Neurons Responsible for Map-Making Change Even in Unchanged Familiar Environments

Recent research from Northwestern University reveals that the brain's internal GPS, used for spatial navigation, is more dynamic than previously believed. Neurobiologists have discovered that even when individuals navigate a familiar environment where conditions remain constant, the neurons involved in creating mental maps continually change. This finding emerged from experiments showing that, despite identical paths and sensory inputs, the specific neurons activated each time differ. Such results challenge the longstanding idea that hippocampal neurons encode fixed spatial memories. Instead, the brain appears to maintain a flexible and ever-evolving internal representation of familiar surroundings.

The study employed advanced virtual reality systems that precisely controlled visual and olfactory cues, aiming to eliminate environmental variables. Mice navigating a virtual maze demonstrated that neuronal activity drifted across sessions, even under consistent sensory inputs. Interestingly, neurons that were more excitable tended to preserve their activation patterns, suggesting a potential link between neuron excitability and memory stability. This phenomenon could also explain age-related memory decline, as neuronal excitability diminishes over time.

Furthermore, the research proposes that the brain might deliberately alter neural representations to encode experiences occurring at different times, thus preventing redundancy in memory storage. These insights enhance our understanding of hippocampal function and could have implications for aging, learning, and memory processes, illustrating the brain’s remarkable capacity for adaptability.

The findings are published in Nature and contribute significantly to the ongoing debate about how the brain encodes spatial and episodic memories, emphasizing the importance of neuronal flexibility in cognitive functions.