[The effect of different regimens of intracellular electrostimulation on the dynamics of neuronal adaptation processes]. / Vliianie razlichnykh rezhimov vnutrikletochnoi élektrostimuliatsii na dinamiku adaptatsionnykh protsessov neironov.

Was studied the influence of rhythmic, random and contingent intracellular electrostimulation on the character of the initial spike activity of individual identified and nonidentified neurons of the isolated CNS of Lymnaea stagnalis snail under the conditions of the controlled experiment. Stimulation and recording of neuron activity were realized via the same microelectrode. In the process of neuron adaptation to the regimens of stimulation used two phases were distinguished being estimated with the help of various statistic criteria. The expression and stability of observed adaptive alterations of endogenous rhythm system were different during the phases determined. At the first phase which reflected a search for the strategy of the optimization of input external influences, the dispersion of interspike intervals and disorder of discharge patterns increased. The true neuron adaptation was developed at the second phase and observed only at contingent reinforcement. Such an adaptation was followed by steady alterations of endogenous rhythm system resulted in minimization or maximization of frequency of associative auto-reinforcements. Alterations accompanying the effect of optimization of external influences were the most expressive at the end of the epoch of corresponding contingent stimulation and remained for some minutes after its cessation. In the paper are discussed the possible mechanisms of the observed endo-neuronal adaptive reconstructions of spike activity.

[The possible mechanisms of the plastic reorganizations of neuronal activity under different regimens of intracellular electrostimulation based on data from systems analysis methods]. / Vozmozhnye mekhanizmy plasticheskikh perestroek aktivnosti neirona pri razlichnykh rezhimakh vnutrikletochnoi élektrostimuliatsii po dannym metodov sistemnogo analiza.

Effects of rhythmical, random and associative intracellular stimulation were studied in identified single neurons of isolated CNS of the Lymnaea stagnalis snail under the conditions of computer controlled experiment. By means of cluster, correlation, and factor methods of analysis were evaluated and compared changes of the character of spontaneous discharge activity induced by above mentioned modes of stimulation. Connections of the basic frequency and temporary characteristics of the endogenous activity of neurons with parameters of external influences were shown to be revealed only during stimulation associated with certain components of endogenous rhythmicity. These connections were practically absent during rhythmical and random stimulation. Three factors were separated which determine the formation of the structure of spike impulsation at application of suprathreshold stimuli. By their variables' composition the factors may be interpreted as: 1) factor of intensity of spontaneous activity; 2) factor of variability of interspike intervals; 3) reinforcing factor. Possible cellular mechanisms of adaptive reorganization of spontaneous activity under the conditions of associative influences are discussed.

[Cellular analog of instrumental behavior on single mollusk neurons during automatic intracellular electrostimulation]. / Izuchenie kletochnogo analoga "instrumental'nogo povedeniia" na otdel'nykh neironakh molliuska pri vnutrikletochnoi avtomaticheskoi élektrostimuliatsii.

In experiments on spontaneously active neurones of isolated CNS of Lymnaea stagnalis the influence was studied of automatic contingent intracellular electrostimulation on the character of spike discharge of these cells. In every tested neurone in some series of stimulation only prolonged interimpulse intervals (greater than their mean background value) were selectively reinforced in other series--only short ones. It is shown that at such contingent reinforcement both of long and short intervals 35% of neurones can directly change the frequency and the pattern of their spontaneous impulse activity to "minimize" ("maximize") the number of autoreinforcements in both regimes of stimulation, what may be considered as a cellular analog of the instrumental reflex. Control rhythmical stimulation of the same cells elicited no significant changes in the character of spontaneous activity. It is suggested that such contingent intracellular electrostimulation is biologically significant for the cell, as it elicits directed reconstruction of the initial discharge pattern, leading to minimization or maximization of the frequency of autoreinforcements. A possible contribution is discussed of such endoneuronal plastic reconstructions in the activity of the neuronal network participating in the performance and regulation of conditioned acts.

[Plastic changes in the spontaneous activity of pond snail neurons during rhythmic and associated intracellular electrostimulation]. / Plasticheskie izmeneniia spontannoi aktivnosti neironov prudovika pri ritmicheskoi i assotsiirovannoi vnutrikletochnoi élektrostimuliatsii.

In experiments on spontaneously active neurones of the isolated CNS of pond snail, under contingent stimulation with selective auto-reinforcement of interpulse intervals longer than their mean background value, 70 per cent of neurones were capable of adaptive rearrangements of the initial firing frequency, leading to frequency minimization or maximization of influences applied to them. After control rhythmic stimulation, usually no substantial changes of spontaneous activity were observed. The detected phenomena of initial transformation of the spontaneous impulse activity are considered as a cellular analogue of the instrumental conditioned reflex.

[Effect of enkephalins on the plasticity of pond snail]. / Vliianie énkefalinov na plastichnost' neironov prudovika.

The effects of introduction of leu- and met-enkephalins (LE and ME) into the perfusion medium on the characteristics of electrical activity, spontaneous firing and habituation of single neurones to repeated intracellular electrical stimulation were studied on isolated CNS of molluscs. The character, speed, and degree of development of endoneuronal habituation changed significantly after application of LE in 67 per cent of the neurones studied and in 25 per cent of neurones after ME application. As a rule the changes of habituation dynamics occurred at constant levels of membrane potential, excitability, and reactivity of the neurone. LE and ME exerted different modulating effects on the initial electrical activity in 60 per cent of neurones. The obtained data on the independence of the effects of enkephalins on different parameters of activity of one and the same neurone give evidence of a mosaic character of excitable neuronal membrane. A suggestion is made about the possible role of the revealed opiate dependence of the endoneuronal functional plasticity in realization of opiate influences at the behavioural level.