[Electrophysiological analysis of functional state of spinal cord motoneurons in rats with parathyroprivous tetany].

In normal rats and of those with parathyroprivous (hypocalcemic) tetany the comparative analysis of background activity (BA), tetanic and posttetanic increase and decrease of frequency of spinal cord (SC) motoneurons (MNs) responses under high-frequency (50, 100Hz) stimulation (HFS) of flexor (G) and extensor (P) hind-limb nerves have been conducted. The on-line selection and program analysis of the spikes was produced. On the 3-7 and 21-22 days of development of acute and chronic tetany, respectively, the significant tetanic and posttetanic changes of MNs activity without meaningful changes in BA was registered.

[Electrophysiological and morphohistochemical study of adrenalectomy on the hippocampal neurons].

Chronic insufficiency of adrenal hormones is a pathology leading to brain dysfunction. In electrophysiological studies, by extracellular recording of spike activity of single hippocampal neurons (HN) caused by high-frequency stimulation of the entorhinal cortex (EC) in rats with unilateral removal of adrenal (adrenalectomy - AE), we analyzed mechanisms of adaptation of neural networks to chronic hormonal deprivation. The balance of excitatory and inhibitory responses, recorded in HN of intact rats was submitted to characteristic changes in dynamics of development of neurodegeneration: the dominating in norm inhibitory responses were decreased at all AE terms (from 42 % to 25 % by the 18th week).

[Can the thalamic projections of medulla oblongata nucleus Z be reorganized following partial deafferentation of the ventral lateral thalamic nucleus?].

Following partial deafferentation of ventral lateral thalamic nucleus by means of HRP retrograde labeling, possible plastic reorganization of projections of the brain stem relay Z nucleus was studied in cats. The partial deafferentation of ventral lateral thalamic nucleus was evoked by preliminary (3 months before) destroying of contralateral cerebellar nucleus interpositus or Deiters' lateral vestibular nucleus. The local intensive labeling of neurons in the Z nucleus and a little group of neurons in the cellular group x of the vestibular complex projecting to ventral lateral thalamic nucleus and overlapping with those projecting from cerebellum was observed.

[Protective effect of Vipera raddei venom damage of peripheral nerve].

In rats, single pulse activity of inter- and motoneurons of the spinal cord lumbar segment was studied in stimulation of cut. n. ischiadicus, extensor (n.

[The characteristics of the synaptic reorganization in the sensorimotor cortex of cats after the destruction of the symmetrical portion of the cortex in the opposite hemisphere].

Intracellular recording technique has been used to study reactions of corticospinal neurons (CSN) to stimulation of the ipsilateral ventrolateral nucleus (VLN) of the thalamus in acute experiments on adult intact cats and on cats after lesion on the contralateral sensorimotor cortex (exposition from 6 months to 1.5 years). Acceleration of the monosynaptic EPSPs rise phase in slow CSN was revealed in operated animals, which presumed the reorganization of the synaptic contacts in the SD membrane of flow CSN.

[Plastic synaptic reorganization in the sensorimotor cortex of adult cats after destruction of the contralateral nucleus intermedius of the cerebellum].

Using the intracellular microelectrode technique the reactions were investigated in corticospinal neurons (CSN) after stimulation of contralateral (cIP) and ipsilateral interpositus nucleus of cerebellum as well as ventrolateral nucleus of thalamus. Experiments were made on adult intact cats and the same preliminary lesion of cIP nucleus (exposition from 1 to 6 months). Acceleration of the monosynaptic thalamo-cortical EPSPs time to peak in slow CSN was revealed in operated animals.

[Reorganization of the synaptic inputs of the sensorimotor cortex to the red nucleus after the destruction of the cerebellar nucleus interpositus in adult cats].

Responses of the red nucleus to neurons to stimulation of the ipsilateral sensorimotor cortex have been studied in acute cats with preliminary lesion of the contralateral cerebellar nucleus interpositus (exposition from two weeks to a year and longer period) by intracellular recording technique. Acceleration of the monosynaptic EPSPs rise testifying to formation of the terminal dendrosomatic sprouting of axons of the corticorubral neurons on proximal segments of the somatodendritic membrane of the red nucleus neurons was observed. Various division of the sensorimotor cortex were unequally involved in the process of reorganization of synaptic inputs on the level of individual red nucleus neurons.

[Intracellular study of the formation of new synapses and collateral sprouting of red nucleus neurons after destruction of the cerebellar nucleus interpositus in the adult cat].

Responses of red nucleus neurons to stimulation of ipsilateral cerebellar nucleus interpositus were studied in cats after lesion of contralateral cerebellar nucleus interpositus within the period ranging from two weeks to one year and seven weeks. Recording of fast and slow mono- and polysynaptic EPSPs showed collateral sprouting of axons of interposito-rubral neurons to occur in various parts of soma-dendritic membrane of rubro-spinal neurons. Stimulation of ipsilateral cerebellar nucleus interpositus evoked antidromic activation in many red nucleus neurons, suggesting the sprouting of axon collaterals from rubro-spinal neurons onto the neurons of ipsilateral cerebellar n.

[Electrophysiologic study of the rubro-nigral projection of the cat].

Peculiarities of short-latency responses evoked in the red nucleus neurons with stimulation of substantia nigra were studied in acute experiments on cats. Analysis of the antidromic activation parameters of these neurons revealed an existence of a rubro-nigral projection. The fact that some rubro-spinal neurons can be antidromically activated from the black substance and n.

[Synaptic responses of neurons of the red nucleus of the alert cat to stimulation of the sensomotor area of the cortex and the nucleus interpositus of the cerebellum].

Postsynaptic potentials of the red nucleus neurons evoked by stimulation of the cortical sensomotor region and the cerebellar nucleus interpositus were studied in chronic experiments on awake cats by means of intracellules revording. Rubro-spinal neurons identified by their antidromic activation in response to the stimulation. A decrease of the critical depolarization level was a specific feature for mono- and polysynaptic responses of the red nucleus neurons in alert animals.

[Synaptic processes in red nucleus neurons in response to stimulation of the entopeduncular nucleus and the globus pallidus of the cat].

Peculiarities of synaptic processes in red nucleus neurons evoked by stimulation of nucleus entopeduncularis and globus pallidus were studied in acute experiments on cats by means of intracellular recording technique. Stimulation of the structures mentioned was found to evoke mono- and polysynaptic excitation of the rubrospinal neurons. Analysis of time parameters of the recorded excitatory postsynaptic potentials suggested activation of axo-somatic and axo-dendritic synapses.

[Neuronal mechanisms of red nucleus interaction with brain stem structures].

Axon collaterals of rubrospinal neurons to various brainstem structures were identified in acute experiments in cats using the technique of intracellular recording of antidromic action potentials in combination with collision testing. A systemic principle of organization of the rubrospinal influences as well as a tendency to synchronous arrival of rubral impulses at various brainstem centres are shown. Most of the brainstem centres are relay nuclei sending direct efferent projections to those cerebellar areas which, in turn, control the red nucleus activity.

[Distribution and characteristics of the axonal collaterals of the rubrospinal neurons at the brain stem level].

In acute experiments on cats, intracellular recording of antidromic APs and the collision test, analysis of correlation between the time of antidromic conduction along the axon's main stem before and after collateral branching as well as the time of conduction in collaterals themselves, revealed a tendency to synchronous arrival of rubrospinal impulses to various brain stem centers at the expense of increased conduction velocity in response to lengthened distance between the brain stem structures and the red nucleus. The data obtained is discussed in the light of sensomotor integration mechanisms and role of the red nucleus in planning and actualization of the motor act.

[Synaptic processes in red nucleus neurons induced in the cat by stimulation of the substantia nigra].

Peculiarities of synaptic processes in red nucleus neurons evoked by stimulation of various parts of substantia nigra and cerebellar interposital nucleus were studied in acute experiments in cats using an intracellular recording technique. Such stimulation is stated to induce mono- and polysynaptic activation of the rubrospinal neurons. Great similarity is found in developing monosynaptic cerebellar and nigral excitatory effects.

[Effect of papaverine on the tonus and contraction of depolarized taenia coli musculature in guinea pigs].

Experiments were performed on the isolated strips of guinea pig taenia coli. The smooth muscle was depolarized in a solution with high potassium concentration (120 mM KCl). The effect of papaverine (in concentration of from 10(-5) to 3.

[Classification of the vestibulospinal neurons of the cat Deiter's nucleus].

The antidromic activation of neurons in the cat Deiters nucleus to stimulation of spinal cerevical segments was studied using the intracellular microelectrode recording technique. Separate components of the antidromic action potential and its after-deflections were analyzed in fast- and slow-conducting neurons. A direct dependence between the parameters of the after-deflections and duration of the refractory period was revealed for these neurons.