Memory hub starts dense, then prunes for sharper learning

A new study shows the hippocampal CA3 memory circuit begins with an excess, randomly connected network after birth and prunes itself into a sparse, structured network by adulthood. This pruning shortens some axons while dendrites grow more receptor sites, shifting memory signaling from single strong connections to distributed, multi-neighbor integration. Computer simulations suggest the sparse network enhances memory storage and retrieval. While informative about brain maturation and infantile amnesia, the work was done in mice on brain slices, and the exact biological triggers remain to be identified.