Featured Research

from universities, journals, and other organizations

Key Brain Link In Associative Learning Directly Observed; New Data Potentially Helpful To Study Of Addiction And Aging’s Effects On The Brain

Date:
September 2, 2003
Source:
Johns Hopkins University
Summary:
Scientists have directly demonstrated in rats that one area of the brain can support the creation of memories by changing nerve cell firing patterns in another part of the brain, aiding the animal's efforts to predict the outcome of an action based on past experience and act on that prediction.

Scientists have directly demonstrated in rats that one area of the brain can support the creation of memories by changing nerve cell firing patterns in another part of the brain, aiding the animal's efforts to predict the outcome of an action based on past experience and act on that prediction.

The process, one scientist says, is something like what happens when a comic strip character sees something and is immediately reminded of something else.

"I like to think of it like a cartoon character with a thought bubble over his head," explained Geoffrey Schoenbaum, an associate psychological and brain sciences research scientist in the Krieger School of Arts and Sciences at Johns Hopkins. "There's a neural representation of something in the mind that is invoked by the environment, but not yet present in the environment."

This comparison led to a cartoon for the cover of the August 28 issue of the journal Neuron, where the study is published. On the cover, a cartoon rat stands at a fork in the road, consults a map, and thinks, in a thought bubble, of cheese. The cheese isn't present in the rat's surroundings, but the rat knows through past experience that choosing the right path could lead him to it.

Schoenbaum, who becomes an assistant professor of anatomy and neurobiology at the University of Maryland School of Medicine on Sept. 1, directly observed the brain mechanisms involved in such predictive associations by using implanted electrodes to record the activity of individual nerve cells in two regions of the brain, the amygdala and the orbitofrontal cortex.

In earlier studies, the researchers had demonstrated that nerve cells in these two connected brain regions changed their firing patterns to reflect the associations between cues and outcomes during learning.

For the study published in Neuron, they examined how changes in neural activity in amygdala might be supporting changes in the orbitofrontal cortex. To do this, they recorded in orbitofrontal cortex from two groups of rats: a normal group and a group with chemical lesions to their amygdalas. Prior to the experiments, the rats' water sources were taken away for a time to make them thirsty. In repeated trials, scientists would then link odors to the appearance a few moments later of either desirable drinking water, which was laced with sugar, or undesirable drinking water, laced with quinine and unpalatable even to thirsty rats.

"We found that the patterns that normally develop in orbitofrontal cortex when rats are smelling the odor cue, which appear to reflect information about the predicted outcome, failed to appear in rats with amygdala lesions." Schoenbaum said.

As normal rats learned to use the odor cues to predict the type of fluid they would receive, the orbitofrontal cortex activity patterns eventually began appearing much more quickly, starting in response to the odor cue but before the fluid was given. In experimental rats, though, early activation of orbitofrontal cortex patterns never occurred.

"This is the most direct evidence yet for how one brain system, the amygdala, controls the way representations are made in another directly connected system," said Michela Gallagher, chairman of psychological and brain science at Johns Hopkins and a co-author of the Neuron paper. "We have long suspected the existence of this network because the amygdala is necessary for the type of learning process we studied, but we have only recently begun to examine how these interactions occur and shape how the world around us is represented in the brain."

Schoenbaum noted that the rats with lesioned amygdalas still learned to avoid the undesirable drinking water, apparently through other mechanisms that back up those normally present in the connection between the amygdala and the orbitofrontal cortex. He added that scientists can't yet say for certain what the brain cell activity patterns they identified in the orbitofrontal cortex represent -- a mental picture of the water to come, for example, or of the gratification or lack of gratification the water will produce, or something else entirely.

Schoenbaum hopes to apply data from the study to research into brain changes brought on by addiction. He's interested in investigating the possibility that addiction may damage or impede the connection between the amygdala and the orbitofrontal cortex, impairing an addict's ability to adequately assess the consequences of his or her actions. Gallagher will use data from the study to aid her studies of how aging can affect memory functions.

This research was supported by grants from the National Institute of Mental Health and the National Institute of Aging. Other authors on the paper were Barry Setlow and Michael Saddoris.


Story Source:

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


Cite This Page:

Johns Hopkins University. "Key Brain Link In Associative Learning Directly Observed; New Data Potentially Helpful To Study Of Addiction And Aging’s Effects On The Brain." ScienceDaily. ScienceDaily, 2 September 2003. <www.sciencedaily.com/releases/2003/09/030902074653.htm>.
Johns Hopkins University. (2003, September 2). Key Brain Link In Associative Learning Directly Observed; New Data Potentially Helpful To Study Of Addiction And Aging’s Effects On The Brain. ScienceDaily. Retrieved October 1, 2014 from www.sciencedaily.com/releases/2003/09/030902074653.htm
Johns Hopkins University. "Key Brain Link In Associative Learning Directly Observed; New Data Potentially Helpful To Study Of Addiction And Aging’s Effects On The Brain." ScienceDaily. www.sciencedaily.com/releases/2003/09/030902074653.htm (accessed October 1, 2014).

Share This



More Health & Medicine News

Wednesday, October 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola Cases Keep Coming for Monrovia's Island Hospital

Ebola Cases Keep Coming for Monrovia's Island Hospital

AFP (Oct. 1, 2014) A look inside Monrovia's Island Hospital, a key treatment centre in the fight against Ebola in Liberia's capital city. Duration: 00:34 Video provided by AFP
Powered by NewsLook.com
Ebola Puts Stress on Liberian Health Workers

Ebola Puts Stress on Liberian Health Workers

AP (Oct. 1, 2014) The Ebola outbreak is putting stress on first responders in Liberia. Ambulance drivers say they are struggling with chronic shortages of safety equipment and patients who don't want to go to the hospital. (Oct. 1) Video provided by AP
Powered by NewsLook.com
Doctors Reassure Public Ebola Patient Won't Cause Outbreak

Doctors Reassure Public Ebola Patient Won't Cause Outbreak

Newsy (Sep. 30, 2014) After the announcement that the first U.S. patient had been diagnosed with Ebola, doctors were quick to say a U.S. outbreak is highly unlikely. Video provided by Newsy
Powered by NewsLook.com
TX Hospital Confirms Patient Admitted With Ebola

TX Hospital Confirms Patient Admitted With Ebola

AP (Sep. 30, 2014) Medical officials from Texas Health Presbyterian Hospital confirm they are treating a patient with the Ebola virus, the first case found in the US. (Sept. 30 Video provided by AP
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