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Poster C160 in Poster Session C - Friday, August 9, 2024, 11:15 am – 1:15 pm, Johnson Ice Rink
Multi-goal spatial navigation is mediated by predictive representations with episodic replay in the human brain
Christoffer J. Gahnstrom1 (), Russell A. Epstein1; 1University of Pennsylvania
What are the neural and computational mechanisms underlying human spatial navigation? Previous studies have suggested that reward prediction and replay might underlie key navigational components such as credit assignment, memory consolidation, and planning. However, these mechanisms are usually tested with relatively simple paradigms, making it is unclear what role they might play in ecologically realistic navigational tasks involving rapidly changing goal locations. To investigate this issue, we scanned participants (N=15) with fMRI while they performed a “taxi-cab” task in a virtual city with multiple possible goals. We found that a successor representation model incorporating episodic replay (SR-DYNA) best fit the observed human behavior. To identify the possible neural systems underlying SR-DYNA, we analyzed BOLD activity in terms of several components of the model. We observed parametric tracking of successor state values in anterior hippocampus, parametric tracking of successor prediction error in a network of cortical regions previously implicated in visuospatial memory, and evidence for remote context-dependent episodic replay in the posterior hippocampus. Our results provide behavioral and neural evidence for predictive representations imbued with episodic reactivations as a plausible mechanism of human flexible navigation.
Keywords: spatial navigation reinforcement learning successor representation computational modeling