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Biomedical subjects

D R Belov

Publications and source records attributed to D R Belov.

9 recordsLinked to original sources
PubMed2006

[Reflection of cortical activation pattern in the human EEG phase structure].

Investigation was fulfilled on healthy subjects (22) and on outpatients (62). The EEG by the standard scheme as recorded at resting with open and closed eyes and under different functional loads. These records were processed in accordance with the EEC phase structure with the aid of computer animation technology. The main idea of the phase structure technology consists in rejection of one supporting lead. Time shifts were measured only between two neighbouring electrodes, so that the oscillations under comparison were always highly coherent. Time errors were evaluated according to crosscorrelation function maximum shift. The differences between high- and low-frequency EEG rhythms were shown to be only quantitative from the phase structure viewpoint. Qualitatively, the rhythm properties were equal and came to slow (second) phase structure oscillations. Low frequency activity compared to high frequency one was characterized by greater phase shifts from electrode to electrode. Phase shifts of potentials are forming the structure which, as a whole, is very similar in different people and is reproduced in different states. Initial EEG waves appearance is statistical linked with main sensory projections: visual (occiput), auditory (temples) and somatic (parietal region) with addition of frontal region. Redistribution of phase leadership in favor of occipital pole and to both temporal regions when eyes are open is described. It is apparently dependent on the sensory surge level from thalamus to a given cortex region. Phase gradient direction seems to reflect the cortex current density gradient which is parallel to surface. It can be used for localization of compact sources lying near to cortex.

Adolescent↗
PubMed1999

[The indices of EEG spatial synchronization in normal 10- to 12-year-old schoolchildren and in learning difficulties].

10-12-year-old schoolchildren were divided into three groups: a normal one, a group with psychological problems, and a third one with medical problems. The EEG was recorded at resting and while reading a text. An obviously higher global spatial synchronisation was found in the normal group as compared with the "medical" one. In the "psychological" group, a diffuse hyperresponsiveness was found in the transition state from resting to activity. The above differences seem to be due to a morpho-functional immaturity and a functional insufficiency of two different portions of the brain ascending activating system. Evidently the "medical" group children have an immaturity of the bulbar and midbrain reticular formation, whereas the "psychological" group children have, probably, an immature diencephalic activating system (the thalamus).

Adaptation, Psychological↗
PubMed1998

[Dependence of human EEG spatial synchronization on the geomagnetic activity on the day of experiment].

Spontaneous EEG was registered under different activity conditions in 26 volunteers. The EEG synchronisation parameters were compared with the geomagnetic and solar activity on the day of experiment. A positive correlation of the EEG data with the geomagnetic activity was revealed, being most obvious in the frontal and central areas. A negative correlation between some local EEG synchronisation parameters and different indices of the solar activity, was also revealed. The degree of synchronisation of the spontaneous EEG seems to reflect sensitivity of the human nervous system to the Earth's magnetic field. A stressor response to strong short-term disturbances in the geomagnetic field reveals itself in the form of enhancement of the EEG global synchronisation. A sedative effect of slow magnetic oscillations is locally revealed in the parameters of the EEG synchronisation within the left hemisphere as well as the interhemisphere synchronisation.

Adolescent↗
PubMed1997

[The effect of sex on the spatial synchronization of the EEG].

The data obtained shows that women are characterised by a significantly larger interindividual variations of the EEG synchronizing than men (except the synchronizing in the left hemisphere). The findings are supposed to be due to a higher level of unspecific cortical activation in men.

Adolescent↗
PubMed1993

[The form of the spontaneous EEG waves under different conditions of mental activity].

Value of the average level of asymmetry of the EEG waves' fronts (ALA) was shown to decrease in posterior leads and increase in anterior leads during the transition from the rest to mental activity. An inter-hemisphere asymmetry of the ALA was found, the asymmetry having a similar direction for all the pairs of symmetrical leads. Two independent factors are supposed to affect the ALA: the level of the cortex activation and the specifics of information processing by the given hemisphere.

Adolescent↗
PubMed1991

[The mean level of EEG wave asymmetry as a possible correlate of the property of lability of the cerebral hemispheres].

The human nervous system's lability was studied with the aid of critic fusion frequency (CFF). The CFF was compared with the mean level of asymmetry of the EEG waves' fronts (MLA). The CFF was shown to be a relatively stable individual parameter whose value depended on the value of difference between occipital and frontal areas' MLA and those in the lower frontal areas.

Adult↗
PubMed1991

[The reflection of functional differences between the hemispheres in the form of the EEG waves].

The EEG was recorded in 3 symmetrical sites of the human brain with subsequent calculation of the parameter of mean level of asymmetry (MLA) in the EEG wave fronts. The MLAs were shown to change after functional loads of visual-spatial and verbal-logical types. The MLA seems to be an informative parameter of qualitative specifics of neural processes in the left and right hemispheres.

Adolescent↗