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[Press release] Why all-nighters don’t work: How sleep and memory go hand-in-hand

Why all-nighters don’t work: How sleep and memory go hand-in-hand 

From the Brandeis University press release

Young Man Studing at Night

Want to ace that test tomorrow? Here’s a tip: Put down the coffee and hit the sack.

Scientists have long known that sleep, memory and learning are deeply connected. Most animals, from flies to humans, have trouble remembering when sleep deprived, and studies have shown that sleep is critical in converting short-term into long-term memory, a process known as memory consolidation.

But just how that process works has remained a mystery.

The question is, does the mechanism that promotes sleep also consolidate memory, or do two distinct processes work together? In other words, is memory consolidated during sleep because the brain is quiet, allowing memory neurons to go to work, or are memory neurons actually putting us to sleep?

h6F72EF3EIn a recent paper in the journal eLife, graduate students Paula Haynes and Bethany Christmann in the Griffith Lab make a case for the latter.

Haynes and Christmann focused their research on dorsal paired medial (DPM) neurons, well-known memory consolidators inDrosophila. They observed, for the first time, that when DPM neurons are activated, the flies slept more; when deactivated, the flies kept buzzing.

These memory consolidators inhibit wakefulness as they start converting short-term to long-term memory. All this takes place in a section of the Drosophila brain called the mushroom body, similar to the hippocampus, where our memories are stored. As it turns out, the parts of the mushroom body responsible for memory and learning also help keep the Drosophila awake.

“It’s almost as if that section of the mushroom body were saying ‘hey, stay awake and learn this,’” says Christmann. “Then, after a while, the DPM neurons start signaling to suppress that section, as if to say ‘you’re going to need sleep if you want to remember this later.’”

Understanding how sleep and memory are connected in a simple system, like Drosophila, can help scientists unravel the secrets of the human brain.

“Knowing that sleep and memory overlap in the fly brain can allow researchers to narrow their search in humans,” Christmann says. “Eventually, it could help us figure out how sleep or memory is affected when things go wrong, as in the case of insomnia or memory disorders.”

To learn more about this and other fly research, check out Christmann’s blog, Fly on the Wall. 

This research was funded by the National Institute of Health

 

January 26, 2015 Posted by | Consumer Health, Medical and Health Research News | , , , , , | Leave a comment

Sleeping Brain Behaves as If It’s Remembering Something

 

English: Entorhinal cortex (red) was thinnest ...

English: Entorhinal cortex (red) was thinnest in youth with Alzheimer’s-related ApoE4 gene variant. View of left entorhinal cortex from beneath the brain, with front of brain at top. Artist’s rendering. Source: Philip Shaw, M.D., NIMH Child Psychiatry Branch http://www.nimh.nih.gov/science-news/2007/cortex-area-thinner-in-youth-with-alzheimers-related-gene.shtml (Photo credit: Wikipedia)

 

From the 7 October 2012 article at Science Daily

 

UCLA researchers have for the first time measured the activity of a brain region known to be involved in learning, memory and Alzheimer’s disease during sleep. They discovered that this part of the brain behaves as if it’s remembering something, even under anesthesia, a finding that counters conventional theories about memory consolidation during sleep.

Mehta and his team looked at three connected brain regions in mice — the new brain or the neocortex, the old brain or the hippocampus, and the entorhinal cortex, an intermediate brain that connects the new and the old brains. While previous studies have suggested that the dialogue between the old and the new brain during sleep was critical for memory formation, researchers had not investigated the contribution of the entorhinal cortex to this conversation, which turned out to be a game changer, Mehta said. His team found that the entorhinal cortex showed what is called persistent activity, which is thought to mediate working memory during waking life, for example when people pay close attention to remember things temporarily, such as recalling a phone number or following directions.

“The big surprise here is that this kind of persistent activity is happening during sleep, pretty much all the time.” Mehta said. “These results are entirely novel and surprising. In fact, this working memory-like persistent activity occurred in the entorhinal cortex even under anesthesia.”

The study appears Oct. 7, 2012 in the early online edition of the journal Nature Neuroscience.

The findings are important, Mehta said, because humans spend one-third of their lives sleeping and a lack of sleep results in adverse effects on health, including learning and memory problems.

It had been shown previously that the neocortex and the hippocampus “talk” to each other during sleep, and it is believed that this conversation plays a critical role in establishing memories, or memory consolidation. However, no one was able to interpret the conversation…..

 

 

 

 

 

October 10, 2012 Posted by | Medical and Health Research News | , , , , , , , | Leave a comment

   

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