Effects of aging on learned suppression of photopositive tendencies in Drosophila melanogaster.

The effect of aging on acquisition of a learned suppression of photopositive tendencies was studied in 1-7-week-old flies of both sexes. Flies had to choose in a T-maze between an alley leading to a lighted vial associated with an aversive stimulus, a quinine hydrochloride solution, and another alley leading to a darkened vial free of quinine. Control groups with either no quinine or water in the lighted vial, respectively, did not learn at any age to avoid the lighted vial or had lower scores than flies trained with quinine. Flies of all ages trained with quinine learned to avoid the lighted vial and a slight decrease of the learning score was observed after the first week of age, no other effect of age being clearly observed. This study also tested whether pretraining enhanced (or impaired) learning score. Pretraining was obtained by subjecting 1-6-week-old flies to trials with a lighted vial without quinine before to subject them to trials with quinine in the lighted vial: pretraining increased learning scores to the same extent at all ages.