Overt visual attention modulates decision-related signals in ventral and dorsal medial prefrontal cortex

When indicating a preference between two options, decision makers are thought to compare and accumulate evidence in an attention-guided process. Little is known about this process’s neural substrates or how visual attention affects the representations of accumulated evidence. We conducted a simultaneous eye-tracking and fMRI experiment in which human subjects gradually learned about the value of two food-lotteries. With this design we were able to extend decisions over a prolonged time-course, manipulate the temporal onset of evidence, and therefore dissociate sampled and accumulated evidence. Consistent with past work, we found correlates of sampled evidence in ventromedial prefrontal cortex (vmPFC), and correlates of accumulated evidence in the prefrontal and parietal cortex. We also found that more gaze at an option increased its choice probability and that gaze amplified sampled-value signals in the vmPFC and ventral striatum. Most importantly, we found that gaze modulated accumulated-value signals in the pre-supplementary motor area (pre-SMA), providing novel evidence that visual attention has lasting effects on decision variables and suggesting that activity in the pre-SMA reflects accumulated evidence and not decision conflict. These results shed new light on the neural mechanisms underlying gaze-driven decision processes.