Navigation Links
Researchers identify neurons that assign value during 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 W├╝rzburg 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.


Source:Cell Press

Related biology news :

1. Researchers discover way to make cells in the eye sensitive to light
2. Researchers find how protein allows insects to detect and respond to pheromones
3. Researchers Uncover Key Step In Manufacture of Memory Protein
4. Researchers reveal the infectious impact of salmon farms on wild salmon
5. Researchers identify target for cancer drugs
6. Researchers discover molecule that causes secondary stroke
7. Researchers find missing genes of ancient organism
8. Researchers trace evolution to relatively simple genetic changes
9. Researchers add new tool to tumor-treatment arsenal
10. UF Researchers Map Bacterial Proteins That Cause Tooth Loss
11. VCU Researchers Identify Networks Of Genes Responding To Alcohol In The Brain
Post Your Comments:

(Date:10/29/2015)... Oct. 29, 2015  Rubicon Genomics, Inc., today ... distribution of its DNA library preparation products, including ... new ThruPLEX Plasma-seq kit. ThruPLEX Plasma-seq has been ... of NGS libraries for liquid biopsies--the analysis of ... prognostic applications in cancer and other conditions. Eurofins ...
(Date:10/29/2015)... , Oct. 29, 2015 Today, ... announced a partnership with 2XU, a global leader ... deliver a smart hat with advanced bio-sensing technology. ... other athletes to monitor key biometrics to improve ... strategic partnership, the two companies will bring together the ...
(Date:10/27/2015)... Calif. , Oct. 27, 2015 Synaptics Inc. ... solutions, today announced that Google has adopted the Synaptics ... touch controller solutions to power its newest flagship smartphones, ... by Huawei. --> ... like Google to provide strategic collaboration in the joint ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... 24, 2015  Asia-Pacific (APAC) holds the third-largest ... market. The trend of outsourcing to low-cost locations ... higher volume share for the region in the ... margins in the CRO industry will improve. ... ( ), finds that the market earned ...
(Date:11/24/2015)... ... 24, 2015 , ... Copper is an essential micronutrient that ... proteins, copper is also toxic to cells. With a $1.3 million award from ... conduct a systematic study of copper in the bacteria Pseudomonas aeruginosa (P. aeruginosa), ...
(Date:11/24/2015)... ... November 24, 2015 , ... This fall, global software solutions leader SAP and ... to develop and pitch their BIG ideas to improve health and wellness in their ... votes to win the title of SAP's Teen Innovator, an all-expenses paid trip to ...
(Date:11/24/2015)... , Nov. 24, 2015 /PRNewswire/ - Aeterna Zentaris ... today that the remaining 11,000 post-share consolidation (or ... Warrants (the "Series B Warrants") subject to the ... on November 23, 2015, which will result in ... giving effect to the issuance of such shares, ...
Breaking Biology Technology: