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Biomedical subjects

K V Baev

Publications and source records attributed to K V Baev.

71 records · Page 4Linked to original sources

[Impulse activity of interneurons of the lumbar portion of the spinal cord during the late long discharges in the motor nerves of immobilized thalamic cats].

Impulse activity of lumbar interneurons was recorded extracellularly during the late long-lasting discharges in efferent nerves of immobilized thalamic animals. 70% of investigated neurons changed their activity during the late discharges. The activity of 35% of neurons increased, during late discharges in flexor nerves, while during activity in extensor nerves it was inhibited. 27% of neurons had the opposite reaction. Neurons, whose activity correspondingly increased (5%) or decreased (3%) during the late discharges both in flexor and extensor nerves were also observed. Most interneurons, changing their activity during late discharges, were located in the lateral parts of intermediate zone and in the lateral ventral horn at the depth of 2.8 mm. Certain dependence between the character of afferent inputs to the neuron and correlation of its activity with late efferent discharges was revealed. Neurons whose activity did not change during late discharges (40%) were mainly located somewhat dorsally, at the depth of about 2.0 mm. Possible role of described interneurons in generation of late discharges is discussed.

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[Activity of interneurons of the lumbar region of the spinal cord during fictive locomotion of thalamic cats].

Impulse activity of lumbar interneurons was recorded extracellularly during fictious locomotion of thalamic cats. Neurons whose activity was modulated in the rhythm of fictitious locomotion were revealed in the lateral intermediate zone and in the lateral ventral born. 41.2% of these neurons were mainly activated at the phase of "flexion", 48.5%--at the phase of "extension" and 10.3%--at both phases. Neurons with tonically increasing or decreasing activity during rhythmic efferent discharges and neurons whose activity did not change during fictitious locomotion were also observed. All these types of neurons were similarly activated during late discharges in efferent nerves. But in this case the depth of modulation of neuronal activity was lower than during fictitious locomotion. Afferent inputs to the recorded interneurons were also investigated. The neuronal organization of the spinal locomotor generator is discussed on the basis of the obtained data.

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[Depolarization of the terminals of different groups of afferent fibers of the lumbar region of the spinal cord during fictive scratching].

Kinetics of lumbar primary afferent depolarization was investigated during fictitious scratching of decerebrated and decapitated cats. Fictitious scratching was accompanied by tonic and phasic primary afferent depolarization. Periodic depolarization of primary afferents was synphasic in different segments of the lumbosacral spinal cord. Tonic depolarization was observed in the terminals of all the investigated groups of fibres (low-threshold cutaneous and of groups 1a and 1b). Phasic changes took place in terminals of low-threshold cutaneous fibres and fibres of group 1b. Physiological significance of modulation of primary afferent depolarization by the spinal scratching generator is discussed on the basis of the data obtained.

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[Depolarization of primary afferents during fictitious scratching of thalamic cats].

The cord dorsum and dorsal root potentials were recorded during fictious scratching in L6 segment of the thalamic cats. It is shown that primary afferent depolrization (PAD) can be modulated by the central generator of scratching. In some afferent fibres antidromic spikes appear on the top of PAD-waves. Antidromic spikes can be also evoked in the period of "rest" by mechanical stimulation of hindlimb receptors. It is supposed that PAD and resulting antidromic spikes which appear during real scratching may effectively control the level of afferent inflow to the spinal neurons.

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[Periodic changes in primary afferent depolarization during fictitious locomotion in thalamic cats].

Dorsal root and cord dorsum potentials were recorded in lumbar segments L6, L7 during fictitious locomotion of thalamic immobilized cats. Negative waves in the dorsal root potential and respectively positive waves in the cord dorsum potential appeared during periodic discharges in the ankle flexor nerve. The conclusion is made that central locomotor generator activity modulates the level of primary afferent depolarization.

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[Spontaneous rhythmic discharges in the motor nerves of posterior limbs of decerebrate immobilized cats].

Spontaneous rhythmic discharges (fictitious locomotion) were recorded in motor hindlimb nerves of decerebrated animals with intact caudal hypothalamic region. Stimulation of this region led to the appearance of fictitious locomotion. Spontaneous discharges did no-appear after decerebration at lower levels and in spinalized cats. A conclusion is made on the presence of structures in the caudal hypothalamus which are necessary for the activation of lower locomotor centres and the production of spontaneous rhythmic discharges in motor nerves.

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[Sequence of discharge appearance in nerves to different hindlimb muscles during fictitious locomotion of thalamic cats].

The sequence of discharges in nerves to 22 hindlimb muscles during fictitious locomotion was investigated on immobilized thalamic cats. It is shown that for most hindlimb muscles the central locomotor program is rather simple and consists of alternating activation of flexors and extensors. A conclusion is made on the existence of interneuronal flexor and extensor centres in each half of the spinal cord, working in turns during locomotion. More complex discharges were recorded from the nerves to Edb and Per. tert. and also from the nerves to biarticular muscles (St, P. bic., Ten.). It is suggested that motoneurons of these muscles are connected to the flexor and extensor centres in a more complex way.

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Central program of hind limb interaction during locomotion in cats.

The central program for interaction between the hind limbs, expressed as the time structure of motor discharges in the nerves to the various muscles, was studied in immobilized decerebrate spinal cats during fictitious locomotion. The program of hind limb interaction (alternating or inphase) in the decerebrate cats was shown to be determined by the relations between the flexor hemicenters. The activity of the latter is either antiphased or cophased. The character of activity of the extensor hemicenters is determined secondarily on account of alternating interaction of each of them with the ipsilateral flexor hemicenter. After injection of dopa into the animals the cophased program of hind limb interaction may be determined by the cophased working of the extensor center.

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