Featured Research

from universities, journals, and other organizations

Scientists Identify Machinery That Helps Make Memories

Date:
November 1, 2008
Source:
Duke University Medical Center
Summary:
Researchers have identified a missing-link molecule that helps to explain the process of plasticity in the brain during memory creation and that could lead to targeted therapies.

A major puzzle for neurobiologists is how the brain can modify one microscopic connection, or synapse, at a time in a brain cell and not affect the thousands of other connections nearby. Plasticity, the ability of the brain to precisely rearrange the connections between its nerve cells, is the framework for learning and forming memories.

Related Articles


Duke University Medical Center researchers have identified a missing-link molecule that helps to explain the process of plasticity and could lead to targeted therapies.

The discovery of a molecule that moves new receptors to the synapse so that the neuron (nerve cell) can respond more strongly helps to explain several observations about plasticity, said Michael Ehlers, M.D., Ph.D., a Duke professor of neurobiology and senior author of the study published in the Oct. 31 issue of Cell. "This may be a general delivery system in the brain and in other types of cells, and could have significance for all cell signaling."

Ehlers said this could be a general way for all cells to locally modify their membranes with receptors, a process critical for many activities -- cell signaling, tumor formation and tissue development.

"Part of plasticity involves getting receptors to the synaptic connections of nerve cells," Ehlers said. "The movement of neurotransmitter (chemical) receptors occurs through little packages that deliver molecules to the synapse when new memories form. What we have discovered is the molecular motor that moves these packages when synapses are active."

When neurons fire at the same time, their connections strengthen and a person can associate certain features. "Once you have heard someone's name, seen his face, where he was standing, all these features can be bound into a unified packet of information – a percept – and at a very cellular level this occurs by strengthening synaptic connections between co-active neurons," said Ehlers, who is also a Howard Hughes Medical Investigator.

To learn and make new associations, the brain alters the strengths of the synapses' electrical inputs onto cells that compute these features. Scientists studied the hippocampus, where memories form, but this machinery could operate in other brain areas.

"One of earliest changes in Alzheimer's disease is synapse dysfunction, so this molecule might be a new target for that disease," he said. "Abnormal movement of receptors may be implicated in brain development, in autism." He said the molecule potentially is involved "in the abnormal electrical activity of epilepsy and the overactive brain pathways of addiction."

In a series of biochemistry and microscopic imaging experiments, Ehlers and colleagues found that the myosin Vb (five-b) molecule in hippocampal neurons responded to a flow of calcium ions from the synaptic space by popping up and into action. One end of the myosin is attached the meshlike actin filaments so it can "walk" to the end of the nerve cells where receptors are. On its other end, it tows an endosome, a packet that contains new receptors.

"These endosomes are like little memories waiting to happen," Ehlers said. "They are reservoirs of neurotransmitter receptors that brain cells deploy to add more receptors to a particular synapse. More receptors equals stronger synapses."

Electrical impulses cause one nerve cell to dump its neurotransmitter, in this case, glutamate, into the small space between neurons (the synapse), which activates neurotransmitter receptors on the receiving side. These are ion channels that open in response to neurotransmitter and generate the electrical impulse.

When the scientists blocked myosin in single cells, this stopped the addition of new receptors and prevented electrical impulses from getting stronger, showing that myosin is essential to enhancing nerve cell connections.

"This is a very basic cellular mechanism of brain plasticity. It is likely fundamental to brain development and disease," Ehlers said. "The myosin Vb molecule gives us a new way to think about designing therapies for treating memory loss, psychiatric disease and brain development."

Other authors included Zhiping Wang and Ian G. Davidson of the Duke Department of Neurobiology and the Howard Hughes Medical Institute (HHMI); Jeffrey G. Edwards, Nathan Riley and Julie A. Kauer of the Department of Molecular Pharmacology, Physiology, and Biotechnology at Brown University; D. William Provance Jr., Ryan Karcher and John A. Mercer of the McLaughlin Research Institute in Great Falls, Montana; and Xiang-dong Li and Mitsuo Ikebe of the Department of Physiology, University of Massachusetts Medical School. The work was supported by grants from the National Institutes of Health and the HHMI.


Story Source:

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


Cite This Page:

Duke University Medical Center. "Scientists Identify Machinery That Helps Make Memories." ScienceDaily. ScienceDaily, 1 November 2008. <www.sciencedaily.com/releases/2008/10/081030123821.htm>.
Duke University Medical Center. (2008, November 1). Scientists Identify Machinery That Helps Make Memories. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2008/10/081030123821.htm
Duke University Medical Center. "Scientists Identify Machinery That Helps Make Memories." ScienceDaily. www.sciencedaily.com/releases/2008/10/081030123821.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

Newsy (Nov. 25, 2014) — The US FDA is announcing new calorie rules on Tuesday that will require everywhere from theaters to vending machines to include calorie counts. Video provided by Newsy
Powered by NewsLook.com
Daily Serving Of Yogurt Could Reduce Risk Of Type 2 Diabetes

Daily Serving Of Yogurt Could Reduce Risk Of Type 2 Diabetes

Newsy (Nov. 25, 2014) — Need another reason to eat yogurt every day? Researchers now say it could reduce a person's risk of developing type 2 diabetes. Video provided by Newsy
Powered by NewsLook.com
Madagascar Working to Contain Plague Outbreak

Madagascar Working to Contain Plague Outbreak

AFP (Nov. 24, 2014) — Madagascar said Monday it is trying to contain an outbreak of plague -- similar to the Black Death that swept Medieval Europe -- that has killed 40 people and is spreading to the capital Antananarivo. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com
Are Female Bosses More Likely To Be Depressed?

Are Female Bosses More Likely To Be Depressed?

Newsy (Nov. 24, 2014) — A new study links greater authority with increased depressive symptoms among women in the workplace. 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:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

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