Uniformity and diversity of structure and function in rhesus monkey prestriate visual cortex.

Abstract

Recordings were made from single neurons, or small clusters of cells, in 5 prestriate visual areas of rhesus monkey cortex. The cells were studied for their binocularity, and for their orientational, motion and color preferences. In all, 1500 cells were studied, 250 cells for each of the areas V2, V3, V3A and the motion area of the posterior bank of the superior temporal sulcus, and 500 cells for V4. All the cells referred to in this study can be placed in 1 prestriate area or another unambiguously. The great majority of cells in all areas were binocularly driven, without monocular preferences. Within each area, there were cells that either preferred binocular stimulation markedly or were responsive to binocular stimulation only. The ocular interaction histograms for all areas were remarkably similar when tested at a fixed disparity. Over 70% of the cells in areas V2, V3 and V3A were selective for orientation. The receptive fields of cells were larger in V3 and V3A than in V2. Less than 50% of the cells in V4 and the motion area of the superior temporal sulcus were orientation selective. Directionally selective cells were found in all areas. But they were present in small numbers (< 15%) in areas V2, V3, V3A and V4. By contrast, 90% of the cells in the motion area of the superior temporal sulcus were directionally selective. Of the cells in V2, 8% had opponent color properties. Cells with such properties were not found in V3, V3A or in the motion area of the superior temporal sulcus. By contrast, 54% of the cells in the V4 complex had opponent color properties. Apparently, despite is uniformity in cytoarchitectural appearance and in ocular interaction patterns, there is a functional division of labor within the prestriate cortex. Evidence for this is seen not only in the different concentrations of functional cell types in distinct areas of the prestriate cortex, but also in the differential anatomical and callosal connexions of each area.