A behavioral-tagging perspective of spaced learning: long-term memory formation during an inhibitory avoidance task.

TINTORELLI, R; H. VIOLA; BUDRIESI, P; LOPES DA CUNHA, P; CORREA, J

Villa Carlos Paz

Congreso; Sociedad Argentina de Neurociencias; 2019

SAN

It is a well established fact that spaced learning sessions result superior than massed training in the formation of long-term memories (LTM). Our study examined the temporal demands of this phenomenon and the cellular processes that underlie the LTM formation using weak inhibitory avoidance (wIA) and weak spatial object recognition (wSOR) learning tasks. A single wIA training session is unable to promote LTM formation registered 24h later. However, using a retraining protocol with two identical wIA training sessions spaced by different inter-trial intervals we found a temporal window ranging from 1 hour to 4 hours in which IA-LTM formation was promoted. This promoting effect was dependent on hippocampal protein synthesis and ERKs1/2 activity. We analyzed these results in the context of "behavioral tagging" hypothesis, which postulates the existence of a tag induced by learning that requires proteins to form LTM. We propose that mainly the same neural contacts are stimulated and tagged by both sessions of a retraining protocol. Additionally, we hypothesize that during an effective retraining, the intracellular mechanisms triggered by each session could be added, reaching the threshold for protein synthesis required for memory consolidation. This addition would not proceed if most of the neural population activated by each training session was different; and in line with this assumption, when we combined a wIA with a wSOR training session spaced by 4 hours, neither of the two tasks formed LTMs. Finally, we performed some experiments suggesting that ERKs1/2 kinases are involved in the protein synthesis process but not setting the IA learning-tag.