Figure 4: Coexpression patterns of DAT, TH, and Vmat2 in SN and VTA dopamine neurons. VTA dopamine neurons display a significantly lower DAT/TH expression ratio compared to their SN counterparts. However, there were no significant differences in DAT/Vmat2 or TH/Vmat2 between the two dopamine neuron populations. There was a trend towards a significantly higher TH/Vmat2 ratio in VTA dopamine neurons ( ). Data are expressed as mean ΔΔCt ± SEM, where the ΔCt of each gene in each region is normalized to 18S. ΔΔCt is then determined between the normalized genes for each region. Asterisks indicate significant difference relative to SN. * , ** ; .