Duração da janela de consolidação sistêmica e dinâmica de generalização de memórias remotas para o córtex infralímbico

Abstract

The transition of short-term memories to long-term memories consists of two serial processes: synaptic consolidation - the process in which memories become more stable and resistant to interference - in the first hours, followed by systems consolidation, that takes place later, in a much larger time scale of weeks. Systems consolidation is the process in which explicit long-term memories become independent of the hippocampus and exclusively dependent on cortical structures for their retrieval. The infralimbic cortex (ILC) participates in remote memory retrieval, although the moment that this structure is effectively recruited for retrieval is not clear. The aim of this work was to characterize the role of the infralimbic cortex (ILC) in the systems consolidation of an aversive contextual memory through the temporary inactivation of this structure with a bilateral intracerebral infusion of GABAA agonist muscimol, 15 minutes prior to the test. To this end, adult male Wistar rats were trained in the Contextual Fear Conditioning (CFC), a hippocampus-dependent task, and tested in the same or in a different context 2, 14 or 28 days later. We found that the inactivation of ILC 2 and 14 days after training had no effect upon memory retrieval. On the other hand, 28 days after training memory retrieval was impaired, showing the involvement of this structure in remote, but not recent memory retrieval. Besides, animals were tested in a different, yet similar context in order to evaluate memory generalization. This experiment allowed us to find that, 28 days after training, that remote memory was generalized, since the inactivation of ILC led to a decrease of freezing for both contexts.