Execution of new trajectories toward a stable goal without a functional hippocampus.

Adrian J Duszkiewicz, Janine I Rossato, Andrea Moreno, Tomonori Takeuchi, Miwako Yamasaki, Lisa Genzel, Patrick Spooner, Santiago Canals, Richard G M Morris

Hippocampus 2023 Jun

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The hippocampus is a critical component of a mammalian spatial navigation system, with the firing sequences of hippocampal place cells during sleep or immobility constituting a "replay" of an animal's past trajectories. A novel spatial navigation task recently revealed that such "replay" sequences of place fields can also prospectively map onto imminent new paths to a goal that occupies a stable location during each session. It was hypothesized that such "prospective replay" sequences may play a causal role in goal-directed navigation. In the present study, we query this putative causal role in finding only minimal effects of muscimol-induced inactivation of the dorsal and intermediate hippocampus on the same spatial navigation task. The concentration of muscimol used demonstrably inhibited hippocampal cell firing in vivo and caused a severe deficit in a hippocampal-dependent "episodic-like" spatial memory task in a watermaze. These findings call into question whether "prospective replay" of an imminent and direct path is actually necessary for its execution in certain navigational tasks. © 2023 The Authors. Hippocampus published by Wiley Periodicals LLC.

Citation

Adrian J Duszkiewicz, Janine I Rossato, Andrea Moreno, Tomonori Takeuchi, Miwako Yamasaki, Lisa Genzel, Patrick Spooner, Santiago Canals, Richard G M Morris. Execution of new trajectories toward a stable goal without a functional hippocampus. Hippocampus. 2023 Jun;33(6):769-786