Direct Evidence Of Role Of Sleep In Memory Formation Is Uncovered

http://www.sciencedaily.com/releases/2009/09/090915174506.htm

by codeodor • 17 years ago

76 31 17 years ago

mgreenbe• 17 years ago

Original article: http://www.nature.com/neuro/journal/vaop/ncurrent/abs/nn.238...

I was inclined to be skeptical---breaking news, shocking the brain during sleep impairs performance---but they used three different groups of rats:

  ...we tested the role of SPW-Rs on memory consolidation.
  Three groups of rats (test group, n = 7; stimulated 
  controls, n = 7; unimplanted controls, n = 12) were 
  trained to find food rewards ... . 

  During post-training rest and sleep, all of the online-
  detected ripples were suppressed by commissural 
  stimulations in test rats (average online detection rate 
  was 86.0 ± 1.3% (s.e.m.) of post hoc detected SPW-Rs;
  ...). Stimulated control rats underwent the same 
  protocol, except that a random delay (80–120 ms)
  was introduced between SPW-R detection and stimulation, 
  ensuring that the stimulations occurred mainly outside of 
  the ripple episodes.

Now check this out:

  Thus, these control rats received the same number of 
  stimulations as test rats, but their hippocampal
  ripples were left largely intact. The global architecture 
  of sleep and the local field potential power in distinct 
  sleep stages were not modified by the suppression of 
  SPW-Rs ... .  As stimulation outside SPW-Rs had
  no detectable effect on task performance ..., the two 
  control groups were pooled and compared with test rats. 
  Performance of the test rats was significantly impaired 
  ... .

Cool experiment design with an intriguing result.

codeodor• 17 years ago

Thanks for that. I was going to include the link to that, but when I clicked for the full text it asked me to subscribe.

Now that I've gone back, I was able to grab the PDF.

jasongullickson• 17 years ago

"Sharp wave ripples are intense, compressed oscillations that occur in the hippocampus when the hippocampus is working off-line, most often during stage four sleep, which, along with stage three, is the deepest level of sleep."

I'm not an expert on the subject, but how can two stages both be the "deepest"?

Leon• 17 years ago

Both stages have delta waves in the same range but induce different effects on the brain. They're both characterized by the same measure for depth (of sleep).

To clarify with more, specific information: http://en.wikipedia.org/wiki/Slow-wave_sleep

dzlobin3• 17 years ago

"Sharp wave ripples are intense, compressed oscillations that occur in the hippocampus when the hippocampus is working “off-line,” most often during stage four sleep, which, along with stage three, is the deepest level of sleep."

So do people who practice polyphasic sleep have awful memory?

skolor4• 17 years ago

The way I understand it, Polyphasic sleep is designed to trick your body into skipping the first two stages of sleep, so you spend all the time in the last two, where the biggest benefits are.

absconditus• 17 years ago

Is there any proof of this or is this just what polyphasic sleepers tell themselves?

dzlobin3• 17 years ago

That seems a bit off, trick your body into skipping the first two stages by...staying awake?

a-priori5• 17 years ago

Unless you know something I don't, there has been zero research into this topic, and anything you read on blogs is a wild guess.

Please prove me wrong by citing some research. I just did a search (terms: "polyphasic", "sleep", "sleep architecture", "REM", "SWS"), that didn't turn up anything.

WilliamLP• 17 years ago

Polyphasic sleepers are a myth. The only truth is a handful of people who tried it for a couple of months and then went back to a conventional sleeping pattern. (However, many of them, for some bizarre reason, are still strong proponents of how great it is.)

Edit: Downmodder - Give me one documented exception please.

johnohara• 17 years ago

Those rats that selectively had all ripple events eliminated by electrical stimulation were impeded in their ability to learn from the training, as compressed information was unable to leave the hippocampus and transfer to the neocortex.

Probably remembered being electrically stimulated instead.

bdr• 17 years ago

I think the experiment design eliminates that possibility. Why would this group of rats do worse than the ones that were electrically stimulated, but not in a way that disrupted the ripple events?

a-priori5• 17 years ago

In doing research for another comment I posted here, I came across an article that does a very good job of summarizing the current state of research into the role of sleep in memory consolidation.

http://www.nature.com/nature/journal/v437/n7063/abs/nature04...

Direct Evidence Of Role Of Sleep In Memory Formation Is Uncovered

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