Reduction in climbing index of Drosophila revealed by Rotor-RING Assay suggests learned helplessness

Negative geotaxis in Drosophila is an instinctive behavior. Rapid iterative negative geotaxis assay (RING) in Drosophila melanogaster is a frequently employed behavioral assay for studying motility in relation to ageing, nutrition and in use of the fly as a disease model. The protocol involves tapping the flies down in a vial and observing the number of flies that climb up to certain level due to negative geotaxis and calculation of climbing index. Tapping the flies down, cause arousal and a mechanical stimulus in addition to sensing gravity that makes the flies climb up. The Rotor-RING assay design described in the present study is a variant, wherein a 25 cm tube containing flies is rotated by a half-turn using a motor at fixed programmable intervals to elicit negative geotaxis. This rotation repeatedly places the flies at the bottom of the tube and elicits climbing. Repetitive trials over a period of 20 days reduces climbing. Thus, an instinctive behavior is gradually quenched. This reduction of climbing index is akin to ‘learned helplessness’ and can be used to assess learning and extinction of innate behavior.