The anterior retrosplenial cortex is required for short-term object in place recognition memory retrieval: Role of ionotropic glutamate receptors in male and female Long-Evans rats

The anterior retrosplenial cortex (aRSC) integrates multimodal sensory information into cohesive associative recognition memories. Little is known about how information is integrated during different learning phases (i.e., encoding and retrieval). Additionally, sex differences are observed in performance of some visuospatial memory tasks; however, inconsistent findings warrant more research. We conducted three experiments using the 1-h delay object-in-place (1-h OiP) test to assess recognition memory retrieval in male and female Long-Evans rats. (i) We found both sexes performed equally in three repeated 1-h OiP test sessions. (ii) We showed infusions of a mixture of muscimol/baclofen (GABA(A/B) receptor agonists) into the aRSC similar to 15-min prior to the test phase disrupted 1-h OiP in both sexes. (iii) We assessed the role of aRSC ionotropic glutamate receptors in 1-h OiP retrieval using another squad of cannulated rats and confirmed that infusions of either the competitive AMPA/Kainate receptor antagonist CNQX (3 mM) or competitive NMDA receptor antagonist AP-5 (30 mM) (volumes = 0.50 uL/side) significantly impaired 1-h OiP retrieval in both sexes compared to controls. Taken together, findings challenge reported sex differences and clearly establish a role for aRSC ionotropic glutamate receptors in short-term visuospatial recognition memory retrieval. Thus, modulating neural activity in the aRSC may alleviate some memory processing impairments in related disorders.