origin and end point of a journey, a recalled story can be told in many ways, connecting the beginning and end through innumerable variations. The neuronal mechanisms that allow the selection of the optimal path in navigation in the physical world can also support the optimal selection of the sequence parts of the experienced memory. Episodic recall is rarely a true sequence of the original experience, and an episode experienced over hours, days or at longer scales can be summarized in a compressed sequence that includes many shortcuts. Theta timescale compression is also beneficial for the continuity and temporal asymmetry requirements of free recall56, for solving transitive inference problems92, for supporting higher-order associations and for solving shortcut and detour problems in both spatial and mental navigation39. Overall, the ability of the theta mechanism to flicker between current, past and future situations provides physiological support for the mental travel model and may also be the mechanism for imagining past and future situations13,53.
