Fig. 5.
Lever responses by the SKF+Quin group during acquisition, extinction, and reinstatement sessions. Data are the mean ± SEM. A within-subject experimental design revealed that rats given 0.50 mm SKF plus 0.50 mm Quin showed reliable preference for the infusion lever over the control lever during the first three sessions [F(1,3) = 13.55; p = 0.01]. It should be noted that the relatively large SEM values were mainly because of the variability among subjects. Within subjects, preference for the infusion lever over the control lever was consistent. The rats exhibited a reduction in lever responses when SKF+Quin was replaced with vehicle in session 4 [the main effect of schedules, F(1,5) = 7.31; p = 0.04]. Although not statistically reliable, rats tended to increase lever responses when SKF+Quin was reinstated in session 5 [the main effect of schedules,F(1,5) = 4.61; p = 0.085].