Cerebral Hemisphere Regulation of Smooth Tracking

The pursuit system utilizes input from cerebral cortical areas specialized for analyzing visual motion. Three parallel pathways analyze different elements of visual information; one pathway is dedicated to motion analysis, another to spatial orientation, and a third to color discrimination. At least 13 discrete cortical areas with relinotopic maps of the visual fields have been identified in the monkey. Striate visual cortex relays signals to ipsilateral parietal and temporal lobe cortex and to the opposite cerebral hemisphere via the corpus callosum. The motion detection pathway includes the middle temporal (MT) visual area within the superior temporal sulcus. Area MT is located in occipitoparietal cortex of rhesus monkeys (it is called MT because it is located in the middle portion of the temporal lobe of owl monkeys, the species in which it was originally described), Striate cortex projects to MT both directly and indirectly via prestriate areas, V2 and V3. From MT, signals are relayed to adjacent areas of he superior temporal sulcus and parietal cortex, including the middle superior temporal visual area and inferior parietal lobule.