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Tag: Brain
How the brain chooses which memories to save during sleep
Memory can be mysterious. Certain life events remain clear in our minds no matter how long ago they occurred, while episodes from the prior day may already be fuzzy and difficult to recall.
A study, published Thursday in Science, reveals why this happens. Scientists have found that the brains of humans and other mammals have a system for choosing which life experiences are important enough to be cemented into long-term memory — and which will be allowed to fade away.
Experiments in mice revealed that during waking hours, cells in the brain’s hippocampus spark in a specific pattern called “sharp-wave ripples,” which tag important experiences for movement into long-term memory storage during sleep.
Although the research was performed in mice, certain brain processes have remained almost the same as mammals have evolved, so the findings can tell us a lot about ourselves, said the study’s senior author, Dr. György Buzsáki, Biggs Professor of Neuroscience at NYU Langone Health.
As part of the research, Buzsáki and his colleagues put mice through a maze that had a sugary reward at the end for those that successfully reached it. Meanwhile, the researchers were monitoring the activity of nerve cells through electrodes implanted in the rodent brains that fed data into computer programs.
They observed that as the mice paused to eat their treats, their brains sparked sharp-wave ripples that were repeated as many as 20 times. The daytime pattern of sharp-wave ripples was replayed during the night, a process that moved the experience into long-term memory.
It’s during sleep when experiences from waking hours deemed to be important are converted into enduring memories.
Events that were followed by very few or no sharp-wave ripples failed to form lasting memories, the researchers noted.
This tagging process during waking hours is totally unconscious, Buzsáki said. “The brain decides on its own, rather than us deciding voluntarily,” he added.
Relaxation needed for long-term memory
Still, the research suggests there are things we can do to increase the likelihood of a memory being stored permanently.
If, like the mice, we pause after an experience, it may help cement the events into long-term memory, Buzsáki said. We need that period of relaxation, when we’re not paying close attention to anything, to allow sharp-wave ripples to spark. That wakeful process is an essential part of creating a permanent memory.
Practically speaking, this means if you like to binge TV series, you’re not likely to remember much of any episode except the last one you watched, Buzsáki said.
“If you watch a movie and would like to remember it, it’s better to go for a walk afterwards,” Buzsáki said. “No double features.”
An intriguing finding of the new research is the discovery that there could be bursts of activity — the sharp-wave ripples — when the mouse is standing still and its brain is essentially idling, said Daniela Schiller, a professor of neuroscience and psychiatry at the Icahn School of Medicine at Mount Sinai.
What’s amazing, Schiller said, is the pattern recorded close to the event was the same as what was seen during sleep. And both patterns mimicked the mouse’s real-life experience.
The study showed that events followed by a pause and electrical bursts in the brain are the ones that we will find in long-term memory, said Daphna Shohamy, director of Columbia University’s Zuckerman Institute. If you observe animals, you can see them pausing during the day after a novel or rewarding experience, she said.
“We did a study a few years ago in which we had humans navigate a maze with random objects along the way, looking for a treasure,” Shohamy said. “If they got the treasure, they were more likely to remember the random object they passed along the way.”
Brain fog and other long COVID symptoms are the focus of new small treatment studies
WASHINGTON (AP) — The National Institutes of Health is beginning a handful of studies to test possible treatments for long COVID, an anxiously awaited step in U.S. efforts against the mysterious condition that afflicts millions.
Monday’s announcement from the NIH’s $1.15 billion RECOVER project comes amid frustration from patients who’ve struggled for months or even years with sometimes-disabling health problems — with no proven treatments and only a smattering of rigorous studies to test potential ones.
“This is a year or two late and smaller in scope than one would hope but nevertheless it’s a step in the right direction,” said Dr. Ziyad Al-Aly of Washington University in St. Louis, who isn’t involved with NIH’s project but whose own research highlighted long COVID’s toll. Getting answers is critical, he added, because “there’s a lot of people out there exploiting patients’ vulnerability” with unproven therapies.
Scientists don’t yet know what causes long COVID, the catchall term for about 200 widely varying symptoms. Between 10% and 30% of people are estimated to have experienced some form of long COVID after recovering from a coronavirus infection, a risk that has dropped somewhat since early in the pandemic.
“If I get 10 people, I get 10 answers of what long COVID really is,” U.S. Health and Human Services Secretary Xavier Becerra said.
That’s why so far the RECOVER initiative has tracked 24,000 patients in observational studies to help define the most common and burdensome symptoms –- findings that now are shaping multipronged treatment trials. The first two will look at:
— Whether taking up to 25 days of Pfizer’s antiviral drug Paxlovid could ease long COVID, because of a theory that some live coronavirus, or its remnants, may hide in the body and trigger the disorder. Normally Paxlovid is used when people first get infected and for just five days.
— Treatments for “brain fog” and other cognitive problems. They include Posit Science Corp.’s BrainHQ cognitive training program, another called PASC-Cognitive Recovery by New York City’s Mount Sinai Health System, and a Soterix Medical device that electrically stimulates brain circuits.
Two additional studies will open in the coming months. One will test treatments for sleep problems. The other will target problems with the autonomic nervous system — which controls unconscious functions like breathing and heartbeat — including the disorder called POTS.
A more controversial study of exercise intolerance and fatigue also is planned, with NIH seeking input from some patient groups worried that exercise may do more harm than good for certain long COVID sufferers.
The trials are enrolling 300 to 900 adult participants for now but have the potential to grow. Unlike typical experiments that test one treatment at a time, these more flexible “platform studies” will let NIH add additional potential therapies on a rolling basis.
“We can rapidly pivot,” Dr. Amy Patterson with the NIH explained. A failing treatment can be dropped without ending the entire trial and “if something promising comes on the horizon, we can plug it in.”
The flexibility could be key, according to Dr. Anthony Komaroff, a Harvard researcher who isn’t involved with the NIH program but has long studied a similarly mysterious disorder known as chronic fatigue syndrome or ME/CFS. For example, he said, the Paxlovid study “makes all sorts of sense,” but if a 25-day dose shows only hints of working, researchers could extend the test to a longer course instead of starting from scratch.
Komaroff also said that he understands people’s frustration over the wait for these treatment trials, but believes NIH appropriately waited “until some clues came in about the underlying biology,” adding: “You’ve got to have targets.”
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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group. The AP is solely responsible for all content.