Recollections of successive events physically entangle each other when brain cells store them.
Think about the first time you met your college roommate. You were probably nervous, talking a little too loudly and laughing a little too heartily. What else does that memory bring to mind? The lunch you shared later? The dorm mates you met that night? Memories beget memories, and as soon as you think of one, you think of more. Now neuroscientists are starting to figure out why.
When two events happen in short succession, they feel somehow linked to each other. It turns out that apparent link has a physical manifestation in our brains, as researchers from the Hospital for Sick Children in Toronto (SickKids), the University of Toronto and Stanford University describe in this week’s Science. “Intuitively we know that there’s a structure to our memory,” says neuroscientist Paul Frankland, affiliated with both the University of Toronto and SickKids. “These experiments are starting to scratch the surface of how memories are linked in the brain.”