Prolonged changes in synaptic efficiency and cellular excitability during learning.

A temporal analysis of changes in the response of the pyramidal tract using a model of prolonged potentiation revealed the substantial role of the mechanism of the heightening of total excitability of the cell at the initial stage of the formation of trace processes (an analog of the "dominant") which apparently promote the greater strengthening of the underlying mechanism of the CR, namely, the increase in the efficiency of synaptic associations. In the development of a CR in response to the stimulation of two points of the cortex, the increase in cell excitability was more marked in those experiments in which reinforcement was supplemented by the stimulation of the lateral hypothalamus, stimulation eliciting an alimentary reaction. These data make it possible to consider membrane plasticity as a cortical mechanism of the motivational component of reinforcement, a mechanism determining the dominant properties of the stage of generalization of the CR.