Featured Research

from universities, journals, and other organizations

Once bitten, twice shy: Temperature switch triggers aversive memory

Date:
July 26, 2010
Source:
Max-Planck-Gesellschaft
Summary:
Neurobiologists can now activate specific nerve cells to study the association between sensations and negative experiences.

Dopamine-releasing nerve cells which extend into the mushroom-body in the brain of the fly. Neurobiologists now succeeded in showing that three nerve cells establish the association between a negative experience and an odor.
Credit: Image courtesy of Max-Planck-Gesellschaft

It is common sense that it's worth learning what things and situations are harmful to us if we want to have a long and healthy life. For example, after getting a nasty sunburn, we learn our lesson, and apply sun cream before going sunbathing next time. The importance of such learned avoidance strategies is reflected by the fact that even fruit flies possess them. These tiny flies can learn to associate a particular odor with a mild electrical shock. Once they learned this association, they steer clear of the source of that particular odor in future.

Related Articles


Scientists at the Max Planck Institute of Neurobiology now succeeded in identifying three nerve cells that play a role in the formation of this complex association. By altering the surrounding temperature, they could selectively switch certain cells on and off while the insects moved about freely and learned.

Prevention is better than cure and avoidance strategies often help to save us from adversity. A child, for example, quickly learns not to touch a hot stove once it burned its fingers. Avoidance behavior is so essential that even the comparatively simple brain of the fruit fly excels in it. If, for example, a fruit fly is presented with a certain odor together with an electric shock, it quickly learns to avoid this particular odor by moving or flying off in the opposite direction. Yet, what actually happens in the brain when two such different stimuli as an odor and an electric shock are linked up with each other to cause a change in behavior? It was precisely this basic phenomenon that scientists at the Max Planck Institute for Neurobiology were determined to track down.

The advantages of the fruit fly

The Max Planck Research Group "Behavioral Genetics," led by Hiromu Tanimoto, investigates what happens in the brain of the fruit fly when it learns to avoid something. Given that the fruit fly's brain is nothing short of minute, one tends to wonder why the scientists investigate this phenomenon in the fruit fly. There are two good reasons for their choice. First of all, the brain of this insect is composed of about one hundred thousand nerve cells and is therefore considerably more straightforward than, say, a human brain which has about one hundred billion nerve cells. The cells responsible for avoidance behavior in the fruit fly can therefore be identified much more readily. What is more, the researchers can use the wide range of genetic tools that is already available for the fruit fly to activate or deactivate certain functions of the animal's brain with great precision.

"We used precisely these qualities to our own advantage," Hiromu Tanimoto explains. The scientists already knew that the connection between an odor and an electric shock occurs inside the mushroom-body -- a structure in the brain of the fly that consists of some 2000 nerve cells. It is also clear that the neurotransmitter dopamine enables the flies to learn to associate a potential source of danger with a certain odor. However, until now, it was unclear as to which of the dopaminergic cells are actually responsible for this.

Non-invasive manipulation

"The problem was that we had to determine which of the nerve cells release dopamine while the flies are moving about and learning to avoid the odor," Tanimoto recapitulates on the study. This is precisely what the scientists have now succeeded in doing. They introduced a "temperature selector" into dopamine-releasing cells that contact cells of the mushroom-body. This stowaway gene stimulated the nerve cells in one set of flies to release dopamine as soon as the room temperature increased slightly. In a second set of flies, a different gene caused the nerve cells to become deactivated once room temperature was increased, no matter what stimulus Tanimoto and his staff presented to the insects. Thus equipped to manipulate, the scientists could demonstrate that the activity of three dopamine-releasing cells is essential for a detected odor to be associated with a negative experience. The decisive role of these three cells was unambiguous: if the cells were temperature-activated while the flies picked up on an odor, then the insects learned to avoid the odor -- even without the electric shock that constituted the negative association with the odor.

"We can now actually examine the function of individual nerve cells in an active and behaving animal. This opens up new horizons," Yoshinori Aso, who is visibly delighted with the outcome of his experiment, adds. Step by step, the scientists now plan to get to the bottom of how experiences are linked to each other and how behavior modification develops.


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. Aso et al. Specific Dopaminergic Neurons for the Formation of Labile Aversive Memory. Current Biology, 2010; DOI: 10.1016/j.cub.2010.06.048

Cite This Page:

Max-Planck-Gesellschaft. "Once bitten, twice shy: Temperature switch triggers aversive memory." ScienceDaily. ScienceDaily, 26 July 2010. <www.sciencedaily.com/releases/2010/07/100726101201.htm>.
Max-Planck-Gesellschaft. (2010, July 26). Once bitten, twice shy: Temperature switch triggers aversive memory. ScienceDaily. Retrieved March 4, 2015 from www.sciencedaily.com/releases/2010/07/100726101201.htm
Max-Planck-Gesellschaft. "Once bitten, twice shy: Temperature switch triggers aversive memory." ScienceDaily. www.sciencedaily.com/releases/2010/07/100726101201.htm (accessed March 4, 2015).

Share This


More From ScienceDaily



More Mind & Brain News

Wednesday, March 4, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Former NFL Players Donate Brains to Science

Former NFL Players Donate Brains to Science

Reuters - US Online Video (Mar. 3, 2015) Super Bowl champions Sidney Rice and Steve Weatherford donate their brains, post-mortem, to scientific research into repetitive brain trauma. Jillian Kitchener reports. Video provided by Reuters
Powered by NewsLook.com
Alzheimer's Protein Plaque Found In 20-Year-Olds

Alzheimer's Protein Plaque Found In 20-Year-Olds

Newsy (Mar. 3, 2015) Researchers found an abnormal protein associated with Alzheimer&apos;s disease in the brains of 20-year-olds. Video provided by Newsy
Powered by NewsLook.com
This Nasal Treatment Could Help Ease Migraine Pain

This Nasal Treatment Could Help Ease Migraine Pain

Newsy (Mar. 2, 2015) Researchers gave lidocaine to 112 patients, and about 88 percent of the subjects said they needed less migraine-relief medicine the next day. Video provided by Newsy
Powered by NewsLook.com
How Facebook Use Can Lead To Depression

How Facebook Use Can Lead To Depression

Newsy (Mar. 1, 2015) Margaret Duffy of the University of Missouri talks about her study on the social network and the envy and depression that Facebook use can cause. 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