Anyone who survived the ’80s and ’90s has gone through the aggravating ritual of rewinding a video or cassette tape. Wanting to catch what someone said in a movie scene or listen to that rad new Def Leppard track one more time meant pressing the rewind button and waiting until the film was inevitably wound too far back or not far enough. Our brains are capable of something similar when it comes to replaying memories.
Memory replay is like the brain’s version of rewinding a VCR. The brain backtracks and replays an experience that had been “encoded,” a mechanism that is necessary for recall and spatial working memory, reinforcement learning, navigation, and consolidating memories. Sometimes it can also be like a Back to the Future-esque clip of time travel. Replaying memories involves many brain regions, especially the hippocampus, whose neurons become active while a task is being carried out, but keep firing when the task is completed and even after sleep sets in. It’s thought these “replayed” events may help with remembering locations in space—and they can even be edited to reveal a new understanding. Neuroscientist Zhe Sage Chen, PhD, of New York University has been studying this phenomenon for decades.
“Some people see the hippocampus like a GPS system,” says Chen. “This is one of the areas we bring up the most when it comes to episodic memory, which is reliving what happened in the past. It basically allows you to memorize some of the things that you experience during the day, but it’s also like a GPS system that guides you with spatial navigation and so on. It also goes beyond the spatial [realm]… Humans can obviously navigate in abstract space.”
Replaying memories is possible because of what are known as place cells and grid cells in the hippocampus. In 1971, Nobel Prize winner John O’Keefe, PhD, was working with rats navigating mazes in his lab when he discovered place cells. These are a type of neuron that is part of our internal GPS. It essentially maps the space around us. O’Keefe had been trying to figure out how the brain controls behavior when he recorded nerve cells and realized those in the hippocampus were activated when the rats stayed in a particular place. In 2005, May-Britt, PhD and her former husband Edvard Moser, PhD, saw that another group of neurons activated as rats passed several locations—these became known as grid cells. They create invisible coordinates that allow us to position ourselves and find our way.
We experience our environment through the perception and positioning that having a sense of place allows for. O’Keefe found that place cells were accumulating memories of an environment, and the Mosers realized cells in the entorhinal cortex were activated when rats made their way through a grid. Replaying these memories tells us where we are. The three scientists jointly won a Nobel Prize for their work in 2014. Fascinated by their discoveries, neurologist Matt Wilson, PhD, of Massachusetts Institute of Technology (MIT) decided to delve further into the role of place and grid cells in memory recall when he was a postdoc (Chen was also formerly an MIT postdoc). His own experiments with rats gave him more insight into how the human brain rewinds and replays.
“The idea was to look at how memories of space are formed as an animal first explores an environment,” Wilson says. “So that was really what I was interested in. I was interested in the formation of memory as animals experience the world. It just happened that as I was doing recordings after these experiments, I would look at the activity of these cells to ensure the quality of the recordings and make sure the electrodes on the animal hadn't moved, but I also had signals coming off these electrodes routed through an audio amplifier. That was how I could hear brain activity.”
What surprised Wilson was that he kept hearing these signals as his furry test subject fell asleep. Not only were place cells still firing, but they were firing the same way in REM sleep as they had been when the rat had been awake and exploring its surroundings.
It turned out the rat had been replaying memories while asleep—and human brains do the same. Because place cells fire when you are in certain locations, they work as a sort of code, with individual cells firing in different combinations depending on where you might be. Every location has its own code in the brain. That code is then expressed again by both visual and spatial cells during sleep, like a movie scene being rewound and replayed ad nauseam.
“It's like you're in like a video editor,” Wilson says. “You have these memory sequences like you had the video recorder on. That’s the online mode. You recorded all this stuff, and then, after you’ve recorded it, you’re sitting in your studio in this offline state. You’re not taking in new information. Now you can go back. You can revisit. You can review, go forward, you can go backward. Then you can possibly edit these things.”
Wilson found out he could create something like a memory movie out of these sequences. If he had a scene from one memory sequence, he could put it together with a piece of another memory sequence that might not have been formed at the same time, but is still related. This made him realize that offline mode—as opposed to online mode—does more than just replay memory. It uses prior experiences for both generating and understanding new memories. Using replay in this way not only gives more insight into memory, but can even shape plans for the future. What is learned from the past can create a future based on memory.
Chen sees memory consolidation during sleep as one of the most important functions related to remembering these past experiences. While short-term memory is temporarily stored in the hippocampus, some of these memories are ranked higher by the brain than others. This is where episodic memory comes in. Episodes of memory, like episodes of a TV series, can be replayed. Some of them can be consolidated when the information in a shorter memory is transferred from the hippocampus to the more stable cerebral cortex. The cortex communicates with the hippocampus to make its availability known, so the hippocampus will transfer information to the cortex, something like going through old videos and deciding which episodes to keep and transfer to a digital format years after they aired.
Sleep can help consolidate memories more effectively than the waking brain. Seeing college students napping right before an exam is no accident. Even if they haven’t studied enough psychology to know what exactly is going on in their gray matter, what they have realized is that they somehow tend to do better on exams when they study and then sleep. There is a much higher chance of memories being consolidated if the brain reaches the phase of REM sleep. Wilson found that it is not only areas associated with memory, like the hippocampus, which are involved in this process, but also sensory areas such as the visual cortex, so memories are being replayed with visual imagery of an event. Memories are then retrieved upon waking. This explains why taking a short nap means potentially remembering more of what is going to be on the exam while still making it to Psych 101 on time.
Memories can also change with each replay because memory is dynamic. Think of recording the same episode on a videotape every time, but there are different commercials, and even things that may have previously gone unnoticed about the episode itself become more obvious. The brain keeps overwriting one version of a memory with another version. After the original recording is overwritten, additional information is filled in, not just to compensate for memory decay, but because communication between neurons responsible for memory is influenced by outside factors. Rewatching that video in a week may reveal what was forgotten.
“I think this happens because the memory itself is not storing something permanently,” Chen says. “You read out the information, but then you put it back. It is read and retrieved. Later on, you rewrite it back into the brain, so the information is dynamic. You selectively believe these are positive memories, and you keep adding information to that. Everything is subjective.”
February / March 2026
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ Archaeologists Found a Skeleton Wearing a Silver Amulet. The Discovery Is Rewriting the History of Christianity.
➡ The Stray Dogs of Chernobyl Are Rapidly Mutating. Scientists Are Still Trying to Figure Out What It Means.
➡ New Evidence Could Upend What We Know About the Charles Lindbergh Baby Murder
➡ Police Found Mysterious Notes in a Dead Man's Pocket. They Turned Out to Be Codes That Not Even the FBI Can Break.
December 2025 / January 2026
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ An Angel of Death Preyed on Hospital Patients for Years.
➡ How America's Most Advanced Lab Brought the Killer to Justice.
➡ A 3,000-Ton Locomotive Was Loose, Unstoppable, and Filled With Toxic Cargo
➡ An Underwater Cave Promised Adventure and Glory. No One Expected It to Become a Tomb.
➡ Your Consciousness Can Predict the Future, Some Scientists Say
October / November 2025
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ Inside the Secret Island Where Death Is Optional
➡ A Legendary Ship Sank Without Warning. Fifty Years Later, Science Could Finally Solve the Mystery of the Edmund Fitzgerald.
➡ This Tech Rebel Threw Away $900 Million in a Municipal Dump. Can Robots Find His Lost Fortune?
➡ Sex Workers, LSD, and Mind Control: What Happened in the CIA's Lab of Nightmares at 225 Chestnut Street
August / September 2025
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ The Worst Air Disaster in American History Happened in Broad Daylight. Will More Mistakes Keep Happening?
➡ NASA Has a Plan to Save Earth from Planet-Destroying Asteroids. It Sounds Even Wilder than Science Fiction.
➡ A Naval Officer Says Underwater UFOs Are Legitimate Threats. The Evidence Is Hard to Ignore.
➡ When You Die, a Psychedelic Molecule Shapes Your Final Moments of Consciousness, a New Theory Reveals.
June/July 2025
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ This Undersea Explorer Found America's Greatest Sunken Treasure. Then Things Got Really Weird.
➡ Is Bigfoot Hiding in the Swamps of Florida? This Group Says It Has Proof.
➡ Scientists May Have Gotten the Global-Warming Timeline Seriously Wrong.
➡ A Third State Now Exists Between Life and Death, Some Scientists Now Believe
April/May 2025
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ Scientists Successfully Revive a Dead Brain, Redefining the Boundary Between Life and Death
➡ Fingerprints Keep Leading to Wrongful Convictions. Why Do Courts Still Rely on Them?
➡ For 80 Years, the North Sea Held a Deadly Killer. Now Scientists Are Racing to Defuse the Threat.
➡ They Built the Quietest Room in the World. Why Is Everyone So Afraid to Step Inside It?
February/March 2025
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ This Guy Says He Knows the Truth About UFOs. Should We Believe Him?
➡ Scientists Are Now One Step Away From Solving Nuclear Fusion—And Unlocking Unlimited Energy.
➡ A Million-Dollar Heist Rocked the Art World— Then Amateur Sleuths Cracked the Case
➡ A New Era of Missile Warfare Has Begun—and the U.S. Isn’t Ready
December/January 2025
This issue is optimized for mobile/tablet viewing.
It's also available on Apple News+.
Featuring:
➡ A Clue Hidden in a 400-Year-Old Map Might Have Just Solved One of America's Greatest Mysteries
➡ Inside the Deranged Plot to Smuggle Cocaine With an Armed Soviet-Era Submarine
➡ This Brilliant Engineer Helped Build the B2 Bomber—Then He Sold America's Stealth Secrets to China
➡ Your Consciousness Can Connect With the Whole Universe
October/November 2024
This issue is optimized for mobile/tablet viewing.
It's also available on Apple News+.
Featuring:
➡Untold Secrets Reveal How the Castle Bravo Test Became America’s Worst Nuclear Disaster
➡ This Body Was Found Preserved on a Block of Ice in a Colorado Shed. It Had Been There for 30 Years.
➡ It Was Supposed to Be America's Greatest Victory in Space—Then It Became NASA’s Worst Nightmare
➡ The Sidewinder Missile Ruled the Air—Then the Soviets Stole the Design
August/September 2024
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡This Man Knows the Truth About Amelia Earhart. Why Doesn't Anyone Believe Him?
➡ The Army's Machine Gun Is No Match for Cheap Chinese Body Armor. So It's Making a New One.
➡ Russia Built a Stunning Rival to the Supersonic Concorde—and Then It Fell From the Sky
➡ A Navy Admiral Says Underwater UFOs Are a Threat—and the Pentagon is Withholding Secrets
June / July 2024
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡4 Black Eggs Have Surfaced From the Depths of the Ocean— and the Mysterious Creatures Inside Are Baffling Science
➡ A $2 Million Treasure Appeared in a Kentucky Cornfield. No One Knows Where It Came From.
➡ A Million-Dollar Heist Rocked the Art World— Then Amateur Sleuths Cracked the Case
➡ A New Era of Missile Warfare Has Begun—and the U.S. Isn’t Ready
April May / 2024
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡The Man Who Knows Too Much About Area 51
➡ How the FBI Took Down the Internet's Most Dangerous Website
➡ A Staggering New Clue Emerges in the D.B. Cooper Hijacking Mystery
➡ The Wildest Prison Break in U.S. History
➡ The Secret to a Perfect Lawn Lies in One of These 10 Electric Lawnmowers
February / March 2024
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡The Incredible Mystery of NASA’s Missing Moondust
➡ Inside the Final Fiery Minutes of the East Palestine Train Wreck
➡ Scientists Believe They’ve Unlocked Consciousness—and It Connects to the Entire Universe
➡ Why This Unstoppable Stealth Bomber Will Rule the Skies
➡ America Is Developing a New Nuclear Bomb—But Can’t Test Whether It Works
➡ The 8 Best, Expert-Recommended Solar-Powered Generators
Special Issue: Nukes
➡ How Deadly Nuclear Waste Is Menacing This St. Louis Neighborhood
➡ The Terrifying History of Russia's Nuclear Submarine Graveyard
➡ Strange Mutations in Stray Dogs Near Chernobyl Suggest They Are Rapidly Evolving
➡ America Dumped 56 Million Gallons of Radioactive Material Along the Columbia River—Then It Started to Leak
December 2023 / January 2024
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ A New Clue In Amelia Earhart's Disappearance Emerges From the Ocean
➡ How an Alleged Water Bandit Stole $25 Million in Water from Thirsty California Farms
➡ A Coal Mine Exploded and 300 Miners Died. What Went Wrong?
➡ China Just Built a Terrifying New Aircraft Carrier and May Soon Dominate the Seas
October / November 2023
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ How Rats Took Over Our Cities—And Why We Can't Stop Them
➡ This Language Is on the Verge of Extinction. Can It Be Saved?
➡ America's Deadliest Warplane Returns in a New Doomsday Role
➡ This Amateur Diving Group Kept Solving Cold Cases. Then Its Own Skeletons Surfaced.
➡ The Scientific Breakthrough That Could Put an End to Gray Hair.
August/September 2023
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ Immortality Is in Reach. But It’s Not What We Imagined.
➡ Your Next iPhone (and Nuclear Subs) Will Be Powered By Space Metal
➡Scientists Now Think We Can Build a Warp Drive
➡ China and Russia Have Cracked the Stealth Code. Can the U.S. Regain Air Dominance?
June/July 2023
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ The CIA’s Secret Plan to Build a Laser Beam Powered by the Human Mind
➡ The 747 Ruled the Skies—Then One Slammed Into a Mountain
➡The Race to Contain AI Before Singularity
➡ These Florida Homes Aren’t Just Hurricane-Proof—They’re Blueprints for the Future
April/May 2023
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ AI Is on the Cusp of Taking Control—This Is How It May All Go Wrong
➡ There’s No Weapon Russia Fears More Than the HIMARS Rocket Launcher
➡The Nuclear-Submarine Arms Race Is Getting Intense, and the U.S. Just Took a Massive Leap Forward
➡ Iran Is Becoming a Drone Superpower—By Stealing American Technology
February/March 2023
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ The Greatest Treasure Hunt in American History Ended—and Then Things Got Weird
➡ These Are the High-Powered Weapons Ukraine Needs to Send Russia Running
➡ The Secret War to Take Out Iran’s Fleet of F-14 Jets
➡ Russia Is Trying to Intimidate the U.S. with Hypersonic Missiles and Big, Scary Nukes—And It's More Than a Threat
December 2022/January 2023
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ Is Death Real?
➡ China and Russia Are Dominating the Hypersonic Arms Race—And It’s Not Even Close
➡ When the South Fork Dam Broke, a Pennsylvania City Washed Away. Which Town Is Next?
➡ The Navy’s New $13 Billion Aircraft Carrier Is Already Obsolete. This Weapon Can Save It.
October/November 2022
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ Can America's M1 Abrams Still Compete With China's and Russia's Latest Battle Tanks?
��� Inside the Final Minutes of the Concorde Disaster—and How It Doomed Supersonic Travel for Decades
➡ How the Massive Cargo Ship Felicity Ace Sank, Taking $400 Million Worth of Exotic Supercars With It
➡ I Turned My Old Gas-Guzzler Into a Zippy EV for $15,000
August/September 2022
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ Cosmic Secrets of the 17 Most Powerful Mega-Telescopes on Earth—and Beyond
➡ Can the Air Force's Secret, Hypersonic Jet Reclaim the Skies From Russia and China?
➡ For 50 Years, the Zodiac Killer's 340 Cipher Stumped the FBI—Then Three Amateurs Cracked the Code
➡ America's Most Fearsome Howitzer Has Entered the War in Ukraine
June/July 2022
This issue is optimized for mobile/tablet viewing. It's also available on Apple News+.
Featuring:
➡ Every Single Drone Fighting in the Skies Over Ukraine
➡ How to Buy a New Car in 2022 Without Getting Fleeced
➡ This Megastructure Could Keep Us Alive Forever
➡ The Race to Revolutionize EV Batteries
Elizabeth Rayne is a creature who writes. Her work has appeared in Popular Mechanics, Ars Technica, SYFY WIRE, Space.com, Live Science, Den of Geek, Forbidden Futures and Collective Tales. She lurks right outside New York City with her parrot, Lestat. When not writing, she can be found drawing, playing the piano or shapeshifting.
此内容由惯性聚合(RSS阅读器)自动聚合整理，仅供阅读参考。 原文来自 — 版权归原作者所有。