Proceedings from the analysis of known experimental data on theta-rhythm (fusiform activity) a determinate model of its generator is proposed. It is based on the mechanism of beats frequencies. The model consists of 2 united identical moduli generating harmonic (rhythmical) oscillations alpha-rhythms of approximating frequencies v1 and v2 = v1 + delta v. The working regime of the generator is determined by the trigger pulse frequency. The proposed quantitative relationships between theta-rhythm parameters--T, n and frequencies of constituent oscillations v and delta v are checked up by analysing oscillograms of barbiturate activity in EEG of dogs. The results obtained are in favour of determinate rather than stochastic mechanism of theta-rhythm.

Alpha Rhythm↗

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Spectral correlation analysis of the EEG in normal and mentally retarded children.

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Attention↗

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Study of the functional role of spatial synchronization of neocortical background potentials. I. Character of neocortical electrical activity at extremal levels of correlation of the EEG from different regions.

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Adult↗

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Study of the functional role of spatial synchronization of neocortical background potentials. II. Role of the level of spatial synchronization of cortical potentials for simple reaction time.

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Adult↗

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[Distribution of evoked responses to electrical stimulation of the cortex at different levels of spatial synchronization of cortical potentials].

In computer controlled experiments it was shown that the averaged cortical responses to direct electrical stimulation, recorded in rabbit's intact cortex or in a neuronally isolated cortical slab, depend on the level of EEG spatial synchronization in the prestimulation period. Latencies of the evoked potentials in both structures were smaller, and their amplitudes -- higher, if stimulation coincided with periods of the maximal synchronization of the background biopotentials, as compared to the same parameters of responses, obtained during the minimal synchronization of potentials. It is assumed that synchronization of the cortical potentials may be provided to a certain degree by processes of intracortical nature and that the increase in the cortical synchronization proper is accompanied by an improvement of the conditions in which the excitation is conducted over the cortex.

Animals↗

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[Functional state of the CNS at extreme levels of spatial synchronization of background potentials of rabbit neocortex].

Neurophysiological mechanisms of facilitation of excitation transmission from receptors to effectors were studied in the case of maximal correlation between cortical potentials. This condition was accompanied by a rise in excitability of the sensorimotor, visual, auditory cortex and of the dorsal hippocampus as well as by an increase of muscle activity. On the basis of the obtained and literature data it is suggested that maximal synchroneity of cortical potentials reflects a certain state not only of the neocortex, but also of other CNS parts, down to spinal centres. This condition is attended with facilitation of excitation irradiation and of its transmission to motor periphery.

Afferent Pathways↗