(a) Schematic of AAV injection to express Cre-inducible hrGFP in Gad67-Cre mice. The dotted brain map area is shown to the right. White rectangular area is shown below. (b) Immunohistochemical studies showing expression of hrGFP in Gad67+ neurons (arrowhead), but not in the nearby DA (arrow) neurons. (c) Pie chart showing the percent of hrGFP expression in DA and non-DA neurons in the VTA (n = 4 mice). (d and e) Expression of hrGFP in VTAGad67+ neurons and some of their projected brain areas are shown. (f) Table showing the comparative scoring of hrGFP signals across different brain areas. Abbreviations- AcbC: Nucleus accumbens core, AcbSh: Nucleus accumbens shell, BLA: Basolateral amygdala, CeA: Central nucleus of the amygdala, CM: Central medial thalamic nucleus, CnF: Cuneiform nucleus, CPu: Caudate putamen (striatum), DEn: Dorsal endopiriform nucleus, DR: Dorsal raphe nucleus, IMD: Intermediodorsal thalamic nucleus, InG: Intermediate gray layer of the superior colliculus, LH: Lateral hypothalamus, LPO: Lateral preoptic area, MM: Medial mammillary nucleus, Pa4: Paratrochlear nucleus, PAG: Periaqueductal gray, PF: Parafascicular thalamic nucleus, PnO: Pontine reticular nucleus, SubB: Subbrachial nucleus, VLL: Ventral nucleus of the lateral lemniscus, VP: Ventral pallidum, Xi: Xiphoid thalamic nucleus and xscp: Decussation of the superior cerebellar peduncles. DAPI (4′,6-diamidino-2-phenylindole) staining was used to label nuclear DNA and also to assist understanding of the anatomical position of VTAGad67+ neuronal projections.