HIGH-FREQUENCY ELECTROENCEPHALOGRAM (EEG) - RESULTS AND PERSPECTIVES OF RESEARCH

At present, the significance of high-frequency (HF) component in brain electrical activity (EA) is widely discussed in literature. In partic ular, 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 auth or's own data concerning the functional estimation of low-voltage HF c omponents of the neocortical EA recorded in the broad band (1-100, 1-2 56 Hz) in the course of instrumental conditioning in dogs. Three diffe rent techniques of EA analysis were used in the study: 1) Fast Fourier Transformation (FFT) of EA in a broad band, 2) developed by us altern ative method of Non-Harmonic Expansion of the EEG curves taking into a ccount their shape, 3) Factor Analysis of the EA spectral densities. C ombination of these techniques allowed us to obtain some novel evidenc e indicative of high informativity of the HF fluctuations. Spatial cor tical localization of the HF components of the EA is much more express ed in comparison with the traditional 1-30 Hz range. Results of factor analysis suggest functional heterogeneity of the HF band. Obtained da ta open new ways for researches concerning the phenomena of the functi onal mosaics in the neocortex as one of fundamental mechanisms in brai n activity organization.