Figure 6.

Nucleus accumbens neurons are modulated by relative reinforcer value. A-D, Example units show a significant change in firing during 3% sucrose consumption as a function of the paired sucrose reinforcer. Responses to 0% sucrose, 3% (paired with 0%), 3% (10%), and 10% sucrose are shown in each panel; all other conventions are identical to those in Figure 2. Spike rates in bar charts are normalized to baseline firing. E, Example unit in which firing is not altered by contrast paradigm. F, Median firing for all units modulated by the relative value of 3% sucrose solution (n = 8). Horizontal bars show significant differences in firing rate (p < 0.05, post hoc comparisons, one-way ANOVA).