VISUAL ACTIVITY IN MACAQUE AREA V4 DEPENDS ON AREA 17 INPUT

IT is known that some direct projections from the lateral geniculate nucleus terminate in area V4 of the macaque monkey. Retinal information can also bypass area 17 and reach V4 through relays in the superior colliculus and pulvinar. This raises the question whether area V4 is visually responsive in the absence of input from area 17. We tested this possibility by recording in area V4 while inactivating a region of area 17 by cooling. This led to a complete abolition of the visual responses of practically all the neurons whose receptive fields were included in the visual field region coded by the inactivated zone in area 17. In contrast, neurons whose receptive fields were outside this region remained visually responsive.