Earlier clinical work, fortified by experiments in monkeys, gave birth to the idea of two distinct visual processing streams. Both originate in the primary visual cortex but then divide to innervate different regions of the cortex dedicated to higher visual and cognitive functions. One flows through V2 and V3 into the inferior temporal cortex and the fusiform gyrus. This is the perceptual, ventral, or what pathway. The other, the action, dorsal, or where pathway, delivers data to the visual-motor regions in the posterior parietal cortex.
