Functional connectivity of the retrosplenial cortex in object recognition memory formation

DE LANDETA, ANA BELÉN; PEREYRA, MAGDALENA; MIRANDA, MAGDALENA; BEKINSCHTEIN, PEDRO; MEDINA, JORGE H.; KATCHE, CYNTHIA

Congreso; XXXV Annual Meeting of the Argentinian Society for Neuroscience Research; 2020

Recently we demonstrated that retrosplenial cortex (RSC) is required for object recognition(OR) memory consolidation. Here, we aimed to study which brain structures interact withthe RSC to process the OR memory in rats. We selected six brain structures that areconnected to the RSC to study their interaction in OR memory formation: perirhinal cortex(PRH), medial prefrontal cortex (mPFC), anteromedial thalamic nuclei (AM), medialentorhinal cortex (MEC), hippocampus (HP) and anterior cingulate cortex (ACC). First, westudied the participation of these structures in OR memory by bilateral infusions of theGABA A  receptor agonist muscimol. We observed an amnesic effect when inactivating thePRH, mPFC, AM and MEC, but not after HP or ACC inactivation. Then, we studied thefunctional connections by unilateral inactivation of RSC and each of the six structures inthe same (ipsilateral) or the opposite (contralateral) hemisphere. Our results showed anamnesic effect of ipsilateral inactivations of RSC-PRH, RSC-mPFC, RSC-AM, or RSC-MEC. Conversely, contralateral inactivation of RSC-ACC produced memory impairment,while RSC-HP inactivation had no effect on memory. Thus, our ipsilateral inactivationfindings reveal that RSC and at least another region involved in OR memory processing arerequired to form OR memory. In conclusion, our results show that several cortico-corticaland cortico-thalamic pathways appear to be important for OR memory consolidation.