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Abstract

Context-dependent preferences in a choice between an upper and a lower visual object of otherwise identical appearance were recorded
during stationary flight of the fruitfly, Drosophila melanogaster, in a flight simulator. The test animal was held in a fixed orientation at the center of a
wing-beat processor that converts attempted turns into counter-rotations of a surrounding cylindrical panorama. This allowed the ny to maneuver the
preferred object into the actual direction of flight. Single flies were trained to avoid a course toward the visual object that had been associated with the
aversive odor benzaldehyde (BAL). Conditioned object avoidance was investigated in different treatment groups by collective evaluation of the scores
from 80 long-lasting flights (>1 hr). In addition to a significant cross-modal association, we found a striking long-term effect of transient exposure to BAL
both in the embryonic and larval states. The preimaginal experience significantly increased the indifference to BAI, in the adult flies. Disturbed vision does
not account for this effect: Neither the perception nor the discrimination of the visual objects was significantly impaired in the investigated flies. Disturbed
olfaction could explain the present results. Recently, however, preimaginal BAL uptake has been found to interfere directly with the retention of
heat-shock-conditioned object avoidance.