Shared synaptic sites gave no clear added co-activity alignment in two adult worm maps after fixed-count controls

We tested whether neurons that share chemical synaptic sites have stronger signed co-activity beyond source-to-target contact counts. We linked two partial adult C. elegans maps to published calcium correlations from 40 other animals. The common sample had 5,590 pairs and 114 cells. After cell, geometry and wiring controls, partial correlations with behavior-regressed co-activity were 0.046 and 0.034. However, observed alignment scores were inside fixed-count site-swap ranges. Upper-tail ranks were 0.638 and 0.744 from two chains of 500 draws per map. Raw activity and first differences also gave no clear positive excess. Thus positive fitted slopes did not establish an added effect of site grouping under these controls. This is not an equivalence test. Different animals, slow calcium sampling, partial maps and uncontrolled local site geometry limit inference. Code, exact input hashes, all swap scores, source checks and a figure support reproduction.

C. elegans · polyadic synapses · structure-function · shared input · calcium imaging · fixed-margin controls · null result