Sadness, protagonist of the film, was not on the wrong path Inside outwhen he defined long-term memory as “a endless maze with shelves” in the brain. “Memories of certain past events (episodic memories) are thought to be stored primarily in the hippocampus, which is like a library of memories, and the medial prefrontal cortex is more like a librarian that tries to ensure that memories are organized in a meaningful way.” to help you find them,” says Christopher Baldassano, researcher at the Incite Institute at Columbia University (New York). The scientific community has been trying to put together the puzzle of memory for some time, but the ins and outs of how this record left in the brain by our life experiences is constructed, stored and retrieved are still not clear.
Baldassano and his team have now taken a step forward to understand how the brain processes daily experiences that will then be recorded in memory and, in an article published this Thursday in the journal Current Biology, They suggest that the brain organizes the events of the day into chapters that are built according to each person’s priorities. That is, what determines the beginning and end of an episode are not only sudden changes in the world, but also what a person cares about at that moment or what they are paying attention to. For example, a new chapter for the brain can begin when entering a restaurant (and going from outside the street to inside a establishment) or, in that restaurant, when reviewing the menu and ordering food.
The scientist admits that there are several competing theories about what exactly triggers a brain to begin a new chapter in memory. “One idea is that experiencing a sudden surprise tells the brain that a new event is beginning,” he exemplifies. However, the scientist explains, his research points in another direction: “The main new finding of this study is that these chapters do not arise solely from the way history is written. People don’t just listen to the author of a story to tell them when a new event begins; “The brain makes active decisions about when to start a new chapter that depend on your current mood and goals,” the researcher summarizes in an email response. According to their study, what drives the brain to record a new chapter are, more than major environmental changes or sensory stimuli, internal scripts that our brain writes based on its experiences or the attention it pays to a detail.
Researchers at Columbia University wanted to understand how the brain processes real situations, complex events that last over time. “We know that organizing an experience in significant events is important for memory. For example, people who are better at this segmentation process are also better at memory tests,” explains Baldassano. In their experiment, the researchers had participants listen to stories while measuring their brain activity using functional magnetic resonance imaging. Each story was a combination of two scripts (that is, two sequences of events at the same time). “For example, a story could be about a marriage proposal at a restaurant and going through the stages of eating at a restaurant (sitting down, ordering food…) while the events of the proposal happen at the same time (taking out the ring). , the proposal, the couple’s reaction…)”, says Baldassano.
In some cases, however, the scientists asked the participants to pay special attention to one of the scripts. “For example, we told them that they would be asked questions about the details of the restaurant and what they ordered [de comer] the characters,” he explains. And when they did this, the researchers found that it “changed the way a participant’s medial prefrontal cortex organized story events into chapters, so that the chapter aligned with the script they were paying attention to.”
The details they were asked to pay attention to influenced what the brain perceived as a new chapter. “Our study found that an important function of the medial prefrontal cortex is to help ensure that experiences are correctly divided into meaningful chapters that are related to your goals and that are easy to find later,” concludes Baldassano.
A “library of memories” in the hippocampus
The Columbia researchers defend that the chapters “are stored in a library of episodic memories in the hippocampus” and that is where memories begin to be generated. “In this article and in my previous work, we discovered that there is a spike of activity in the hippocampus right at the end of a chapter, which we assume is a sign that a new memory is being created,” says Baldassano. The event script that a person prioritizes, he adds, can change what they remember in two different ways. “First, it could change what is stored in memory during the experience: if you are not paying attention to something or it is not relevant to the script you are currently attending to, that information may never reach memory. Second, it might change your strategy for finding the memory later: if you have a good understanding of how an event unfolds in general, that can help provide clues for retrieving elements of a specific memory,” he reflects.
The scientist admits that this second step is the most complex and causes forgetting: “In general, people are much better at recognition memory (being shown something and asked if it happened or not) than at recall memory ( having to search for a memory by oneself), which makes us think that there are many things that are in our memory library but we are not good at finding them.
The overall goal of this type of research is to better understand how our perceptual and memory processes work, and also to understand the ways in which they can go wrong.
Christopher Baldassano, researcher at the Incite Institute at Columbia University (New York) and author of the study
In this sense, Baldassano ensures that having memories well organized in these chapters guarantees that information from unrelated events is not mixed. And it also helps to evoke memories later. “If I try to remember my commute to work this morning, I can find chapters organized according to each step of the journey: walking to the train station, riding the train, walking to the office, etc. “The overall goal of this type of research is to better understand how our perceptual and memory processes work, and also to understand the ways in which they can go wrong.”
The neuroscientist Rodrigo Quian Quiroga, researcher in the group of Perception and Memory of the Hospital del Mar Research Instituteassures that this study, in which he has not participated, “attempts to understand how memory works in real life.” “We know a lot about memory in controlled laboratory processes, but from there to how it works in real life there is a huge leap. We need to understand memory in real life and this paper helps you understand how you segment experiences to be able to process them,” he values. It makes sense, he says, that life experiences, which are complex narratives, are segmented: “It is a classic in memory. When you have a lot of information, you try to break it into small pieces to make it more manageable.” And he gives the example of how telephone numbers are learned, which are also cut into groups of three or four to process them.
It also makes “a lot of sense,” he adds, that perspective changes the segmentation of the story. “If I tell you to go to the Camp Nou to watch a match and you don’t like football, but you come to see us and share some time together, your episodes of that experience will be different from mine, since I do like football. I will probably divide them into first half, rest and second half; but your episodes will begin at the moment we meet, when we say goodbye… Depending on interest, you can break up an event in different ways.”
Unresolved issues
However, Quian Quiroga warns that there are unresolved questions. “In general, these papers They tell you where, but not how. They tell you which brain areas are involved, but they don’t tell you how the neurons interact to do that,” he points out. Precisely, the neuroscientist is trying to clarify how and understand the neural mechanisms that generate memory: “Let us not assume that the neural mechanisms of the human brain are analogous to those we see in rats in the laboratory,” he warns.
Ignacio Morgado, emeritus professor of Psychobiology at the Institute of Neuroscience and the Faculty of Psychology of the Autonomous University of Barcelona, also focuses on the questions that this research does not resolve. “It seems to me that the conclusions are not completely clear, they are provisional,” he weighs. And regarding the role that Baldassano gives to the medial prefrontal cortex, as a guarantor that lived experiences are correctly organized into chapters related to individual priorities, Morgado points out that “it is a hypothesis that needs precision because they do not say how” it does it. “The line of work of these authors goes in the direction of how information that enters the brain is better linked in memory when it is related to other information that is already consolidated,” he points out.
in his book Learn, remember and forget: Brain keys to memory and educationMorgado also explores the role of various brain areas in the construction of memory and maintains that “the prior knowledge that we have stored in the brain plays an important role when it comes to encoding and consolidating new information.” “When in the cerebral cortex there is already a previous and congruent neural network or scheme with the new information to be learned, it stops depending on the hippocampus and is quickly assimilated and integrated into it. If this is not the case, the participation of the prefrontal cortex is required to accommodate the new learning into the schemes already existing in the brain (…). The prefrontal cortex functions, therefore, as a reconciler of associations in the formation of schemas or semantic memory in the brain,” he explains in his book.
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