Parallel mechanisms of visual memory formation across distinct regions of the honey bee brain

Authors: Avalos, Arian; TRANIELLO, IAN - University Of Illinois; PEREZ CLAUDIO, EDDIE - University Of Puerto Rico; GIRAY, TUGRUL - University Of Puerto Rico

Submitted to: Journal of Experimental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2021
Publication Date: 10/8/2021
Citation: Avalos, A., Traniello, I.M., Perez Claudio, E., Giray, T. 2021. Parallel mechanisms of visual memory formation across distinct regions of the honey bee brain. Journal of Experimental Biology. 224(19):jeb242292. https://doi.org/10.1242/jeb.242292.
DOI: https://doi.org/10.1242/jeb.242292

Interpretive Summary: Our understanding of how a memory is formed in honey bee brains is limited. In this study we used a negative reinforcement assay together with measures of the relative amounts of target genes to analyze how visual memory may be formed in the honey bee brain. For our analysis of gene expression we focused on three genes, two (CREB and CaMKii) which have been well studied as indicators of memory processes in the brain, and a novel gene (fen-1) involved in negatively-reinforced learning in other animals. Using this approach, we saw that memory process in the honey bee brain occur across different tissues and even involve parts of the brain, such as the optic lobes, previously thought to act only as signal reception centers.

Technical Abstract: Visual learning is vital to the behavioral ecology of the Western honey bee (Apis mellifera). Honey bee workers forage for floral resources, a behavior that requires the learning and long-term memory of visual landmarks, but how these memories are mapped to the brain remains poorly understood. To address this gap in our understanding, we collected bees that successfully learned visual associations in a conditioned aversion paradigm and compared gene expression correlates of memory formation in the mushroom bodies, a higher-order sensory integration center classically thought to contribute to learning, as well as the optic lobes, the primary visual neuropil responsible for sensory transduction of visual information. We quantitated expression of CREB and CaMKii, two classical genetic markers of learning and fen-1, a gene specifically associated with punishment learning in vertebrates. As expected, we report substantial involvement of the mushroom bodies for all three markers but additionally demonstrate an unexpected involvement of the optic lobes across a similar time course. Our findings imply the molecular involvement of a sensory neuropil during visual associative learning parallel to a higher-order brain region, furthering our understanding of how a tiny brain processes environmental signals.