mCherry-labeled GABAergic SI (case 151) neurons (red) sparsely project to ChAT neurons (blue) of the PPT and LDT while heavily projecting to TH-labeled neurons (green) in the VTA, SNc, and RRF (A8). mCherry fibers innervate the lateral PB, the PB “waist area” and caudal PBm, but avoid the outer portion of the PBel that is dense with tyrosine hydroxylase fibers, plus the LC and LDT.