promotion or impairment of long term memory mediated by stress

LOPES DA CUNHA, PAMELA; BALLARINI, FABRICIO; VIOLA, HAYDÉE; CHISARI, LUCÍA

Congreso; Federation of Latin American and Caribbean Neuroscience Societies; 2016

Long -term memory (LTM) formation requires protein synthesis. We have demonstrated that a weak learning task which only induces short-term memory (STM) can be stabilized into LTM if an event of acute stress is experienced 1 hour after. This promoting effect depends on protein synthesis in the dorsal hippocampus. It was postulated that stress provides the necessary proteins, which could be captured at tagged sites induced by the weak learning task, process referred to as behavioral tagging. The promoting effect of stress depends on glucocorticoids (GR) and mineralocorticoids receptors (MR) activity in the dorsal hippocampus too. However it was observed that if stress occurs in certain times close to weak learning is not able to promote a LTM and we wonder if stress can be negatively affecting learning tag induced by a weak training experience. In this case, the effect of stress could not be recovered by another event with promoting effects on memory. Rats were subjected to a weak training (spatial object recognition-SOR) that only induces STM, and we show the promoting effect of stress (elevated plataform -EP-) experienced 1 hour post SOR-training. Likewise we show that the promoting effect open field (OF) 1 hour after SOR-training is not observed when stressful event, instead, is experienced 1 hour before the learning task. The same stress impair memory when rats were subjected to a strong SOR-training that induce LTM. These results suggests an effect of stress (1h pre SOR) on the tag. Surprisingly, when the rats were exposed to a stress 1 hour post strong SOR-training the promoting effect didn ́t occur, but can be recovered with exposition to OF. It could be due to competition for resources necessary for memory consolidation. Finally, we investigated the role of stress induced by exams on the promotion of LTM in students and its temporal curse. The behavioral results were similar to those found in rodents.