Mapping value based planning and extensively trained choice in the human brain

Abstract

Using a combination of fMRI in humans and computational modeling, the authors show that different striatal nuclei encode different kinds of decision-making information. The anterior caudate nucleus encodes the value of individual steps in a decision tree, whereas the putamen encodes values learnt during extensive training. Investigations of the underlying mechanisms of choice in humans have focused on learning from prediction errors, leaving the computational structure of value based planning comparatively underexplored. Using behavioral and neuroimaging analyses of a minimax decision task, we found that the computational processes underlying forward planning are expressed in the anterior caudate nucleus as values of individual branching steps in a decision tree. In contrast, values represented in the putamen pertain solely to values learned during extensive training. During actual choice, both striatal areas showed a functional coupling to ventromedial prefrontal cortex, consistent with this region acting as a value comparator. Our findings point toward an architecture of choice in which segregated value systems operate in parallel in the striatum for planning and extensively trained choices, with medial prefrontal cortex integrating their outputs.