The cortical visual area V6 in macaque and human brains.

Single cell recording and neuro-anatomical techniques in the monkey have allowed to find a mosaic of visual areas in the temporo-parieto-occipital cortex. Thanks to neuroimaging methods, several of these areas have been mapped also in the human brain and named in humans based on homologies in their visuotopic organization with non-human primate areas. We have recently found a new, retinotopically-organized cortical visual area, that we have called V6. Area V6 was first described in the macaque monkey and then, recently, in the human. In both primates, it is located in the medial parieto-occipital region of the brain. Like the other extrastriate areas, V6 contains a retinotopic map of the entire contralateral hemifield, but unlike other extrastriate areas, V6 lacks an emphasis of the central visual field. In macaque, area V6 receives visual information directly from V1 and from other extrastriate areas of the occipital lobe, and sends visual information to several parietal areas, all belonging to the so called dorsal visual stream. The neurons of macaque V6 are very sensitive to the direction of motion of visual stimuli and act as real-motion detectors. It has been reported that patients with cortical damages which include the cortical region where human V6 is located are unable to recognize the direction of motion of visual stimuli, or to detect the visual motion per se. According to these data, we suggest that V6 is involved in the 'recognition' of movement in the visual field.