Olfactory Coding in the Honeybee Lateral Horn

Highlights

• Calcium imaging recordings of the insect LH reveal odor-specific maps

• Odor-similarity relationships are mostly conserved between the AL and the LH

• Odor maps in the LH predict bees’ olfactory behavior

• Information about different pheromones is segregated in the honeybee LH

Summary

Olfactory systems dynamically encode odor information in the nervous system. Insects constitute a well-established model for the study of the neural processes underlying olfactory perception. In insects, odors are detected by sensory neurons located in the antennae, whose axons project to a primary processing center, the antennal lobe [1, 2]. There, the olfactory message is reshaped and further conveyed to higher-order centers, the mushroom bodies and the lateral horn [3, 4, 5]. Previous work has intensively analyzed the principles of olfactory processing in the antennal lobe and in the mushroom bodies [6, 7, 8, 9]. However, how the lateral horn participates in olfactory coding remains comparatively more enigmatic. We studied odor representation at the input to the lateral horn of the honeybee, a social insect that relies on both floral odors for foraging and pheromones for social communication [10, 11]. Using in vivo calcium imaging, we show consistent neural activity in the honeybee lateral horn upon stimulation with both floral volatiles and social pheromones. Recordings reveal odor-specific maps in this brain region as stimulations with the same odorant elicit more similar spatial activity patterns than stimulations with different odorants. Odor-similarity relationships are mostly conserved between antennal lobe and lateral horn, so that odor maps recorded in the lateral horn allow predicting bees’ behavioral responses to floral odorants. In addition, a clear segregation of odorants based on pheromone type is found in both structures. The lateral horn thus contains an odor-specific map with distinct representations for the different bee pheromones, a prerequisite for eliciting specific behaviors.