A cervical primary afferent input to vestibular nuclei as demonstrated by retrograde transport of wheat germ agglutinin-horseradish peroxidase in the rat.

Wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) was microiontophoretically injected into the vestibular nuclear complex of the rat. Retrogradely labeled neurons were found in ipsilateral spinal ganglia C2-C3 only if the injection site was in the caudal part of the medial vestibular nucleus (MVN). Injections into rostral parts of the MVN, the superior, lateral and descending vestibular nuclei (SVN, LVN, DVN), the nucleus of the solitary tract (STN) and the reticular formation did not result in spinal ganglion labeling. Thus, the caudal part of the MVN appears to be the main vestibular termination site for rostral cervical primary afferents.