CONICET | Buscador de Institutos y Recursos Humanos

Several studies demonstrated that the retrosplenial cortex (RSC) is involved in navigation and contextual memory. Recently it was demonstrated that the RSC also participates in two of the three recognition memory components; the ?where? long-term memory (LTM) and the ?when? short-term memory (STM), but its role in the ?what" memory component remains unclear. Therefore, our work aims to elucidate the RSC requirement in the ?what? component of recognition memory. We inactivated the anterior RSC (aRSC) by GABA A agonist (muscimol, Mus) infusions at different time-points of a non-spatial Y-maze object recognition (Y-OR) task. Our results show that the aRSC integrity is required for memory consolidation and retrieval. However, the aRSC is not involved in the STM processing. As well, the aRSC requirement in memory consolidation is time dependent, since Mus infusion immediately after sample phase produced memory deficit, but animals infused 3 h after sample phase showed intact memory. On the other hand, LTM remained intact when the aRSC was inactivated during memory acquisition. Then, we wondered whether the aRSC inactivation during acquisition interferes with its recruitment in memory processing. Animals were subjected to a double-inactivation of the aRSC, in order to affect both acquisition and consolidation or both acquisition and retrieval. Our results showed that the first Mus infusion would disengage the aRSC from memory processing, thus leaving consolidation and retrieval intact, despite the second infusion targeting them. In addition, we observed an increase in c-Fos levels 1 h after the Y-OR sample phase that is required for LTM. Our findings suggest that aRSC is required for the ?what? memory component consolidation and retrieval, but if it is not active during acquisition other brain structures may take control of memory processing.