Cortical and callosal connections concerned with the vertical meridian of visual fields in the cat.

Abstract

By recording single cells simultaneously in opposite hemispheres of the cat it was shown that the receptive fields of some cortical cells near the 17 - 18 boundary overlap the vertical midline of the visual fields. Overlapping was found only in the transitional zone between 17 and 18, and the adjacent part of 18. These areas are known anatomically to be interconnected, and to receive connections from the most lateral part of area 17. Of 34 single fibers recorded from the posterior corpus callosum, all but 1 or 2 could be driven by visual stimulation, and of these all but 1 had receptive fields that overlapped the vertical midline or came up to within a degree or less of it. About half of the receptive fields were clustered around the area centralis; the rest were scattered widely above and below the horizontal meridian. Seven cells had "simple" properties, the others being complex or hypercomplex. Certain fibers in the corpus callosum may link cells whose fields lie on or close to the vertical meridian. These fibers apparently serve the same functions as intracortical fibers linking cells with receptive fields clustered in more outlying parts of the visual fields.