By studying an artificial neural network, researchers at New York University in the US may have gained a better understanding of how and why our memories fade over time. The team has found evidence that the stable, repeating neural patterns associated with newer memories transform into more chaotic patterns over time, and eventually fade to random noise. This could be a mechanism used by our brains to clear space for new memories. In some models of the brain, memories are stored in repeating patterns of information exchange called attractor networks. These form within webs of interconnected nodes that are used to represent the neurons in our brains. These nodes convey information by emitting signals at specific firing rates. Nodes that receive signals will then generate their own signals, thereby exchanging information with their neighbours. The strengths of these exchanges are weighted by the degree of synchronization between pairs of nodes.
Researchers suggest that our brains must have evolved a mechanism for losing memories over time. To test this theory, they simulated neural networks in which the weights between connected nodes in an attractor network will gradually diminish as new memories are imprinted. They found that this caused older attractor networks to shift into more chaotic states over time. These networks featured faster fluctuating patterns. These patterns of firing signals never perfectly repeat, and can coexist far better with newer, stable attractor networks. Eventually, this increasing randomness causes older attractor networks to fade into random noise, and the memory they carry is forgotten. Altogether, the researchers hope their theory could help to explain how our minds are able to constantly take in new information, at the price of losing older memories. Their insights could help neurologist to better understands how our brains store and retrieve memories, and why they ultimately fade over time.
More information:
https://physicsworld.com/a/chaos-plays-a-role-in-how-memories-are-forgotten-simulations-suggest/