Gap junction innexin asymmetry in C. elegans suggests a diode blocking mechanism to prevent antidromic backpropagation from motor neurons to command interneurons.

In C. elegans , gap junctions between command interneurons and motor neurons mediate rapid behavioural transitions. However, antidromic backpropagation driven by the putative proprioceptive activity of motor neurons with Extended Longitudinal Neurites (ELNs) must be blocked to maintain circuit directionality. Analysing single-cell transcriptomics (CeNGEN), I identify systematic innexin gene expression asymmetry across major motor circuit electrical synapses. Presynaptic interneurons and postsynaptic motor neurons express distinct, non-overlapping innexin subunits. This molecular asymmetry suggests a rectified, diode-like gating mechanism that favours orthodromic signalling while preventing antidromic backpropagation from proprioceptive motor neurons, providing a structural framework for directional electrical transmission.