Representative schematic illustration of the microinjection sites for drug administration into the VL PAG (A) and electrode positions within RVM (B). Coronal brain slices containing the VL PAG and recording sites into the RVM were processed after the experiment for histological analysis. The numbers above the illustration show the distance from the bregma (Paxinos and Watson, 1998). Black squares indicate microinjection site tips into the VL PAG and white squares those intentionally performed outside the PAG for placement controls (A). Circles indicate electrode tips in the RVM, in particular white circles represent ON cells and black circles the OFF cells with overlapping tip positions indicated with a single symbol (B). RMn, RGcn and RGcnα refer to nucleus raphe magnus, nucleus reticularis paragigantocellularis, nucleus reticularis gigantocellularis pars α, respectively.