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Biomedical subjects

A I Fedotchev

Publications and source records attributed to A I Fedotchev.

17 recordsLinked to original sources
PubMed1990

Stability of resonance EEG reactions to flickering light in humans.

In order to study resonance phenomena in the EEG response to flickering light, 10 subjects were exposed to intermittent photic stimulation with the frequency of flashes linearly changing from 1 to 15 Hz and vice versa. Spectral analysis of occipital electrical activity revealed the occurrence of peaks of spectral density in those frequency components which coincide with the frequency of flashes. Such resonance peaks were observed at individually specific frequencies of stimulation. To assess the stability of the characteristics of the resonance phenomena, a repeated trial with 4-fold higher rate of changing the flash frequency was performed 3 months later. In a repeated trial the resonance phenomena were less pronounced, but were registered at the same frequencies as in the initial trial, showing significant test-retest reliability. The data obtained are interpreted in terms of provoking the activity of multiple brain oscillators having a narrow tuning to individually specific frequencies of photic stimulation by flickering light with the changing frequency of flashes.

Adult↗
PubMed1988

[Effect of intermittent photostimulation of varying frequency on the formation of trace processes and spectral components in the human EEG].

The EEG of occipital areas was recorded in adult healthy male subjects on presentation of haphazardly alternating intermittent light stimuli with frequencies varying from 15 to 5 Hz and from 15 to 25 Hz every 5 sec. Two groups were distinguished in respect to a greater or lesser domineering of the main frequency band of the range. Dynamic spectral analysis revealed obvious shifts of the EEG spectral composition in respect to the background under the effect of the stimulation, an enhancement of different bands of the range in light flickering, and the suppression of the EEG trace responses to the time in the EEG range coinciding in frequency with the frequency range of the photostimulation. The above changes were mainly characteristic of the 2nd group of subjects and mostly of the left hemisphere of the brain.

Adult↗
PubMedDate not supplied

Electrical activity of the cortex and reaction times to auditory signals and light stimuli.

We investigated the electrical activity of the occipital, sensorimotor, and frontal zones in the right and left hemispheres of the cerebral cortex and times for bimanual motor response in healthy adult experimental subjects between the ages of 15 and 25 receiving photostimulation by means of pulse trains with frequencies increasing from 15 to 25 Hz and pulse trains with frequencies decreasing from 15 to 5 Hz. We observed nonspecific physiological reactions in the organism regardless of the type of photostimulation presented and also observed specific reactions dictated by the parameters of the light stimulus acting upon the brain. It was demonstrated that the action of the light was most effective when the frequency of the stimuli was gradually increased. The expressiveness of the alpha-band of oscillations in the electrical brain activity increased in this case, and the asymmetry of the bimanual motor responses changed significantly. A definite connection was noted between the physiological reactions of the experimental subjects and their subjective states.

Acoustic Stimulation↗
PubMedDate not supplied

[Temporal changes in conscious and unconscious trace phenomena in six to seven-year-old children].

Development in time of unconscious trace reactions as well as a change in the time of reproduction of verbal material in natural conditions was studied by the conditioned reflex to time method on 107 school children aged from six to seven years and on 35 subjects of the same age from a kindergarten. It has been found that in schoolchildren the transfer of trace reactions to long-term storage is completed faster, and their voluntary acts in the course of conscious reproduction of an interstimuli intervals are more adequate than in the kindergarten children of the same age. The trace phenomena formed in natural conditions and in the laboratory experiment develop in time in a similar way. The change in time of conscious trace phenomena is of a more complex nature than of the unconscious phenomena. The practical significance of the data obtained is noted.

Brain↗
PubMedDate not supplied

[The dynamic and regional characteristics of the high-resolution EEG structure in voluntary activity].

For revealing the dynamics of interrelations between EEG components having stable tuning to individually determined frequencies a dynamical high resolution EEG structure analysis was used. There were three successive experimental stages: rest, motor reproduction of time interval and tapping. Significant increase of EEG components intercorrelations for the right frontal area, minimal number of significant relationships between EEG and movement temporal characteristics, and the occurrence of hemispheric asymmetry in the number of EEG-movement correlations were observed for time reproduction task. This task specifics and the possibilities of used approach for precise functional states differentiation are discussed.

Adult↗
PubMedDate not supplied

[Dynamics of the formation and interrelationship of trace phenomena in 6--7-year-old children].

The dynamics of formation, the reproduction characteristics and interrelation of trace phenomena in conditions of a stable vs. unstable pause between the stimuli in Konorski test were studied in 148 6--7 year old children. It has been shown that with a stable interstimuli pause, along with correct voluntary reactions, based on stimuli traces, two types of electropgraphic trace reaction to time are elaborated--anticipatory and post-stimulatory. In this case trace phenomena are formed much more rapidly and their connection with the volume of the children's short-term memory is tighter than in experiments with an unstable interstimuli pause. It has been also shown that children's school resluts significantly correlate with the caracteristics of their mnemic activity--the volume of the short-term memory and Konorski test data.

Brain↗