BarcelonaThe first time you saw snow, the magical Twelfth Night, or the day your little brother was born. Despite the passage of time, there are memories that we hold onto for a lifetime. But what is the mechanism that makes this possible? A pioneering study by a team of American researchers, published in Scientific progressProvide a biological explanation for long-term memories. The key to the research is understanding the role of a molecule called KIBRA, which acts as a glue with other molecules and allows memories to stabilize and solidify over the long term.
The answer to how memories are stored in the brain is one of the big questions that neuroscience has not yet found a final solution to. Right now, the simplest answer is that the brain itself is restructured with each memory through the actions of synapses, that is, when neurons communicate with each other to transmit information. It is in this process that memories are formed and stored.
“When a memory is formed, the connectivity between neurons changes,” says Luis Fuentemilla, a researcher at the University of Barcelona (UB) and the Bellvitge Biomedical Research Institute (Idibell). “The brain prioritizes the preservation of those memories associated with strong emotions, whether good or bad,” adds Raúl Andero, a researcher at ICREA from the Autonomous University of Barcelona (UAB).
Neurons store information in memory in two types: strong synapses and weak synapses. “For example, a weak one is what I ate ten weeks ago, and a strong one is, for example, when I rode a motorcycle for the first time,” Andero explains. However, the molecules in synapses are unstable, meaning they are constantly moving around the neurons and wearing out. In fact, they are replaced within days or even hours. So how can memories remain stable for decades if the basic element of the neural process is so changeable?
According to research from New York University, the answer to this question lies in the molecule KIBRA, which is found in the kidneys and brain. The scientists studied lab mice and analyzed how this element interacted with other molecules necessary for memory formation, such as the protein PKMzeta, which is essential for generating memories but is also highly degradable. This allowed them to determine that KIBRA acts as a “persistent synaptic marker.” Simply put, it acts like a sticky glue that sticks to strong synapses and PKMzeta, preserving memories longer and avoiding weak synapses.
For Fuentemilla, everything depends on the signaling process. Humans, unlike AI, are able to learn something from a single experience. “The formation of memories involves very rapid structural changes, one after the other. And this is the paradox: when a new memory is generated, all the synapses are restructured, and immediately what you just remembered is lost to make room for a newer memory,” he explains. In other words, the same mechanism must be able to preserve the memory acquired immediately or long ago, but leave room for the creation of new memories.
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“The KIBRA protein identifies the most important changes,” says the expert. “In other words, while you are building memories, you are keeping the synapses strong,” he says, referring to the memory that defines you. The process can be likened to a traffic light: there are a series of rapid changes that occur one after the other, and once they occur, they are marked. The brain marks in green those memories that it should keep because they are important. Instead, it marks in red those that can be dispensed with.
However, this classification “does not depend on what happens, but on how the brain subsequently processes this information,” the UB researcher points out. “In forming memories, it’s not just the moment we experience them, but also how these memories continue to function in the brain over time.” At the same time, the research underscores the importance of the interaction of the PKMzeta and KIBRA proteins. “We know of hundreds of proteins that are essential for memory to exist,” Anderu adds. “But these authors have shown for the first time that these two proteins must work together for it to form.”
Understanding how memories are stored and maintained in our brains is important for explaining and treating diseases such as Alzheimer’s. It could also, according to Andero, advance the development of new drugs and accumulate valuable scientific knowledge in the long term. “In the future, someone will take this idea and give it a completely unexpected twist,” he says.
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