Hippocampal representations of foraging trajectories depend upon spatial context

Overview

Model based analysis of learning and neural activity in mice trained to find reward in both a spatial, navigational and relational, non-navigational context revealed dissociable contributions of hippocampus depending upon spatial context.

Scientists

Wan-Chen Jiang

Shengjin Xu

Abstract

Animals learn trajectories to rewards in both spatial, navigational contexts and relational, non-navigational contexts. Synchronous reactivation of hippocampal activity is thought to be critical for recall and evaluation of trajectories for learning. Do hippocampal representations differentially contribute to experience-dependent learning of trajectories across spatial and relational contexts? Here we trained mice to navigate to a hidden target in a physical arena or manipulate a joystick to a virtual target to collect delayed rewards. In a navigational context, calcium imaging in freely moving mice revealed synchronous CA1 reactivation was retrospective and important for evaluation of prior navigational trajectories. In a non-navigational context, reactivation was prospective and important for initiation of joystick trajectories - even in the same animals trained in both contexts. Adaptation of trajectories to a new target was well explained by a common learning algorithm in which hippocampal activity makes dissociable contributions to reinforcement learning computations depending upon spatial context.