Vestibular and medullary brain stem afferents to the abducens nucleus in the cat.

Brain stem neurons that project to the abducens nucleus (nVI) were labeled by the technique of retrograde transport of horseradish peroxidase (HRP). Following iontophoresis of HRP into nVI a large number of labeled cells are found in the ipsilateral vestibular nuclear complex, extending from the rostral medial vestibular nucleus into the ventral lateral vestibular nucleus. A smaller number of HRP-positive cells are also found in the contralateral medial vestibular nucleus. In addition, labeled cells are localized to the contralateral dorsomedial gigantocellular tegmental field as well as the nucleus praepositus hypoglossi of both sides, evidence that these neuronal groups may also be involved in eye movement control.