[Dynamics of the activity of cerebellar Purkinje cells induced by changes in the duration of complex spikes].

The relationship between complex and simple spikes of Purkinje cells from vermis cerebelli of guinea pigs has been investigated. The ratio of complex spikes innervated by the processes of one and the same liana-like fiber ("twins cells") has also been studied. Three types of complex spikes in each Purkinje cell from vermis cerebelli of guinea pigs (n = 44) have been differentiated, which differ in duration. It was found that long (10.28 +/- 0.27 ms) complex spikes in all cells lead to a more pronounced inhibition of simple spikes than complex spikes of short duration (6.08 +/- 0.25 ms). It was shown that the dynamics of duration of complex spikes coordinates with changes in the activity of some Purkinje cells and their local groups: (a) complex spikes generated before the onset of pauses of simple spikes are longer than complex spikes generated before the termination of pauses; (b) in "twins cells" innervated by one liana-like fiber, the properties of complex spikes change simultaneously; (c) The degree of synchronism of complex spikes in closely-spaced (to 150 microm) Purkinje cells receiving the inputs from different liana-like fibers increases with their duration. A possible functional role and the mechanisms of generation of complex spikes are discussed.

[Characteristics of activity of "fast" and "slow" Purkinje cells of the cerebellum]. / Osobennosti aktivnosti "bystrykh" i "medlennykh" kletok Purkin'e mozzhechka.

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.

[Activity of the climbing fiber innervating various Purkinje cells]. / Aktivnost' vetvei liannogo volokna, innerviruiushchikh raznye kletki Purkin'e.

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.

Cross-correlation analysis of neuron connections in the cerebellum of conscious rabbits.

Cross-interval and cross-correlation analysis of neuron activity was used to study cell interactions in the cerebellar vermis of conscious rabbits. The cross-correlation method, based on post-synaptic potentials (PSP) from one member of a pair of neurons, supplements the cross-interval analysis used for evaluating the interactions of neurons in terms of action potentials. A total of 16 neuron pairs were analyzed, in which the activity of one neuron was recorded intracellularly and that of the other extra- or intracellularly. Interactions were observed in 10 pairs. Most pairs showed inhibitory interactions. Pairs with inhibitory interactions included those in which the activity of one or both neurons contained complex spikes. Also of interest was the analysis of connections in which influences were excitatory in one direction and inhibitory in the other. In these cases, neuron discharges were invariably simple spikes. Variability and plasticity in the output signals of Purkinje cells were greater than the variability and plasticity of the common inputs to Purkinje cells.

[Cross-correlational analysis of the neuronal connections of the cerebellum in the waking rabbit]. / Krosskorreliatsionnyi analiz sviazei neironov mozzhechka bodrstvuiushchego krolika.

The methods of cross-interval and crosscorrelation analysis were used to study interneuronal connections in cerebellar vermis in awake rabbit. Crosscorrelation, or spike-triggering method, complemented the analysis of cross-intervals which estimated the neuronal interaction comparing spike sequences as point processes. Among 16 neuronal pairs recorded intra- or extracellularly 10 pairs were considered as interconnected. Inhibitory interconnections dominated. The inhibitory neuronal interconnections were revealed in pairs with complex spikes. Neurons which constituted pairs with reciprocal excitatory-inhibitory interaction fired only simple spikes. The variability and plasticity of common inputs to Purkinje cells were seemingly lower than those of direct connections which probably transmitted the output signals of Purkinje cells.

[Assessment of the contribution of complex and simple Purkinje cell impulses to local potentials of the cerebellar cortex]. / Otsenka vklada slozhnykh i prostykh impul'sov kletok purkin'e v lokal'nye potentsialy kory mozzhechka.

Potentials amplitude decrement with the distance between referent cell and test electrode is estimated by means of potential averaging synchronous with complex and simple spikes of the referent Purkinje cell. Anisotropy of recorded fields in accordance with natural planes of anisotropy of cerebellar cortex and temporal parameters of complex and simple spikes has been described. Use of synchronous averaging for increase of a probability of finding of Purkinje cells pairs controlled with the same climbing fiber is discussed.

[Analysis of membrane heterogeneity and non-linearity of summation of postsynaptic potentials in a simulation model of the Purkinje cell]. / Analiz neodnorodnosti membrany i nelineinosti summatsii vozbuzhdaiushchikh postsinapticheskikh potentsialov na imitatsionnoi modeli kletki Purkin'e.

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.

[Increase in the efficiency of parallel fiber synapses on Purkinje cells of the frog after simultaneous activation of climbing and parallel fibers]. / Uvelichenie éffektivnosti sinapsov parallel'nykh volokon na kletkakh Purkin'e liagushki posle odnovremennoi aktivatsii liannykh i parallel'nykh volokon.

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.

[A matrix of connections of mossy fibers with glandular cells in the cerebellum]. / Matritsa sviazei mshistykh volokon s zernistymi kletkami mozzhechka.

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.

[Configuration generators of neuronal rhythm]. / Konfiguratsionnye generatory neironnoi ritmiki.

Neural nets that exhibit oscillations with a period n, so that n greater than N (N--number of neurons) are analysed. It is shown that the nets capable of learning can be taught to be patterned oscillators. These modes of activity may be considered as a generalization of selfwaves in topologically simple excitable tissues on more complex structures.

[Intracellular recording of potentials of cells of isolated cerebellum in the frog]. / Vnutrikletochnoe otvedenie potentsialov kletok izolirovannogo mozzhechka liagushki.

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.

[Transistorized electrometric intensifier for recording low-amplitude bioelectric activity]. / Tranzistornyi élektrometricheskii usilitel' dlia otvedeniia nizkoamplitudnoi bioélektricheskoi aktivnosti

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.

[Work of large information systems]. / O rabote bol'shikh informatsionnykh sistem

The problem of application of informational ideas to the study of large informational systems, such as brain, is considered. Analysis follows some ideas of Winograd and Kowan's theory of reliable computations in the presence of noise. In the beginning of paper the "material analogy" for intuitive understanding of Shannon's results is proposed. Afterwards there is given the formulation of coding theorem for the case of "informational collective"--a large group of informational sources and receivers. In conclusion it is shown that such properties of neuronal structures as "stochastic" neural connections are reasonable from the point of information theory.

[Principles of neuronal organization. II. Information capacity of Purkinje cells and climbing-nuclear cerebellar unit]. / Printsipy neironnoi organizatsii. II. Informatsionnaia emkost' kletki Purkin'e i lianno-iadernoi iacheiki mozzhechka

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.

[Principles of neuronal organization. I. Memory as a process of information transmission]. / Printsipy neironnoi organizatsii. I. Pamiat' kak protsess peredachi informatsii

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.

[Electrical characteristics of normal and transformed fibroblasts in tissue culture]. / Elektricheskie kharakteristiki normal'nykh i transformirovannykh fibroblastov v kulture tkani

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.