Possible mechanisms of plastic reorganizations of neuronal activity during different schedules of intracellular electrostimulation according to the data of systems analysis.

The influence of rhythmic, random, and associative intracellular electrostimulation has been studied in individual identified and nonidentified neurons of the isolated CNS of the pond snail under the conditions of a controllable experiment. Using the methods of cluster, correlation, and factor analyses, an assessment is given and a comparison made of the changes in the character of the spontaneous spike activity induced by these modes of influence. It has been shown that the associations of the principal frequency-temporal characteristics of the endogenous rhythmicity of the neurons with the parameters of the external influences are identified only during stimulation associated with specific components of the endogenous rhythmicity, and are practically absent in the case of rhythmic and random electrostimulation. Three factors determining the formation of the structure of the spike impulse activity during the application of suprathreshold stimulations were distinguished. With respect to the composition of the variables included in them, they can be interpreted as: 1) the factor of intensity of the spontaneous activity; 2) the factor of the variability of the interimpulse intervals; and 3) the reinforcing factor. The possible endoneuronal mechanisms of the formation of adaptive reorganizations of the spontaneous activity under the conditions of associative influences are discussed.