Survival of pattern vision after removal of striate cortex in the adult cat

Behavioral, anatomical and electrophysiological data are presented for three cats. One had complete removal of area 17 as evidenced by gross and histological examination of the remaining cortex and by the degeneration in the lateral geniculate body. Dorsal portions of areas 18 and 19 were essentially intact and much of the central and medial interlaminar nuclei of the lateral geniculate body survived. This cat had excellent pattern vision. So too did a cat in which all of the posterior suprasylvian gyrus, dorsal surface of the middle suprasylvian gyrus and much of anterior marginal gyrus had been extirpated. In contrast, an animal lacking area 18 and most of area 19 in addition to area 17, and thus having near “total” degeneration of the lateral geniculate body, was incapable of pattern discrimination. Photically evoked potentials could nevertheless be demonstrated throughout an extensive suprasylvian field in the latter animal. It is concluded that area 17 is not essential for pattern vision in the cat, but that in its absence, even in the case of ablations performed neonatally, cortex receiving major projection from the central and medial interlaminar nuclei, i.e., areas 18 and 19, is required.