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Biomedical subjects

V N Dumenko

Publications and source records attributed to V N Dumenko.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

[Correlations among cortical potentials in the dog during the elaboration of motor alimentary conditioned reflexes].

Background electrocortical activity in a frequency band of 1-100 Hz of dogs with electrodes implanted in different neocortical areas was studied before and after elaboration of motor (lever pressing) alimentary conditioned responses. Conditioning led to a significant change of the distribution histograms of cross-correlation coefficients (CC) between the cortical potentials, i. e. the dispersion of CC values decreased and the level of correlation changed as well. In more tranquil animals (with lower CC values before conditioning) the level of correlation significantly increased, in excitable ones (with higher CC values before conditioning) it decreased. CC distributions after the conditioned response elaboration became similar in both cases apparently indicating the formation of a uniform state characteristic for the type of a conditioned response under study.

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PubMedDate not supplied

[Regional features of the electrical activity of the neocortex in the dog over a wide range of frequencies].

Autospectral characteristics (ASC) of potentials of different neocortical areas of dogs in a state of quiet wakefulness were studied in a wide frequency band (1-100 Hz) by means of correlation-spectral analysis. A transition from evaluation of the mean power tendencies to a construction of distributions of different power levels for each of five arbitrarily chosen frequency bands permitted to reveal regional differences in ASC of each animal as well as interindividual EEG distinctions. The regional differences observed in all frequency bands (though not equally expressed) including the higher ones indicate not only the informativity of high-frequency components of electrical neocortical activity but also their neuronal origin.

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PubMedDate not supplied

[High-frequency components of the electrical activity of the dog neocortex during formation of motor alimentary conditioned reflexes].

Power spectra of electrical activity of different dogs neocortical areas within a wide frequency band (1-100 Hz) were studied by correlation-spectral analysis during elaboration of motor (pressing the pedal) alimentary conditioned reflexes (CR) to acoustic stimuli. Considerable redistribution of autospectra power (ASP) within one of the five selected frequency ranges (from I to V, 20 Hz each) was observed. The frequencies of III-V ranges (41-100 Hz) were the most reactive; the degree of power increase after CR stabilization was determined by its initial level before CR elaboration which significantly differed in various animals. The weaker were presented in the EEG high frequencies before learning, the higher was the increase of their power in the process of elaboration of the given type of CR, and on the contrary, a definite level of "saturation" was preserved. Relatively low frequencies (below 20 Hz) were characterized after CR elaboration by lowering of the power. Deliberate lowering of the alimentary motivation led to a weakening of CR and power decrease (in comparison with stabilized CR) of all frequency components; however, its level remained higher, than before CR elaboration.

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PubMedDate not supplied

[Analysis of changes in the electrical activity of the neocortex in dogs during the formation of the stereotype of food-procuring conditioned reflexes in them].

A system of food-procuring conditioned reflexes (dynamic stereotype after I.P. Pavlov) was elaborated in dogs. In the interstimuli periods, 0.6 to 0.8 sec. prior the action of the conditioned stimulus, they exhibited a "state of expectancy" characterized by an increase of frequency (up to 80 per sec.) of potential oscillations of a small amplitude (20 to 30 mcv) and their pronounced sychroneity, predominantly in the anterior parts of the neocortex. The conditioned signal acting against such background produced specific reactions in the form of a limited number of bursts (3 to 4 in 0.5 sec.) of highfrequency (up to 100 per sec.) synchronized activity (HSA) of considerable amplitude (50 to 60 mcv) which always preceded conditioned reactions, being in certain temporal relations with them. A correlation-spectral analysis has shown that in the HSA period, electrical activity became considerably more regular; in the intensity spectra the extreme frequencies of the analyzed band (5 to 7 c/s and 90 to 100 c/s) became prominent, and in most cases high values of the coherence function were due to them. HSA reactions are regarded as a major link in the trigger mechanism of conditioned food-procuring reactions.

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PubMedDate not supplied

[Alimentary instrumental conditioned reflexes in dogs with different types of nervous system].

Alimentary conditioned reflexes in the form of pressing (with an effort not less than 600 g) with a fore-leg on the pedal of a nearby feeding-trough, were elaborated by means of classical secretory technique in 15 dogs with defined typological characteristics of the higher nervous activity. The motor habit was formed in about a half of the animals. The ability to instrumental learning was assessed on a five-points scale in accordance with four stages of habit formation. The study revealed an absence of direct dependance between the obtained typological characteristics of the animals and their ability to instrumental conditioning.

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[Attempts to divide the high-frequency range (40-200 cycle/sec) of the brain electrical activity in dogs into frequency bands].

The work was aimed to reveal the functional significance of separate narrow-frequency bands in the high-frequency range (40-200 Hz) of brain electrical activity of dogs in the process of lever-pressing instrumental conditioning. In order to divide this range into separate bands we applied one of the methods of multivariate statistics, factor analysis (FA) with varimax rotation. Values of function of spectral density in the wide range (1-200 Hz) were factorized. The structure of factors reflected both regional cortical characteristics of electrical activity and individual features. Conditioning induced changes in factor description of brain electrical activity mainly in the high-frequency part of the spectra. A number of new factors appeared which divided high-frequency band of the brain activity into narrower parts with definite functional significance.

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PubMedDate not supplied

[The dynamic shifts in the parameters of the traditional frequency-range of the EEG during learning in dogs].

Parameters of EEG recorded from some areas of the cortex and olfactory bulbs were studied during lever-pressing alimentary conditioning in dogs and analysed using FFT in a wide frequency range (1-100 Hz). Parameters of electrical activity in the cortex ans olfactory bulbs were shown to have different dynamics. Power level of cortical potentials increased in the high frequency band (40 Hz and upwards) and that of the olfactory bulbs increased in both high frequency and alpha bands. Coherent-phase characteristics of the cortical potentials give evidence that in the process of conditioning more stable relations establish between activities of different cortical areas in both high frequency and alpha bands than in the state of quiet wakefulness. At the same time relations between potentials in the cortex and in the bulbs were characterized by the larger phase shifts, increase of coherence attributed only to the high frequency but not traditional bands. Possible role of the alpha frequencies along with the high frequency band in the process of information processing is discussed.

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PubMedDate not supplied

[An evaluation of the high-frequency components in the EEG reactions to positive and differentiated conditional stimuli in motor-food conditioned reflexes in dogs].

EEG reactions to positive and differentiated signals were compared during lever-pressing alimentary conditioning in dogs by means of described by us earlier non-standard forms of EEG analysis in a wide frequency band (1-256 Hz). Findings concerning EEG reactions to positive stimuli, confirmed the earlier obtained data on a high representativeness of the high-frequency components of dog's EEG. EEG reactions to differentiated stimuli were also excitatory. Developed by us techniques allowed us to show some quantitative characteristics of these reactions. Diversity of expression of high-frequency components in different dogs, accompanied by similarity of their effector reactions (absence of movement), was considered as a reflection of individual features of their CNS.

Acoustic Stimulation↗