The background electrical activity of the neocortex in the interstimulus periods at the stage of generalization during the development of alimentary motor conditioned reflexes (CR) in dogs was the investigational object. It was characterized by the appearance of brief (0.1-0.3 sec) trains of high frequencies (HF), significantly exceeding the adjacent initial baseline in frequency and amplitude. The relative variance index which we had developed made it possible to distinguish this EEG phenomenon in the initial realizations of the background activity when they were inputted into a digital computer. It was not possible to evaluate the parameters of the HF chains by means of a spectral correlation analysis. Nonstandard techniques of computer analysis directed toward the decomposition of the EEG tracing into a system of oscillations and toward the obtaining of the corresponding amplitude-frequency distributions (maps) were developed by us for the purpose of accomplishing this objective. It was demonstrated that HF trains were localized in these maps in specific, quite compact regions.

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This study was undertaken with the aim of identifying frequency bands with correlated changes in the spectral power amplitudes of brain electrical activity, including high-frequency components (the 1-200 Hz band) in four dogs, using one-dimensional analysis. Factor and cluster analysis of the spectral densities of various parts of the cortex and the olfactory bulb were carried out. The ratios of factors in different parts of the brain, both in terms of the proportions of the total dispersity and in terms of weightings, provided data on regional and individual differences in electrical activity. During learning (development of a motor habit consisting of pressing a feeder pedal), the factor organization of electrical activity became more, complex, particularly in the high-frequency part of the spectrum (40-170 Hz). The changes consisted of the appearance of narrower frequency sub-bands, each of which was present at high weighting (0.7-0.9) for one of the factors. The use of high-frequency components allowed functional mosaicism of the neocortex to be detected.

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