Locomotor action sequences impact the scale of representation in hippocampus and posterior parietal cortex

The hippocampus and posterior parietal cortex are implicated in both episodic memory and encoding of position in an environment. In the present study, we examine the impact of locomotor behaviors associated with movement in both the horizontal and vertical dimensions on population activity patterns in these two brain structures. We utilized a five-looped, squared spiral track containing stair segments, ramp segments, and flat segments. In addition to encoding locations along the full route, posterior parietal cortex population activity demonstrates strong pattern recurrence for similar action types at different locations in the environment. Additionally, posterior parietal and hippocampal neurons exhibit parallel modulation in the scale of representation that follows behavioral dynamics required for track traversal. These findings build on prior work examining spatial mapping in the vertical dimension and provide a better understanding of how a series of actions and visited locations can be coordinated in the generation of episodic memory.