Featured Research

from universities, journals, and other organizations

Accepted model of memory formation refuted

Date:
January 2, 2013
Source:
Johns Hopkins Medicine
Summary:
A widely accepted model of long-term memory formation — that it hinges on a single enzyme in the brain — is flawed, according to new research. The new study found that mice lacking the enzyme that purportedly builds memory were in fact still able to form long-term memories as well as normal mice could.

A study by Johns Hopkins researchers has shown that a widely accepted model of long-term memory formation -- that it hinges on a single enzyme in the brain -- is flawed.
Credit: HP_Photo / Fotolia

A study by Johns Hopkins researchers has shown that a widely accepted model of long-term memory formation -- that it hinges on a single enzyme in the brain -- is flawed. The new study, published in the Jan. 2 issue of Nature, found that mice lacking the enzyme that purportedly builds memory were in fact still able to form long-term memories as well as normal mice could.

Related Articles


"The prevailing theory is that when you learn something, you strengthen connections between your brain cells called synapses," explains Richard Huganir, Ph.D., a professor and director of the Johns Hopkins University School of Medicine's Department of Neuroscience. "The question is, how exactly does this strengthening happen?"

A research group at SUNY Downstate, led by Todd Sacktor, Ph.D., has suggested that key to the process is an enzyme they discovered, known as PKMζ (pronounced PKM-zeta). In 2006, Sacktor's group made waves when it created a molecule that seemed to block the action of PKMζ -- and only PKMζ. When the molecule, dubbed ZIP, was given to mice, it erased existing long-term memories. The molecule caught the attention of reporters and bloggers, who mused on the social and ethical implications of memory erasure.

But for researchers, ZIP was exciting primarily as a means for studying PKMζ. "Since 2006, many papers have been published on PKMζ and ZIP, but no one knew what PKMζ was acting on," says Lenora Volk, Ph.D., a member of Huganir's team. "We thought that learning the enzyme's target could tell us a lot about how memories are stored and maintained."

For the current study, Volk and fellow team member Julia Bachman made mice that lacked working PKMζ, so-called genetic "knockouts." The goal was to compare the synapses of the modified mice with those of normal mice, and find clues about how the enzyme works. But, says Volk, "what we got was not at all what we expected. We thought the strengthening capacity of the synapses would be impaired, but it wasn't." The brains of the mice without PKMζ were indistinguishable from those of other mice, she says. Additionally, the synapses of the PKMζ-less mice responded to the memory-erasing ZIP molecule just as the synapses of normal mice do.

The team then considered whether, in the absence of PKMζ, the mouse brains had honed a substitute synapse-building pathway, much in the way that a blind person learns to glean more information from her other senses. So the researchers made mice whose PKMζ genes functioned normally until they were given a drug that would suddenly shut the gene down. This allowed them to study PKMζ-less adult mice that had had no opportunity to develop a way around the loss of the gene. Still, the synapses of the so-called conditional knockout mice responded to stimuli just as synapses in normal mice did.

What this means, the researchers say, is that PKMζ is not the key long-term memory molecule previous studies had suggested, although it may have some role in memory. "We don't know what this ZIP peptide is really acting on," says Volk. "Finding out what its target is will be quite important, because then we can begin to understand at the molecular level how synapses strengthen and how memories form in response to stimuli." Other authors on the paper are Richard Johnson and Yilin Yu, both of the Johns Hopkins University School of Medicine.

This study was supported with funds from the National Institute of Neurological Disorders and Stroke (grant number NS36715), the National Institute of Mental Health (grant number T32MH15330) and the Howard Hughes Medical Institute.


Story Source:

The above story is based on materials provided by Johns Hopkins Medicine. Note: Materials may be edited for content and length.


Journal Reference:

  1. Lenora J. Volk, Julia L. Bachman, Richard Johnson, Yilin Yu, Richard L. Huganir. PKM-ζ is not required for hippocampal synaptic plasticity, learning and memory. Nature, 2013; DOI: 10.1038/nature11802

Cite This Page:

Johns Hopkins Medicine. "Accepted model of memory formation refuted." ScienceDaily. ScienceDaily, 2 January 2013. <www.sciencedaily.com/releases/2013/01/130102140133.htm>.
Johns Hopkins Medicine. (2013, January 2). Accepted model of memory formation refuted. ScienceDaily. Retrieved November 23, 2014 from www.sciencedaily.com/releases/2013/01/130102140133.htm
Johns Hopkins Medicine. "Accepted model of memory formation refuted." ScienceDaily. www.sciencedaily.com/releases/2013/01/130102140133.htm (accessed November 23, 2014).

Share This


More From ScienceDaily



More Mind & Brain News

Sunday, November 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Could Your Genes Be The Reason You're Single?

Could Your Genes Be The Reason You're Single?

Newsy (Nov. 21, 2014) Researchers in Beijing discovered a gene called 5-HTA1, and carriers are reportedly 20 percent more likely to be single. Video provided by Newsy
Powered by NewsLook.com
Milestone Birthdays Can Bring Existential Crisis, Study Says

Milestone Birthdays Can Bring Existential Crisis, Study Says

Newsy (Nov. 21, 2014) Researchers find that as people approach new decades in their lives they make bigger life decisions. Video provided by Newsy
Powered by NewsLook.com
You Don't Have To Be Alcohol Dependent To Need Treatment

You Don't Have To Be Alcohol Dependent To Need Treatment

Newsy (Nov. 21, 2014) A study by the Centers for Disease Control and Prevention found 9 out of 10 excessive drinkers in the country are not alcohol dependent. Video provided by Newsy
Powered by NewsLook.com
Your Complicated Job Might Keep Your Brain Young

Your Complicated Job Might Keep Your Brain Young

Newsy (Nov. 20, 2014) Researchers at the University of Edinburgh found the more complex your job is, the sharper your cognitive skills will likely be as you age. 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