Figure 3.
Sustained delay period activity in orbitofrontal cortex. A, fMRI results from the active maintenance analysis (regressor 6) demonstrating sustained activity in left OFC, x = −46, y = 26, z = −6 (arrows). Statistical parametric maps are shown superimposed onto the canonical average T1-weighted MNI brain. B, Sustained activity is displayed in the line graph representing the signal intensity time course extracted from suprathreshold voxels within a 5 mm sphere surrounding the ROIs peak activation (green, DMS trials; gray, CON trials). Blue and red horizontal bars indicate time points when sample and test faces were presented and the intervening delay period, respectively. Shaded areas indicate time points that were averaged to obtain signal amplitudes for sample, delay, and test components of the task. C, Transient dissociation between EMO and ID tasks in OFC. Greater activity was found for EMO than ID during sample face presentations. In contrast, significant delay period activity was similar for EMO and ID tasks. The bar graph represents signal difference values (DMS − CON) for sample, delay, and test. Signal intensity values for CON trials were subtracted from corresponding values for DMS trials to compute a signal difference value for each task component. D, Greater OFC activity at test for EMO_DMS trials with negative valence. During test phase face presentations within EMO trials, negatively valenced faces elicited a significantly greater signal than positively valenced faces. L, Left; R, right. Error bars indicate SEM. Asterisks indicate significant difference.