Seven C. elegans brain maps had more mirrored chemical edges than sampled controls with fixed degrees and four contact area bins

We tested chemical wiring among the same 150 embryonic neurons in seven C. elegans brain maps. The maps span birth to adulthood. A mirrored edge joins the left-right partners of the source and target neurons. Each control kept every neuron's input and output connection counts, allowed edges only at recorded physical contacts, and kept edge totals in four contact area bins. The measured fraction of edges with a mirrored partner was 66.7 to 74.7 percent. Control means were 33.0 to 46.5 percent. Each measured score exceeded all 1,000 saved control scores for that map. A three-synapse threshold and independent-edge models gave the same direction. The four-bin chains passed the stated score and source-overlap checks. These checks do not prove full graph-space coverage. Some eight-bin chains remained slow; their limits are reported. The work adds contact area controls to prior bilateral wiring studies. These graph constraints do not account for the recorded mirror structure within the tested reference. The result does not identify a biological cause or estimate variation between animals. Code, source hashes, sampled results, figures, and repeat instructions are preserved. Original source data remain at pinned public URLs.

Caenorhabditis elegans · bilateral symmetry · physical contact · contact area · development · graph reference models