Hippocampus maintains a flexible and coherent map under reward flavor-landmark cue conflict.

Abstract

Animals predominantly use salient visual cues (landmarks) for efficient navigation over other sensory modalities. When the relative position of the visual cues is altered, the hippocampal population exhibits heterogeneous responses and constructs context-specific spatial maps. Another critical factor that can strongly modulate spatial representation is the presence of reward. Reward features can drive behavior and are known to bias spatial attention. However, it is unclear whether reward flavors are used for spatial reference in the presence of distal cues and how the hippocampus population dynamics changes when the association between reward flavors and distal cues is altered. We investigated these questions by recording place cells from the CA1 while the rats ran in an environment with the conflicting association between reward flavors and distal cues. We report that the hippocampal place cells coherently and dynamically bind to reward flavors or distal cues across sessions, but not simultaneously suggesting the use of a single spatial map. We found that place cells maintained their spatial offset in the cue conflict conditions, thus showing a robust spatial coupling featuring an attractor-like property in the CA1. When the textures were added on the track, the coherency of the CA1 is degraded, as the hippocampus showed a heterogeneous response and weak spatial coupling of co-recorded cells suggesting a break away from the attractor network. These results indicate that reward flavors alone may be used for spatial reference but may not cause sufficient input difference to create context-specific spatial maps in the CA1.