The neural link between subjective value and decision entropy

We evaluated whether the brain organises value and confidence signals in a systematic fashion that reflects the overall desirability of decision options. If so, regions that respond positively to increases in value should also respond positively to increases in confidence. Likewise, regions that respond negatively to both value and confidence should be widespread. We strongly confirmed these predictions through a model-based fMRI analysis of a mixed gambles task that assessed subjective value (SV) and inverse decision entropy (iDE), which is related to confidence. Purported value areas more strongly signalled iDE than SV, underscoring how intertwined value and confidence are. Smooth maps tied to the desirability of actions transitioned from positive SV and iDE in ventromedial prefrontal cortex to negative SV and iDE in dorsal medial prefrontal cortex. This non-accidental organisation of SV and iDE signals was found across the brain and was strongest in purported value areas.