[Narrow-band changes in the spectral composition of the EEG under the influence of an agonist and antagonist of the cholinergic neuromediator system].

The EEG effects of intake of the mean therapeutic single dose of cholinomimetic amiridin (20 mg) or cholinolytic amizyl (2 mg) were studied in 7 healthy subjects. After the intake of the drugs with agonistic and antagonistic action, significant opposite changes in the EEG spectral density were observed in the frequency ranges of 0.6-6.7, 7.7-11.4, and 24.8-29.7 Hz. Amizyl produced an enhancement of the spectral density of the delta-, theta- and beta 2 activity and reduction of the alpha-rhythm power, while under the action of amiridin the spectral density of these rhythms changed in opposite directions. The oppositely directed changes in the alpha range were most pronounced. The peak frequency of amiridin-induced shift was equal to 9.8-10 Hz, and the same value of the spectral change induced by amizyl was 10.8-11.4 Hz. It is suggested that the spectral power density of the alpha-rhythm is an EEG index of the level of cholinergic activation.