Dissecting the object recognition memory network and its change upon retrosplenial cortex inactivation - a CBF SPECT imaging study in rats

DE LANDETA, ANA BELÉN; OELSCHLEGEL A; MEDINA, JORGE H.; KATCHE, CYNTHIA; GOLDSCHMIDT, J

Congreso; 16th Annual Meeting of the European Society for Molecular Imaging; 2021

Little is known about the object recognition memory (ORM) network. Recently we foundthat the retrosplenial cortex (RSC) is required for ORM consolidation and retrieval; yetRSC inactivation during acquisition prevents its requirement for consolidation andretrieval, suggesting that the ORM network modifies when RSC is inactive duringacquisition. To assess this we use a cerebral blood flow (CBF) SPECT for imagining ratsbrain activity patterns during habituation (H), training (TR), test (TS, 24 h) and re-test(reTS, 7 d after training) in two groups; animal infused with saline (control, Ctl, n=10) ormuscimol (Musc, GABA A agonist, 0.1 µg/side, n=10) into the RSC 15 min before TR. Thewithin group comparison showed that CBF during TR compared to H decreased over themidline cortical regions from the prefrontal cortex to the RSC. Also, CBF increased duringTR in the lateral thalamic nuclei, lateral hypothalamus and lateral superior colliculus.During TS compared to TR CBF increased in the piriform and lateral entorhinal cortex.When compared reTS to TS (n=7), CBF decreased in the anterior cingulate cortex and theventral thalamic nuclei. The deactivation of the RSC during TR was stronger in the Muscgroup, but the largest differences between both groups were found during TS. In thiscondition, CBF in the orbitofrontal cortex and dorsal hippocampus decreased in the Muscgroup while CBF in the RSC was higher in this group.