[The high-frequency electroencephalogram: the results and outlook].

At present, the significance of high-frequency (HF) components in brain electrical activity (EA) is widely discussed in literature. In particular, the gamma range of human EEG is considered as one of the indices of cognitive activity. In the paper a review is presented of the author's own data concerning the functional estimation of low-voltage HF components of the neocortical EA recorded in the broad band (1-100, 1-256 Hz) in the course of instrumental conditioning in dogs. Three different techniques of EA analysis were used in the study: 1) fast Fourier transformation (FFT) of EA in a broad band, 2) developed by us alternative method of non-harmonic expansion of the EEG curves taking into account their shape, 3) factor analysis of the EA spectral densities. Combination of these techniques allowed us to obtain some novel evidence indicative of high informativity of the HF fluctuations. Spatial cortical localization of the HF components of the EA is much more expressed in comparison with the traditional 1-30 Hz range. Results of factor analysis suggest functional heterogeneity of the HF band. Obtained data open new ways for researches concerning the phenomena of the functional mosaics in the neocortex as one of fundamental mechanisms in brain activity organization.