brain stem afferents to the advr were found from the laminar nucleus of the torus semicircularis ( possibly comparable to the mammalian periaqueductal gray ) , from the midbrain reticular formation , from the substantia nigra ( pars compacta and reticulata ) and the adjacent ventral tegmental area , from the nucleus raphes superior , from the locus coeruleus , from the parabrachial region , from the nucleus of the lateral lemniscus and even from the most caudal part of the brain stem ( a few neurons in the nucleus of the solitary tract and lateral reticular formation , possibly comparable to the mammalian a2 and a1 groups , respectively ) .
C0006121
brain stem
C0034671
raphes