Fig. 3.

FoxP1 neurons in the RMTg, but not other midbrain regions, project to the VTA and SNc in rats. a-g. FoxP1 is found throughout the midbrain, but is particularly dense in a region closely matching previous descriptions of the RMTg (each circle = 1 cell). h-n. Neurons labeled with retrograde tracer (CTB) from the VTA (injection site in Fig. 1h) are found throughout the midbrain, but particularly in the FoxP1-dense region, where neurons double-labeled for FoxP1 and CTB are abundant. Magenta dashed lines indicate the RMTg. Translucent blue shows location where heavy CTB fiber expression precluded accurate neuronal labeling. o-u. Neurons labeled with a retrograde tracer (FG) from the SNc (injection site in Fig. 1h) are also found throughout midbrain, although neurons double-labeled for FoxP1 and FG are prominent in the lateral extent of the RMTg. Neurons triple-labeled for FoxP1, CTB, and FG are also shown. Anatomical landmarks are noted, including the red nucleus (R), interpeduncular nucleus (IPN), superior cerebellar and ventral tegmental decussation, and anterior tegmental nucleus (ATg). Scalebar = 1 mm.