The Rostrolateral Prefrontal Cortex Mediates a Preference for High-Agency Environments.

Abstract

The ability to exert flexible instrumental control over one's environment is a defining feature of adaptive decision-making. Here, we investigated neural substrates mediating a preference for environments with greater instrumental divergence, the distance between outcome probability distributions associated with alternative actions. A formal index of agency, instrumental divergence allows an organism to flexibly obtain the currently most desired outcome as preferences change. As such, it may have intrinsic utility, guiding decisions toward environments that maximize instrumental power. Consistent with this notion, we found that a measure of expected value that treats instrumental divergence as a reward surrogate provided a better account of male and female human participants' choice preferences than did a conventional model, sensitive only to monetary reward. Using model-based fMRI, we found that activity in the rostrolateral and ventromedial PFC, regions associated with abstract cognitive inferences and subjective value computations, respectively, scaled with the divergence-based account of expected value. Implications for a neural common currency of information theoretic and motivational variables are discussed.SIGNIFICANCE STATEMENT Agency is a central concept in philosophy and psychology. While research thus far has focused on cognitive and perceptual measures of agency, recent work demonstrating a strong preference for high-agency environments indicates a salient motivational dimension. Here, using instrumental divergence, the distance between outcome distributions associated with alternative actions, as a formal index of agency, we found that brain regions associated with directed exploration and subjective value computations, respectively, were selectively modulated by a model that treated agency as a reward surrogate, over models that assigned utility only to monetary payoffs. In a subset of regions, such effects were predicted by the influence of instrumental divergence on economic choice preferences. Our results elucidate neural mechanisms mediating the utility of agency.