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Biomedical subjects

V N Kiroĭ

Publications and source records attributed to V N Kiroĭ.

At least 19 recordsLinked to original sources
PubMed1998

[Spectral EEG characteristics in emotional stress model in cats].

Emotional stress induced a global activation of the brain electrical activity: a decrease in the power of the theta-, alpha-, and beta-1-frequency bands in animals with active behaviour, and a decrease in the power of the theta- and alpha-frequency bands in animals with behavioural inhibition. The findings suggest that two forms of emotional behaviour correspond to different patterns of the brain activity. Appearance of spindle-like activity in passive animals' parietal and occipital leads suggests a hypothetical suppression in associative parietal and visual neocortical areas involved in processing the sensory information.

Animals↗
PubMed1998

[Comparative analysis of electroencephalographic effects of trimetidon and phenazepam on the brain function during emotional stress in cats].

Trimetidon decreased the high-frequency spectral power and enhanced theta-, alpha-band frequencies in recordings from parietal and visual areas as well as beta-1-band frequencies recorded from the sensomotor area during emotional stress in cats. Phenazepam desynchronised the EEG. The latter state alternated with sedation-associated spindles and slow waves. The trimetidon effect was similar to that of 1.4-benzodiazepines.

Animals↗
PubMed1995

[A neurophysiological assessment of the effect of trimetidon on brain function in the cat].

Stimulation of the cat brain mesencephalic RF augmented the high-frequency activity in control animals and failed to do so after 4-oxopyrimidine administration. These and some other EEG changes suggest presence of an anxiolytic component in the trimethidone, the latter thus being similar by its effect to 1,4-benzodiazepines and endogenous pyrimidines.

Analog-Digital Conversion↗
PubMedDate not supplied

[The mechanisms of the formation and the role of the oscillatory activity of the neuronal populations in brain systemic activities].

Experimental findings and theoretical concepts that have led to a new insight into the neurophysiological mechanisms underlying information processing and brain state are presented in this review. It is assumed that the brain information processing associated with elementary neuronal assembles is reflected by oscillations in the range of 30-70 Hz and their spatio-temporal organization in millisecond intervals. He functional brain state associated with the non-specific systems is reflected in synchronization or desynchronization of activity of large neuronal populations in the frequency range of 20 Hz.

Brain↗
PubMedDate not supplied

[The neuronal ensembles of the brain].

The conclusion about availability of two types of neuron ensembles in the central nervous structures was made on the basis of proper experimental studies and appropriate literature data analysis. The first is presented by neurons functional cooperation (Hebbian ensembles) formed during learning process on the basis of synchronization by high-frequency oscillator activity. The second is presented by morphological-and-functional structures (Kogan's neuron ensembles) formed during neurogenesis process and genetically destined for biologically valuable patterns recognition. The control of functional state of the brain neuron networks and occurred information processes is realized by non-specific systems either restrict the neurons capability of joining in the rate of global synchronization by synchronization and desynchronization actions or form and maintain the common rhythm of activity in considerable neuron populations. The latter block single elements ability to enter into specific interactions.

Animals↗
PubMedDate not supplied

[Changes in characteristics of sensory evoked potentials in dynamics of monotonous activity].

Visual and auditory evoked potentials were recorded in 19 volunteers during their monotonous activity. Three groups of subjects different in performance quality were set aside. Characteristics of evoked potential components were subjected to analysis of variance. The latency of P1 component of visual and auditory evoked potentials recorded in respective projection cortical areas significantly increased over the course of the long-term monotonous activity. These changes were associated with performance deterioration. The observed changes in performance quality and brain functional state were determined by individual features of subjects.

Adolescent↗
PubMedDate not supplied

[The general laws of formation of a condition monotony].

In article results of research of spectral characteristics and a level of coherence basic rhythms EEG being under inspection of 19 with use are of resulted multifactorial dispersive analyses surveyed. On the basis of the received material an assumption comes out, that realization of base conditions of wakefulness is provided by own "built-in" regulating with mechanisms. Absence of such "built-in" mechanisms for a condition of monotonous causes "search" character of activity of regulating systems which results in the expressed periodicity in changes both a functional condition of a brain, and quality of activity carried out by the person.

Adolescent↗
PubMedDate not supplied

[Individual resistance to factors of monotony reflected in the EEG].

Three groups of operators substantially different in their performance quality were examined. Under conditions of monotonous activity, subjects with the highest initial level of activation, minimum EEG total spectral power, and minimum level of EEG coherence in the frontal cortical areas worked most steadily. Under the same conditions, subjects with a rather high spectral power of the theta and beta2 EEG frequency components, highest coherence in the frontal areas, and low coherence in the caudal areas of the cortex worked least steadily. EEG phenomena testify to a rather low level of activation of the frontal cortical areas associated with a facilitation of cortico-subcortical neuronal interactions and an attenuation of the operating neural streams. This results in a decrease in the level of any attention, its involuntary switching, and short-term loss of the control over the current performance.

Acoustic Stimulation↗
PubMedDate not supplied

[Changes in the space-time organization of the bioelectrical activity of the human brain on completing the solution of a mental task].

Changes in spatial-temporal organization of human bioelectrical brain activity were studied following formal completion of the process of solution of mental tasks of various complexity. It was shown that in the first seconds after the response, desynchronization took place of cortical potentials, identical to the one observed in the process of solution; at frequencies of alpha- and beta-2-rhythms, predominant decrease took place of parameters of spatial-temporal biopotentials conjunction as compared to the level of calm alertness. Dynamics of recovery of calm alertness EEG characteristics is determined by subjective complexity for the subject of previous activity and by the degree of his confidence in the correctness of the obtained result. The latter is determined by individual-typological properties of the subject.

Adult↗
PubMedDate not supplied

[Reflection in the electrical activity of the brain of the activities of the mechanisms regulating the functional state].

On the basis of analysis of the results of author's studies and literature data, theoretical notions are developed, according to which spatial-temporal organization of cortical biopotentials is a result of activity of nonspecific different level systems subtly regulating current alertness in conformity with needs of the actual and forthcoming activities. In the hierarchy of regulating systems, in conditions of alertness, nonspecific thalamic and midbrain system is leading. Activity of these regulation levels provides in alertness for formation and destruction of functional neuronal ensembles which realize elementary informational transformations. The role is emphasized of asynchronous processes in the central nervous system activity.

Animals↗
PubMedDate not supplied

[Space-time organization of the electrical activity of the human brain in a state of calm wakefulness and during the solution of intellectual tasks].

In a series of experiments it has been shown that during solution of mental tasks of various complexity, a marked desynchronization is observed of the cortical rhythmic activity characteristic of the state of calm wakefulness. In the range of main wakefulness frequencies (alpha and beta), a significant lowering is observed of the level of spatial biopotential synchronizations. Its increase in these conditions is connected with the range of slow EEG rhythms; there exist different opinions about their functional significance in wakefulness.

Adolescent↗