A salient feature of animal olfactory systems is the presence of multiple tracts that relay information from early sensory stages to higher-order centers, raising the possibility that parallel pathways process information differentially. In Apis mellifera, there are two output projection neuron tracts, connecting the primary olfactory center with higher processing centers; this offers a system to test whether odor information is differentially routed across pathways. Building on evidence that bees recognize appetitive- and aversive-associated odorants in complex mixtures, we asked whether odor information with different hedonic values is segregated across these pathways. To address this, we combined classical conditioning with behavioral readouts, pathway-specific lesions, in vivo calcium imaging, and computational models. Our behavioral data reveal asymmetric processing of learned odorant within mixtures under different hedonic context. Moreover, severing the lateral tract impairs appetitive memory expression, whereas medial tract lesions affect aversive memory expression. Last experiments are testing how inhibitory networks shape the coding in both subsystems, in addition, with computational models to link hypotheses about circuit organization with behavioral and physiological results. Together, these findings support a functional separation between parallel olfactory pathways, with distinct contributions to the processing of odorants with different hedonic values.
