Scientists discover why you forget some memories and remember others

Life events that you take time to think about shortly after they happen are more likely to be engraved in your brain as long-term memory, neuroscientists have found.

The researchers discovered a consistent pattern of neurons, or brain cells, firing a small symphony of coordinated electrical signals shortly after events that were later stored in long-term memory during nighttime sleep.

Although these bursts of electrical activity in the brain – called “sharp wave ripples” – are unconscious, the researchers say that by thinking about an event on the day it happened, a person can increase the chance of forming a long-term memory.

Their findings offer sound advice for those who struggle to remember what they watched on Netflix, TikTok, or any other platform with auto-loading videos.

“If you watch a movie and want to remember it, it’s better to go for a walk afterwards,” says the lead neuroscientist behind the new study. ‘No duplicate features.’

Dr. Gyorgy BuzsakiBiggs Professor of Neuroscience at NYU Langone Health, senior author of the study, along with four other NYU researchers and a data analyst from the Mila-Quebec AI Institute, focused on the hippocampus for their new study.

The hippocampus, hidden deep in the center of the brain, is integral to the transfer of information from short-term to long-term memory.

The neuroscientists used double-sided silicon probes to record as many as 500 neurons simultaneously in the hippocampal region of laboratory mice as the tiny creatures attempted to navigate a maze in pursuit of sweet, snackable rewards.

The team noticed that telltale “sharp wave ripples,” about five to 20 at a time, were recorded when a mouse paused to enjoy its treat after a successful maze run.

“The brain decides for itself,” as Dr. Buzsáki summarized it NBC News‘rather than us deciding voluntarily.’

Each “sharp wave ripple” consists of a near-simultaneous, wave-like firing of 15 percent of the hippocampal neurons as they alert the rest of the brain to a momentous event.

Their findings offer sound advice for those who struggle to remember what they’ve watched on Netflix or another platform with auto-loading videos. “If you watch a movie and want to remember it, you might as well go for a walk afterwards,” said one scientist. ‘No duplicate features’

These wave ripples get their name from the shape they produce when their neural information is recorded by scientists from electrodes to a graph.

Later in that mouse maze experiment, those electrodes recorded a matching series of sharp wave ripples in the mice as they slept.

The same hippocampal ‘place cells’ of the mice that had fired after the daytime maze events fired again, at high speed, while the small sleeping test animals ‘replayed the recorded event thousands (or) times per night’.

Dr. Buzsáki and his team now theorize that this firing of the ‘place cells’ in the hippocampus stores geographic information in memory, such as every room a person enters, or every twist and turn of the maze explored by a mouse.

“Our study shows that sharp wave ripples are the physiological mechanism used by the brain to ‘decide’ what to keep and what to throw away,” said Dr. Buzsaki.

Previous research had already established that the ripples were an integral part of memory formation during sleep, but that is new study, published Thursday in Sciencewas the first to correlate nighttime brain activity with corresponding hippocampal behavior during the day.

Crucially, events the mice experienced, which were followed by little or no “sharp wave ripples,” did not lead to the formation of solid, lasting memories.

The main character of the study, Dr. Winnie Yang, a graduate student in Buzsáki’s lab, hopes the new findings can be used in therapies to help people with memory problems or, in the case of people suffering from post-traumatic stress disorder (PTSD), problems. forget.

“Why such a system emerged is still a mystery,” said Dr. Yang in a statement, “but future research may reveal devices or therapies that can modify sharp wave ripples to improve memory, or even reduce recall of traumatic events.”

Daphna Shohamy, director of Columbia University’s Zuckerman Institute, noted that aspects of this research have been confirmed beyond mice, in humans.

“A few years ago we did a study where we had people navigate a maze of random objects,” Shohamy told NBC News, “looking for treasure.”

“If they had the treasure,” she said, “they would be more likely to remember the random object they saw along the way.”