Skip to comments.Scientists decipher the formation of lasting memories
Posted on 11/10/2009 7:19:06 AM PST by Pharmboy
[PRESS RELEASE, 10 November 2009] Researchers at Karolinska Institutet have discovered a mechanism that controls the brain's ability to create lasting memories. In experiments on genetically manipulated mice, they were able to switch on and off the animals' ability to form lasting memories by adding a substance to their drinking water. The findings, which are published in the scientific journal PNAS, are of potential significance to the future treatment of Alzheimer's and stroke.
Lars Olson Photo: Camilla Svensk
"We are constantly being swamped with sensory impression," says Professor Lars Olson, who led the study. "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."
The ability to convert new sensory impressions into lasting memories in the brain is the basis for all learning. Much is known about the first steps of this process, those that lead to memories lasting a few hours, whereby altered signalling between neurons causes a series of chemical changes in the connections between nerve fibers, called synapses. However, less is understood about how the chemical changes in the synapses are converted into lasting memories stored in the cerebral cortex.
A research team at Karolinska Institutet has now discovered that signalling via a receptor molecule called nogo receptor 1 (NgR1) in the nerve membrane plays a key part in this process. When nerve cells are activated, the gene for NgR1 is switched off, and the team suspected that this inactivation might be important in the creation of long-term memories. To test this hypothesis they created mice with an extra NgR1 gene that could remain active even when the normal NgR1 was switched off.
"Doing this, we found that the ability to retain something in the memory for the first 24 hours was normal in the genetically modified mice," says Professor 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."
Alexandra Karlén Photo: Mattias Karlén
In order to be able to switch the extra NgR1 gene on and off, the group attached a regulatory mechanism to the gene that reacted to a harmless additive in their drinking water. When the extra gene was then switched off, the mice retained their normal ability to form long-term memories. By subsequently switching it off at different times after a memory-forming event, they were able to pinpoint the effect of the NgR1 gene to the first week after such an event.
"We know that concussion can cause someone to forget events that occurred in the week before the injury, what we call retrograde amnesia, even though they can remember events that occurred earlier than about a week before. This we believe tallies with our findings," says Alexandra Karlén, one of the scientists involved in the study.
The scientists hope that their findings will eventually be of use in the development of new treatments for memory impairments, such as those related to Alzheimer's and stroke. Medicines designed to target the NgR1 receptor system would be able to improve the brain's ability to form long-term memories. The studies were conducted in collaboration with American researchers at the National Institute on Drug Abuse (NIDA), NIH.
Publication: A. Karlén, T. E. Karlsson, A. Mattsson, K. Lundströmer, S. Codeluppi, T. M. Pham, C. M. Bäckman, S. O. Ögren, E. Åberg, A. F. Hoffman, M. A. Sherling, C. R. Lupica, B. J. Hoffer, C. Spenger, A. Josephson, S. Brené, & L. Olson
Nogo receptor 1 regulates formation of lasting memories PNAS, Online Early Edition, 9-13 november 2009
There’s hope for old Freepers, ping...
My water is tasting funny.
What did Congress vote on last Saturday?
Nah! Hussein will never let this be wasted on us old people.
Its interesting what we remember. I have vivid memories of things from when I was little more than a toddler but have to think about what I did yesterday.
I will bet that Alexandra would stay in my memory, well at least for that weekend.
Indeed...becasue of that well-known phenomenon, neuroscientists have long suspected that short- and long-term memories form under different biologic circumstances.
I still remember my Mom breastfeeding my Sister. I was three years old at the time. Yet I have trouble remembering some people’s names that I met a week ago.
While Alexandra is not a classic Swedish beauty, she’s got that Mona Lisa thingy going on with that smile. Yep...late nights in the lab with her around wouldn’t be that bad.
C2H5OH added to my water does the trick for me.
For a little while.
Not too obscure I hope!
...they were able to switch on and off the animals’ ability to form lasting memories by adding a substance to their drinking water.
Around here, we call that substance bourbon.
I have vivid memories of things from when I was little more than a toddler but have to think about what I did yesterday.
I have often pondered this. My late father-in-law remembered in his 90s the names of all of the students in his 6th grade class. He remembered in vivid detail many, many events from his life. I suspect that we retain those childhood memories so well because they were stored when all of the equipment was newer and had not been battered much. I put that facetiously, but I am sure there is some biochemical and neurological analogy.
Always astounding is the way a particular odor can take you back to a moment far, far in the past. For example, whenever I smell an orange, I think of childhood Christmases because we always had an orange in our stockings.
I know that smell is pretty closely tied to memory. The sight of an old shotgun shell laying on the ground brings the smell back in a big hurry.
Another take on the "it must be something in the water" description of Washington politicians.
(I was going to write something clever but I forgot what it was.)
She’s pretty cute.
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