The Neural Control of Vision

E. The Striate Cortex

Figure 9 shows a top view of the monkey cortex with some of the major landmarks labeled. The primary visual cortex, most commonly referred to as V1, is in the posterior, occipital region of the brain, demarcated by the lunate sulcus. The contralateral half of the visual field is laid out in a neat, topographic order in this structure. The gray matter in the cortex of monkeys is about 2mm thick and divides into several layers. The major input from the LGN is to the intermediate layers (4c alpha and beta).

In V1 the input from the LGN is dramatically reorganized as discovered by the Nobel Laureates David Hubel and Torsten Wiesel. The major transforms are orientation, direction, and spatial frequency selectivity, as well as convergent inputs from the two eyes, from the ON and OFF cells, and from the midget and parasol systems.