Subcluster analyses of the dopaminergic (SN/VTA, cluster 4, 919 cells) and cholinergic (GP/NB, cluster 1, n=218 cells) clusters revealed that dopaminergic neurons were indeed more heterogeneous than the cholinergic neurons (DA: 6 biological ICs, 9 subclusters; ACh: 2 biological ICs, 2 subclusters)(Figure 6A,F). While aspects of DA diversity related to spatial positioning – for example, delineating the dorsal (IC 10) from ventral (IC 12) VTA (Figure 6L–N) - cholinergic neurons exhibited only a Neurofilament-like signal (IC 4), with no spatial component (Figure 6O,P). Thus, DA neurons are more transcriptionally regionalized than cholinergic neurons. Sampling cholinergic neurons from other areas of the basal forebrain (Zaborszky et al., 2013) could reveal additional signals.
