Hippocampal Contributions to Model-Based Planning and Spatial Memory

• Published in: Neuron (Cambridge, Mass.) Vol. 102; no. 3; pp. 683 - 693.e4
• Main Authors: Vikbladh, Oliver M., Meager, Michael R., King, John, Blackmon, Karen, Devinsky, Orrin, Shohamy, Daphna, Burgess, Neil, Daw, Nathaniel D.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 08.05.2019; Elsevier Limited
• Subjects: Adult; Animal memory; anterior temporal lobe; Anterior Temporal Lobectomy; Boundaries; Case-Control Studies; Cognitive models; Decision Making; Epilepsy; Epilepsy, Temporal Lobe - surgery; Female; Hippocampus; Hippocampus - diagnostic imaging; Hippocampus - physiology; Hippocampus - physiopathology; Hippocampus - surgery; human; Humans; Investigations; lesion; Localization; Male; memory; model-based; Planning; reinforcement learning; spatial; Spatial Learning - physiology; Spatial memory; Spatial Memory - physiology; Task analysis; Task Performance and Analysis; planning; memory; hippocampus; decision-making; anterior temporal lobe; model-based; spatial; human; lesion; reinforcement learning
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/j.neuron.2019.02.014

Little is known about the neural mechanisms that allow humans and animals to plan actions using knowledge of task contingencies. Emerging theories hypothesize that it involves the same hippocampal mechanisms that support self-localization and memory for locations. Yet limited direct evidence supports the link between planning and the hippocampal place map. We addressed this by investigating model-based planning and place memory in healthy controls and epilepsy patients treated using unilateral anterior temporal lobectomy with hippocampal resection. Both functions were impaired in the patient group. Specifically, the planning impairment was related to right hippocampal lesion size, controlling for overall lesion size. Furthermore, although planning and boundary-driven place memory covaried in the control group, this relationship was attenuated in patients, consistent with both functions relying on the same structure in the healthy brain. These findings clarify both the neural mechanism of model-based planning and the scope of hippocampal contributions to behavior. •We tested planning and spatial memory in patients with hippocampal damage and controls•Patients relied less on both model-based planning and allocentric spatial memory•The planning impairment was related to the amount of damage to right hippocampus•Planning and place memory covaried in controls but were less related in patients Testing patients with hippocampal damage, Vikbladh et al. demonstrate that model-based planning and place memory rely on a common hippocampal substrate. The study bridges the reinforcement learning and spatial memory literatures to clarify the scope of hippocampal contributions to behavior.