Saturday, December 8, 2012

Effect of aging on learning in Drosophila melanogaster




My passion for fruit fly pushes me to look for a peer review journal on flies that I want to share with you. We all know that as people age, they tend to have memory dysfunctions and their learning ability decrease. To study the effect of age on learning, a researcher, Eric Le Bourg, did some experiment on fruit- fly Drosophila melanogaster to see the relationship between age and learning. He chose flies because they have a short life span and they can study many generations and also they have a well-known genetics. This journal article studies the effects of aging on learned suppression of photopositive tendencies in Drosophila melanogaster. To begin his experiment, the researcher makes the hypothesis that as flies age, the ability to learn decreases. To test his hypothesis, he proceeded to three different experiments. He used light as a conditioned stimulus associated an aversive unconditioned stimulus, the taste of quinine, and the darkened arm which was not associated with an aversive stimulus. It turned out that flies run away from light to avoid the quinine. He pointed out that quinine does not induce sensitization and has been used for many decades in learning studies using D. melanogaster because of its bitter taste.
The first experiment tested whether flies of different ages can avoid lighted vial associated with an aversive stimulus. The second tested if they can avoid the lighted vial associated with a strong (quinine) or weak (distilled water) aversive stimulus. Before both experiment, half of the flies were subjected to training with the aversive stimulus that will be used in the experiment. In the third experiment, one half of the flies was subjected to training with a lighted vial containing a paper wetted with quinine and the other half was subjected to 16 trials with a lighted vial containing a dry paper and after that, the same group of flies to 16 training trials with another lighted vial containing a paper wetted with quinine on each trial.
These experiments have shown flies of all age learn to avoid the light when it is associated with quinine or water. Quinine has a bitter taste that flies do not like and the water prevent them from flying that is why they avoid these two stimuli. However, the learning score in the older age flies decrease little bit compared to the first week age flies. Therefore, it can be concluded that age had different effects on locomotor activity and learning. Old flies walk slower but the locomotion had a slight effect on learning.
After reading this, my question is, does this conclusion also apply to human? As we grow old, do we really get stupid or we know everything but we just don’t want to talk?

                                  Drosophila melanogaster


Click here to read this article

Citation:
Eric Le Bourg, Effects of aging on learned suppression of photopositive tendencies in Drosophila melanogaster, Neurobiology of Aging, Volume 25, Issue 9, October 2004,
Pages 1241-1252, ISBN 0197-4580, 10.1016/j.neurobiolaging.2003.12.004.
(http://www.sciencedirect.com/science/article/pii/S0197458004000326)


1 comment:

  1. As to whether humans get dumber or just don't talk as they get older :-) I think it's probably a little of both. And sometimes older folks don't think anyone wants to hear what we have to say :-)

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