A structural change in the brain may temporarily interrupt access to memories formed during early adolescence, according to a new study. Memories created during early adolescence have long puzzled neuroscientists because they often seem to become harder to access later in life. Their production is controlled by the growth factor TGFβ2, whose genetic activity also fell sharply in the retrosplenial cortex while remaining stable in the hippocampus. Researchers found that far fewer parvalbumin cells were enclosed within the rebuilt nets than during early adolescence, and no other inhibitory cell type replaced them. The study concludes that the retrosplenial cortex undergoes an unexpected dismantling and rebuilding of its supporting scaffold well after early adolescence, temporarily reducing access to memories formed before this developmental remodeling.