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Biomedical subjects

I N Krylov

Publications and source records attributed to I N Krylov.

15 recordsLinked to original sources
PubMed1995

[The characteristics of endogenous evoked potentials during normal psychomotor reactions and during basal ganglionic dysfunction in man].

Averaged cortical EPs (or the ERPs) in response to light stimuli were analysed in the Fz, Pz and Oz leads in healthy subjects and in Parkinsonian patients. The largest CNV and Nd (negative difference) were recorded in the Fz, the negative waves being inversely related to each other. A delay in psychomotor responses was accompanied by a decrease in the endogenous ERPs in all the leads in Parkinsonian patients. The ERp attenuation seems to be connected with the cortical hypoactivation due to the basal ganglia disfunction.

Basal Ganglia↗
PubMed1993

[Pharmacologic correction of learning and memory disorders induced by exposure to high-frequency electromagnetic radiation].

Acute exposure of rats to microwaves (12.6 chr, 2375 MHz, power density 1 mW/cm2) induced the retrograde amnesia. It was show the role of opioidergic, benzodiazepine, GABAergic and cholinergic components in the amnesic effects of microwaves. Piracetam (100 mg/kg, i. p.) and oxiracetam (10 mg/kg, i. p.) prevented the negative effects of microwaves on memory processes.

Animals↗
PubMed1984

[Effect of ethanol on components of the nonspecific startle reaction in man].

The components of the startle reaction (SR) (reactions of nonspecific motor activation, the wink reflex and reflectory alleviation of motoneurones) were utilized as indices of the functional status of the midbrain system of cerebral nonspecific activation. Healthy subjects and chronic alcoholics in the abstinence period were examined. The patients exhibited significantly lower SR thresholds, a shortened latent period and a stronger reaction as compared with the healthy subjects which was suggestive of the irritation of the mesencephalic activating mechanisms in patients during the period of abstinence. Intake of the euphorizing doses of ethanol depressed the acoustic SR in both patients and controls. It is concluded that ethanol exerts an inhibitory action on the midbrain system of brain nonspecific activation.

Acoustic Stimulation↗
PubMed1979

[Changes in motor neuron excitability during the organization of voluntary movements].

In healthy subjects, H-testing revealed no specific changes of motoneuron excitability during the latency period of voluntary motor activity of movement agonist whereas the H-reflex was augmented prior to movements triggered by a sound signal, the augmentation being the result of the sound activating effect mainly (startle--response). Sharp augmentation of the H-reflex occurs at the beginning of agonist voluntary activation due to interaction between the reflex and the voluntary muscular activities (interaction of peripheral and supraspinal effects on the motoneurons).

Cues↗
PubMed1978

[Nonspecific activation response upon exposure to unanticipated and voluntarily controlled acoustic stimuli].

Normal subjects revealed these components of startle-response to unexpected stimulation followed by no visible wincing: blink reflex, facilitation of spinal motoneurons (augmentation of the H-reflex), the EEG vertex potential, and skin galvanic response. With voluntary, control of the stimulation the components of the response are either absent or less obvious, excepting skin galvanic response. The weakening of the startle-response in this case seems to be associated with the mechanisms of the selective sensory attention and to be determined by cortico-fugal inhibition of reticular interneurons mediating in this response.

Acoustic Stimulation↗
PubMedDate not supplied

Possible mechanisms of delay in initiation of voluntary movements.

Studies were made of psychomotor responses and accompanying cortical evoked potentials in healthy subjects and patients with Parkinson's disease. Measurements showed that delays in a variety of psychomotor responses resulted from delays in movement initiation. The frontal regions showed increases in the N2 component of evoked potentials and delayed development of P3 waves. It is suggested that delayed initiation of movements in patients with Parkinson's disease might be associated with strengthening of frontal inhibitory systems, preventing the onset of movements.

Contingent Negative Variation↗
PubMedDate not supplied

[Possible mechanisms of delay in the voluntary movement initiation].

A delay in the movement initiation was shown to entail an augmentation of the N2 wave ascending front and a delay in the ERPs P3 wave in frontal leads in healthy subjects and in parkinsonian patients. The modulation of the N2 wave seems to reflect inhibitory processes in frontal areas of the brain.

Contingent Negative Variation↗
PubMedDate not supplied

[The simplest form of emotional-motor reaction in man].

In the present paper, human startle reaction (SR) characteristics were estimated by the amplitude of eye-lid reflex and extent of monosynaptic H-reflexes increase. SR depended not only on the parameters of sound stimulation (strength, unexpectedness) but also on the subject's functional state (attention, emotional background). Differences are given of the SR parameters from the orienting reaction. It is supposed that SR is an independent form of emotional-motor reaction of an adaptive character.

Acoustic Stimulation↗
PubMedDate not supplied

[Endogenous cortical evoked potentials in parkinsonism].

Averaged cortical evoked potentials (EP) to light stimuli were studied in 19 Parkinsonian patients and 12 healthy subjects under the conditions of passive perception ("the background") and during different psycho-motor reactions. Differential EP waves between "the reaction" and "the background" were analysed, i.e. the endogenous potentials. A retardation of the psycho-motor reactions in patients was found to be accompanied by a decrease of endogenous EP in the frontal recording. This decrease mainly concerned the potentials connected rather with the motor acts than with the cognitive operations. The retardation of the voluntary movements in parkinsonism is assumed to be connected with a "deficit" of the frontal activation due to a disfunction of the basal ganglia.

Electroencephalography↗
PubMedDate not supplied

[The stabilization of cortical evoked potentials during selective visual attention].

The event-related potentials (ERP) to lateralized moving visual stimuli (administered to the right and to the left of the subject) were recorded in six derivations in eight healthy subjects during passive viewing and selective attention to one of the stimuli (the relevant one), which demanded precise and rapid motor reaction. It was shown that during the selective voluntary attention correlation between successive ERP was substantially higher than that under conditions of passive (involuntary) attention, i.e. the ERP in the occipital, parietal, and frontal derivations during voluntary attention were more stable. The less was correlation between the ERP at passive viewing, the greater was the difference between the values of correlation coefficients during selective and passive attention. It is suggested that role of selected attention consists in stabilization of activity of the cortical structures, which are involved in solving the behavioral task.

Attention↗