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 .
C0026605
motivation
C0006104
brain