N. Fresquet et J. Medioni, EFFECTS OF AGING ON VISUAL-DISCRIMINATION LEARNING IN DROSOPHILA-MELANOGASTER, The Quarterly journal of experimental psychology. B, Comparative andphysiological psychology, 46(4), 1993, pp. 399-412
Two experiments examined conditioned suppression of the Proboscis Exte
nsion Response (PER), unconditionally released by sucrose stimulation
of gustatory tarsal receptors, in young (7-day-old), middle-aged (30-d
ay-old) and old (50-day-old) Drosophila melanogaster males, reared at
25-degrees-C. Individual flies were trained in a differential conditio
ning procedure in which a white stimulus signalled a quinine reinforce
r, whereas a black stimulus was non-reinforced. When trained from the
outset with the discriminative procedure, flies of all ages acquired t
he discrimination, although the acquisition of PER suppression to the
white stimulus was retarded in middle-aged and old flies. The retardat
ion of the acquisition of PER suppression in middle-aged and old flies
was replicated in a second study in which the flies received simple c
onditioning to the white stimulus prior to discrimination training.