[Computer-assisted analysis of the electroencephalogram with a theta ground rhythm variant]

From 8 men and 12 women with a slow posterior rhythm on the one hand and from 7 male and 5 female healthy volunteers with a regular alpha-EEG on the other closed-eye-EEGs were registered at 8:00 a.m., 12:00 noon, 4:00 p.m., and 8:00 p.m. and recorded on tape for computer processing. Simultaneously each time the body temperature was measured.

In 11 of the 20 patients the slow posterior rhythm shows a right-sided accentuation, in 6 a left-sided. Besides the activity of all frequency-bands favours occipital and occipital-central the right hemisphere. The control group shows only an insignificant right-sided accentuation of alpha-power and alpha-peak-power. The alpha-peak-frequency of the 20 patients is slower than in the controls, the body temperature on the contrary is higher. The physiological circadian shift of the alpha-peak-frequency and of the body temperature does not come up to a similar extent as in the controls. Striking slight is the circadian shift of the frequency of the slow posterior rhythm. Furthermore the day-time related shifts of the alpha-power and of the beta-power take other courses than in the controls. And the maxima of the alpha-power and of the alpha-peak-power are mostly located parietal instead of occipital. All in all the slow posterior rhythm seems to be connected with far-reaching peculiarities of the cerebral function.