Discrimination learning of an instrumental response in individual Drosophila melanogaster.

By using a unique methodology and a versatile series of choice points in two distinct apparatuses, individual Drosophila were shown to possess the ability to learn. This behavior can be controlled by a discriminative stimulus (substrate texture). Following a correct response in the presence of the discriminative stimulus at a horizontal choice point, fruit flies bred for negative geotaxis were given the opportunity to ascend a vertical alley leading to another choice point. When cues were consistent, reliable learning occurred. When cues were inconsistent, learning did not occur. Cue reversal produced the classic temporary increase in "incorrect" responses. The success of this paradigm is due, in large part, to the reduction of noxious and competing stimuli.