Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.05.22.110312v1?rss=1 Authors: Fenyves, B. G., Szilagyi, G. S., Zsolt, V., Csaba, S., Csermely, P. Abstract: Graph theoretical analyses of nervous systems usually omit the aspect of connection polarity, due to data insufficiency. The chemical synapse network of Caenorhabditis elegans is a well-reconstructed directed network, but the signs of its connections are yet to be elucidated. Here, we present the gene expression-based sign prediction of the C. elegans connectome, incorporating presynaptic neurotransmitter and postsynaptic receptor gene expression data (3,638 connections and 20,589 synapses total). We made successful predictions for more than two-thirds of all chemical synapses and determined a ratio of excitatory-inhibitory (E:I) interneuronal ionotropic chemical connections close to 4:1 which was found similar to that observed in many real-world networks. Our open source tool ( http://EleganSign.linkgroup.hu ) is simple but efficient in predicting polarities by integrating neuronal connectome and gene expression data. Copy rights belong to original authors. Visit the link for more info