Fig. 1.

Photograph of a dissected rat brain dorsal side up. The cerebellum has been removed so that the brainstem and proximal spinal cord are visible. Red lines delineate the area in the pons from which slices were taken to study the locus coeruleus (LC). Blue lines define the area spanning the pons and medulla from which the slices containing retrotrapezoid nucleus (RTN) were taken. Green lines show the area in the medulla from which slices were made to study the nucleus tractus solitarii (NTS). Right: drawings of representative transverse slices indicating the location of the LC (top), RTN (middle), and NTS (bottom).