• M A Casagrande, R R Porto, J Haubrich, A Kautzmann, and L de Oliveira Álvares.
• Laboratório de Neurobiologia da Memória, Departamento de Biofísica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, Prédio 43422, Sala 216, CEP 91.501-970 Porto Alegre, Rio Grande do Sul, Brasil.
• Neuroscience. 2023 Dec 15; 535: 184193184-193.

AbstractRecent studies have explored the circuitry involving the ventral hippocampus (vHPC), the amygdala, and the prefrontal cortex, a pathway mainly activated to store contextual information efficiently. Lesions in the vHPC impair remote memory, but not in the short term. However, how the vHPC is affected by distinct memory strength or its role in systems consolidation has not yet been elucidated. Here, we investigated how distinct training intensities, with strong or weak contextual fear conditioning, affect activation of the dorsal hippocampus (dHPC) and the vHPC. We found that the time course of memory consolidation differs in fear memories of different training intensities in both the dHPC and vHPC. Our results also indicate that memory generalization happens alongside greater activation of the vHPC, and these processes occur faster with stronger fear memories. The vHPC is required for the expression of remote fear memory and may control contextual fear generalization, a view corroborated by the fact that inactivation of the vHPC suppresses generalized fear expression, making memory more precise again. Systems consolidation occurs concomitantly with greater activation of the vHPC, which is accelerated in stronger fear memories. These findings lead us to propose that greater activation of the vHPC could be used as a marker for memory generalization.Copyright © 2023 IBRO. Published by Elsevier Ltd. All rights reserved.

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