bands (theta1, 4- 6 Hz, theta2, 6-8 Hz; alpha1, 8-10 Hz; alpha2, 10-13 Hz; beta1, 13-16 Hz; beta2, 16-20 Hz; beta3, 20-36 Hz) and the 40-Hz EEG band (36-44 Hz ) for each experimental condition were extracted. In eyes-open and -cl osed conditions in waking and hypnosis highly-hypnotizable subjects pr oduced a greater 40-Hz EEG amplitude than did low hypnotizable subject s at all frontal, central and posterior locations. In the early and mi ddle hypnotic induction highly-hypnotizables displayed a greater amoun t of beta3 than did low hypnotizables and this difference was even mor e pronounced in the left hemisphere. With posterior scalp recordings, during hypnotic dream and age regression, high hypnotizables displayed , as compared with the rest-hypnosis condition, a decrease in alpha1 a nd alpha2 amplitudes. This effect was absent for low hypnotizables. Be ta1, beta2 and beta3 amplitudes increased in the left hemisphere durin g age regression for high hypnotizables; low hypnotizables, in contras t, displayed hemispheric balance across imaginative tasks. High hypnot izables during the hypnotic dream also displayed in the right hemisphe re a greater 40-Hz EEG amplitude as compared with the left hemisphere. This difference was even more evident for posterior recording sites. This hemispheric trend was not evidenced for low hypnotizable subjects . Theta power was never a predictor of hypnotic susceptibility, 40-Hz EEG amplitude displayed a very high main effect (p < 0.004) for hypnot izability in hypnotic conditions by displaying a greater 40-Hz EEG amp litude in high hypnotizables with respect to lows.