Abstract
Different primate species, including humans, have evolved by a repeated branching of lineages, some of which have become extinct. The problem of determining the relationships among cortical areas within the brains of the surviving branches (e.g. humans, macaque monkeys, owl monkeys) is difficult for several reasons. First, evolutionary intermediates are missing, second, measurement techniques are different in different primate species, third, species differ in body size, and fourth, brain areas can duplicate, fuse, or reorganize between and within lineages. In addition, invasive studies in non-human primates suggest that visual areas can vary substantially in size, specific orientation, and sometimes even neighbor relations between individuals. After reviewing methodological issues, current ideas about the homologies of cortical visual areas in primates are presented. Comprehensive maps from single human individuals are then described to document evidence for additional retinotopic visual areas beyond those already reported in posterior cingulate cortex, dorsal parietal cortex, the post-central suclus, the posterior lateral sulcus, and the fusiform gyrus.