Table 1.

Sequence of behavioral testing. Listed are the experiments that were performed. Separate mice were used for each row. Details of the experiments, groups, measurements, and conditioning contexts are described in Section 2

Experiments	Groups and N	Measurement	Conditioning context	Figure
Fentanyl-induced and conditional  locomotion	Control: N = 9 Conditioned: N = 10 Unconditioned: N = 10	Distance (cm) Percent distance in outer zone	Open field	1a, 2a and b and 3
Cocaine-induced and conditional  locomotion	Control: N = 10 Conditioned: N = 11 Unconditioned: N = 10	Distance (cm) Percent distance in outer zone	Open field	1a and 2c and d
Acute and conditional Straub tail to fentanyl	Control: N = 8 Conditioned: N = 8 Unconditioned: N = 8	Percent time that the tape is above the line	Unheated hot plate	1b and 4a and b
No acute or conditional Straub tail to  cocaine	Control: N = 4 Conditioned: N = 4 Unconditioned: N = 3	Percent time that the tape is above the line	Unheated hot plate	1b and 4c and d
Acute fentanyl analgesia	Vehicle: N = 11 Fentanyl: N = 9	Hot plate latency (s)	52.5 °C hot plate	5a
Conditional analgesia	Control: N = 10 Conditioned: N = 19 Unconditioned: N = 14	Hot plate latency (s)	Train: unheated hot plate Test: 52.5 °C hot plate	1b and 5b
Effect of drug expectation on conditional  place preference and locomotion	Daily: N = 21 Drug: N = 19 No drug: N = 21	Time on fentanyl side (s); distance (cm)	Train: drug- and vehicle-paired chambers Test: access to all 3 chambers	1c and 6a and b
Effect of vehicle injections on change in  preference and locomotor activity	N = 15	Time spent on all three sides (s); distance (cm)	Train: vehicle in both chambers. Test: access to all 3 chambers	6c and d