Learning and memory are fundamental cognitive processes that allow animals to persistently and stably store information and flexibly adapt to dynamic environments. My research has focused on how persistent changes to circuit functions allow our brain to acquire long-lasting memory while accomplishing sustained cognitive enhancement in new learning. First, I studied how cognitive control training induces general cognitive enhancement by altering hippocampal neural circuit function beyond forming specific and explicit memories. I showed that cognitive control facilitated learning new tasks and rapidly changed medial entorhinal cortex (MEC)-to-dentate gyrus (DG) synaptic circuit function, resulting in an excitatory-inhibitory sub-circuit change that persists for months. Specifically, cognitive control training increases inhibition that attenuates the DG response to MEC input and, through disinhibition, potentiates the response to strong inputs, pointing to overall signal-to-noise enhancement. Next, I studied whether genetically increasing neurogenesis recruits inhibitory interneuron plasticity in the hippocampus to improve social recognition memory. I found that enhancing neurogenesis promoted social recognition, augmented PV inhibitory contacts in CA2 and enhanced functional inhibitory synaptic inputs onto CA2. Moreover, increasing neurogenesis also impact on the generation of the Sharp Wave Ripples (SWRs) in CA1 and CA2 as well as the power of the SWR, which may impact on memory consolidation process. These neurobiological findings suggest that sustained inhibitory circuit function changes store item–event associations and optimize information processing for improving cognition.