Table S1: Raw data and exact values of statistical tests. Excel file with all underlying data for all experiments of this study. The data of each subfigure are displayed in a separate sheet. Data within each subfigure are organized according to experimental condition (genotype, and where applicable, testing condition). The exact results of all statistical tests are displayed below the data of the respective subfigure.

Learning where to find nutrients while at the same time avoiding toxic food is essential for survival of any animal. Using <i>Drosophila melanogaster</i> larvae as a study case, we investigate the role of gustatory sensory neurons expressing IR76b for associative learning of amino acids, the building blocks of proteins. We found surprising complexity in the neuronal underpinnings of sensing amino acids, and a functional division of sensory neurons. We found that the IR76b receptor is dispensable for amino acid learning, whereas the neurons expressing IR76b are specifically required for the rewarding but not the punishing effect of amino acids. This unexpected dissociation in neuronal processing of amino acids for different behavioural functions provides a study case for functional divisions of labour in gustatory systems.