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V L Dunin-Barkovskiĭ

Publications and source records attributed to V L Dunin-Barkovskiĭ.

At least 19 recordsLinked to original sources
PubMed1987

[Increase in the efficiency of parallel fiber synapses on Purkinje cells of the frog after simultaneous activation of climbing and parallel fibers].

Ability of the Purkinje cells to long-term plasticity changes after joint stimulation of parallel and climbing fibres has been studied in the isolated cerebellum-medulla oblongata preparation of frog. 18 neurons have been chosen on the ground of the presence of clearly identifiable monosynaptic response to parallel fibre stimulation and stability of the background activity within two hours. These neurons belonged to three distinct categories: those having the clear climbing fibre response, those having the climbing fibre-like response and those without the climbing fibre response. The neurons of the first group showed a significant increase of the ability to respond to parallel fibre stimulation after joint stimulation of both types of fibres. The stimulating current strength which was necessary for the Purkinje cell firing index 1/2 was reduced after conditioning procedures in this neuron group to 0.7 of its original value. There were no substantial changes in parallel fibre stimulation efficiency in two other neuron groups.

Afferent Pathways↗
PubMed1983

[Intracellular recording of potentials of cells of isolated cerebellum in the frog].

Intracellular potentials of granular, Purkinje and glial cells were recorded in an isolated frog cerebellum in response to electrical stimulation of cerebellar peduncle. The stimuli inhibited strongly the activity of most granular cells. "Slow" (20-50 ms) and "fast" (1-2 ms) spikes were recorded in Purkinje cells. Glial cell responses consisted of a slow waves of depolarization summated with repetitive stimuli and reached an amplitude of 20 mV.

Animals↗
PubMed1976

[Transistorized electrometric intensifier for recording low-amplitude bioelectric activity].

An amplifer is described which is intended to register a low amplitude bioelectric activity at intra- and extracellular recordings using high ohm electrodes. The increase of real sensitivity (increase of the ratio signal/noise) is reached selectively for each case by a smooth change of the amplifier frequency band, as well as by applying field transistors with little noise at the output stage of the amplifier.

Electrophysiology↗
PubMed1975

[Electrical characteristics of normal and transformed fibroblasts in tissue culture].

The two-electrode method of input resistance measuring was shown to give lower values of resistance compared with the one-electrode balance method. Gradual growth of estimates of input resistance and membrane potential in the cause of experiment is associated with decrease in the shunting effect of the electrode puncture. The mean values of steady Rin of sparse and confluent culture did not differ when the cells were electrically disconnected (38 plus or minus 1.2 MO and 41 plus or minus 1.8 MO respectively) and differed in electrically coupled fibroblasts (54 plus or minus 4.9 MO --sparse; 29 plus or minus 2.2 MO -- confluent culture). This difference is thought to be associated with shunting effect of electrical connections. The specific resistance of membrane was estimated in normal and transformed fibroblasts.

Animals↗
PubMedDate not supplied

[Activity of the climbing fiber innervating various Purkinje cells].

Low-amplitude potentials (10-130 microV) related to the action of a distant branch of the climbing fiber, which elicits complex spikes of the reference Purkinje cell were revealed by means of potential averaging synchronously with complex spikes of Purkinje cells in 10 out of 255 paired records of cerebellar Purkinje cells activity and extracellular field potentials at interelectrode distances of 200-1500 microns. These potential waves had a stable form in independent sets of data. In 3 out of 10 cases, the low-amplitude potentials included a slow (about 100 ms in duration) component. In one case, both test and reference electrodes recorded both simple and complex spikes of different Purkinje cells so that complex spikes of both cells were practically synchronous (conditional probability of complex spikes p = 0.97, onset time difference 0.54 ms). Thus for the first time in cerebellar physiology both simple and complex spikes activity of two Purkinje cells controlled by the same climbing fiber was recorded.

Animals↗
PubMedDate not supplied

[Characteristics of activity of "fast" and "slow" Purkinje cells of the cerebellum].

In the guinea pig cerebellar cortex, three types of Purkinje cells were identified according to the properties of complex spikes: fast, intermediate, and slow cells. Fast Purkinje cells have following properties as compared with slow Purkinje cells: (i) salient components with short intervals in complex impulses (on the average, five components with a period of about 2 ms versus two components with a period of about 4 ms); (ii) a short duration of simple spikes (in the average, 2.13 +/- 0.53 ms versus 3.9 +/- 0.65 ms) and a quick restoration of their amplitude after preceding simple spikes (in the mean, 2.83 +/- 0.75 ms versus 11.0 +/- 2.82 ms); and (iii) a more pronounced rebound in the auto-correlation histogram of simple spikes (3.09 +/- 2.12 versus 1.45 +/- 0.36) and a short-latency excitation of simple spikes after complex spikes (2.81 +/- 1.64 versus 1.26 +/- 0.52). A decrease of interspike intervals in simple spike activity of all Purkinje cells was revealed (5.25 +/- 2.71 ms versus 9.71 +/- 3.48 ms in activity fragments without complex spikes). It is supposed that the properties of complex spikes depend on the type of Purkinje cells and may be one of the basic factors determining the interactions between the inputs of climbing and parallel fibers in Purkinje cells.

Animals↗
PubMedDate not supplied

[Principles of neuronal organization. I. Memory as a process of information transmission].

The process of memory is considered as the process of information transmission from "wrighter" to "reader" with an aid of memory device. A special attention is paid to memory which work with errors: "false memorising" and missing some words. The results obtained are useful for evaluation of possibilities of neuronal memory circuits of Brindley-Marr type.

Memory↗
PubMedDate not supplied

[Principles of neuronal organization. II. Information capacity of Purkinje cells and climbing-nuclear cerebellar unit].

On the ground of the author's information-theoretic approach to the neuronal memory informational capacity of P-cell is evaluated. The values of one and 1n2 bit/synaps are obtained in different cases. The latter case corresponds to most probably situations. In this case P-cells exhibit a great degree of false memory -- only 10% of the information presented to the cell is preserved. There is considered also a functional group of few P-cells governed by common climbing and mossy fibres and different granula cells. In this functional unit all the information presented is preserved with the efficiency of 1n2 bit/synaps. The scheme is of the class proposed by Cowan and Winograd. It is thought that the real cerebellum operates according to the proposed ideas.

Cerebellum↗
PubMedDate not supplied

[Analysis of membrane heterogeneity and non-linearity of summation of postsynaptic potentials in a simulation model of the Purkinje cell].

Propagation and summation of EPSP was studied by means of a numerical model of rat Purkinje neuron. It was shown that the difference between the membrane resistivity of the soma and dendrites can be determined experimentally by the character of EPSP attenuation, while comparing intra- and extracellular recordings. It was also shown that at an increase of synaptic input the nonlinear increase of the potential is more pronounced in the soma that in the synaptic region. The role of this fact for the interpretation of the experimental data is discussed.

Animals↗
PubMedDate not supplied

[A matrix of connections of mossy fibers with glandular cells in the cerebellum].

An analytical formulation of known structural data and succeeding calculation are used to show that non-zero elements of the mossy-granule connection matrix are located near the main matrix diagonal. The width of this "non-zero" matrix strip is 10 fibres and 1000 cells in mossy and granula coordinates respectively. Depending on this result estimates of mossy-granula mapping informational properties are presented.

Animals↗