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Biomedical subjects

S A Evdokimov

Publications and source records attributed to S A Evdokimov.

At least 19 recordsLinked to original sources
PubMed1982

[Sensitivity of "silent" and spontaneously active neurons of the cat cerebral cortex to anoxia].

Using the complex methodical approach on the basis of in vivo microscopy of the cat motor cortex preparation the common principle of reaction of both the "silent" and the spontaneously active pyramidal neurons was revealed: their "seizure discharges" activation in hypoxia only occurred in a certain rather obvious disturbance of the intracellular redox-systems condition. At the initial stages of the firing changes in the spontaneously active neurons, no noticeable increase in their redox-systems restoration was observed.

Animals↗
PubMed1979

[Bilateral motor cortex effects on interneurons of the ventral horn of the lumbar segments].

The ventral horn interneurons in the spinal cord L6-7 segments were recorded in anesthetized cats during stimulation of the pericruciate cortex of both cerebral hemispheres. The majority of ventral interneurons are activated by volleys from the contralateral motor cortex and nearly half of them--by volleys from the ipsilateral cortex as well. Two kinds of firing patterns occurred: separate spikes and bursts of spikes. The latency of the 1st type firing was significantly greater than that of the 2nd one. There was a close relation of convergence of the afferent and corticospinal volleys on ventral horn interneurons: neurons activated by ipsilateral afferents only received synaptic influence only from the contralateral motor cortex whereas neurons with ipsilateral as well as contralateral inputs were activated by corticospinal volleys from both hemispheres. The interneurons with bilateral segmental and supraspinal connections seem to be involved in integrative action as important elements of the neuronal mechanism of bilateral motor coordination.

Action Potentials↗
PubMed1977

[Role of parameters of rhythmic cortical stimulation in synaptic activation of motor neurons].

Postsynaptic potentials (PSPs) evoked by stimulation of contralateral motor cortex with trains of square stimuli were recorded intracellularly in cat lumbar motoneurons. The influence of number of stimuli in a train and of interval between them upon amplitude, duration and latency of PSPs, was analysed. Rise of stimuli frequency in a train of constant duration (i.e. rise of number of stimuli accompanied by shortening of intervals) produced a snyaptic effect that was much more pronounced than in cases of shortening of intervals between equal number of stimuli (i.e. reduction of a train) or in cases of increase of number of stimuli with equal intervals (elongation of a train). Possible neuronal mechanisms of the leading role of train frequency in supraspinal activation of motoneurons are discussed.

Animals↗
PubMed1976

[The interaction of symmetrical cortical descending influences on lumbar motoneurons].

Postsynaptic potentials (PSPs) of the cat motoneurons elicited by stimulation of contralateral and ipsilateral motor cortex, and their changes during combination of both kinds of stimulation were studied with use of the intracellular recording technique. For elicitation of ipsilateral PSPs, the cortex stimulation of greater intensity was needed as compared with contralateral activation. The ipsilateral synaptic reactions had a longer latency and time of segmental delay than the contralateral ones. Conditioning stimulation of the ipsilateral cortex exerted an inhibitory effect upon contralateral cortically evoked EPSP and IPSP of motoneurons and upon potential recorded at the spinal cord surface. Suppression of conditioned PSPs occurred without changes of their sign or pattern in most cases. The data obtained suggest that inhibitory interaction of cortically evoked descending activities involves segmentary inhibitory interneurons and is realized at an interneuronal level and/or at the membrane of the motoneurons.

Animals↗