The influence of acetylcholine and atropine on the temporary connection in neuronal populations of the motor cortex.

The activity of neurons of the sensorimotor cortex during the paired combination of stimulations of brain structures (the medial lemniscus, the reticular nucleus of the midbrain tegmentum, and the pyramidal tract), with an interstimulus interval of 1.2 sec, was investigated in awake nonimmobilized rabbits. During the omission of the reinforcing stimulus at a place of its expected delivery, a complicated complex of reorganizations of the impulse activity of the neurons develops, consisting of the reproduction of responses and changes in impulse activity which differ in configuration from them, and which usually appear at later periods. The direct application of acetylcholine to the cortex facilitates the manifestation of both types of reorganizations of the neuronal activity. The application, on the other hand, of atropine suppresses primarily the second type of reorganizations. In addition, acetylcholine increases the total duration of these electrical indices of the temporary connection of the developed reactions, while atropine decreases it.