Distinct brain regions map olfactory and visual spaces

Abstract

The hippocampus contains a multisensory cognitive map that incorporates spatial cues from across the senses, such as vision and olfaction. However, how primary sensory information transforms along pathways to the hippocampus into this single, combined map is largely unknown. Specifically, does the hippocampus generate or inherit the multisensory map of space? Here, we used multisensory virtual reality and large-scale functional imaging to determine if and how the main input regions to hippocampus, the lateral and medial entorhinal cortices (LEC and MEC, respectively), map olfactory and visual sensory spaces in navigating mice. We discovered that, in contrast to multisensory mapping in the hippocampus, LEC preferentially maps olfactory space while MEC preferentially maps visual space, regardless of the behavioral relevance of the spaces. This establishes the existence of largely independent brain maps for different sensory spaces, suggesting that the hippocampus builds the cognitive map by combining modality-specific maps from pre-synaptic cortical regions.