Conditioned visual flight orientation in Drosophila melanogaster abolished by benzaldehyde

To study learning and memory of Drosophila melanogaster in the flight simulator, single flies are trained in an operant conditioning paradigm to avoid a course towards visual objects that are associated with heat. The results demonstrate that normal flies (wild-type "Berlin") can quickly learn to avoid the heat-associated objects and retain the memory. This allows us to further explore a recently communicated long-term effect of preimaginal benzaldehyde (BAL) influence on the association of visual objects with the aversive odor of BAL. Here we show that flies, exposed to BAL in the embryonic, larval or adult stage, do not accompany by a similar indifference to heat shocks. The flies are successfully trained to avoid the heat-associated visual patterns. It shows that the learning acquisition is not affected during the operant conditioning in the flight simulator. Neither object perception nor object discrimination is altered after exposure to BAL, as is shown by Fourier analysis. However, the test results after training show that exposure to BAL interferes directly with memory formation in Drosophila. It takes at least two generations of growth on the noncontaminated medium that the strain recovers fully from BAL-induced amnesia. The BAL treatment seems not only to affect the associative memory formation, but in addition the flies' development in general, as is indicated by prolonged developmental time. However, the impaired memory after BAL treatment in different stages seems to have nothing to do with an influence of BAL on the cAMP-level.