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V D Taranenko

Publications and source records attributed to V D Taranenko.

At least 19 recordsLinked to original sources
PubMed1992

[Changes in the responsive ability of parietal associative cortex neurons to stimulation of associative thalamic nuclei during development of inhibition].

Neuronal responses of area 7 of the parietal associative cortex (PAC) to paired stimulation of the nLD and nLP thalamic nuclei were investigated by extra- and intracellular recording methods. It was found out that testing stimulation of the associative nuclei resulted in inhibition, facilitation or absence of clear neuronal responses. Inhibition was observed more often then other types of reactions. The intracellular recording has shown that inhibition of responses to testing stimuli developed during the initial phase of IPSP, while in the repolarization phase a facilitation was possible. The reversion of a Cl- -dependent component of IPSP did not lead to inhibition of responses to the testing stimulation in that period. It is suggested that inhibition of responses to the testing stimulus occurs in the presence of inward Cl- -dependent current, while facilitation of responses may be a result of activation of the late EPSPs.

Animals↗
PubMed1991

[Excitation and inhibition in parietal associative cortex neurons during stimulation of thalamic associative nuclei].

Responses of the parietal association cortex neurons to stimulation of lateralis dorsalis (LD) and lateralis posterior (LP) thalamic nuclei were investigated. Primary IPSP were observed in 62.5% of cases after stimulation of LD and in 79.6% of cases after LP stimulation. Latent periods of EPSP and IPSP were longer in case of LD stimulation rather than after LP stimulation. EPSP amplitude to association nuclei stimulation increased and decreased gradually, while amplitude of IPSP increased quickly and decreased slowly. Amplitude of EPSP which has appeared during IPSP development was larger than in case of the resting potential. Amplitude and duration of EPSP of the certain neuron after stimulation of different nuclei were rather similar. It is supposed that with stimulation of different association nuclei the same cortical inhibitory interneurons are involved. IPSP duration is shorter as compared to inhibition of the background impulse activity. A supposition is advanced that such a difference in duration is determined primarily by properties of these neurons.

Animals↗
PubMed1991

[Spread of excitation in the upper layers of the auditory cortex with the participation of intracortical interneuronal connections].

In the chronically isolated slab of the cat auditory cortex when lower layers were additionally undercut and one, two or three cortical layers under the pial surface remained structurally intact, impulse reactions of slab neurons to the intracortical stimulation applied on the other side of this additional undercut were investigated. High effectiveness of axo-dendritic and axo-spinal excitatory contacts formed by nerve elements of intracortical origin in the upper cortical layers was shown. Participation of geniculo-cortical fibres in the spread of excitation in the cortex through synaptic contacts in layer I with dendrites of pyramidal neurons of the lower layers is discussed. The possibility to generate polysynaptic excitatory reactions by neurons shows that in the isolated cortical slab with an undercut of the lower layers the complex interneuronal relations are retained.

Animals↗
PubMed1990

Paroxysmal afterpotentials and role of calcium-dependent potassium conductivity in neuronal activity of strychninized neocortex.

Reactions of cortical suprasylvian gyrus neurons were investigated intracellularly after supracortical strychnine application in immobilized and anaesthetized cats. It was shown that paroxysmal depolarizing shifts of membrane potential could be accompanied by de- and hyperpolarizing afterpotentials. When passing from epileptiform to normal physiological activity, short afterhyperpolarizations, 300-500 ms in duration, were converted into inhibitory postsynaptic potentials which were also accompanied by a decrease in membrane potential. When the frequency of paroxysmal discharge was less than 1 s, prolonged (1-2 s) afterhyperpolarizations were observed; at a higher frequency their summation led to tonic hyperpolarization of the membrane. The ictal discharges were accompanied by postictal hyperpolarizations of up to 30 s duration. The intracellular injection of EGTA blocking Ca2(+)-dependent potassium conductivity eliminated prolonged after- and postictal hyperpolarizations and produced depolarizing afterpotentials and a gradual depolarization of cell membranes. Our results indicate that the development of short hyperpolarizing afterpotentials could be determined by the inhibitory synaptic effects. The activation of Ca2(+)-dependent potassium conductivity caused by the development of prolonged afterhyperpolarizations and postictal polarizations, as well as maintained tonic hyperpolarization of cell membranes. Obviously, the depolarizing afterpotentials are of a non-synaptic origin and can be induced by inward calcium current.

Animals↗
PubMed1990

[The postsynaptic components of the paroxysmal reactions of the neurons in the strychninized neocortex].

Intracellular responses of neurons of cortical strychninized suprasylvian gyrus were investigated in experiments on immobilized and unanaesthetized cats. Paroxysmal depolarizing shifts (PDS) of the neuronal membrane potential were registered. They consisted of the burst discharge (BD) and slow depolarization wave. By means of intracellular stimulation it was shown that PDS could be summarized and were able to change their form and size. BD in PDS were triggered by large EPSPs which could be elicited from paroxysmal responses. Presumably, the intradendritic recordings have shown the presence of large EPSPs during generation of epileptiform discharges in the neocortex. In some neurons PDSs were accompanied by hyperpolarizing potentials which were apparently IPSPs because they were reversed at the intracellular Cl- injections. The contribution of excitatory and inhibitory synaptic influences to the neuronal paroxysmal responses is discussed.

Animals↗
PubMed1990

[Prolonged depolarizing potentials of the neurons in a strychninized isolated strip of the cat cerebral cortex].

Reactions of isolated cortical slab neurons to the supracortical application of strychnine were investigated with intracellular registration in experiments on unanaesthetized and immobilized cats. It was shown that some neurons demonstrated prolonged depolarizing potentials (PDP) spontaneously and as reactions to single intracortical electrical stimuli. The development of these potentials could be a result of transformation of the reaction of the "paroxysmal depolarizing shift (PDS)--hyperpolarization" type, where hyperpolarizations were replaced by depolarizing potentials. A gradual increase of depolarizing afterpotentials resulted in DDP generation. These transformations, as a rule, were accompanied by amplification of the summary epileptiform activity in an isolated cortical slab. The suggestion was made that the DDP generation was determined by an increase in the Ca(++)-conductance of the neuronal membrane in an isolated cortical slab with the intensification of paroxysmal reactions.

Animals↗
PubMed1990

[The cellular reactions of a strychninized isolated strip of the cat cerebral cortex].

Reactions of neuronal and glial cells of an isolated cortical slab to direct electrical stimulation after supracortical strychnine application were investigated in experiments on immobilized and unanaesthetized cats. Strychnine evoked single epileptiform discharges and afterdischarges in the isolated cortical slab and large paroxysmal depolarization shifts (PDS) of the membrane potential (MP) in the neurons. It was shown that spontaneous summary epileptiform discharges and cellular activity of neurons investigated were synchronized slightly. Electrical stimuli produced a generalized paroxysmal activity in the isolated slab. Neuronal PDSs were accompanied by refractory periods which development did not depend on the MP level. Strychnine enhanced a number of neurons with the background activity in which PDS were generated by rhythmic depolarizing MP oscillations of the nonsynaptic origin. It was shown also that epileptiform reactions of the strychninized isolated cortical slab to the single stimuli were accompanied by large depolarization shifts of the glial cells' MP. The suggestion is made that the paroxysmal excitation development in the strychninized isolated cortical slab was determined by non-synaptic factors and was strongly related to the changes of the extracellular potassium concentration.

Action Potentials↗
PubMed1989

[Responses of neurons of an isolated cortical strip in a state of convulsive excitation to single electrical stimuli].

Responses of isolated cortical slab neurons to single stimuli before, during and after the development of epileptiform state in a slab were investigated in experiments on immobilized and locally anaesthetized cats. It was shown that during the development of generalized seizure activity in an isolated cortical slab its neurons generate EPSP and paroxysmal depolarizing shifts (PDS) of the membrane potential (MP) accompanied by refractory periods. Refractory periods coincide with PDS plato and MP repolarizing shifts. During these shifts single electrical stimuli produce gradually transforming PDS. After cessation of the ictal activity neurons are still able to generate PDS to single stimuli for some time. It is suggested that the role of postsynaptic responses in genesis of the epileptiform activity is not the most important. Nonsynaptic factors are, probably, involved in its generation.

Animals↗
PubMed1988

[Electrical activity of the neurons in an epileptic focus created in an isolated strip of cerebral cortex by electrical stimulation].

The peculiarities of the activity of cortical isolated slab neurons were investigated in experiments on unanaesthetized and immobilized cats during the development of seizure spikes evoked by repetitive powerful stimulation. It was shown that in the investigated focus of epileptiform discharges the neurons were not differentiated by the degree of pathological alterations, since paroxysmal membrane potential shifts of all neurons were recorded intracellularly. All these neurons were characterized by a lack of the spike activity. At the same time bursting spike discharges of isolated slab neurons were recorded extracellularly and they did not propagate to the soma. Simultaneous extra- and intracellular recordings of the activity from the same neurons have shown that during the epileptiform activity action potentials were generated in some trigger zones without propagating to the cell bodies. Possible mechanisms of the origin of the spike activity in isolated slab neurons during the development of generalized epileptiform state are discussed.

Animals↗
PubMed1988

[Spreading excitation in the upper (I-III) layers of an isolated strip of cat auditory cortex].

Lower layers of the isolated slab in the auditory cortex were cut, one, two or three cortical layers under the pial surface remaining intact. Impulse reactions of neurons to the intracortical stimulation applied on the other side of this additional cut were investigated in acute experiments on unanaesthetized immobilized cats. It was shown that stimulation of layer IV generated a flow of excitation ascending to the upper cortical layers and activating mono- and polysynaptically neurons of all layers through the vertical bundles of apical dendrites of pyramidal cells. Suggestion is made about an important role a large bundle of axons of layer III plays in the horizontal spread of excitation in the cerebral cortex.

Animals↗
PubMed1985

[Mechanisms of the effect of diazepam on the paroxysmal electrical activity of an isolated strip of cat cerebral cortex].

Diazepam effect on paroxysmal electrical activity of an isolated auditory cortex slab and inhibitory responses of its neurons evoked by intracortical electrical stimulation were studied in experiments with cats. Diazepam (2 mg/kg, intravenously) evoked suppression of the paroxysmal electrical activity and increased the number of inhibited neurons both in acute isolated and three-week slabs as compared with the intact cortex. However in this case the number of disynaptic responses decreased, especially in the long-isolated slab. It is supposed that diazepam activated GABA-ergic inhibitory neurons synchronizing inhibition and increasing duration of IPSP. Its action is probably manifested in the first place in the very initial links of cortical neuronal chains.

Animals↗
PubMed1984

[Inhibitory responses of neurons of an isolated strip of auditory cortex to intracortical stimulation in the cat].

Neuronal reactions to intracortical stimulation at a depth of 1.2-1.4 mm have been investigated in an acutely isolated auditory cortex slab from the cat brain (A-1). It is shown that among neuronal reactions to such stimulation primary inhibitory postsynaptical potentials (IPSPs) prevailed. Latent periods of the inhibitory reactions did not exceed 10 ms. Amplitude and duration of IPSPs did not differ from those of inhibitory responses of neurons in the intact auditory cortex. Some peculiarities in the development of inhibitory responses were found in different layers. The distribution of neurons reacting by IPSP was analyzed according to the slab depth, the duration of primary IPSPs and their latent periods, depending on the distance between the recording microelectrode and stimulating electrode. The mechanisms of inhibitory process spreading in an isolated slab and the mechanisms providing prolongation of cortical inhibitory responses are discussed.

Animals↗
PubMed1984

[Effect of nembutal on inhibitory responses of neurons of an isolated strip of cat auditory cortex induced by intracortical stimulation].

Neuronal responses in acute isolated slab of the auditory cortex (AI zone) to intracortical stimulation were studied intracellularly in experiments on nembutal anaesthetized cats. It was found that 77% of the neuronal responses were primary IPSPs, and taking into consideration secondary inhibitory responses 92% of neurons exhibited inhibition. All types of neuronal responses in the slab had short latencies. The longest latent period did not exceed 5 ms. Neurons responding by IPSPs to intracortical stimulation were found throughout the depth of the slab. Their distribution was analysed in connection with amplitude and latencies of inhibitory responses. Mechanisms of barbiturate influence on some characteristics of inhibitory responses, particularly on amplitude and duration of IPSPs and their latent periods are discussed.

Animals↗
PubMed1984

[Primary inhibitory responses of neurons of a chronically isolated band of auditory cortex to intracortical stimulation].

The reactions of 579 neurons to intracortical stimulation of an auditory cortex slab (three weeks after its isolation) were studied intracellularly in three series of experiments on cats. The distances between stimulating and recording electrodes were 0.5, 1.0 and 2.0 mm. It was shown that 67.7% of neurons responded to intracortical stimulation by primary IPSP, which is by 10% more than that in acute isolated slab. The distribution of neurons reacting by primary IPSP was analysed according to the depth of location in the isolated slab and to the duration of IPSPs and their latent periods depending on the distance between the point of stimulating and recording microelectrodes. Latent periods of IPSPs did not exceed 10 ms like in an acute isolated slab. Amplitude and duration of IPSP were in the same range as in acute isolated slab and intact auditory cortex of cat brain. The histological structure of the chronically isolated auditory cortex slab is described.

Animals↗
PubMed1984

[Responses of neurons of a chronically isolated strip of cat auditory cortex to intracortical stimulation during paroxysmal electrical activity].

Responses of 155 neurons to single intracortical stimulation during paroxysmal electrical activity caused by series of frequent stimuli (10-20/c) by means of the electrical current were investigated extracellularly in the three-week isolated auditory cortex slab from non-anaesthetized tubocurarin immobilized cats. Depending on the behaviour of neurons during paroxysmal electrical activity and preservation of the ability to respond to intracortical stimulation all investigated neurons of the isolated slab were divided into four groups. Their distribution according to layers and duration of latent periods were investigated. It was shown that 2/3 of the investigated neurons generated impulse activity at the time of paroxysmal discharges, the rest did not manifest such activity.

Animals↗
PubMed1984

[Intrinsic cholinergic components in the cholinergic innervation of the auditory cortex in the cat (zone AI)].

Neuronally isolated auditory cortical slabs (zone Al) of cat were studied using histochemical AChE reaction 3 days and 1, 2, 3 weeks after isolation. Following structures were observed: cholinergic long-axon associative neurons responding to the cortex isolation by retrograde degeneration and AChE hyperreaction (Cajal-Retzius cells of layer I and neurons of layer VI whose axons travel to the subcortical layer of the associative fibres); cholinergic short-axon associative cells of layers II-VI, which retain normal structure and moderate AChE activity after isolation; their axon collaterals terminate on neighbouring neurons; short-axon neurons are more numerous in deeper layers of the cortex; on the whole they predominate over the long-axon associative neurons; cholinoceptive cells (pyramidal and stellate) were found with cholinergic terminals on the soma and proximal parts of the dendrites; these terminals were formed by associative cell axons. Cholinoceptive neurons occurred more frequently in deeper layers of the cortex.

Acetylcholinesterase↗