By tracking brain activity when an animal stops to look around its environment, neuroscientists can mark the birth of a memory. The hippocampus is the brain's warehouse for long- and short-term processing of episodic memories, such as memories of a specific experience like a trip to Maine or a recent dinner. What no one knew was what happens in the hippocampus the moment an experience imprints itself as a memory. New research is lending clues to what they call "spatial mapping functions" in the brain.