Double-opponent Cells Research Articles

The Orientation Selectivity of Color-Responsive Neurons in Macaque V1

Form has a strong influence on color perception. We investigated the neural basis of the form-color link in macaque primary visual cortex (V1) by studying orientation selectivity of single V1 cells for pure color patterns. Neurons that responded to color were classified, based on cone inputs and spatial selectivity, into chromatically single-opponent and double-opponent groups. Single-opponent cells responded well to color but weakly to luminance contrast; they were not orientation selective for color patterns. Most double-opponent cells were orientation selective to pure color stimuli as well as to achromatic patterns. We also found non-opponent cells that responded weakly or not at all to pure color; most were orientation selective for luminance patterns. Double-opponent and non-opponent cells' orientation selectivities were not contrast invariant; selectivity usually increased with contrast. Double-opponent cells were approximately equally orientation selective for luminance and equiluminant color stimuli when stimuli were matched in average cone contrast. V1 double-opponent cells could be the neural basis of the influence of form on color perception. The combined activities of single- and double-opponent cells in V1 are needed for the full repertoire of color perception.

Passion for pathology: beauty is in the eye of the beholder

Dear Editor, We read with great interest the editorial by G. Bussolati on the mental processes that lead to pathological diagnoses [2], which is the first published approach to this process. We would like to stress/add a few points that we think are of great importance. Besides the perception of form, color is important for detecting objects and patterns that would otherwise not be noticed. We all know from experience that black and white microscopic figures loose much of their information content. A haematoxylin–eosin-stained glass slide makes us look twice if it is over-stained with haematoxylin, since we have unconsciously associated “bluish” with hypercellular/suspicious lesions. Color opponency, simultaneous color contrast and color constancy are the key features of color vision. Color is coded in the retina and in the lateral geniculate nucleus by color-opponent cells and processed in the cortex by concentric double-opponent cells in the blob zones (area V1 of the cortex) [3].

Cone inputs in macaque primary visual cortex.

To understand the role of primary visual cortex (V1) in color vision, we measured directly the input from the 3 cone types in macaque V1 neurons. Cells were classified as luminance-preferring, color-luminance, or color-preferring from the ratio of the peak amplitudes of spatial frequency responses to red/green equiluminant and to black/white (luminance) grating patterns, respectively. In this study we used L-, M-, and S-cone-isolating gratings to measure spatial frequency response functions for each cone type separately. From peak responses to cone-isolating stimuli we estimated relative cone weights and whether cone inputs were the same or opposite sign. For most V1 cells the relative S-cone weight was <0.1. All color-preferring cells were cone opponent and their L/M cone weight ratio was clustered around a value of -1, which is roughly equal and opposite L and M cone signals. Almost all cells (88%) classified as luminance cells were cone nonopponent, with a broad distribution of cone weights. Most cells (73%) classified as color-luminance cells were cone opponent. This result supports our conclusion that V1 color-luminance cells are double-opponent. Such neurons are more sensitive to color boundaries than to areas of color and thereby could play an important role in color perception. The color-luminance population had a broad distribution of L/M cone weight ratios, implying a broad distribution of preferred colors for the double-opponent cells.

Reviews: Neural Mechanisms of Color Vision: Double-Opponent Cells in the Visual Cortex

Reviews: Neural Mechanisms of Color Vision: Double-Opponent Cells in the Visual Cortex

Color-opponent responses of small and giant bipolar cells in the carp retina.

The physiological and morphological properties of color-opponent bipolar cells in the carp retina were studied. Fifty nine OFF-center bipolar cells and 63 ON-center bipolar cells out of about 500 total bipolar cells recorded showed color-opponent responses. The OFF-center color-opponent bipolar cells were classified into three subgroups according to their spectral and spatial responses. Fifty OFF-center color-opponent cells responded with depolarization to a blue light spot and with hyperpolarization to a red spot in the receptive-field center. The polarity of the surround response was opposite to that of center response at each wavelength. Therefore these cells were classified as OFF double-opponent cells (OFF-DO). Eight cells responded with hyperpolarization to a blue and green spot and with depolarization to a red spot. The surround responses of those cells were depolarizing at any wavelength (R+G- cell). One responded with hyperpolarization to a blue and red spot and with depolarization to a green spot. The surround response showed a different spectral characteristic from that of the center response. It responded with depolarization to a blue and green annulus and with hyperpolarization to a red annulus (R-G+B- cell). The ON-center color-opponent bipolar cells were similarly classified into three subgroups. Sixty of ON-center color-opponent cells were the double color-opponent type (ON-DO cell), showing the responses of opposite polarity to the OFF-DO cells. Two cells were classified as R- G+ cell, and one cell as R+G-B+ cell. Both OFF- and ON-DO cells were identified by their morphology as Cajal's giant bipolar cells, and R+G-, R-G+, R-G+B-, and R+G-B+ cells as Cajal's small bipolar cells. The analysis of the latency and the ionic mechanisms of their responses suggest that DO cells under light-adapted conditions receive direct inputs from long-wavelength (red) cones, RG cells from middle-wavelength (green) cones, and RGB cells from short-wavelength (blue) cones. Possible mechanisms of the opponent inputs to these bipolar cells are discussed.

Color Contrast and Color Preference

This article attempts to put the science of color preference on a firm theoretical footing. A model of color contrast, in which the perceived color of an area is influenced by the surrounding colors, is proposed. It is based on double opponent cells, neural units which respond preferentially to one of the four opponent colors, blue, yellow, red, and green. It is shown that by modeling the receptive fields (RFs) of these cells, one can account for a number of color contrast effects. These include the direction of the color contrast shift, the magnitude of the shift as a function of the extent of the surround, and the self-inhibitory nature of a colored area. It is then demonstrated, with an additional assumption relating mean activation of the double opponent units to liking, that the same model can be used to advantage in understanding color preference. It is first shown that the model predicts that preference should increase with increasing saturation. Next, it is shown that the inhibition of a fully saturated field on a less saturated field is greater than vice versa, in keeping with preference results in priming experiments. The model is then shown to predict that complementary colors are in maximum harmony, also in accord with observed results. Finally, the concept of virtual saturation is introduced in order to make predictions regarding hue preference.

Colors of the spectrum: Do you wonder where the yellow went?

The spectrum of white light dispersed by a prism or grating often appears as just three main colored bands, red, green, and blue, with yellow barely discernible. When this spectrum is compared with the appearance of narrow wavelength bands seen in isolation, the lack of color is surprising. An explanation is offered based on two factors: (1) The yellow-appearing wavelengths of the spectrum comprise only ~5% of the whole and have a luminance comparable with that of the adjacent red and green portions and (2) the response of double-opponent cells, observed in the primate visual cortex, could enhance the red and green and obscure the yellow in the spectral image.

Color categorization and color constancy in a neural network model of V4

We develop a neural network model that instantiates color constancy and color categorization in a single unified framework. Previous models achieve similar effects but ignore important biological constraints. Color constancy in this model is achieved by a new application of the double opponent cells found in the "blobs" of the visual cortex. Color categorization emerges naturally, as a consequence of processing chromatic stimuli as vectors in a four-dimensional color space. A computer simulation of this model is subjected to the classic psychophysical tests that first uncovered these phenomena, and its response matches psychophysical results very closely.

The relationship between simple and double opponent cells

Little is known about the formation of double opponent cells (DOCs) from geniculate afferents. Three LGN cell types have been considered as DOC precursors. No simple wiring scheme based on these cell types is consistent with the available evidence. The color and luminance multiplexed signal of P β ganglion cells (Type I receptive fields) contains the information necessary to construct DOCs, provided that filtering operations can separate the two signals. Electrophysiological and anatomical evidence is consistent with Type I cells being filtered prior to the formation of DOCs. Cortical Type II and Type III cells can also be created by filtering.

The organization of chromatic and spatial interactions in the primate striate cortex

The cytochrome oxidase-rich patches or blobs of the monkey striate cortex have been shown to contain cells that have unoriented receptive fields, many of which are color selective. We studied the functional organization of color opponency in the blob regions of the parafoveal representation of the visual cortex. We also examined the patterns of connectivity among blob and nonblob cells by multiple electrode penetrations and cross-correlation analysis. Some of the color-selective cells in the blobs exhibited receptive fields that were similar to those found in the parvocellular layers of the lateral geniculate nucleus (LGN): one type exhibited center-surround spatial and chromatic opponency corresponding to the Type I cell found in the LGN; another had center-only chromatic opponency, corresponding to the Type II cell of the LGN. A blob color-selective cell with no LGN counterpart had center color opponency with a nonchromatically opponent surround antagonism. We termed this cell the "modified Type II" cell. Contrary to previous reports, few true double color-opponent cells were found. Some blob cells previously characterized as double opponent probably belong to our modified Type II category and, unlike true double opponent cells, do not respond well to isoluminant color boundaries. Occasional color-selective oriented cells were either intermixed or in close proximity to blob cells. Neighboring electrode penetrations within the same blob yielded cells of the same color opponency, either red versus green or blue versus yellow, suggesting that individual blobs are dedicated to processing one color opponency. Blobs dedicated to red/green color opponency were 3 times more numerous than blue/yellow blobs. Furthermore, the cells in layer 4C lying beneath blobs of a given color opponency had identical color opponency to the overlying cells in blobs. Cross-correlation analysis of pairs of nonblob, oriented cells in the superficial layers showed interactions between cells with matched orientation and eye preference, at varying horizontal separations. Such interactions are consistent with anatomically demonstrated clustered horizontal connections. Positive cross-correlograms were found between blob cells in the same and in adjacent blobs when the cells' receptive field type, color opponency, and ocular dominance matched. Correlograms also indicated monosynaptic connections from Type II to modified Type II cells of the same color opponency, suggesting that Type II cells may contribute to the construction of the modified Type II fields in the cortex.(ABSTRACT TRUNCATED AT 400 WORDS)

Cortical dynamics of three-dimensional form, color, and brightness perception: II. Binocular theory.

A real-time visual processing theory is developed to explain how three-dimensional form, color, and brightness percepts are coherently synthesized. The theory describes how several fundamental uncertainty principles which limit the computation of visual information at individual processing stages are resolved through parallel and hierarchical interactions among several processing stages. The theory hereby provides a unified analysis and many predictions of data about stereopsis, binocular rivalry, hyperacuity, McCollough effect, textural grouping, border distinctness, surface perception, monocular and binocular brightness percepts, filling-in, metacontrast, transparency, figural aftereffects, lateral inhibition within spatial frequency channels, proximity-luminance covariance, tissue contrast, motion segmentation, and illusory figures, as well as about reciprocal interactions among the hypercolumns, blobs, and stripes of cortical areas VI, V2, and V4. Monocular and binocular interactions between a Boundary Contour (BC) System and a Feature Contour (FC) System are developed. The BC System, defined by a hierarchy of oriented interactions, synthesizes an emergent and coherent binocular boundary segmentation from combinations of unoriented and oriented scenic elements. These BC System interactions instantiate a new theory of stereopsis and of how mechanisms of stereopsis are related to mechanisms of boundary segmentation. Interactions between the BC System and the FC System explain why boundary completion and segmentation processes become binocular at an earlier processing stage than do color and brightness perception processes. The new stereopsis theory includes a new model of how chromatically broadband cortical complex cells can be adaptively tuned to multiplex information about position, orientation, spatial frequency, positional disparity, and orientational disparity. These binocular cells input to spatially short-range competitive interactions (within orientations and between positions, followed by between orientations and within positions) that initiate suppression of binocular double images as they complete boundaries at scenic line ends and corners. The competitive interactions interact via both feedforward and feedback pathways with spatially long-range-oriented cooperative gating interactions that generate a coherent, multiple-scale, three-dimensional boundary segmentation as they complete the suppression of double-image boundaries. The completed BC System boundary segmentation generates output signals, called filling-in generators (FIGs) and filling-in barriers (FIBs), along parallel pathways to two successive FC System stages: the monocular syncytium and the binocular syncytium. FIB signals at the monocular syncytium suppress monocular color and brightness signals that are binocularly inconsistent and select binocularly consistent, monocular FC signals as outputs to the binocular syncytium. Binocular matching of these FC signals further suppresses binocularly inconsistent color and brightness signals. Binocular FC contour signals that survive these multiple suppressive events interact with FEB signals at the binocular syncytium to fill-in a multiplescale representation of form-and-color-in-depth. To achieve these properties, distinct syncytia correspond to each spatial scale of the BC System. Each syncytium is composed of opponent subsyncytia that generate output signals through a network of double-opponent cells. Although composed of unoriented wavelength-sensitive cells, double-opponent networks detect oriented properties of form when they interact with FIG signals, yet also generate nonselective properties of binocular rivalry. Electrotonic and chemical transmitter interactions within the syncytia are formally akin to interactions in HI horizontal cells of turtle retina. The cortical syncytia are hypothesized to be encephalizations of ancestral retinal syncytia. In addition to double-opponent-cell networks, electrotonic syncytial interactions, and resistive gating signals due to BC System outputs, the FC System processes also include habituative transmitters and non-Hebbian adaptive filters that maintain the positional and chromatic selectivity of FC interactions. Alternative perceptual theories are evaluated in light of these results. The theoretical circuits provide qualitatively new design principles and architectures for computer vision applications.

Cortical dynamics of three-dimensional form, color, and brightness perception: I. Monocular theory.

A real-time visual processing theory is developed to explain how three-dimensional form, color, and brightness percepts are coherently synthesized. The theory describes how several fundamental uncertainty principles which limit the computation of visual information at individual processing stages are resolved through parallel and hierarchical interactions among several processing stages. The theory hereby provides a unified analysis and many predictions of data about stereopsis, binocular rivalry, hyperacuity, McCollough effect, textural grouping, border distinctness, surface perception, monocular and binocular brightness percepts, filling-in, metacontrast, transparency, figural aftereffects, lateral inhibition within spatial frequency channels, proximity-luminance covariance, tissue contrast, motion segmentation, and illusory figures, as well as about reciprocal interactions among the hypercolumns, blobs, and stripes of cortical areas VI, V2, and V4. Monocular and binocular interactions between a Boundary Contour (BC) System and a Feature Contour (FC) System are developed. The BC System, defined by a hierarchy of oriented interactions, synthesizes an emergent and coherent binocular boundary segmentation from combinations of unoriented and oriented scenic elements. These BC System interactions instantiate a new theory of stereopsis and of how mechanisms of stereopsis are related to mechanisms of boundary segmentation. Interactions between the BC System and the FC System explain why boundary completion and segmentation processes become binocular at an earlier processing stage than do color and brightness perception processes. The new stereopsis theory includes a new model of how chromatically broadband cortical complex cells can be adaptively tuned to multiplex information about position, orientation, spatial frequency, positional disparity, and orientational disparity. These binocular cells input to spatially short-range competitive interactions (within orientations and between positions, followed by between orientations and within positions) that initiate suppression of binocular double images as they complete boundaries at scenic line ends and corners. The competitive interactions interact via both feedforward and feedback pathways with spatially long-range-oriented cooperative gating interactions that generate a coherent, multiple-scale, three-dimensional boundary segmentation as they complete the suppression of double-image boundaries. The completed BC System boundary segmentation generates output signals, called filling-in generators (FIGs) and filling-in barriers (FIBs), along parallel pathways to two successive FC System stages: the monocular syncytium and the binocular syncytium. FIB signals at the monocular syncytium suppress monocular color and brightness signals that are binocularly inconsistent and select binocularly consistent, monocular FC signals as outputs to the binocular syncytium. Binocular matching of these FC signals further suppresses binocularly inconsistent color and brightness signals. Binocular FC contour signals that survive these multiple suppressive events interact with FEB signals at the binocular syncytium to fill-in a multiple-scale representation of form-and-color-in-depth. To achieve these properties, distinct syncytia correspond to each spatial scale of the BC System. Each syncytium is composed of opponent subsyncytia that generate output signals through a network of double-opponent cells. Although composed of unoriented wavelength-sensitive cells, double-opponent networks detect oriented properties of form when they interact with FIG signals, yet also generate nonselective properties of binocular rivalry. Electrotonic and chemical transmitter interactions within the syncytia are formally akin to interactions in HI horizontal cells of turtle retina. The cortical syncytia are hypothesized to be encephalizations of ancestral retinal syncytia. In addition to double-opponent-cell networks, electrotonic syncytial interactions, and resistive gating signals due to BC System outputs, the FC System processes also include habituative transmitters and non-Hebbian adaptive filters that maintain the positional and chromatic selectivity of FC interactions. Alternative perceptual theories are evaluated in light of these results. The theoretical circuits provide qualitatively new design principles and architectures for computer vision applications.

Colour and brightness coding in the central nervous system: theoretical aspects and visual evoked potentials to homogeneous red and green stimuli.

We designed visual evoked potentials experiments to study the differential aspects of colour and brightness coding in man. The substitution of equally bright red and green stimuli for a background yellow was investigated and compared with different luminance increments and decrements of red and green. A dominant N87 component was found for a colour change from yellow to brighter red colours, which was less pronounced for green and absent for yellow luminance changes. It is also absent for pure red luminance increments and green luminance changes, but reappears with red luminance decrements or red-offset. The data are discussed within the framework of a new concept of how the visual system fuses red-green information and black-white border information. Retinal X-cells can transmit colour and high spatial frequency achromatic information simultaneously by encoding only the presence of edges (a.c.) for the black-white stimuli and the presence of both edges (a.c.) and uniform areas of colour (d.c.) for red-green stimuli. Phylogenetically this kind of information transmission enables colour vision to be implemented in a retina such as the cat's by adding only a second class of cones. Barlow's economy principle will be violated for colour in the periphery, but restored early in the striate cortex where there is an early decoding of the combined chromatic and achromatic information by the concentric double opponent cells. The N87 behaviour correlates with the proposed discharge of peripheral X-type cells, but not with the discharge of cortical double opponent concentric or simple cells, which no longer respond to homogeneous colour stimuli. It is suggested that N87 may be generated by geniculate afferents in the dendritic arborization of cortical cells, reflecting the behaviour of peripheral units, and thus the violation of the economy principle, rather than the next step in cortical processing. The early cortical restoration of the economy principle is supported by the absence of any further dissociated behaviour for colour and brightness in later components.

Anatomy and physiology of a color system in the primate visual cortex

Staining for the mitochondrial enzyme cytochrome oxidase reveals an array of dense regions (blobs) in the primate primary visual cortex. They are most obvious in the upper layers, 2 and 3, but can also be seen in layers 4B, 5, and 6, in register with the blobs in layers 2 and 3. We compared cells inside and outside blobs in macaque and squirrel monkeys, looking at their physiological responses and anatomical connections. Cells within blobs did not show orientation selectivity, whereas cells between blobs were highly orientation selective. Receptive fields of blob cells had circular symmetry and were of three main types, Broad-Band Center-Surround, Red-Green Double-Opponent, and Yellow-Blue Double-Opponent. Double-Opponent cells responded poorly or not at all to white light in any form, or to diffuse light at any wavelength. In contrast to blob cells, none of the cells recorded in layer 4C beta were Double-Opponent: like the majority of cells in the parvocellular geniculate layers, they were either Broad-Band or Color-Opponent Center-Surround, e.g., red-on-center green-off-surround. To our surprise cells in layer 4C alpha were orientation selective. In tangential penetrations throughout layers 2 and 3, optium orientation, when plotted against electrode position, formed long, regular, usually linear sequences, which were interrupted but not perturbed by the blobs. Staining area 18 for cytochrome oxidase reveals a series of alternating wide and narrow dense stripes, separated by paler interstripes. After small injections of horseradish peroxidase into area 18, we saw a precise set of connections from the blobs in area 17 to thin stripes in area 18, and from the interblob regions in area 17 to interstripes in area 18. Specific reciprocal connections also ran from thin stripes to blobs and from interstripes to interblobs. We have not yet determined the area 17 connections to thick stripes in area 18. In addition, within area 18 there are stripe-to-stripe and interstripe-to-interstripe intrinsic connections. These results suggest that a system involved in the processing of color information, especially color-spatial interactions, runs parallel to and separate from the orientation-specific system. Color, encoded in three coordinates by the major blob cell types, red-green, yellow-blue, and black-white, can be transformed into the three coordinates, red, green, and blue, of the Retinex algorithm of Land.

Color vision and image intensities: when are changes material?

The difficulty in understanding a biological system or its components without some idea of its goals has been emphasized by Marr. In this paper, a preliminary goal for color vision is proposed and analyzed. That goal is to determine where changes of material occur in a scene (using only spectral information). The goal is challenging because the effects of many processes (shadowing, shading from surface orientation changes, highlights, variations in pigment density) are confounded with the effects of material changes in the available image intensities. We show there is a minimal and unique condition, the spectral crosspoint that rejects instances of these confounding processes. (If plots are made of image intensity versus wavelength from two image regions, and the plots intersect, we say that there is a spectral crosspoint.) An operator is designed to detect crosspoints; it turns out to resemble double-opponent cells described in primate visual cortex.

Light responses of ganglion cells in the retina of the turtle.

1. Recordings were made from single axons of 218 ganglion cells in the optic nerve of the turtle, Pseudemys scripta elegans. Responses to light stimuli were used to classify 182 of the cells into four functional groups.2. Movement-sensitive cells (113 units) responded best to moving stimuli independent of the stimulus colour or direction of motion. Their receptive fields were organized into antagonistic centres and surrounds with the same spectral sensitivity. Based on their patterns of response they were of three types: ON-centre, OFF-centre, and ON-OFF.3. Directionally selective cells (sixty-five units) responded best to stimuli that moved in one preferred direction and not to stimuli that moved in the opposite direction. Their receptive fields had antagonistic centres and surrounds with the same spectral sensitivity. An area of silent inhibition could be shown on one side of the receptive fields. The preferred directions appeared to fall into three groups separated by about 120 degrees. Response patterns were of two types; OFF-centre and ON-OFF.4. Sensitizable colour cells (two units) had centre-surround organization with red-green opponent responses from both the centre and the surround (double opponent cells). In addition, the sensitivity to either of the opponent colours was effectively turned on or off by a steady background of the other opponent colour.5. Orientation cells (two units) responded best to moving bars of specific orientations in the visual field. Their receptive fields consisted of adjacent mutually antagonistic areas with linear boundaries.6. Under photopic conditions all of the ganglion cells were most sensitive to light near 630 nm wave-length, the spectral maximum of the red-sensitive single cones in the turtle retina. About 75% of the cells had a secondary spectral peak near 560 nm, the spectral maximum of the green-sensitive single cones. Three cells had unusually broad sensitivity extending into the blue portion of the spectrum. Over half of the cells received additional input from rods as evidenced by a shift in spectral sensitivity and increases in latencies and receptive field sizes with dark-adaptation.7. Measurements of the absolute sensitivity of the ganglion cells showed that a threshold response required absorption of several hundred photons in the red-sensitive cones of the receptive field centre. After 10 min dark adaptation the rods required absorption of about 20 photons.

Saturation enhancement in colored hermann grids varying only in chroma

Red, green-yellow, and purple-blue Hermann grids varying in chroma, but not in value, were evaluated for the strength and nature of the illusions occurring at the intersections. Each grid was made up of stripes representing 5 steps on the Munsell chroma scale and was shown against each of 5 backgrounds having the same Munsell notations. For its occurrence, the illusion required the same formal relationships between upper stripe, lower stripe, and background as were derived for brightness changes in achromatic grids varying in luminance ( Spillmann and Levine, 1971). By means of color matching, the illusory shifts were shown to occur mostly along the dimension of chroma, i.e. saturation. The physiological mechanism responsible for this enhancement may reside in the Type III cells or the double-opponent cells of the lateral geniculate nucleus and visual cortex.

Color and spatial specificity of single units in Rhesus monkey foveal striate cortex.

Color and spatial specificity of single units in Rhesus monkey foveal striate cortex.B M Dow, and P GourasB M Dow, and P GourasPublished Online:01 Jan 1973https://doi.org/10.1152/jn.1973.36.1.79MoreSectionsPDF (3 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited BySpatial receptive field structure of double-opponent cells in macaque V1Abhishek De and Gregory D. Horwitz16 March 2021 | Journal of Neurophysiology, Vol. 125, No. 3Processing of chromatic information in a deep convolutional neural network30 March 2018 | Journal of the Optical Society of America A, Vol. 35, No. 4C OLOR V ISIONAnnual Review of Neuroscience, Vol. 26, No. 1Color Processing in Macaque Striate Cortex: Electrophysiological PropertiesCarole E. Landisman, and Daniel Y. Ts'O1 June 2002 | Journal of Neurophysiology, Vol. 87, No. 6Color Processing in Macaque Striate Cortex: Relationships to Ocular Dominance, Cytochrome Oxidase, and OrientationCarole E. Landisman, and Daniel Y. Ts'o1 June 2002 | Journal of Neurophysiology, Vol. 87, No. 6Illusory contours induced by isoluminant chromatic patternsVision Research, Vol. 28, No. 12Occipital and inferotemporal responses to visual signals in the monkeyExperimental Neurology, Vol. 90, No. 2Spatial mapping of monkey VI cells with pure color and luminance stimuliVision Research, Vol. 24, No. 7Colour coding in the cerebral cortex: The reaction of cells in monkey visual cortex to wavelengths and coloursNeuroscience, Vol. 9, No. 4Test and field spectral sensitivities of colour mechanisms obtained on small white backgrounds: Actions of unitary opponent-colour processes?Vision Research, Vol. 23, No. 8Multiplexing in single cells of the alert monkey's visual cortex during brightness discriminationNeuropsychologia, Vol. 20, No. 1Colour selectivity in the tilt after-effect: Comments upon Wade and WenderothVision Research, Vol. 21, No. 3Temporal response characteristics of cells in monkey striate cortex measured with metacontrast masking and brightness discriminationBrain Research, Vol. 196, No. 2Parallel visual pathways: A reviewVision Research, Vol. 20, No. 7Schematic Concept Formation: Psychophysical Analysis of Early Reading Skill6 October 2016 | Perceptual and Motor Skills, Vol. 49, No. 3Causality among Cross-Cultural Correlations: A Psychological Interpretation14 September 2016 | Behavior Science Research, Vol. 14, No. 2Spatial frequency, orientation and color: Interocular effects of adaptation on the perceived duration of gratingsVision Research, Vol. 19, No. 11Form-Colour Aftereffects: Selectivity to Local Luminance Contrast25 June 2016 | Perception, Vol. 7, No. 4Orientation anisotropy in monkey visual cortexBrain Research, Vol. 149, No. 1Response of movement detecting cells in the optic tectum of pigeons to change of wavelengthVision Research, Vol. 17, No. 10The effects of color-specific adaptation on the perceived duration of gratingsVision Research, Vol. 17, No. 1Interference in Colour-Contingent Motion After-Effects1 January 2018 | Quarterly Journal of Experimental Psychology, Vol. 28, No. 4Psychophysical Measurement of Cortical Color Mechanisms Not Sensitive to Spatial Frequency25 June 2016 | Perception, Vol. 5, No. 2Representation of fovea in the striate cortex of vervet monkey, Cercopithecus ˦thiops pygerythrusVision Research, Vol. 16, No. 6Motion aftereffects: Evidence for parallel processing in motion perceptionVision Research, Vol. 16, No. 2Spatial and chromatic properties of neurons subserving foveal and parafoveal vision in rhesus monkeyBrain Research, Vol. 100, No. 1Trichromacy in normally reared and light deprived infant monkeys (Macaca nemestrina)Vision Research, Vol. 15, No. 11Increment spectral sensitivity and colour discrimination in the primate, studied by means of graded potentials from the striate cortexVision Research, Vol. 15, No. 10The Effect of Stationary Patterns on Adaptation for Movement: Evidence for Inhibitory Interaction25 June 2016 | Perception, Vol. 4, No. 3The effects of orientation-specific adaptation on the duration of short-term visual storageVision Research, Vol. 15, No. 5Monocular and Binocular Rivalry between Contours25 June 2016 | Perception, Vol. 4, No. 1Stabilized images: Probe analysis of pattern and color analytic mechanismsVision Research, Vol. 15, No. 2Physiological consequences of unilateral and bilateral eye closure in macaque monkeys: some further observationsBrain Research, Vol. 84, No. 1Responses of motor cortex cells to visual stimuliBrain Research, Vol. 82, No. 2Adaptation to pairs of coloured gratings: Inhibition between colour-specific spatial detectors in the human visual system?Vision Research, Vol. 14, No. 12Singly and doubly contingent after-effects involving color, orientation and spatial frequencyVision Research, Vol. 14, No. 11Edge detection in luminance and colour discriminationVision Research, Vol. 14, No. 10The characteristics of a visual defect associated with abnormal responses to both colour and luminanceVision Research, Vol. 14, No. 6Chromatic substitution with stabilized images: Evidence for chromatic-specific pattern processing in the human visual systemVision Research, Vol. 14, No. 1Visual and somatosensory receptive fields of neurons in the squirrel monkey pulvinarBrain Research, Vol. 64 More from this issue > Volume 36Issue 1January 1973Pages 79-100 https://doi.org/10.1152/jn.1973.36.1.79PubMed4350278History Published online 1 January 1973 Published in print 1 January 1973 Metrics