The correlation between changes in synaptic efficiency and cellular excitability during the development of a conditioned reflex analog

Abstract

The calculation of the coefficient of correlation between changes in the direct (D) and monosynaptic (I) components of the pyramidal tract (PT) response made it possible to establish the presence of a positive linear association between conditioned reflex changes in synaptic efficiency and the shifts in cellular excitability observed at the same time. The coincidence of the maximal strength of this association with the greatest increase in cellular excitability which is dependent on the activation of motivatiogenic structures points to the role of these subcortical structures in the launching of intracellular reactions which leads to the formation of the overall molecular substrate which underlies interaction of membrane and synaptic mechanisms. The preceding of the greatest enhancement of synaptic efficiency by the maximal manifestation of the interaction attests to the contribution of this process to the manifestation of the principal mechanism of the conditioned reflex (CR).

Temporospatial organization of membrane-synaptic modifications and topograms of slow oscillations in cortical potentials during learning

“…The active nature of release of the resultant increase in cellular excitability suggests that the late stage of the organization of the conditioned reflex is characterized by a negative correlation between changes in cellular excitability and synaptic efficiency, unlike the previously noted positive linear relationship [6,7]. Calculation of the coefficient of correlation between changes in the amplitudes of the first and second pyramidal tract waves at the first stage of presentation of combinations (combinations 1-96) revealed a positive correlation between changes in cellular excitability and synaptic efficiency; at the later stage (combinations 97-160), the correlation was weak and negative (p < 0.1).…”

“…Considering data indicating that cellular excitability and oscillations m membrane potential depend on neuronal depolarization, and that cellular excitability and spatial synchronization of oscillations in slow cortical potentials depend on activation of the lateral hypothalamus, it appears that the characteristics of cellular modification and EEG parameters at the early stages of the conditioned reflex are largely determined by differentiated levels of cortical depolarization, which,depends on the predominance of activating hypothalamic influences of motivational and emotional origin [7]. The heterogeneity of hypothalamic influence is demonstrated by data showing that the emotionally positive and negative structures of the hypothalamus show reciprocal changes in the spike activity of "motivational" neurons, with reductions in the spike frequency after feeding of deprived animals, as well as changes in the spike activity of "reinforcement" neurons, with increases in discharge frequency in this situation [13].…”

“…B) The contribution of activation of the lateral hypothalamus to conditioned reflex changes in membrane excitability: a) histograms showing relative changes in the first wave of the pyramidal tract responses to the conditioned stimulus in experiments with stimulation of two points on the cortical surface; b) combination of stimulation of these points with stimulation of the lateral hypothalamus as an additional reinforcement. [5,7] with the features of systemic changes in the spatial-temporal organization of overall slow cortical potentials. In the present work, interactions at these levels of CNS activity were studied (1) by comparing their characteristics at the two classical stages of a conditioned reflex, i.e., generalization and specialization, which occur during the formation of any kind of conditioned reflex action; (2) in terms of the presence (as shown from measurements of slow and cellular activities) of a transfer step from one stage to the next: and (3) by comparing the relationship between cortical plasticity and electrical activation of the hypothalamus.…”