Neural correlates of evidence accumulation during value-based decisions revealed via simultaneous EEG-fMRI

摘要

Current computational accounts posit that, in simple binary choices, humans accumulateudevidence in favour of the different alternatives before committing to a decision. Neuraludcorrelates of this accumulating activity have been found during perceptual decisions inudparietal and prefrontal cortex; however the source of such activity in value-based choicesudremains unknown. Here we use simultaneous EEG–fMRI and computational modelling toudidentify EEG signals reflecting an accumulation process and demonstrate that the within- andudacross-trial variability in these signals explains fMRI responses in posterior-medial frontaludcortex. Consistent with its role in integrating the evidence prior to reaching a decision, thisudregion also exhibits task-dependent coupling with the ventromedial prefrontal cortex andudthe striatum, brain areas known to encode the subjective value of the decision alternatives.udThese results further endorse the proposition of an evidence accumulation processudduring value-based decisions in humans and implicate the posterior-medial frontal cortex inudthis process.