Goal-directed hippocampal theta sweeps during memory-guided navigation

During navigation, animals continuously sample their environment and plan routes to distant goals. Flexible navigation requires neural dynamics capable of rapidly deploying task-relevant information to direct behavior toward goals. Hippocampal spiking sequences within theta cycles, which sweep along spatial trajectories ahead of the animal, serve as a potential candidate. Previous research identified experience-independent, left-right-alternating theta sweeps as a mechanism for local spatial sampling. However, it remains unclear whether theta sweeps also facilitate trajectory evaluation toward distant, remembered goals. In rats performing goal-directed navigation in an open arena, we identified a distinct form of learning-dependent theta sequences that predicted upcoming goal-directed trajectories. These sequences coordinated with prefrontal cortical activity and were preferentially replayed during sharp-wave ripples. We described a circuit mechanism whereby egocentric goal-direction signals, combined with reduced feedback inhibition, generated goal-directed theta sweeps. Experience-dependent and goal-dependent theta sweeps thus provide a flexible mechanism for goal-directed navigation in open environments.