| Neurobiologists can enable individual nerve cells specifically and to study the linking of sensation |
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For a long and healthy life it is quite helpful to learn what things and situations are harmful. So learn that most of us, for example, through painful sunburn cream to her the next time before sun exposure. The importance of these prevention strategies are learned shows that fruit flies themselves are in a situation. You can learn to get a smell and a current pulse in the compound and then to avoid odor source in the future.
Scientists at the Max Planck Institute of Neurobiology have now identified three nerve cells that play a role in this complex process. It managed to single cells targeted by changes in ambient temperature on-off or - and that, while the animals moved freely and learned (Current Biology, July 15, 2010). Avoid is good. Of course this is not generally, but in many cases, we keep a prevention strategy against any damage. Thus a child learns very quickly to keep away from the hot stove when it has once burned. The principle of this learned avoidance is so essential that even the comparatively simple brains of fruit flies are able to do so. Provides one fruit flies, for example, a particular scent along with a current pulse, the animals learn after a few attempts to avoid the scent - they run or fly in the opposite direction. But what happens in the brain when different stimuli such as a fragrance and a current pulse are connected with each other and this leads to a change in behavior? This essential question is scientists from the Max-Planck-Institute for Neurobiology in Martinsried on the track.The benefits of the fruit fly On the fruit fly model examines the Max-Planck Research Group "behavioral genetics", led by Hiromu Tanimoto, what happens in the brain when the animals learn to avoid. The question suggests itself why the scientists are studying this is happening to the fruit fly, whose brain is admittedly small. This has two reasons: First, is the brain of these animals with just hundreds of thousands of nerve cells developed significantly easier than for example a human brain with a hundred billion nerve cells. In the fruit fly, it is therefore much easier to identify the cells that are important for the development of avoidance behavior. On the other hand there is the fruit fly a wide range of genetic tools that can, for example, certain brain functions are activated and deactivated. "These same advantages we have taken advantage of," said Hiromu Tanimoto. The scientists knew that the combination of smell and current pulse is within the mushroom body - a structure in the fly brain with some 2000 nerve cells. Moreover, it is known that the neurotransmitter dopamine is important so that the flies can learn to associate an odor with a potential risk. Which dopamine cells, this distribution is possible, however, exactly which remained still unclear. Manipulation without direct intervention The difficulty was to know that we had to distribute the dopamine nerve cells, while running around and the flies learn to avoid an odor says Tanimoto up the challenge. This is precisely the neurobiologists have succeeded. They built up a "temperature switch" in distributing the dopamine nerve cells associated with the cells of the mushroom body in contact. "Resulted in one group of flies, the injected gene means that a slight increase in room temperature, the nerve cells activated, so that these dopamine free up, resulted in a second fly-group had a different gene cause the increase in temperature inactivated the neurons, regardless of the stimuli, we the animals offered, said Tanimoto. This allowed the researchers show that three of the distribution of dopamine cells must be active for a perceived scent is associated with a negative experience. The crucial role of these cells was clear: Were the three nerve cells activated by a temperature increase while the flies a scent perceived, then got the animals to avoid the smell - and then even if the current pulse was missing as a negative relationship with the fragrance. 'We can now effectively study the function of individual nerve cells in a freely moving animal - this opens up new possibilities, "says Yoshinori Aso on the success of his work. Now the scientists want to decode step by step how experiences are linked and how this produces a change in behavior. |
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