Data for acquisition (ACQ) and extinction (EXT) training was based on average performance across the last 3 days of each phase. EXT significantly decreased active lever presses (a) (p < 0.001), but significantly increased inactive lever presses (b) (p < 0.01), when compared to ACQ. There was a significant increase in active lever responses during both the cue-induced (CUE) (p < 0.001), and MDPV-primed reinstatement tests (MDPV) (p < 0.05), relative to EXT. Data are shown as mean + S.E.M. (n = 14). +++p < 0.001, ++p < 0.01 relative to ACQ; ***p < 0.001, *p < 0.05 relative to EXT.