Figure 1.

Photomicrographs of macaque brain sections showing injection of biotinylated rhodamine dextran confined to the superior colliculus (SC). Sections are shown stacked consecutively from bottom right to top left covering ∼1.2 mm distance. Orientation of stacked sections is from inferior (bottom right) to superior (top left); orientation of individual sections is from rostral (bottom edge of section) to caudal (top edge). Inset at top right shows a drawing of macaque brain with the plane of sectioning indicated by the black line. Inset micrograph at right illustrates distinct terminal labeling observed surrounding the cell bodies of neurons within the magnocellular LGN layers, presumably originating from axon collaterals of ganglion cells retrogradely labeled by tracer injections made in the superior colliculus.