Featured Research

from universities, journals, and other organizations

Study In Flies Allows Researchers To Visualize Formation Of A Memory

Date:
May 14, 2004
Source:
NIH/National Institute Of Neurological Disorders And Stroke
Summary:
For the first time, researchers have used a technique called optical imaging to visualize changes in nerve connections when flies learn. These changes may be the beginning of a complex chain of events that leads to formation of lasting memories.

For the first time, researchers have used a technique called optical imaging to visualize changes in nerve connections when flies learn. These changes may be the beginning of a complex chain of events that leads to formation of lasting memories. The study was funded in part by the NIH's National Institute of Neurological Disorders and Stroke (NINDS) and appears in the May 13, 2004, issue of Neuron.*

Scientists have long been captivated by the questions of how memories form and how they are represented in the brain. The answers to these questions may help researchers understand how to treat or prevent memory problems, drug addiction, and other human ailments. Thousands of changes in gene expression, neuron formation, nerve signaling, and other characteristics may be involved in the formation of just a single memory. Scientists refer to any learning-induced change in the brain as a "memory trace."

In the new study, Ronald L. Davis, Ph.D., and colleagues at Baylor College of Medicine in Houston developed fruit flies with special genes that caused the flies' neuronal connections to become fluorescent during nerve signaling (synaptic transmission). They then exposed the flies to brief puffs of an odor while they received a shock. This caused them to learn a new association between the odor and the shock – a type of learning called classical conditioning.

Using a high-powered microscope to watch the fluorescent signals in flies' brains with as they learned, the researchers discovered that a specific set of neurons, called projection neurons, had a greater number of active connections with other neurons after the conditioning experiment. These newly active connections appeared within 3 minutes after the experiment, suggesting that the synapses which became active after the learning took place were already formed but remained "silent" until they were needed to represent the new memory. The new synaptic activity disappeared by 7 minutes after the experiment, but the flies continued to avoid the odor they associated with the shock.

This is the first time that optical imaging has been used to visualize a memory trace, Dr. Davis says. "It's phenomenally powerful, like a movie appearing in front of you," he adds. The study suggests that the earliest representation of a new memory occurs by rapid changes – "like flipping a switch" – in the number of neuronal connections that respond to the odor, rather than by formation of new connections or by an increase in the number of neurons that represent an odor, he adds.

The fact that the flies continued to show a learned response even after the new synaptic activity waned suggests that other memory traces found at higher levels in the brain took over to encode the memory for a longer period of time, Dr. Davis suggests. If so, the rapid changes of nerve transmission that the researchers saw may be the all-important switch that initiates the formation of new memories.

This research suggests a previously unknown mechanism for how memories are formed, Dr. Davis says. While this study looked only at learning related to odors, this newly identified process may be at work in many other kinds of learning as well. It is likely that these or similar mechanisms are important for memory in humans and other animals, he adds.

"This is a remarkable study which uses molecular genetic approaches to visualize memory formation in a living organism. It demonstrates that, in this model system, short term memory involves the recruitment of new synaptic connections into pre-existing ensembles of synapses. It will be critical to determine whether similar principles control memory formation in higher organisms," says Robert Finkelstein, Ph.D., a program director at NINDS.

The researchers now plan to put fluorescent genes into a variety of other neurons of the brain in order to determine which ones respond to different kinds of stimuli. This will allow them to learn how the changes they identified affect higher-level neurons. They also hope to begin studying similar mechanisms in other animal models, such as mice.

###

The NINDS is a component of the National Institutes of Health within the Department of Health and Human Services and is the nation's primary supporter of biomedical research on the brain and nervous system.

*Yu D, Ponomarev A, Davis RL. "Altered representation of the spatial code for odors after olfactory classical conditioning: memory trace formation by synaptic recruitment." Neuron, May 13, 2004, Vol. 42, No. 3, pp. 437–449.


Story Source:

The above story is based on materials provided by NIH/National Institute Of Neurological Disorders And Stroke. Note: Materials may be edited for content and length.


Cite This Page:

NIH/National Institute Of Neurological Disorders And Stroke. "Study In Flies Allows Researchers To Visualize Formation Of A Memory." ScienceDaily. ScienceDaily, 14 May 2004. <www.sciencedaily.com/releases/2004/05/040514065817.htm>.
NIH/National Institute Of Neurological Disorders And Stroke. (2004, May 14). Study In Flies Allows Researchers To Visualize Formation Of A Memory. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2004/05/040514065817.htm
NIH/National Institute Of Neurological Disorders And Stroke. "Study In Flies Allows Researchers To Visualize Formation Of A Memory." ScienceDaily. www.sciencedaily.com/releases/2004/05/040514065817.htm (accessed April 18, 2014).

Share This



More Mind & Brain News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Study On Artists' Brain Shows They're 'Structurally Unique'

Study On Artists' Brain Shows They're 'Structurally Unique'

Newsy (Apr. 17, 2014) The brains of artists aren't really left-brain or right-brain, but rather have extra neural matter in visual and motor control areas. Video provided by Newsy
Powered by NewsLook.com
Is Apathy A Sign Of A Shrinking Brain?

Is Apathy A Sign Of A Shrinking Brain?

Newsy (Apr. 17, 2014) A recent study links apathetic feelings to a smaller brain. Researchers say the results indicate a need for apathy screening for at-risk seniors. Video provided by Newsy
Powered by NewsLook.com
Are School Dress Codes Too Strict?

Are School Dress Codes Too Strict?

AP (Apr. 16, 2014) Pushing the limits on style and self-expression is a rite of passage for teens and even younger kids. How far should schools go with their dress codes? The courts have sided with schools in an era when school safety is paramount. (April 16) Video provided by AP
Powered by NewsLook.com
Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. 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