Our overall objective is to determine how information is processed in the cortical visual areas in primates and ultimately to ascertain the role of each cortical visual area in the behavior of primates, including man. Our principal techniques is to record with microelectrodes the responses of single neurons in the cortical visual areas to optical stimuli. We have 3 specific objectives: (1) Determine what specific types of visual information are transmitted by the two classes of neurons (Layer IVb pyramids and Meynert cells) in primary visual cortex (V-I) that project to the Middle Temporal Visual Area (MT) in New World monkeys. (2) Determine the specialized function of each of the five separate representations of the visual field that are located in the third tier (Area 19 of Brodmann) in New World monkeys. (3) Record the activity of single neurons in the visual cortex in alert, behaving monkeys while the animals are experiencing binocular rivalry. We have trained a monkey to report the alternating changes in perception that occur in binocular rivalry induced by presenting different stimuli to each eye. We seek to determine in this and subsequent monkeys whether the activity of visual cortical neurons changes during binocular retinal rivalry and discover the mechanism by which input from each eye is alternatively suppressed.