Synapse volume raised adult match rates when count ties were broken to keep half the chemical edges in four early C. elegans maps

We tested whether measured synapse volume adds information to synapse count when selecting early chemical connections that occur in two adult C. elegans brains. We used four early maps at 0, 5, 8 and 16 hours from Witvliet et al. (2021), with a fixed panel of 162 embryonic neurons. Each rule kept floor(N/2) of the observed directed edges. Uniform weights gave exact expected results for count ties. Ranking by count then target-allocated active-zone volume raised the fraction found in both adults from 89.30 to 92.58%, 89.89 to 92.36%, 89.89 to 90.52%, and 90.98 to 91.43%. The gains were 3.28, 2.47, 0.63 and 0.45 percentage points. All four gains stayed positive at 25% and 75% retention and when at least two adult annotations were required. Volume alone performed worse than count in three maps. Adding volume after own count then mirror count gave gains from -0.18 to 0.26 points. Adding it after the sum of own and mirror counts gave gains of 0.18 to 2.20 points. Removing single neuron classes removed the small gains in some 8-hour and 16-hour comparisons. The results support a limited use of volume to resolve count ties in these files. They do not identify synapse survival or signal transmission. The comparisons share two adult animals and do not estimate a population effect. The package preserves code, aggregate measurements, selection weights, source hashes, figures and repeat instructions. Independent decimal and rational calculations checked the main results against the original inputs.

Caenorhabditis elegans · connectome · synapse volume · synapse count · edge selection · bilateral symmetry · reproducibility