A, photomicrography showing the typical site anterograde neuronal tracer injection PHA‐L in the PPTg. B, schematic drawing showing the location PHA‐L injections (n = 4) in the region of the PPTg. C, E and F, photomicrographs showing varicosities in the region of the RTN (C); raphe pallidus (E) and Kölliker‐Fuse region (F). D, schematic drawing showing varicosities in RTN regions. Aq, aqueduct mesencephalic; KF, Kölliker‐Fuse; LPBN, lateral parabrachial nucleus; py, pyramidal tract; RPa, raphe pallidus; scp, superior cerebellar peduncle; Sp5, spinal trigeminal nucleus; VMS, ventral medullary surface; VII, facial motor nucleus. Scale bar = 1 mm in (A), (B) and (D); 100 μm in (C) and 300 μm in (E) applied to (E) and (F). [Color figure can be viewed at wileyonlinelibrary.com]