For mouse and rat discrimination studies, the percentage of responses on the drug manipulandum and response rate (responses/s) were calculated. When appropriate, ED50 values were calculated on the linear part of the drug manipulandum selection dose-response curve for each drug using least squares linear regression analysis, followed by calculation of 95% confidence intervals (CI). Since animals that responded less than 10 times during a test session did not respond sufficiently on either manipulandum to earn a reinforcer, their data were excluded from analysis of drug manipulandum selection, but response rate data were included. Response-rate data were analyzed using a repeated-measures analysis of variance (ANOVA). Mean substitution was used in cases where an individual animal was not tested on one of the doses. Repeated measures ANOVAs were also used to analyze percentage drug manipulandum responding for drug combination tests (e.g., URB597 and JZL184, rimonabant and JZL184). Significant ANOVAs were further analyzed with Tukey post hoc tests (α = 0.05) to specify differences between means. All indications of significance in the results section refer to the results of these post hoc tests.
