Is there a high concentration of color-selective cells in area V4 of monkey visual cortex?

Abstract

1. Recordings were made from neurons located within the central-field representation of the V4 area of extrastriate visual cortex using a semichronic, nitrous-oxide preparation; the properties of 174 cells were examined in sufficient detail to permit their classification. Cyto- and myeloarchitectural studies confirmed the identification of the area. 2. Color-selective cells with either color-biased or color-opponent properties represented about 20% of the examined population. Their incidence was not significantly different from that of similar cells encountered in penetrations into the central-field representation of area V2. 3. Most color-selective cells had color-biased properties, responding best to wave-lengths shorter than 460 nm, or longer than 580 n, or both. No examples of "green-biased" cells were found. Some color-biased cells responded to photopically matched white light, while others did not. Very few cells showed overt color-opponent responses. The spectral sensitivity of color-selective cells was not unusually narrow. 4. Cells lacking color selectivity and responding equally well to chromatic and achromatic lights of equal photopic luminosity, were the most commonly encountered cell type in penetrations of different parts of the V4 area (56%). Other than color, these cells showed stimulus preferences like those of color-selective cells. 5. One-fourth of V4 cells could not be systematically driven with the various stimuli used. This finding is consistent with recent results of recordings from the prelunate gyrus of the behaving monkey suggesting that some V4 cells receive extraretinal signals. 6. Our results do not support recent claims that V4 is specialized in the detailed analysis of color information.

Processing of color, form and disparity information in visual areas VP and V2 of ventral extrastriate cortex in the macaque monkey

“…By combining the cutoffs for both the CI and WI, we then divided the dual-index graph into 4 domains. These domains were labeled in a manner similar to the scheme used by Schein et al (1982) in their study of V4. On the basis of qualitatively assessed responses, they classified cells as color opponent, color biased, color biased with opponency, or nonselective for color.…”

“…Another important aspect of receptive field properties in the retina and LGN is that there is considerable variability in the balance between antagonistic center-surround mechanisms in different cells, ranging from near equality in some cells to strong dominance by the center mechanism in other cells (DeMonasterio and Schein, 1982;Derrington et al, 1984). To illustrate the significance of this variability, consider as examples 2 red On-center, green Off-surround cells, one having a perfectly balanced center-surround antagonism and the other having a center that strongly dominates the surround.…”

“…Area V4 contains a substantial percentage of color-selective cells, suggesting a role of this area in color vision (Z&i, 1978, 1983a). However, many cells in V4 lack obvious color selectivity (Schein et al, 1982; …”

“…Area V4 contains a substantial percentage of color-selective cells, suggesting a role of this area in color vision (Z&i, 1978, 1983a). However, many cells in V4 lack obvious color selectivity (Schein et al, 1982;Van Essen and Zeki, 1978) suggesting that it is not simply a "color area." Moreover, color-selective cells are found in areas other than V4 and direction-selective cells in areas other than MT (Baizer, 1982;Baizer et al, 1977;DeYoe and Van Essen, 1985;Hubel and Livingstone, 1985;Livingstone and Hubel, 1984;Shipp and Zeki, 1985;Zeki, 1978).…”

The pattern of interhemispheric connections and its relationship to extrastriate visual areas in the macaque monkey

“…The available anatomical and physiological evidence is consistent with this hypothesis but also with alternative possibilities in which V4 is either much larger or much smaller. The key observations are (i) that most or all of region D and the immediately adjoining callosal recipient cortex receives inputs from dorsal V2 (Zeki, 1971; A. Burkhalter, W. T. Newsome, and D. C. Van Essen, unpublished evidence); (ii) that there is little or no input to this region from ventral V2 (A. Burkhalter, W. T. Newsome, and D. C. Van Essen, unpublished evidence); (iii) that there is little or no representation of superior visual fields in this region (Zeki, 1977;Van Essen and Zeki, 1978;Van Essen et al, 1981); and (iv) that there are inhomogeneities in this region with respect to its architecture, topographic organization, and functional properties (Zeki, 1971(Zeki, , 1977(Zeki, , 1978cVan Essen and Zeki, 1978;Schein et al, 1982). Thus, one could plausibly argue (i) that V4 occupies all of this region but is internally complex and lacks a complete representation of the visual field; (ii) that V4 occupies only part of this region, with an additional area interposed between it and MT; or (iii) that V4 occupies all or' this area and more, extending into region E ventrally (see below).…”