Supplementary Figure: spread of fluorescence baseline, effect on the responses. A: Distribution of baseline fluorescence for each cell pair tested. Pairs are colored according to the "anatomical" class they belong to (overlapping, non-overlapping and self-activation). B: Same as A, but pooled by class. C: Correlations between the response signed distance and the baseline values of significantly responding pairs. Inhibitory responses are (as expected) correlated, but excitatory pairs also show a mild correlation. D: Example of distance to baseline relationship in 4 pairs. (i) PF-LCre to SMPL-L, corresponding to figure \ref{489066}Ai. (ii) GL-N1 to P-EN1, corresponding to figure \ref{489066}Aii. (iii) GL-N1 to L-Ei, corresponding to figure \ref{489066}Aiii. (iv) PF-LCre to PF-LCre.