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The Drosophila olfactory conditioning situation is an olfactory classical conditioning device for training large number of fruit flies simultaneously. The technique is used extensively to look at a number of training variables such as (a) the number of training trails, (b) type of conditioned and unconditioned stimuli, (c) motivational variables, (d) retention, and (e) strain of animal. Its primary function, however, is to isolate genetic mutants
During training, groups of flies are exposed to two sequential odors. One odor is paired with a rewarding event, and the other serves as a non-rewarded control. Following several training experiences with both odors, the animals are given an unreinforced choice test in a T maze. One arm of the maze contains the rewarded odor and the other arm, the control odor. The basic data consist of the fraction of flies choosing the rewarded odor minus the fraction choosing the non-rewarded odor. An index of 0 indicated no learning. In other words, the T maze choice test revealed that the flies distributed themselves equally in both arms of the maze. An index of 1 indicates that all flies were found in the arm containing the previously rewarded odor, indicating learning; a value of -1 indicates that all flies were found in the arm containing the control odor.