Figure 2.

Cocaine maintains a dose-dependent increase in cocaine choice in monkeys and humans responding under homologous cocaine choice procedures. Panels A (monkeys; N = 4) and B (humans; N = 8) show the mean ± SEM number of trials completed for cocaine (open bars), trials completed for the non-drug alternative reinforcer (closed bars; food pellets in monkeys and money in humans), or omitted trials (i.e., choice of neither cocaine or the alternative; gray bars) as a function of cocaine dose on the X-axis. Data were analyzed by 2-way ANOVA, and significant ANOVAs were followed by the Holm-Sidak post hoc test. Asterisks indicate statistical significance (p < 0.05) within a trial outcome (cocaine choice, food choice, omission) compared to the 0 dose cocaine data. Dollar signs indicate statistical significance (p < 0.05) with a cocaine dose between the numbers of cocaine vs food trials completed. Panel C shows a significant correlation in cocaine choice data for monkeys and humans. Triangle denotes 0 cocaine dose condition. Diamond denotes 3-mg/70-kg cocaine dose condition. Square denotes 10 mg/70 kg cocaine dose condition. Circle denotes 30-mg/70-kg cocaine dose condition. Adapted from (Johnson et al. 2016; Lile et al. 2016).