The multineuronal activity was recorded in cats with a developed conditioned food-procuring reflex to time. Cross-correlation histograms were plotted on the basis of the impulse activity of individual neurons isolated from the multineuronal activity, and an analysis was made of the distribution in real time of the impulses constituting the peaks on these histograms. The secondary analysis of the histograms made it possible to identify the dynamics of the changes in the functional connections between neurons over the course of the phase of active waiting on the basis of the distribution of coupled impulses. It was demonstrated in simultaneously recorded neuronal pairs that the concentration of coupled impulses was observed at various moments in time. Neuronal pairs, the concentration of whose coupled impulses is found towards the end of the conditioned reflex interval, were noted; this is regarded as the manifestation of a conditioned reflex reaction at the level of interneuronal interaction.
A defensive dominant was created in rabbits using rhythmic electrocutaneous stimulation of the left forelimb at a frequency of 0.5 Hz. After stimulation ended, the latent excitation state was tested using sound stimuli. Animals responded either with increases in non-rhythmic paw muscle activity or with rhythmic twitching of the paw at a frequency close to that of the electrocutaneous stimulation. After hypnotization, the incidence of rhythmic responses to the stimulation testing the dominant focus increased, while the incidence of non-rhythmic responses decreased.
Analysis of the distribution of linked spike activity showed changes occurring within the structure of interneuron functional connections during learning. In an electric shock defensive reflex, concentration of linked spikes from cat motor cortex neurons was observed on signal presentation, while in a conditioned food-procuring reflex to time, this was confined to the moment at which reinforcement was provided. This can be regarded as the appearance of a reflex at the level of interneuron interactions. This conclusion is supported by the observation that in well-trained animals, concentrations of linked spikes could be seen at the place of the conditioned reflex response, even in the absence of defensive and food-procuring movements.
A latent focus of excitation with a rhythmic nature (a defensive dominant focus) was created in the CNS of rabbits. The focus was formed by threshold electrocutaneous stimulation of the left forelimb using series of impulses consisting of 15-20 stimuli with interstimulus intervals of 2 sec. The linked activity of cells in the sensorimotor cortex of the right and left hemispheres was analyzed. When cross-correlation histograms of the spike activity of sensorimotor cortex neurons in the left hemisphere were constructed and analyzed in relation to spikes of high and intermediate amplitude recorded in the right hemisphere, the linked activity of 15% and 23% of neuron pairs, respectively, showed predominance of a rhythm equal or close to the stimulation rhythm used to form the dominant focus. When the appearance times of spikes from neurons in the sensorimotor cortex of the right hemisphere were analyzed in relation to spikes of high and intermediate amplitude recorded in the cortex of the left hemisphere, predominance of 2-sec rhythms was seen in the linked activity of only 3% and 10% of neuron pairs, respectively. After induction of "animal hypnosis," differences between the hemispheres in relation to this measure leveled out.
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