In Search of Lost Childhood Memories: Unveiling the Neural Mechanisms of Infantile Amnesia

Infantile amnesia, the loss of early childhood memories, remains a complex and poorly understood phenomenon. The underlying biological conditions and effects on memory engrams are yet to be fully elucidated. We employed engram labeling technology and mouse models of infantile amnesia to investigate the neurobiology of this developmental memory loss. We discovered that male offspring in maternal immune activation models of autism spectrum disorder do not demonstrate infantile amnesia. Using optogenetic techniques, we successfully reactivated forgotten infantile memories by targeting engram cells in the dentate gyrus that were labeled during critical infant developmental experiences. Importantly, we demonstrate the reversible nature of infantile amnesia, by permanently reinstating lost memories through artificial manipulation of the memory engram. Lastly we provide evidence that the effect of immune activation on infantile amnesia is mediated by the downstream effector cytokine IL-17a.