To associate neuronal cell types with their neuotransmitters (Figures 1C, 7B, and S7 and Table S3), we trinarized the expression of genes coding for neurotransmitter transporters or enzymes crucial to their synthesis (Figure S6D, asterisks); combined with manual inspection of the expression on a single-cell level. Trinarization was carried out as described in the section above, with f = 0.05 (present in at least 5% of cells) and posterior error probability (PEP) 0.05, except for Nos1 where f = 0.2. Given a set of genes defining a neurotransmitter phenotype, we conservatively required all genes to pass the trinarization threshold. For glutamatergic neurons, we used the individual vesicular glutamate transporters (VGLUT1-3) separately.
