Subjective value, not a grid-like code, describes neural activity in ventromedial prefrontal cortex during decision-making
Lee, S., Yu, L. Q., & Kable, J. W.
Across numerous studies, ventromedial prefrontal cortex (vmPFC) has been found to encode subjective value during value-based decision-making. Recently, however, activity in vmPFC has also been shown to encode hexagonal grid-cell signal used for navigation through physical as well as conceptual space. These findings raise an interesting proposal that such grid-cell signal could broadly underlie complex cognition and, specifically, may be used for comparisons between options in decision-making. In this paper, we first assess the plausibility of this idea by showing that, in theory, the activity correlated with subjective value observed in vmPFC may actually be a grid-cell signal. We then empirically test for grid-like modulation in a large fMRI dataset of individuals making intertemporal choices. Here, however, we find that grid-like model fails confirmatory tests and does not provide the best description the neural activity during decision-making. Our results constrain the type of tasks for which grid-like modulation is observed in vmPFC and further confirm that subjective value remains a good description of neural activity in vmPFC during decision-making.