Conditioning the behavior of Drosophila melanogaster by means of electric shocks.

Eighty male Drosophila melanogaster were observed individually for extended periods (1-2 hr) as they moved about in a small chamber consisting of a narrow, clear plastic ring whose vertical walls were thin epoxy plates with electric grids by means of which an 80-V shock could be delivered to the fly. Males (whether initially subjected to 0, 1, 2, or 3 electric shocks) that were observed for 10 consecutive 5-min sessions, given a supplemental electric shock (followed by a 2-min rest), and then observed for 5 additional 5-min sessions spent only 88.9% as much time on the grids after the supplemental shock as they had been spending earlier. This avoidance of the potentially electrified grids corresponds to that observed in tests involving the exposure of flies to 0, 1, 2, or 3 electric shocks preceding the 10 5-min sessions. The results reveal (i) an extreme variation in the normal behavior among unshocked (control) males and (ii) an exponential decline in the length of time spent on the grids immediately after receiving 1, 2, or 3 shocks. These data confirm earlier reports on the conditioning of behavior in Drosophila by means of electric shocks; in addition, they remove an ambiguity inherent in the earlier studies, which relied on a presumed exposure of each of 150 or more flies to each shock as it was delivered.