[The temporal consistency of phasic conversions in the basic frequency components of the EEG].

The study is dedicated to the problem of piecewise description of stationary segments of the EEG basic rhythms. Temporal consistency was studied of the moments of sharp changes in characteristics of the individual basic EEG frequency components within the same realization. In 6 human subjects (in the state of quiet wakefulness with eyes closed) a rather high number was shown of nonrandom paired coincidences of the moments of sharp changes in characteristics of 5 EEG basic rhythms. Such between-component consistency was most expressed for a combination of alpha2-beta1 frequency ranges. The main topographic feature of this phenomenon was a substantial (2-4 times) increase in the indices of between-frequency consistency from the occipital to frontal areas. The character of changes in these indices was closely the same in 10 paired combinations of the EEG frequency bands, at least in the frontal and central derivations. The obtained results suggest the existence of a special operational synchrony of the EEG basic rhythms. In contrast to the classical phase-frequency synchronization, this kind of synchrony reflects the temporal consistency of quasistationary modes of brain activity.