Article Figures & Data
Figures
- Figure 1.
Subject-rated behavioral measures. A, Average subject ratings (with SEM bars) of incentive value of menu items in each experimental condition. The rating scale ranged from 1 to 5, with higher scores indicating greater incentive value for menu items. High-incentive conditions were rated as being of a significantly greater incentive value than low-incentive conditions (for both choice and nonchoice comparisons: Wilcoxon z = 3.06, p < 0.005). B, Average subject ratings of the difficulty of making choices relating to menu items in the high- and low-incentive categories. The rating scale ranged from 1 to 5, with lower scores indicating a greater difficulty (Diff.) in selecting a goal. Subjects found it significantly more difficult to make choices regarding high-incentive menu items than low-incentive items (Wilcoxon z = 2.47, p < 0.05).
- Figure 2.
Significant rCBF changes in the main effect contrast of incentive value. A, A region of the left amygdala (x = -16, y = -4, z = -14) showed increased rCBF in the high-incentive condition. A similar region of the left amygdala (x = -16, y = -6, z = -18) showed a significant covariation of activity with subject-rated incentive value of the menu items (see Fig. 4 A). B, A region of the left medial orbitofrontal cortex (x = -8, y = 44, z = -20) also showed increased rCBF in the high-incentive condition.
- Figure 3.
Significant rCBF changes in the main effect contrast of choice (A and C) and in the interaction between incentive value and choice (B). A, An area of left medial orbitofrontal cortex (x = -8, y = 36, z = 16) showed significantly greater rCBF in choice trials over no-choice trials. This peak is in a location similar to the one observed for the main effect contrast of incentive value (Fig. 2 B). B, A region of the right lateral orbitofrontal cortex (x = 48, y = 52, z = -14) showed increased activity for the incentive value × choice interaction, specifically when subjects selected between high-incentive alternatives. C, Significant changes in rCBF were also seen in the medial striatum (x = 16, y = 14, z = 4) in the main effect contrast of choice.
- Figure 4.
Correlations between rCBF and subject-rated behavioral measures. Open circles, Low incentive condition; filled circles, high incentive condition. A, rCBF in the amygdala (x = -16, y = -6, z = -18) showed a significant covariation with the subjects' own ratings of the incentive value of menu items such that the greater the incentive value rating the greater the rCBF (Spearman's rho = 0.28). B, rCBF in the left medial orbitofrontal cortex (x = -14, y = 42, z = -24) covaried significantly with choice difficulty (x-axis: greater choice difficulty is indicated by a lower rating). The more difficult the subjects rated the selection, the greater the rCBF in this brain region (Spearman's rho = -0.39).
