A crescent-shaped cortical visual area surrounding the middle temporal area (MT) in the owl monkey (Aotus trivirgatus)

The visuotopic organization of the cortex adjoining the middle temporal visual area (MT) of the owl monkey was determined by relating receptive field locations to microelectrode recording sites. A representation of the contralateral half of the visual field was found in a histologically distinct crescent-shaped area which wraps around MT. The representation in the crescent is not a simple transformation of the visual hemifield like the primary visual area and MT. Instead, the representation of the upper and lower quadrants of the visual field are in the separate ends of the crescent just as the upper and lower quadrants are split along the horizontal meridian and represented in opposite ends of the second visual area (V II). The posterior border or base of the crescent adjoins V II, and the visuotopic organizations of MT and the crescent together form a miniature mirror-image of the V I–V II system