Featured Research

from universities, journals, and other organizations

Why It Is Easy To Encode New Memories But Hard To Hold Onto Them

Date:
July 14, 2009
Source:
Rockefeller University Press
Summary:
Memories aren't made of actin filaments. But their assembly is crucial for long-term potentiation (LTP), an increase in synapse sensitivity that researchers think helps to lay down memories. Scientists reveal that LTP's actin reorganization occurs in two stages that are controlled by different pathways, a discovery that helps explain why it is easy to encode new memories but hard to hold onto them.

Activated PAK (red) gathers at synapses (green), and might help consolidate fresh memories.
Credit: Rex, C.S., et al. 2009. J. Cell Biol. doi:10.1083/jcb.200901084

Memories aren't made of actin filaments. But their assembly is crucial for long-term potentiation (LTP), an increase in synapse sensitivity that researchers think helps to lay down memories. In the July 13, 2009 issue of the Journal of Cell Biology, Rex et al. reveal that LTP's actin reorganization occurs in two stages that are controlled by different pathways, a discovery that helps explain why it is easy to encode new memories but hard to hold onto them.

If you can't seem to forget those ABBA lyrics you heard in seventh grade but can't remember Lincoln's Gettysburg address, the vagaries of LTP might be to blame. Neuroscientists think that the process, in which a brain synapse becomes more potent after repeated stimulation, underlies the formation and stabilization of new memories. LTP involves changes in the anatomy of synapses and dendritic spines, a process that depends on reorganization of the supporting actin cytoskeleton. However, researchers didn't know what controlled these changes.

Rex et al. tackled the question by dosing slices of rat hippocampus with adenosine, a naturally occurring signal that squelches LTP. Adenosine prevents phosphorylation and inactivation of cofilin, an inhibitor of actin filament assembly, the team found. Cofilin's involvement, in turn, implicates signaling cascades headed by GTPases, such as the RhoA-ROCK and Rac-PAK pathways. The researchers showed that a ROCK inhibitor stalled actin polymerization and resulted in a short-lived LTP. A Rac-blocking compound had no effect.

That doesn't mean the Rac-PAK pathway isn't involved in LTP, however. The team discovered that the Rac inhibitor prolonged cells' vulnerability to a molecule that prevents the stabilization of new actin filaments. That result led Rex et al. to conclude that the two pathways exert their effects at different points. The Rho-ROCK pathway initiates the cytoskeletal changes of LTP, and the Rac-PAK pathway solidifies them so that heightened synapse sensitivity can persist. The researchers hypothesize that one pathway encodes memories, while the other makes sure they stick around.

Journal reference: Rex, C.S., et al. 2009. J. Cell Biol. doi:10.1083/jcb.200901084.


Story Source:

The above story is based on materials provided by Rockefeller University Press. Note: Materials may be edited for content and length.


Cite This Page:

Rockefeller University Press. "Why It Is Easy To Encode New Memories But Hard To Hold Onto Them." ScienceDaily. ScienceDaily, 14 July 2009. <www.sciencedaily.com/releases/2009/07/090713100910.htm>.
Rockefeller University Press. (2009, July 14). Why It Is Easy To Encode New Memories But Hard To Hold Onto Them. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2009/07/090713100910.htm
Rockefeller University Press. "Why It Is Easy To Encode New Memories But Hard To Hold Onto Them." ScienceDaily. www.sciencedaily.com/releases/2009/07/090713100910.htm (accessed July 24, 2014).

Share This




More Mind & Brain News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

New Painkiller Designed To Discourage Abuse: Will It Work?

New Painkiller Designed To Discourage Abuse: Will It Work?

Newsy (July 24, 2014) The FDA approved Targiniq ER on Wednesday, a painkiller designed to keep users from abusing it. Like any new medication, however, it has doubters. Video provided by Newsy
Powered by NewsLook.com
Can Watching TV Make You Feel Like A Failure?

Can Watching TV Make You Feel Like A Failure?

Newsy (July 24, 2014) A study by German researchers claims watching TV while you're stressed out can make you feel guilty and like a failure. Video provided by Newsy
Powered by NewsLook.com
China's Ageing Millions Look Forward to Bleak Future

China's Ageing Millions Look Forward to Bleak Future

AFP (July 24, 2014) China's elderly population is expanding so quickly that children struggle to look after them, pushing them to do something unexpected in Chinese society- move their parents into a nursing home. Duration: 02:07 Video provided by AFP
Powered by NewsLook.com
Idaho Boy Helps Brother With Disabilities Complete Triathlon

Idaho Boy Helps Brother With Disabilities Complete Triathlon

Newsy (July 23, 2014) An 8-year-old boy helped his younger brother, who has a rare genetic condition that's confined him to a wheelchair, finish a triathlon. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins