For decades, neuroscientists were convinced that the brain stores memories of places and familiar environmental features in one location. More specifically, in neurons called “place cells” that light up when you enter familiar areas, such as your bedroom or your favorite Taco Bell.
These cells, located in the hippocampus, were thought to create a stable internal map where every neuron had its place. It was neat, tidy, and orderly. New research from Northwestern University is throwing all that order out of whack.
The study, led by neurobiology professor Daniel Dombeck, reveals that our memories of places aren’t stored in fixed brain cells. Instead, they drift. Over time, the neurons associated with a memory of a location change, shifting from one set of cells to another, like a relay race.
But instead of a baton, it’s passing along your memory of a place.
Your Brain Constantly Reorganizes Your Memories, Study Finds
The researchers put mice on little treadmills surrounded by screens depicting a maze. The mice used the treadmill to navigate the digital maze as familiar smells were sprayed in. All the while, the researchers were monitoring hippocampal cells in real-time, essentially giving them a live peek into the workings of the brain as it navigates through space.
Dombeck told Live Science, “I was sure that the memory was going to look more stable over days—and that’s not what we found.”
As they ran the mice through the maze, the team observed that only a small percentage of cells, around 5 to 10, behaved like conventional place cells. I reached the point where the team can predict which cells a memory is likely to drift to next based on its level of activity.
This idea challenges decades of thinking, dating back to the 1960s, that each place you remember had its own personal ‘home’ neuron. The new findings suggest that your brain is constantly reassigning locations to different neurons over time.
For now, researchers know that it’s happening. It’s going to take a lot more research to figure out the why of it all. It could be a feature, not a bug—a way for the brain to refresh its wiring, preventing neural burnout or freeing up space for new memories, in the same way old hard drives needed to be defragmented periodically.
It could be how memory stays strong even as individual brain cells age and die off. The researchers don’t know yet. All those questions are left to be answered by research teams in the years to come.
The big takeaway is that your memories aren’t set in stone and kept neatly on a shelf for easy access. If this research holds, your memories could be more like the white flakes that settle at the bottom of a snow globe, only to be shifted around with a vigorous shake every so often.
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