The birth of new brain cells bumps old memories into long-term storage, according to new research which upends earlier theories. Researchers working with rodents found that the creation of new neurons destabilized existing connections in the hippocampus instead of strengthening them as they had expected, effectively "clearing the inbox" and causing short-term memories to be transferred elsewhere in the brain
Clearing old memories in this way made space for new ones, the researchers say. The memories shunted out of short-term storage were ones associated with fear, but the scientists believe the same process occurs with all memories, Wired reports. Exercise sped up both the process of neuron creation and the transfer or memories.