Figure 1.

Single unit recording from macaque orbitofrontal cortex during a social decision making task. (A) Left, trial structure. Monkeys fixated a central stimulus, then shifted gaze to T1, resulting in a fluid reward, or T2, resulting in a fluid reward and the subsequent presentation of an image. The volume of fluid reward and the image category displayed varied in a nested block design [9]. The social category of the image pool remained stationary for superblocks of approximately 60–100 trials, whereas the amount of fluid reward associated with the two targets remained stationary for blocks of ~20 trials. Right, exemplars of social image categories. (B) Monkeys differentially value distinct classes of social images. Left, image values for each image category as derived from session-by-session choice behavior. The y-axis represents the percent of juice supplement paired with T1 necessary to induce indifference between T1 and T2. The x-axis indicates the image category paired with T2. Positive values indicate that animals sacrifice juice to view an image category, whereas negative values indicate that monkeys must be “bribed” to view an image. Right, viewing time durations for each image category for the trials in which the monkey viewed an image display. Y-axis represents the percent of samples for which the monkey’s eye position fell within the confines of the presented image while that image was being displayed. *indicates p<0.05 ** indicates p<0.001. (C) Location of recording sites from all three monkeys, depicted on coronal cross sections from a macaque brain atlas [40]. Each dot represents one neuron. Cool-colored dots represent those neurons grouped into Areas 14/25 (medial OFC), and hot-colored dots represent neurons grouped into Areas 11/13 (lateral/orbital OFC). Different colors within each shad represent individual monkeys.