A cognitive map of subjective value space for human risky choice
Individuals are thought to make choices based on subjective valuations of options that integrate multiple attributes into a unified subjective value signal in the brains "value coding system." How these attributes are transformed into a subjective valuation remains poorly understood. One candidate is the "cognitive mapping system," which efficiently represents relational, multi-dimensional information and has been proposed to afford novel inferences. We develop a risky decision-making task and use fMRI to show that a two-dimensional (2D) subjective value space of reward probability and amount is represented in the cognitive mapping system as both a grid-like representation of decision vectors and a 2D "positional" code in entorhinal cortex (EC) and medial prefrontal cortex (mPFC). The strength of grid-like and subjective value representations are positively correlated, suggesting the cognitive mapping and value coding systems work in tandem. These findings bridge these systems and support a new framework for how the brain constructs values.