The article explores the perplexing nature of memory, specifically why the neural representations of our memories aren’t fixed but seem to “wander” or “drift” over time. It centers on a recent study published in *Nature* that investigates this phenomenon, known as “representational drift,” to understand its mechanisms and purpose.
The Mouse in the Virtual World
The core of the article discusses a new experiment where scientists placed mice in a highly controlled, virtual reality-like environment (a treadmill surrounded by screens) to ensure each experience was identical. By monitoring their hippocampal activity, researchers observed that only a small, stable group of neurons (5-10%), called “place cells,” activated consistently each time the mice navigated the virtual space. The majority of neurons involved in creating the mental map changed over time. A key finding was that less excitable neurons were more likely to be part of this drifting population, linking long-term memory stability to a neuron’s readiness to fire.
A Flexible ‘Brain GPS’ with Implications for Aging
Researchers hypothesize that this drift isn’t a bug but a feature. It may be a mechanism that allows the brain to separate very similar experiences into distinct memories. For example, it could help differentiate memories of walking a familiar route whether you’re going to work or to a store. While the study has limitations (conducted on mice, observing only 1% of hippocampal neurons), the findings have significant implications. The decline in memory associated with aging in both humans and mice is linked to a decrease in the excitability of hippocampal cells. The study’s lead author suggests that if we could find a way to increase neuronal excitability, we might be able to prevent or mitigate age-related memory problems.
Mentoring question
The article suggests that memory ‘drift’ could be a feature for distinguishing similar experiences. How might this constant, subtle updating of your ‘mental maps’ be beneficial or detrimental in your professional or personal life?
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