FUNCTIONAL-ORGANIZATION OF THE PROJECTIONS FROM THE RABBITS SUPERIOR COLLICULUS TO THE LATERAL POSTERIOR NUCLEUS

The chapter reviews the major anatomical and neurophysiological findings related to the lateral posterior pulvinar (LP-P) complex. In all mammals, the LP-P complex does not receive any substantial direct projections from the retina, and the few retinofugal fibers can hardly account for the overall visual responsiveness of the LP-P complex. Its main inputs come from the mesencephalon (primarily the superior colliculus) and the neocortex (almost all visual cortical areas are reciprocally connected with the LP-P complex). In rabbits, as it is for most mammals, tecto-LP cells are located in the lower half of the stratum griseum superficiale (SGSl) of the superficial layers of the colliculus. The tecto-LP units are large, multipolar cells and their fibers terminate mainly in the upper or dorsal half of LP. Projections from the deep collicular layers to LP are also demonstrated in rabbits. This chapter attempts to test this hypothesis— that is, LP serves as a relay nucleus along an extrageniculate ascendant pathway, which originates from the superior colliculus and terminates in the visual cortex. © 1993, Academic Press Inc.