New research by neurobiologists at Northwestern University and the University of Illinois Urbana-Champaign reveals that the brain’s internal GPS changes as individuals navigate familiar environments. These findings shed light on the essential mystery of how the brain encodes and retains spatial memories, influencing scientists’ perspectives on memory, learning, and even aging.
Memories navigating familiar paths are more fluid than previously thought and activate different neurons on each journey. Image credit: Zeinab vessel.
“Our study confirms that the spatial memories in the brain are not fixed but rather dynamic,” stated Professor Daniel Dombeck from Northwestern University.
“You can’t simply point to a specific group of neurons and claim that their memories are located there.”
“We are uncovering the fact that memories shift between neurons over time.”
“The same experience triggers different neurons each time. It’s not an abrupt change; it evolves gradually.”
The hippocampus, situated deep within the temporal lobe, is integral for storing memories related to spatial navigation.
For many years, neurobiologists believed that the same hippocampal neurons encoded the same memory in a consistent location.
This led to the assumption that a person’s route from the bedroom to the kitchen would activate identical neuron sequences during a midnight quest for water.
However, about a decade ago, researchers studied the brains of mice traversing a maze.
Despite running through the identical maze daily, different neurons fired with each run, prompting scientists to question whether this outcome was an anomaly. Perhaps the mice’s experiences were affected by subtle environmental cues.
To delve deeper into these inquiries, Professor Dombeck and his team devised an experiment that meticulously controlled mouse sensory input.
The mice navigated a virtual maze on a treadmill, allowing precise measurements of their speed.
The maze was presented through a multisensory virtual reality platform developed by the researchers.
This setup ensured that the mice experienced the same visual stimuli and odors during all sessions, minimizing environmental variability.
After conducting multiple trials, the results indicated a different set of neurons activated each time, even in the highly controlled virtual setting.
This revelation confirms that the brain’s spatial mapping is inherently dynamic, constantly adapting, even in supposedly stable settings.
“Our findings suggest that memory is fluid,” commented Jason Climer, a professor at the University of Illinois at Urbana-Champaign.
“This ties into a broader question regarding modern AI and why the brain can learn and adapt in ways machines struggle with.”
“It may also be linked to natural forgetting, which is often overlooked but essential for healthy memory function.”
While there were few discernible patterns throughout the experiment, one consistent observation emerged. The more excitable neurons were more successfully activated, leading to stable spatial memory across multiple sessions in the virtual mazes.
Given that neuronal excitability diminishes with age, this finding aids in understanding how aging and related diseases impact the brain’s ability to form new memories.
“The small clusters of stable neurons are unique, and gaining insights into what makes them special could pave the way for new treatments for memory disorders,” stated Professor Climer.
“Memory impairment is a hallmark of Alzheimer’s disease and presents significant challenges for individuals with various neuropsychiatric conditions, such as schizophrenia.”
“By deepening our understanding of fundamental memory aspects, like temporal changes highlighted in our study, we can identify new targets for understanding brain differences in these patients and develop new treatment strategies.”
“Learning about how the brain deals with memory challenges can also inform improvements in computers and AI.”
Survey results were published in the journal on July 23, 2025, in Nature.
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JR Climer et al. The hippocampus expression drifts in a stable, multisensory environment. Nature Published online on July 23, 2025. doi:10.1038/s41586-025-09245-y
Source: www.sci.news
