Abstract
Planning is a fundamental part of navigation. The notion of a cognitive
map of space in the brain is intertwined with the idea that organisms can plan, imagine,
and mentally navigate this cognitive map to choose which routes to follow, and
to execute trajectories to reach a desired goal. Memory systems in the mammalian
brain that function to store information and remember the past also have a role in
imagining the future and planning actions; memories of the past contribute to planning
the future. This link between the past and future aligns with the role of a default
mode network in the brain, which is active both for memories and imagination. The
primary drive behind navigational planning is linked to goal representations. The
hippocampus and prefrontal cortex—core of the episodic memory and executive
functioning systems, respectively, in the mammalian brain—are key for using past
experiences to guide the future and support planning, to deliberate options leading
to goals, to execute decisions to choose a path, and to make online changes to the
navigation plan, such as rerouting. It is therefore critical to understand (a) navigational
representations in the hippocampus and prefrontal cortical regions at multiple
timescales (e.g., spatial maps, reward signals, goal coding, context and rule representations)
and (b) how interactions between the two regions support planning and
execution of navigational strategies. This chapter examines hippocampal-prefrontal
spatial representations and their interactions, especially in rodents, for navigational
planning.