How the brain decides what to remember

“There has to be some kind of triage to remember what's important and forget the rest,” Zugalo says. “We didn't yet understand how certain memories were selected for storage… Now we have a good clue.”

Last December, a team led by Bendall at University College London published related results in Nature Communications, anticipating Yang and Buzzaki's results. They also When mice are awake and asleep Their analysis appeared to tag experiences for memory, but it averaged across several different trials, an approach that was less precise than what Yang and Buzaki achieved.

The NYU team's key innovation was to incorporate the element of time, which distinguishes between similar memories, into their analysis: Though the mice ran through the same maze pattern, the researchers were able to distinguish between blocks of trials at the neuronal level, a resolution that had not been achieved before.

The brain patterns record “something that's a little bit like what happened, but a little bit different from common knowledge,” he says. Lauren Frank“I think this is a really interesting finding,” said a neuroscientist at the University of California, San Francisco, who was not involved in the study.

“This suggests that the brain may be creating some kind of temporal code to distinguish between different memories that occur in the same place.” Freya OlafsdottirRadboud University neuroscientist who was not involved in the study.

Shantanu JadhavThe Brandeis University neuroscientist praised the study. “This is a good start,” he said. But he'd like to see follow-up experiments that involve behavioral tests. Demonstrating whether animals forgot or remembered specific blocks of trials would be “real proof that this is a tagging mechanism.”

The study doesn't answer the important question of why some experiences are chosen over others. The new research suggests how the brain tags certain experiences for memory, but it doesn't tell us how the brain decides which ones are worth remembering.

Sometimes what we remember is random or irrelevant, and clearly different from what we would choose if we had the choice. “There's a sense in which the brain prioritizes things based on 'importance,'” Frank says. Research suggests that emotional or new experiences tend to be more memorable, so internal fluctuations in our levels of arousal or memory may be the reason why some memories are more likely to stick in our memory. Neuromodulators Other chemicals acting on neurons, such as dopamine and adrenaline, ultimately select for experiences, he suggested.

Jadhav agreed, saying that “an organism's internal state may bias experiences so that they are more effectively encoded and remembered.” But he added that it's unclear why some experiences are more likely to be remembered than others. And in Yang and Bouzaki's case, it's not clear why the mice remembered some trials better than others.

While Buzsaki remains committed to exploring the role sharp wave ripples play in the hippocampus, he and his team are also interested in applications that could emerge from these observations. For example, he said, scientists might be able to disrupt the ripples as part of a treatment for conditions such as post-traumatic stress disorder, in which people remember certain experiences all too vividly. “The easy solution here would be to turn off the sharp waves and forget what they experienced.”

But for now, Buzaki plans to keep an eye on these powerful brain waves to learn more about what we remember.

original work Reprinted with permission. Quanta Magazinean editorially independent publication Simons Foundation Its mission is to advance public understanding of science through reporting on research developments and trends in mathematics, physical sciences, and life sciences.