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. 2013 Feb 13;33(7):3202–3211. doi: 10.1523/JNEUROSCI.2532-12.2013

Figure 2.

Figure 2.

Reward–identity representations independent of predictive stimulus. A, D, Regions representing the identity of rewarding food items were identified using repetition suppression, revealing a bilateral cluster in caudal OFC. Trials in which participants repeatedly imagined the same food reward in response to two different predictive stimuli were contrasted with those in which participants imagined two different food rewards (DSSIf vs DSDIf), and the resulting effect compared with that of neutral items ((DSDIf − DSSIf) − (DSDIn − DSSIn)). Whereas this analysis enabled identification of within-trial adaptation to the identity of food rewards (A), a second contrast was used to analyze adaptation effects of repeated representation of food rewards across adjacent trials to give a measure of between-trial adaptation (D) ((DIf − SIf) − (DIn − SIn)). In both contrasts, adaptation to reward–identity is found in caudal OFC (both p < 0.05) and shown in green; the extracted ROIs in caudal OFC are overlaid for visualization and shown in blue. B, Parameter estimates (± SEM) and (C) peristimulus BOLD time courses (shaded area shows SEM) demonstrate within-trial adaptation to reward–identity for food rewards (red, SSSIf; green, DSSIf; blue, DSDIf), with relative suppression of the BOLD signal to the representation of two identical food rewards (SSSIf or DSSIf) versus two different food rewards (DSDIf). As demonstrated by the parameter estimates, no such effect is present in the neutral conditions (gray, SSSIn, DSSIn, and DSDIn). Crucially, parameter estimates and time courses were extracted from an orthogonal ROI defined based on the between-trial adaptation contrast. E, F, For those trials where the same food reward was repeatedly elicited across adjacent trials, a similar suppression in the BOLD response can be observed, providing evidence for adaptation to reward–identity between trials. Parameter estimates and time courses are shown as in B and C, except that the orthogonal ROI from which they were extracted was defined from the within-trial contrast.