Experimental trial outline and example behavioral performance during training. A, After a variable intertrial interval (ITI), the odor and vacuum solenoid valves were turned on for 13 s, after which the vacuum would turn off for 2 s, allowing for the odor to flow toward the nose of the animal. A water reward was available if animals licked a spout during rewarded odors, but not for licking during unrewarded odors. B, Average evoked PID trace in response to eight presentations of 1,7-octadiene, illustrating the rapid temporal dynamics (∼110 and 120 ms at 10% and 50% of baseline, respectively) and stability of odor presentation (3 Hz, low-pass, second-order filter). Dashed horizontal line indicates the average baseline. C, Average behavioral performance in the first two and last two blocks of the four training phases (for details, see Materials and Methods). After meeting high-performance criterion for at least two consecutive blocks (red dashed line), animals were advanced to the next training phase. Chance performance is 50% correct. Not all mice performed the same number of blocks per phase. Inset, Average number of sessions per training phase. Data from individual mice are plotted in gray. Jitter was added to data along the x-axis to help visualize overlapping points. On average, the 16 mice used for data analysis in this study learned the task to criterion performance after 8.8 ± 0.7 training sessions (inset), and their average block performance was 88 ± 2% correct responses across all odor discrimination experimental sessions.