Xiaojun Bao, Eva Gjorgieva, Laura K. Shanahan, James D. Howard, Thorsten Kahnt, and Jay A. Gottfried. Grid-like Neural Representations Support Olfactory Navigation of a Two-Dimensional Odor Space. Neuron(2019), https://doi.org/10.1016/j.neuron.2019.03.034 

Grid cells in entorhinal cortex underlie spatial orientation and path finding. Baoet al. show that entorhinal grid-like codes with behavioral relevance emerge when humans mentally navigate an olfactory landscape, highlighting potential neural mechanisms for locating odor sources in odiferous environments.

Highlights

• How the human brain supports navigation in an odorous landscape is poorly understood

• Subjects learn to orient within a 2D intensity space defined by two different odors

• Odor navigation elicits grid-cell-like activity in prefrontal and entorhinal cortices

• Findings suggest a mechanism by which the brain constructs olfactory cognitive maps

Fig. Experimental Design and Navigation Performance. Source: Bao et al. 2019.

In this study, they asked human subjects to mentally navigate along a trajectory defined by a “start” odor and an “end” odor and to indicate whether their predicted translation corresponded to the veridical end odor. Success on this task requires access to an internalized map of odor space, and their behavioral data revealed above-chance accuracy in orienting within this space. They demonstrate that grid-like representations with hexagonal periodicity emerged in ERC and ventromedial prefrontal cortex (vmPFC) during olfactory navigation, with grid strength in ERC correlating with behavioral performance across subjects. Their findings reveal that two-dimensional arrays of odor intensities, which themselves cannot be topographically encoded as a set of Cartesian coordinates on the olfactory epithelial sheet, nevertheless map onto grid-like scaffolds that can support spatial orientation and route planning within an olfactory space.

For further info, please read the paper Bao et al. 2019.

Xiaojun Bao, Eva Gjorgieva, Laura K. Shanahan, James D. Howard, Thorsten Kahnt, and Jay A. Gottfried. Grid-like Neural Representations Support Olfactory Navigation of a Two-Dimensional Odor Space. Neuron(2019), https://doi.org/10.1016/j.neuron.2019.03.034