Groups of 50 4-5 day old males were trained using odor training boxes described in the conditioned preference protocol above, and tested in the Y-maze apparatus described above. Flies were food deprived for 16-20 hrs prior to training. Reciprocal training was performed to ensure that inherent preference for either odor did not affect conditioning scored. Training consisted of 10 min habituation to the training chamber with air (flow rate 130), 10 min presentation of odor 1 with plain filter paper pre-soaked in water and dried, then 10 min of odor 2 with filter paper pre-soaked in 2M sucrose and dried. Simultaneously, a separate group of flies was trained using odor 1 as the sucrose-paired odor. Vials of flies from Group 1 and Group 2 were paired according to placement in the training chamber and tested simultaneously 10 min following training. Preference and performance indices for conditioned sucrose preference were calculated in the same way as for conditioned ethanol preference (described above).
