Substantia nigra projection to medullary reticular formation: relevance to oculomotor and related motor functions in the cat.

Wheat germ lectin-horseradish peroxidase was injected into the medial medullary reticular formation in 4 cats. Retrogradely labeled cell bodies were observed in the ipsilateral substantia nigra pars reticulata and bilaterally in the superior colliculus, oculomotor nucleus and fastigial nucleus of the cerebellum. The nigral projection to this reticular formation area, which receives diffuse afferents from cortex, cerebellum, oculomotor system and vestibular nucleus and projects to spinal cord, may be of some relevance in understanding the nigral role in postural, head- and eye-movement control.