a Putative synaptic boutons (dots) identified in a 30 μm-thick transverse sections of the medulla oblongata at the level of the area postrema in a DBH-Cre mouse with floxed-ChR2mCherry AAV2 injected into the left RVLM. a1 Photomicrograph of the boxed region shown in (a). b Putative synaptic boutons identified in a transverse section of the thoracic spinal cord. b1 Photomicrograph of the boxed region drawn in (b). a, a1 The RVLM catecholaminergic neurons target the nucleus of the solitary tract (Sol) and dorsal motor nucleus of the vagus (10) but totally eschew the dorsal column nuclei (cuneate, Cu and gracile, Gr). b, b1 The catecholaminergic neurons of the RVLM target exclusively lamina X, the intermediolateral (IML) and intermediomedial cell column around the central canal (cc) but lack projections to the dorsal horn. Scale bar = 500 μm (a,b), 100 μm (a1, b1).