Life events you take time to reflect upon shortly after they happen are more likely to be etched into your brain as a long-term memory, neuroscientists have discovered.
The researchers detected a consistent pattern of neurons, or brain cells, firing a small symphony of concerted electrical signals, shortly after events that were later committed to long-term memory during that night’s rest.
While these bursts of electrical activity inside the brain — dubbed ‘sharp wave-ripples’ — are unconscious, the researchers said a person could raise the likelihood that a long-term memory is formed by reflecting on an event the day it occurred.
Their findings offer sound advice for those struggling to remember what they binged-watched on Netflix, TikTok or any other platform with auto-loading videos.
‘If you watch a movie and would like to remember it, it’s better to go for a walk afterwards,’ the head neuroscientist behind the new study said. ‘No double features.’
Life events you take time to reflect upon shortly after they happen are more likely to be etched into your brain as a long-term memory, neuroscientists have discovered. The researchers, mostly from NYU, focused on the hippocampus (in yellow, above) for the new study
Dr. György Buzsáki, Biggs professor of neuroscience at NYU Langone Health, the study’s senior author, along with four other NYU researchers and an data analyst from the Mila-Quebec AI Institute, focused on the hippocampus for their new study.
Tucked deep into the center of the brain, the hippocampus is integral to the passage of information from short-term to long-term memory.
The neuroscientists employed dual-sided silicon probes to record as many as 500 neurons simultaneously in the hippocampus area of lab mice as the little creatures attempted to navigate a maze on the hunt of sugary, snackable rewards.
The team noted that tell-tale ‘sharp wave-ripples,’ about five to 20 each time, were recorded when a mouse paused to enjoy its treat after a successful maze run.
‘The brain decides on its own,’ as Dr. Buzsáki summed it up for NBC News, ‘rather than us deciding voluntarily.’
Each ‘sharp wave-ripple’ is comprised of a nearly simultaneous, wave-like firing of 15 percent of the hippocampal neurons, as they alert the rest of the brain to a memorable event.
Their findings offer sound advice for those struggling to remember what they binged-watched on Netflix or any other platform with auto-loading videos. ‘If you watch a movie and would like to remember it, it’s better to go for a walk afterwards,’ one scientist said. ‘No double features’
These wave-ripples take 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 set of sharp wave-ripples in the mice as they slept.
The mice’s same hippocampal ‘place cells’ that had fired after the daytime maze events fired one again, and at high speed, as the little sleeping lab animals were ‘playing back the recorded event thousands [of] times per night.’
Dr. Buzsáki and his team now theorize that this firing of the hippocampal ‘place cells’ commits geographic information to memory — like every room a person enters, or each twist and turn of the maze explored by a mouse.
‘Our study finds that sharp wave-ripples are the physiological mechanism used by the brain to “decide” what to keep and what to discard,’ Dr. Buzsáki said.
Previous research had already determined that the ripples were integral to memory formation during sleep, but the new study, published Thursday in Science, was the first to correlate that nighttime brain activity to matching hippocampal behavior during the day.
Crucially, events experienced by the mice that were followed by little or no ‘sharp wave-ripples’ did not lead to the formation of any solid, lasting memories.
The study’s lead other, Dr. Winnie Yang, a graduate student in Buzsáki’s lab, hopes the new findings can be used in therapies to help people with trouble remembering or, in the case of those suffering with Post Traumatic Stress Disorder (PTSD), trouble forgetting.
‘Why such a system evolved is still a mystery,’ Dr. Yang said in a statement, ‘but future research may reveal devices or therapies that can adjust sharp wave-ripples to improve memory, or even lessen recall of traumatic events.’
Daphna Shohamy, director of Columbia University’s Zuckerman Institute, noted that aspects of this research has also been confirmed outside of mice, in human beings.
‘We did a study a few years ago in which we had humans navigate a maze with random objects along the way,’ Shohamy told NBC News, ‘looking for a treasure.’
‘If they got the treasure,’ she said, ‘they were more likely to remember the random object they passed along the way.’