RECEPTIVE FIELDS AND FUNCTIONAL ARCHITECTURE IN TWO NONSTRIATE VISUAL AREAS (18 AND 19) OF THE CAT

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Abstract
In recordings from single cells we have confirmed the findings of Talbot and Marshall of 2 separate but adjacent projections of the contralateral field of vision in each hemisphere (visual areas I and II), and have found a 3rd projection (visual III) bordering on and lateral to visual II. These 3 areas seem to be identical to areas 17, 18, and 19, as defined in the cat by Otsuka and Hassler. In experiments using Nauta methods, cells in areas 17 projected both to 18 and 19 bilaterally. The great majority of cells in visual II and half of those in visual III resembled cells of visual I termed "complex". Other cells had more elaborate properties and were termed "hypercomplex". Hypercomplex cells, like complex ones, responded either to a slit, an edge, or a dark bar, and for optimum response the orientation of the line was critical. For hypercomplex cells, however, it was necessary to limit the length of the stimulus in one or both directions. This type of cell behaved as though it received inputs from 2 complex cells or sets of cells, one excitatory to the cell and one inhibitory. In visual areas II and III, as in visual I, complex and hypercomplex cells with the same receptive-field orientation were segregated into regions of columnar shape. The majority of cells of visual II and III were driven from both eyes, and the distribution of cells according to relative ocular dominance was similar in all 3 visual areas.