Group | Phase | Parameters | Stimulus | Daysa |
---|---|---|---|---|
All | Response ball training (center, left, right; 2×) | 25 m per response ball | Water | 6 |
All | Side training (left, right; 3×) | 0 s time-out; 180 s limited holdb | Water or 0.6 m NaCl | 6 |
All | Alternation-4c | 10 s time-out; 15 s limited hold | Water versus 0.6 m NaCl | 1 |
All | Alternation-2 | 20 s time-out; 15 s limited hold | Water versus 0.6 m NaCl | 1 |
All | Alternation-1 | 30 s time-out; 15 s limited hold | Water versus 0.6 m NaCl | 1 |
All | Discrimination training | 30 s time-out; 15 s limited hold | Water versus 0.6 m NaCl | 32–72d |
All | Detection | 30 s time-out; 15 s limited hold | Water versus 0.6–0.00078 m NaCl | 33–43 |
All | Discrimination training | 30 s time-out; 15 s limited hold | Water versus 0.2 m MSG | 13–28 |
All | Detection | 30 s time-out; 15 s limited hold | Water versus 0.2–0.00078 m MSGe | 26–42 |
All | Stimulus control | 30 s time-out; 15 s limited hold | Water versus 0.6 m NaCl | 6–17 |
T1R2, T1R3 | Discrimination training | 30 s time-out; 15 s limited hold | 100 μm amiloride versus 0.2 m MSG + 100 μm amiloride | 2 |
T1R2, T1R3 | Discrimination training | 30 s time-out; 15 s limited hold | 100 μm amiloride versus 0.6 m MSG + 100 μm amiloride | 17 |
T1R2, T1R3 | Stimulus control | 30 s time-out; 15 s limited hold | Water versus 0.6 m NaCl | 15–20 |
All | Discrimination training | 30 s time-out; 15 s limited hold | 100 μm amiloride versus 0.6 m MSG + 100 μm amiloride + 2.5 mm IMP | 49–69 |
All | Detection | 30 s time-out; 15 s limited hold | Water versus 0.6–0.003125 m MSG + 100 μm amiloride + 2.5 mm IMP | 24–26 |
All | Discrimination training | 30 s time-out; 15 s limited hold | 100 μm amiloride versus 2.5 mm IMP + 100 μm amiloride | 2 |
All | Stimulus control | 30 s time-out; 15 s limited hold | Water versus 0.6 m NaCl | 15–21 |
T1R1 | Discrimination training | 30 s time-out; 15 s limited hold | Water versus 0.6 m l-lysine | 13–17 |
T1R1 | Detection | 30 s time-out; 15 s limited hold | Water versus 0.6–0.003125 m l-lysine | 30 |
T1R1 | Stimulus control | 30 s time-out; 15 s limited hold | Water versus 0.6 m NaCl | 5 |
T1R1 | Discrimination training | 30 s time-out; 15 s limited hold | 100 μm amiloride versus 0.6 m MSG + 100 μm amiloride | 20–22 |
T1R1 | Stimulus control | 30 s time-out; 15 s limited hold | Water versus 0.6 m NaCl | 13 |
All | Water control test | 30 s time-out; 15 s limited hold | Water | 1–2 |
↵aNumber of sessions varied between experiments and phases because of variability across all mice within each experiment reaching the established criteria (see Procedure). Following Alternation-1 Training, all further session totals include only stimulus discrimination sessions, not side training sessions.
↵bTime-out is the duration following an incorrect response in which onset of the subsequent trial was delayed and no water was delivered from the reinforcement balls. Limited hold is time allotted for the animal to make a response after licking the stimulus from the sample ball.
↵cNumber of correct responses required before proceeding to the alternate stimulus.
↵dAccounts for all NaCl versus water discrimination days, including previous testing experience in the T1R2 + T1R3 group (see Stimuli and Procedure).
↵eT1R2, T1R3, and T1R2 + T1R3 groups were only tested as low as 0.00156 m MSG.