Choice coding in frontal cortex during stimulus-guided or action-guided decision-making.

To optimally obtain desirable outcomes, organisms must track outcomes predicted by stimuli in the environment (stimulus-outcome or SO associations) and outcomes predicted by their own actions (action-outcome or AO associations). Anterior cingulate cortex (ACC) and orbitofrontal cortex (OFC) are implicated in tracking outcomes, but anatomical and functional studies suggest a dissociation, with ACC and OFC responsible for encoding AO and SO associations, respectively. To examine whether this dissociation held at the single neuron level, we trained two subjects to perform choice tasks that required using AO or SO associations. OFC and ACC neurons encoded the action that the subject used to indicate its choice, but this encoding was stronger in OFC during the SO task and stronger in ACC during the AO task. These results are consistent with a division of labor between the two areas in terms of using rewards associated with either stimuli or actions to guide decision-making.