Chemical inputs from cells near the light spot gave no clear link to positive calcium responses in a fixed test of 2,417 distant neuron pairs in immobilized C. elegans

We tested a possible chemical relay after targeted neural activation in immobilized transgenic C. elegans. Cells near the light spot could send signals to distant response cells. We used measured image distances and two adult C. elegans maps to score these routes. The main panel had 19,853 observations from 1,585 stimulations, 2,417 ordered neuron pairs and 101 recordings. Pair separation was at least 20 micrometres in the image plane. The model held each neuron pair and each stimulation event fixed. It controlled direct image distances, fluorescence noise and cell-label coverage. Under an assumed Gaussian footprint with planar and axial SDs of 3 and 6 micrometres, the positive-response term was +0.117 percentage points per score SD. Its pointwise 95% interval was -0.176 to +0.410. All five probability intervals included zero. Continuous-response slopes were small and positive. Two width checks had unadjusted p values below 0.05, but no width passed five-test Holm correction. Separate anatomical maps, a stricter light-spot distance rule and an alternate count export gave similar probability results. The test found no clear support for this fixed chemical relay score. It does not exclude unintended activation, small effects, or other signal routes. The package preserves source tables, code, figures, complete results, source hashes and repeat instructions.

C. elegans · connectome · calcium imaging · optogenetics · chemical synapses · signal propagation · recording geometry · fixed effects · reproducible research