Experimental design
| Groups | Phase I (days 3-4) | Probe CER (day 5) | Phase II (days 5-6) | Probe CER (day 7) | FDG test (day 7) |
|---|---|---|---|---|---|
| Extinction (extinction after acquisition) | T→S | CER | T | No CER | T |
| Non-extinction (no extinction after acquisition) | T→S | CER | No T | CER | T |
| Pseudorandom (no extinction, no acquisition) | T,S | No CER | T/No T | No CER | T |
T, 1-2 kHz FM tone sweep (15 sec); S, 0.5 mA foot shock (0.75 sec); →, temporally contiguous tone/shock; comma, pseudorandomly timed discontiguous tone and shock; CER, freezing behavior scored during 15 sec tone.