[Connection of efferent neurons and afferent vestibular nuclei in rat].

OBJECTIVE: To study the connection between the efferent and afferent vestibular neurons in the center neural system. METHODS: In the present study, a retrograde neuron tracer horseradish peroxidase (HRP) was injected into the surrounding of efferent vestibular neurons located in the inner side of the facial genu of the rat and after following 48 hours for the retrograde axonal transport of this tracer, then its presence in neurons of the brain stem was demonstrated histochemically. RESULTS: Neurons labeled with HRP were found bilaterally in both Medial vestibular nuclei (MVe) and lateral vestibular nuclei (LVe). Approximately 80% of the neurons in each were located in the MVe on the side ipsilateral to the injection. CONCLUSIONS: There is a direct connection between the efferent and afferent vestibular neurons. These findings suggest that there is an afferent-efferent feedback regulatory mechanism in the vestibular system.