Spaced learning and the mechanisms that optimize memory formation.

RAMIRO TINTORELLI; JULIETA CORREA; PAMELA LOPES DA CUNHA; PABLO BUDRIESI; HAYDÉE VIOLA

CORDOBA

Congreso; XXXIII Congreso Anual de la Sociedad Argentina de Investigación en Neurociencias; 2018

The superiority of spaced learning over the massed one is a fundamental fact in the formation of long-term memories (LTM). We studied the cellular processes and the temporal demands of this phenomenon, using weak spatial object recognition (wSOR) and weak inhibitory avoidance (wIA) learning tasks. We observed SOR-LTM promotion when two identical wSOR, which individually induced short-term memories but did not form LTM, were spaced by an inter trial interval (ITI) ranged between 15 min to 4 hr. The promoting effect was dependent on hippocampal protein synthesis and MAPKs activity. Also, two identical wIA training sessions spaced by 4 hr, promoted IA-LTM. In contrast, when we combined one wIA with a wSOR, neither of the two tasks formed LTMs.We discuss these results under the "behavioral tagging" hypothesis which postulate the existence of a tag induced by learning that utilize proteins to form LTM. We suggest that the neural contacts stimulated by the first training session are re-tagged by retraining. Moreover, after retraining, the intracellular mechanisms triggered by both sessions could be added, reaching the threshold for protein synthesis required for memory consolidation. On the other hand, when animals are trained in two different and weak tasks, the processes triggered by them would not meet the spatial requirements necessary to form LTM.