Intracranial self-stimulation improves memory consolidation in rats with little training

Post-training intracranial electrical self-stimulation can improve learning and memory consolidation in rats. However, the molecular mechanisms involved are not known yet. Since previous paradigms of this kind of facilitation are relatively unsuitable to try a molecular approach, here we develop a single and short model of learning and memory facilitation by post-training self-stimulation that could make easier the research of its neural and molecular basis. Thus, three consecutive experiments were carried out to ascertain whether post-training self-stimulation is able to facilitate memory when learning consists of only a brief (5 trials) two-way active avoidance conditioning session. The results of Experiment 1 showed that it is actually possible, and that 48 h after the acquisition session is a very good time to observe the memory improvement. As a way to probe the retroactive effect of self-stimulation, in Experiment 2 we observed that the same self-stimulation treatment given to the subjects not post-training but 48 h before a single two-way active avoidance session does not improve the acquisition of conditioning. In Experiment 3, we showed that the SS facilitative effect observed 48 h after the acquisition session in Experiment 1 was still maintained one week later. We concluded that post-training intracranial self-stimulation can consistently improve memory consolidation even when little acquisition training is given to the animals in a single training session. © 2007 Elsevier Inc. All rights reserved.