Lingering Options: How Choice Context Shapes Hippocampal Memory Representations

There exists a dynamic interplay among the neural mechanisms that underlie decision-making and memory in the brain, with mounting evidence suggesting that the anterior hippocampus plays a role in how we represent past experiences as well as how we engage in choice behavior. A key question, then, is how the anterior hippocampus represents memories of our choices. Prior research has identified conceptual similarity between choice options as a critical factor influencing hippocampal involvement in decision-making. Building on this, we investigated how remembering chosen versus unchosen options from conceptually similar and dissimilar choice scenarios affects hippocampal memory representations. In a preregistered fMRI study, participants made a series of decisions between pairs of food options that were either conceptually similar or dissimilar and then completed an item recognition memory task for the previously presented options. Using representational similarity analysis, we examined hippocampal overlap during recognition among chosen and unchosen options from both similar and dissimilar choice trials. Our key finding was higher anterior but not posterior hippocampal similarity when remembering options from the conceptually similar compared with conceptually dissimilar trials, and further analysis showed that this was not explained simply by concept overlap. Complementary multivariate whole-brain analysis further revealed neural patterns of covariance that distinguished between memory for chosen/unchosen options across the similar and dissimilar trials. Taken together, these findings suggest that the way the brain-particularly the anterior hippocampus-stores and retrieves memories is profoundly impacted by the context in which deliberation occurs.