R. Riemann et S. Reuss, PROJECTION NEURONS IN THE SUPERIOR OLIVARY COMPLEX OF THE RAT AUDITORY BRAIN-STEM - A DOUBLE RETROGRADE TRACING STUDY, ORL, 60(5), 1998, pp. 278-282
The superior olivary complex (SOC), a group of interrelated brainstem
nuclei, sends efferents to a variety of neuronal structures including
the cochlea and the inferior colliculus (IC). In the present study con
ducted in rats, we sought to investigate whether single SOC efferent n
eurons project to both cochlea and IC. These neurons were identified b
y retrograde axonal transport of the neuronal tracers fluoro-gold upon
application to the cochlea and cholera toxin B subunit injected into
the central nucleus of the IC. Projections to the cochlea were found t
o stem predominantly from the ipsilateral lateral superior olive (LSO)
and medial superior olive (MSO) as well as from the bilateral superio
r paraolivary nucleus (SPO), dorsal periolivary groups (DPO) and the m
edial nucleus of the trapezoid body (MNTB). Neurons innervating the IC
were seen in the bilateral LSO and DPO, in the SPO predominantly ipsi
lateral, as well as in the ipsilateral MSO and MNTB. We further observ
ed that some neurons ill the ipsilateral LSO, and a considerable part
of those of the SPO were double-labeled. However, cells projecting to
either IC or cochlea were much more numerous than double-labeled neuro
ns.