Changes of RNA base composition in nerve cells of monkeys subjected to visual discrimination and delayed alternation performance

Abstract

Rhesus monkeys were subjected to visual discrimination and delayed alternation training. Controls were exposed to the same experimental conditions and training procedures, but with rewards given at random. The results of these active controls were compared with those of the learning animals. The amount of RNA per nerve cell and RNA base composition were determined in pyramidal nerve cells in the CA3 region of the hippocampus and in pyramidal nerve cells from the fifth layers of the inferior temporal gyrus and the gyrus principalis. With visual discrimination learning, significant RNA base ration changes occurred in the nerve cells of the inferior temporal gyrus, the integrity of which is a prerequisite for the monkey to resolve the task by a correct behavior. No changes were observed in the gyrus principalis. A different type of RNA base composition change occured on delayed alternation learning in the gyrus principalis which is known to be specifically involved in that type of behavior. During both these kinds of training the RNA of the hippocampal nerve cells responded with the same type of changes involving adenine cytosine, indicating a biochemical and functional response of the CA3 neurons whenever a new behavior is acquired. Thus, with the acquisition of different behavioral patterns, specific brain regions respond with different RNA changes induced by so far unknown mechanisms.