Featured Research

from universities, journals, and other organizations

Researchers Identify Neurons That Assign Value During Learning

Date:
September 17, 2006
Source:
Cell Press
Summary:
By using an experimental trick to activate certain sets of neurons and effectively substitute activation of these cells for positive or negative experiences, researchers have been able to identify neurons in the fruit fly Drosophila that are responsible for assigning value to stimuli during so-called associative learning.

By using an experimental trick to activate certain sets of neurons and effectively substitute activation of these cells for positive or negative experiences, researchers have been able to identify neurons in the fruit fly Drosophila that are responsible for assigning value to stimuli during so-called associative learning. The findings, which advance our understanding of how, at the cellular level, we learn to associate cues with positive and negative experiences, are reported by Andre Fiala and colleagues at the University of Würzburg in Germany and appear in the September 5th issue of Current Biology, published by Cell Press.

During associative learning, animals learn to change their behavior in response to a particular stimulus that would otherwise have a neutral influence on behavior. For example, if an animal such as a fruit fly learns to associate a particular odor with a punishing stimulus, the odor itself can become repulsive. Conversely, an odor associated with a reward can become attractive. Despite its relatively modest brain complexity, the fruit fly larva is able to perform such associative-learning tasks. Because of its neuronal simplicity and the fact that it can be genetically manipulated, the fruit fly offers a favorable study case to address a principal question in the field of learning and behavior: Which neurons attribute attractive or aversive values to so-called neutral stimuli, such as odors, in the course of associative learning?

Past work had indicated that certain neurotransmitters played key roles in assigning attractive or aversive values to neutral stimuli--for example, neurons expressing dopamine are required for aversive learning, whereas neurons expressing another neurotransmitter, octopamine, are required for appetitive learning (association of a stimulus with a reward). However, it was unclear whether a common set of neurons were responsible, or whether attractive and aversive values were assigned to neutral stimuli by independent sets of neurons.

To tackle this question, the researchers engineered transgenic fruit flies that express in distinct nerve cells a special ion channel, "channelrhodopsin-2," whose activity is light-sensitive (the protein is normally found in green algae). As a result of expressing channelrhodopsin-2, neurons could be activated simply by illuminating fruit fly larvae with blue light. This tool allowed the researchers to test whether such an activation of certain neurons can actually substitute for external stimuli--for example, reward or punishment--in an associative-learning experiment. The researchers found that if an odor is presented while a group of dopamine-releasing neurons are experimentally light-activated, the larvae learn to avoid this odor in a later test, despite the fact that no negative stimulus was presented to the larvae along with the odor. Conversely, if an odor is presented while a different group of neurons--releasing octopamine and/or tyramine--are experimentally light-activated, the odor becomes attractive. These findings demonstrate that antagonistic subsets of neurons are responsible for assigning positive or negative values to odor stimuli. It will be of interest to see whether this principal concept of antagonistic neuronal populations mediating positive or negative values during learning holds true for much more complex mammalian brains as well.

The researchers include Christian Schroll, Thomas Riemensperger, Daniel Bucher, Julia Ehmer, Thomas Völler, Karen Erbguth, Bertram Gerber, Erich Buchner, Georg Nagel, and André Fiala of Universität Würzburg Biozentrum in Würzburg, Germany; Thomas Hendel of Universität Würzburg Biozentrum in Würzburg, Germany and Max-Planck-Institut für Neurobiologie in Martinsried, Germany.

This work was supported by the Deutsche Forschungsgemeinschaft (SFB 554, GRK 1156, and a Heisenberg Fellowship to B.G.).


Story Source:

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


Cite This Page:

Cell Press. "Researchers Identify Neurons That Assign Value During Learning." ScienceDaily. ScienceDaily, 17 September 2006. <www.sciencedaily.com/releases/2006/09/060915205043.htm>.
Cell Press. (2006, September 17). Researchers Identify Neurons That Assign Value During Learning. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2006/09/060915205043.htm
Cell Press. "Researchers Identify Neurons That Assign Value During Learning." ScienceDaily. www.sciencedaily.com/releases/2006/09/060915205043.htm (accessed July 28, 2014).

Share This




More Health & Medicine News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

$15B Deal on Vets' Health Care Reached

$15B Deal on Vets' Health Care Reached

AP (July 28, 2014) — A bipartisan deal to improve veterans health care would authorize at least $15 billion in emergency spending to fix a veterans program scandalized by long patient wait times and falsified records. (July 28) Video provided by AP
Powered by NewsLook.com
Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) — Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
West Africa Gripped by Deadly Ebola Outbreak

West Africa Gripped by Deadly Ebola Outbreak

AFP (July 28, 2014) — The worst-ever outbreak of the deadly Ebola epidemic grips west Africa, killing hundreds. Duration: 00:48 Video provided by AFP
Powered by NewsLook.com
Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) — A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. 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