Figure 4.

Relative reinforcing effectiveness of benzodiazepine agonists and novel compounds under progressive-ratio schedules of midazolam (a) or cocaine (b) injection. Data are derived from break points, ie, the highest response requirement completed in a session, and expressed in terms of BP_max, which is the highest break point obtained irrespective of dose. Data are median (± interquartile range) due to lack of homogeneity of variance associated with break point data sets (see text for details). Note that *P<0.05 vs median BP_max for midazolam, Dunnett's test for ranks. Also note that # indicates that self-administration was not significantly different from vehicle for any dose which did not allow determination of break point values.