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. 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. (Current Biology, 15. July 2010)
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.
"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.
Original work:Yoshinori Aso, Igor Siwanowicz, Lasse Bräcker, Kei Ito, Toshihiro Kitamoto, Hiromu Tanimoto
Barbara Abrell | Max Planck Society
Researchers develop eco-friendly, 4-in-1 catalyst
25.04.2017 | Brown University
Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017
25.04.2017 | Laser Zentrum Hannover e.V.
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
25.04.2017 | Physics and Astronomy
25.04.2017 | Materials Sciences
25.04.2017 | Life Sciences