Perirhinal and postrhinal cortices are necessary for retrieving latently-acquired stimulus associations
The perirhinal and postrhinal cortices reside in the parahippocampal region of the medial temporal lobe. They receive and process sensory information from cortical and subcortical sources and support hippocampal functions via direct connectivity and indirectly via the entorhinal cortex. Previous studies using the sensory preconditioning paradigm have shown that the perirhinal and postrhinal cortices are necessary for associating cues during preconditioning and retrieving the associations during conditioning. However, the question of whether these regions are also required for stimulus association retrieval during re-exposure to the preconditioning cue had not been addressed. Using a chemogenetic approach, we temporarily suppressed the perirhinal or postrhinal cortex in adult male rats during the preconditioning cue test phase. Both suppression groups showed impaired sensory preconditioning compared to sham surgery controls, as indicated by significantly reduced preferential responding.