The Organization of Visual Cortex in Primates: Problems, Conclusions, and the Use of Comparative Studies in Understanding the Human Brain

Publisher Summary All primates appear to have a complex visual system with a hierarchy of interconnected processing areas. The first visual area, V-I or area 17, of primates is unique in that there is a laminar segregation of geniculate inputs from the M (magnocellular) and P (parvocellular) streams; a distributed system of blob-like modules with W stream geniculate inputs in most, if not all, primates; and a tendency for the segregation of geniculate inputs related to each eye into ocular dominance bands that is marginally expressed in some primates and pronounced in others. Middle temporal (MT) area is so distinctive that it is easily identified in all primates, and yet no field in non-primates, including the close relatives of primates, the archontan mammals, that have a field with all of MTs features. In diurnal macaque monkeys, squirrel monkeys, and cebus monkeys, MT is well displaced from the second visual area, V- II, border into the temporal lobe. Possibly, an even greater displacement exists in humans.