Do superior colliculus projection zones in the inferior pulvinar project to MT in primates?

In order to determine the relationship of superior colliculus inputs to tha lamic neurons projecting to the middle temporal visual area (MT), injection s of wheat germ agglutinin conjugated with horseradish peroxidase were plac ed in the superior colliculus of three owl monkeys, with injections of Fast Blue in the MT. The locations of labelled terminals and neurons in the pos terior thalamus were related to four architectonically distinct nuclei of t he inferior pulvinar (Stepniewska & Kaas, Vis. Neurosci. 14, pp.1043-1060, 1997). Fast Blue injections in the MT labelled neurons largely in the media l nucleus of the inferior pulvinar. A few labelled neurons were found in th e adjoining central medial nucleus of the inferior pulvinar, as well as in the lateral pulvinar and the dorsal lateral geniculate nucleus. Superior co lliculus inputs were most dense in the posterior and medial nuclei of the i nferior pulvinar. There were sparser inputs to the central lateral nucleus of the inferior pulvinar, locations in the lateral and medial pulvinar, and the dorsal lateral geniculate nucleus. The results indicate that the media l nucleus of the inferior pulvinar, the major projection zone to the MT, do es not receive a significant input from the superior colliculus.