Fig. 4.

(A) Low power image of VTA through fluorescent filter to show TH immunoreactivity. Scale bar=400 µm. (Bl) Higher magnification of areas enclosed by right red box in (A) through fluorescence filter to show TH immunoreactivity (left, B1) and merged fluorescence filters (right, B12) to show retrogradely labeled cells. (B2) Higher magnification of areas enclosed by left red box in (A) through fluorescence filter to show TH immunoreactivity (top, Bl) and merged fluorescence filters (bottom, B12) to show retrogradely labeled cells. Arrowheads and roman numerals indicate locations of cells represented in (C). Scale bars for B = 200 µm. (C) High power images of individual retrogradely labeled VTA neurons indicated by arrowheads in B through various fluorescence filters to show tracers with which they were labeled and therefore to which subregions of PFC they project. Individual columns show the same cell through various fluorescence filters; individual rows show different cells through the same fluorescence filter. Scale bar=20 µm. VTA, ventral tegmental area; FR, fasciculus retroflexus; MP, mammilary peduncle; TH, tyrosine hydroxylase; OFC, orbitofrontal cortex; mPFC, medial prefrontal cortex; ACC, anterior cingulate cortex.