Abstract
Many decisions are based on an internal model of the world. Yet, how such a model is constructed from experience and represented in memory remains unknown. We test the hypothesis that reward shapes memory for sequences of events by retroactively prioritizing memory for objects as a function of their distance from reward. Human participants encountered neutral objects while exploring a series of mazes for reward. Across six data sets, we find that reward systematically modulates memory for neutral objects, retroactively prioritizing memory for objects closest to the reward. This effect of reward on memory emerges only after a 24-hour delay and is stronger for mazes followed by a longer rest interval, suggesting a role for post-reward replay and overnight consolidation, as predicted by neurobiological data in animals. These findings demonstrate that reward retroactively prioritizes memory along a sequential gradient, consistent with the role of memory in supporting adaptive decision-making.
Highlights
Many decisions are based on an internal model of the world
The hippocampus, known for its role in longterm episodic and spatial memory, is likely to contribute to the sort of structured associations that underlie the construction of a world model[1,9,13,14,15,16,17]
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Sequential proximity. Together, these findings demonstrate that both recognition memory and spatial memory for neutral events encountered during goal-directed exploration are retroactively modulated by reward
Summary
Many decisions are based on an internal model of the world. Yet, how such a model is constructed from experience and represented in memory remains unknown. We find that reward systematically modulates memory for neutral objects, retroactively prioritizing memory for objects closest to the reward This effect of reward on memory emerges only after a 24-hour delay and is stronger for mazes followed by a longer rest interval, suggesting a role for post-reward replay and overnight consolidation, as predicted by neurobiological data in animals. Theoretical work has suggested that the role of the hippocampus in building a world model may be linked to its broader role in relational and temporal memories for individual events[18] It remains unknown whether and how memory for sequences of events is shaped by reward in humans. Rewards have been shown to increase the amount of reverse replay, suggesting a mechanism by which rewards could selectively strengthen memory for the preceding neutral events[22,23]
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