You probably remember exactly what you were doing when you first heard the news on 9/11. That's because the brain has ways to file information so that things that happen at the same time are forever linked in our minds. Now a study published in the journal Neuron; says that newborn cells in a structure called the hippocampus help us remember concurrent events. The hippocampus is part of the brain that allows us to lay down new memories. And about ten years ago, scientists were surprised to find that new neurons pop up in this region every day, even in adult animals and people. But what do these new cells do? Scientists turned to computer modeling to help them find out. They put in what they knew about the behavior of these new cells, which start out like puppies that get totally excited over every little thing, and eventually mature into more discerning members of neuronal society. And they found that the hyperactivity of these excitable young cells, which react with great gusto to everything that goes on, could help stamp memories with a sort of "time code" that indicates which things happened together. So if you still remember what you were eating when you dumped your loser boyfriend, you can thank your newborn neurons.