Fig. 4: Activity of VTA DA neurons is necessary and sufficient to induce PL glutamatergic neurons to switch their transmitter identity.

a Experimental protocol. Cartoon after⁷⁵. b Expression of PSAML-GlyR-GFP in the VTA. Scale bar, 500 μm. c VGLUT1 and GAD1 expression in the PL following saline/drug treatment combined with chemogenetic inhibition of VTA dopaminergic neurons. (Blue rectangles) neurons co-expressing VGLUT1 and GAD1 illustrated at high magnification in the insets. Scale bar, 50 μm. d Quantification of GAD1⁺/VGLUT1⁺ neurons in the PL (n = 4 mice). e Experimental protocol. Cartoon after⁷⁵. f Expression of ChR2-YFP in the VTA and fiber ___location. Scale bar, 500 μm. g VGLUT1 and GAD1 expression in the PL following 10 days of VTA optogenetic stimulation. (Insets) Higher magnification of neurons co-expressing VGLUT1 and GAD1. Scale bar, 50 μm. h Quantification of GAD1⁺/VGLUT1⁺ neurons in the PL (n = 5 mice). Statistical significance (****P < 0.0001) was assessed using two-way ANOVA with Tukey’s multiple-comparisons test (d) and two-sided unpaired t-test (h). Data are presented as mean ± SEM. The exact p-values and additional statistical details can be found in Supplementary Table 4.