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Swedish researchers reveal key to forming lasting memories

Published: 10 Nov 2009 08:30 GMT+01:00
Updated: 10 Nov 2009 08:30 GMT+01:00

“We are constantly being swamped with sensory impression,” Professor Lars Olson, who led the study, said in a statement.

“After a while, the brain must decide what’s to be stored long term. It’s this mechanism for how the connections between nerve fibers are altered so as to store selected memories that we’ve been able to describe.”

Short-term memories occur as a result of chemical changes caused by altered signaling between different nerve cells in the brain, a process which is relatively well understood.

But scientists are less certain about how the brain converts sensory impressions into lasting memories, which are then stored in the cerebral cortex.

The researchers discovered that signaling via the nerve membrane’s nogo receptor 1 (NgR1) receptor molecule plays a key role in the formation of long-term memories.

When nerve cells are activated, the gene for NgR1 is switched off, leading the team to believe that this inactivation might be important in the creation of long-term memories.

Using genetically modified mice with an extra NgR1 gene that could remain active even when the normal NgR1 was switched off, Olson and his team were able to switch the animal’s ability to form lasting memories on and off by adding a substance to their drinking water.

“We found that the ability to retain something in the memory for the first 24 hours was normal in the genetically modified mice,” said Olson.

“However, two different memory tests showed that the mice had serious difficulties converting their normal short-term memories to long-term ones, the kind that last for months.”

The scientists hope that their findings will help in the development of new treatments for a variety of conditions which affect people’s memory, including those related to Alzheimer's and strokes.

Medicines which target the NgR1 receptor system, for example, could improve the brain’s ability to form long-term memories.

The research was conducted in collaboration with American researchers at the National Institute on Drug Abuse (NIDA) at the National Institutes of Health (NIH).

The findings are published in the Proceedings of the National Academy of Sciences (PNAS).

David Landes (david.landes@thelocal.se)

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Your comments about this article

18:47 November 10, 2009 by zircon
"Pickabar, pickabar, what was that again? I'm sure it means something, but I can't remember why... OH Yeah, now I remember... Pick up Bart from school..." The Simpsons, one episode. Good study!
21:44 November 10, 2009 by Nemesis
Another sucess for Swedish science. The Karolinska does it again.

The research in the Karolinska is world class and goes from strength to strength. I hope there sucess continues.
01:17 November 11, 2009 by code850
The journal PNAS who published these results has lost and still loosing its credibility. It is even the subject of jokes for serious scientist. It is difficult to say whether Karolinska 'has done it again', because the success of an institute should be estimated taking into account the amount of rubish research and misleading papers produced. Since there is no serious statistics on this issue we can not say well done karolinska institute.
13:25 November 12, 2009 by Nemesis
@ code850,

So I should judge american institutes by there publications in PNAS.

Thank you for informing me that all major US institutions are basically a joke.

The Karolinska researchers regularly publich in the journals Nature and Science. The Karolinska is one of the most respected insitutes on the entire planet, for very good reason. It is world class.

If you have an issue with Swedish researchers, why are you in Sweden?

@ zircon

The Simpsons are nothing to do with publishing research papers in scientific journals.
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