Barry E. Stein

Chapter 13 Corticotectal relationships: direct and “indirect” corticotectal pathways

Publisher Summary The chapter explains direct corticotectal projections to understand the anatomical substrate and the physiological mechanisms by which they interact. The lateral suprasylvian (LS) cortex is a primary source of direct visual cortical afferents to the deep laminae of the superior colliculus (SC). The observation that visual neurons become unresponsive or unselective after LS removal is interpreted as being consequence of losing direct corticotectal excitation. There are anatomical data consistent with an indirect corticotectal route via the striatum and substantia nigra, an alternative pathway by which the visual cortical activity can access the deep aminae of the superior colliculus. Recent experiments described in the chapter provide anatomical and physiological evidence to support this hypothesis and are consistent with the idea that, in addition to a direct influence on deep lamina neurons, LS may modulate tecto spinal neurons indirectly via its projection to the striaturn.