Figure 1.

This figure shows the effect of ratio requirement on the number of lever presses emitted and operant pellets consumed in rats with accumbens DA depletions compared to rats in the vehicle control group. Figure (A) is re-drawn based upon Aberman and Salamone (1999); these data are depicted in terms of number of responses, as in the original article. For (B), the data are represented as number of operant pellets consumed. Each data point shown is the mean value from each group at each ratio level. Although comparable levels of consumption in DA depleted and control groups were seen with the FR1 schedule, DA-depleted rats showed markedly reduced consumption relative to the control group at higher ratio levels.