WHERE GOALS MEET SPACE: NEOCORTICAL-HIPPOCAMPAL INTERACTIONS ON CHEESEBOARD LEARNING TASKS

Recent research has highlighted the PPC's involvement in spatial cognition by revealing place- and goal-coding activity. Due to its connectivity, PPC has also been suggested to transform allocentric maps into self-referential egocentric maps. However, the mechanism by which PPC neurons interact locally and with the hippocampus (HC-CA1) to support spatial coding and map transformations is not understood. Here, freely foraging rats performed a dual-reference-frame cheeseboard memory task (and subsequent sleep) while simultaneously monitoring cross-area activity in PPC and CA1. In the allocentric frame of the task, both regions exhibited spatial tuning, with hippocampal cells providing a stronger spatial signal. Population rate maps showed position-modulated activity that collectively tiled task trajectories. PPC cells also formed spatial maps surrounding goals. Goal-related PPC activity flexibly scaled with behavioural context in the task, but it indicated a more drifty code than CA1.

As for next steps, we will probe task-related dynamics within the body-centered frame of the cheeseboard task, aiming to analyze latent variables that influence both population codes during awake/sleep states.