Neurobiologists at Northwestern University have discovered that the brain's internal GPS changes with each navigation of a familiar environment. The study, published in Nature, shows that even when walking the same path daily under identical conditions, different neurons activate each time.
“Our study confirms that spatial memories in the brain aren’t stable and fixed,” said Daniel Dombeck, senior author and professor of neurobiology at Northwestern’s Weinberg College of Arts and Sciences. He explained that memories are passed among neurons and involve different neurons every time.
The research involved precise control over sensory inputs for mice navigating a virtual maze. Despite efforts to replicate the same experience, results showed neuron activity varied with each run. This suggests spatial maps in the brain are dynamic and continuously updating.
“This evidence suggests that memories are fluid,” said Jason Climer, co-first author and assistant professor at the University of Illinois, Urbana-Champaign. He noted this might relate to why brains can learn continuously, unlike modern AI.
Dombeck also observed that more excitable neurons maintained stable spatial memories across runs. As neuron excitability decreases with age, this finding could inform understanding of aging's impact on memory encoding.
Dombeck suggested timing might explain changing neuron activation despite static environments: “If I hike the same path twice...I probably still want to remember that I did the same hike twice.”
The study was supported by grants from the National Institutes of Health.