Figure 6.

(A) The PVH projects densely to the pre-locus coeruleus nucleus (pre-LC) (red, PHAL-immunoreactive axons), and not to the LC proper (ice-blue, TH-immunoreactive neurons) except for an occasional fiber as shown in this sagittal section. The region targeted by the PVH is also separate from the cholinergic neurons of the LDT (green) (Case #2697). Insert drawing showing the position and plane of this sagittal section. Scale bar = 100 μm.

(B) The PVH projection to the superior salivary nucleus (SSN) is shown in the sagittal plane (Case #2511; see Fig. 7 for injection site). The SSN contains a cluster of small, cholinergic parasympathetic preganglionic neurons (green, ChAT), centered just rostral and dorsolateral to the large motor neurons of the facial nucleus (VII, green labeled ChAT neurons) and bordered ventrally by A5 noradrenergic neurons (ice-blue, TH) running above the lateral superior olive. A few PVH axons were seen in the A5 noradrenergic cell group and an occasional fiber produced a small number of varicosities that contacted their TH-ir dendrites (not shown). Insert line drawing was adapted from Paxinos and Watson (1998) with modifications. Scale bar = 100 μm.