Cortical Visual Areas and Their Interactions

Of all the sensory systems, the visual system is probably the best understood. Yet even for vision we still know very little about central mechanisms, about what happens after retinal impulses reach the striate cortex. The discovery some years ago that there is a visual area in the temporal lobe (Chow, 1951; Mishkin, 1954) opened up this black box a little. At least it made it clear that vision does not begin and end in the striate cortex as Lashley (1948) believed he had demonstrated. But what role the inferior temporal cortex plays in vision, and how it plays this role, have proved to be extremely baffling questions. I should like here to pursue these questions by bringing together some new evidence on the nature of the visual functions of the inferior temporal cortex and of the neural mechanisms on which these functions depend. My goal will be to develop a scheme for the way in which the cortical visual areas — the striate, the prestriate, and the inferotemporal — might interact to form a single, extended, cortical visual system. To begin, I shall describe some experiments I did in collaboration with Eiichi Iwai (Iwai and Mishkin, 1968), who was in our laboratory recently as a visiting scientist from Fukushima Medical College, Japan.