Abstract: Episodic memory involves learning and recalling associations between items and their spatio-temporal context. Those memories can be further used to generate internal models of the world that enable making predictions. While the circuit mechanisms implementing those computations are not well understood, the hippocampus has been implicated in both processes. In this talk, I will describe the neural circuit dynamics and plasticity mechanisms that support the formation and use of internal models of the environment to guide flexible navigation. I will show recent results illustrating how neural population dynamics and the coordinated activity of cell assemblies encode different task variables such as space, time, and choice. I will then explain how these internal representations and rapidly deployed during behavior to guide flexible navigation and planning. I will also describe recent work from my lab in studying the neural circuit mechanisms of rodent foraging and social behaviors in natural outdoor environments, and how these studies have been enabled by novel technology we developed for months-long recording of the same neurons and miniaturized wireless neural interfaces for behaving animals.