Assessing the object recognition memory dynamic network upon retrosplenial cortex inactivation- a functional neuroimaging study in rats

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

Congreso; SAN 2021 XXXVI Annual Meeting; 2021

Little is known about the object recognition memory (ORM) network. Recently we found that the retrosplenial cortex (RSC) is required for ORM consolidation and retrieval; yet RSC inactivation during acquisition prevents its requirement for consolidation and retrieval, suggesting that the ORM network modifies when RSC is inactive during acquisition. To assess this we use a cerebral blood flow (CBF) SPECT for imagining rats brain 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) or muscimol (Musc, GABA A agonist, 0.1 µg/side, n=10) into the RSC 15 min before TR. The within group comparison showed that CBF during TR compared to H decreased over the midline cortical regions from the prefrontal cortex to the RSC. Also, CBF increased during TR 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 the ventral thalamic nuclei. The deactivation of the RSC during TR was stronger in the Musc group, but the largest differences between both groups were found during TS. In this condition, CBF in the orbitofrontal cortex and dorsal hippocampus decreased in the Musc group while CBF in the RSC was higher in this group.