The invitation by the editors of the series "studies of brain function" to contribute a monograph on the visual cortex gives me the opportunity to present in a concentrated manner much of the work I have done on the visual cortical areas of cat and monkey. However, the field of visual cortical physi ology is so active and so diverse that the presentation of only my own work would have given a very incomplete view of visual cortical functioning. Therefore this monograph also reviews most of the studies carried out on the subject in the last two decades. Where possible I have tried not only to...