Adult-born granule cells modulate CA2 network activity during retrieval of developmental memories of the mother

Adult-born granule cells (abGCs) project to the CA2 region of the hippocampus, but no previous studies have assigned a behavioral function to this circuit. Here we show that abGC input to the CA2 is necessary for the retrieval of remote social memories. We also found that abGCs are necessary for differential CA2 network activity, including theta-gamma coupling and sharp wave-ripples, in response to novel versus familiar social stimuli.