Goal-directed hippocampal theta sweeps during memory-guided navigation
During navigation animals continuously sample their surrounding space and plan trajectories to distant goals. The brain mechanisms underlying these behaviors and how they coordinate to support memory-guided navigation in open environments is not understood. Using large scale recordings from behaving rats, we found two distinct types of place cell sequences within theta cycles that encoded trajectories sweeping beyond the animal's current location: stereotypic left-right alternating sweeps and learning-dependent goal-directed sweeps. Goal-directed sweeps predicted upcoming trajectories to remembered goal locations, were coordinated with prefrontal cortex activity and preferentially replayed during sharp-wave ripples. We describe a circuit mechanism for goal-directed theta sweeps involving an egocentric goal-direction signal in a subpopulation of CA1 cells together with reduced feedback inhibition. These results indicate a flexible mechanism to support different behavioral demands during navigation.