Some aspects of conditioned reflex activity during sleep

Acquisition, retrieval and extinction of instrumental alimentary reflexes during various types of sleep was studied in cats with metallic electrodes chronically implanted in different brain structures. The possible acquisition and extinction of a defensive conditioned reflex with the onset of paradoxical sleep (PS) serving as a conditioned signal and painful electrical stimulation of the skin as unconditioned was investigated. Results suggest that: (i) in the presence of a high food motivation the conditioned signals delivered during sleep cause the retrieval of previously acquired instrumental alimentary reflexes, and in PS the brain is capable of discriminating conditioned signals more accurately than during slow wave sleep, (ii) after a conditioned reaction to one of two conditioned signals is extinguished through non- reinforcement, the second signal remains effective, causing an instrumental alimentary reflex, (iii) the extinction of instrumental alimentary reflexes effected during sleep is not retained after the animal's awakening, whereas the extinction of a defensive conditioned reflex is retained, (iv) PS may serve as an endogenous conditioned signal during the acquisition of a defensive conditioned reflex. Thus motivational processes developing during PS are effective endogenous stimuli eliciting past experience dreams.