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Mascio AA, Roman AJ, Cideciyan AV, Sheplock R, Wu V, Garafalo AV, Sumaroka A, Pirkle S, Kohl S, Wissinger B, Jacobson SG, Barbur JL. Color Vision in Blue Cone Monochromacy: Outcome Measures for a Clinical Trial. Transl Vis Sci Technol 2023; 12:25. [PMID: 36692456 PMCID: PMC9896867 DOI: 10.1167/tvst.12.1.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Purpose Blue cone monochromacy (BCM) is an X-linked retinopathy due to mutations in the OPN1LW/OPN1MW gene cluster. Symptoms include reduced visual acuity and disturbed color vision. We studied BCM color vision to determine outcome measures for future clinical trials. Methods Patients with BCM and normal-vision participants were examined with Farnsworth-Munsell (FM) arrangement tests and the Color Assessment and Diagnosis (CAD) test. A retrospective case series in 36 patients with BCM (ages 6-70) was performed with the FM D-15 test. A subset of six patients also had Roth-28 Hue and CAD tests. Results All patients with BCM had abnormal results for D-15, Roth-28, and CAD tests. With D-15, there was protan-deutan confusion and no bimodal tendency. Roth-28 results reinforced that finding. There was symmetry in color vision metrics between the two eyes and coherence between sessions with the arrangement tests and CAD. Severe abnormalities in red-green sensitivity with CAD were expected. Unexpected were different levels of yellow-blue results with two patterns of abnormal thresholds: moderate elevation in two younger patients and severe elevation in four patients ≥35 years. Coefficients of repeatability and intersession means were tabulated for all test modalities. Conclusions Given understanding of advantages, disadvantages, and complexities of interpretation of results, both an arrangement test and CAD should be useful monitors of color vision through a clinical trial in BCM. Translational Relevance Our pilot studies in BCM of arrangement and CAD tests indicated both were clinically feasible and interpretable in the context of this cone gene disease.
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Affiliation(s)
- Abraham A. Mascio
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Alejandro J. Roman
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Artur V. Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Rebecca Sheplock
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Vivian Wu
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Alexandra V. Garafalo
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Alexander Sumaroka
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Sydney Pirkle
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Susanne Kohl
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany
| | - Samuel G. Jacobson
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - John L. Barbur
- Centre for Applied Vision Research, School of Health Sciences, City, University of London, London, UK
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Optogenetic restoration of high sensitivity vision with bReaChES, a red-shifted channelrhodopsin. Sci Rep 2022; 12:19312. [PMID: 36369267 PMCID: PMC9652428 DOI: 10.1038/s41598-022-23572-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/02/2022] [Indexed: 11/13/2022] Open
Abstract
The common final pathway to blindness in many forms of retinal degeneration is the death of the light-sensitive primary retinal neurons. However, the normally light-insensitive second- and third-order neurons persist optogenetic gene therapy aims to restore sight by rendering such neurons light-sensitive. Here, we investigate whether bReaChES, a newly described high sensitivity Type I opsin with peak sensitivity to long-wavelength visible light, can restore vision in a murine model of severe early-onset retinal degeneration. Intravitreal injection of an adeno-associated viral vector carrying the sequence for bReaChES downstream of the calcium calmodulin kinase IIα promoter resulted in sustained retinal expression of bReaChES. Retinal ganglion cells (RGCs) expressing bReaChES generated action potentials at light levels consistent with bright indoor lighting (from 13.6 log photons cm-2 s-1). They could also detect flicker at up to 50 Hz, which approaches the upper temporal limit of human photopic vision. Topological response maps of bReaChES-expressing RGCs suggest that optogenetically activated RGCs may demonstrate similar topographical responses to RGCs stimulated by photoreceptor activation. Furthermore, treated dystrophic mice displayed restored cortical neuronal activity in response to light and rescued behavioral responses to a looming stimulus that simulated an aerial predator. Finally, human surgical retinal explants exposed to the bReaChES treatment vector demonstrated transduction. Together, these findings suggest that intravitreal gene therapy to deliver bReaChES to the retina may restore vision in human retinal degeneration in vivo at ecologically relevant light levels with spectral and temporal response characteristics approaching those of normal human photopic vision.
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Suchkov N, Kurian T, Schwarz C, Leube A, Wahl S. SLM-based interferometer for assessing the polychromatic neural transfer function of the eye. BIOMEDICAL OPTICS EXPRESS 2021; 12:6040-6054. [PMID: 34745720 PMCID: PMC8548005 DOI: 10.1364/boe.432744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 08/23/2021] [Accepted: 08/23/2021] [Indexed: 06/13/2023]
Abstract
A novel interferometric instrument for measuring neural transfer function (NTF) of the eye is presented. The device is based on a liquid-crystal-on-silicon spatial light modulator (SLM), which is used to create two laterally separated wavefronts in the pupil plane of the eye that interfere on the retina. The phase mask on the SLM, consisting of two diffraction gratings mixed in a checkerboard pattern and acting as a shearing interferometer, allows independent control of spatial frequency, orientation, and contrast of the fringes, as well as the field of view in a wide polychromatic spectrum. Coupled with a supercontinuum source, the system is able to produce achromatic fringes on the retina. The instrument was successfully tested in six normal subjects in four light conditions: polychromatic light and monochromatic blue, green and red light respectively (central wavelengths - 450, 550 and 650 nm). On average, the NTF in polychromatic light was approximately 20% higher than for green and red light, although not statistically significant due to high intersubject variability. Due to all-digital control of the interference fringes, the device is optically simple and virtually unsusceptible to vibrations, allowing its use in a non-laboratory environment. The study also contributes to color vision research, allowing to evaluate contrast sensitivity function without monochromatic or chromatic aberrations.
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Affiliation(s)
- Nikolai Suchkov
- Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen 72076, Germany
| | - Tobin Kurian
- Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen 72076, Germany
| | - Christina Schwarz
- Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen 72076, Germany
| | | | - Siegfried Wahl
- Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen 72076, Germany
- Carl Zeiss Vision International GmbH, Aalen 73430, Germany
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Semenov EP, Sheplock R, Roman AJ, McGuigan DB, Swider M, Cideciyan AV, Jacobson SG. Reading Performance in Blue Cone Monochromacy: Defining an Outcome Measure for a Clinical Trial. Transl Vis Sci Technol 2020; 9:13. [PMID: 33344057 PMCID: PMC7726588 DOI: 10.1167/tvst.9.13.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 10/12/2020] [Indexed: 11/24/2022] Open
Abstract
Purpose Blue cone monochromacy (BCM), a congenital X-linked retinal disease caused by mutations in the OPN1LW/OPN1MW gene cluster, is under consideration for intravitreal gene therapy. Difficulties with near vision tasks experienced by these patients prompted this study of reading performance as a potential outcome measure for a future clinical trial. Methods Clinically and molecularly diagnosed patients with BCM (n = 17; ages 15–63 years) and subjects with normal vision (n = 22; ages 18–72 years) were examined with the MNREAD acuity chart for both uniocular and binocular conditions. Parameters derived from the measurements in patients were compared with normal data and also within the group of patients. Intersession, interocular and between-subject variabilities were determined. The frequent complaint of light sensitivity in BCM was examined by comparing results from black text on a white background (regular polarity) versus white on black (reverse polarity) conditions. Results MNREAD curves of print size versus reading speed were right-shifted compared with normal in all patients with BCM. All parameters in patients with BCM indicated abnormal reading performance. Intersession variability was slightly higher in BCM than in normal, but comparable with results previously reported for other patients with maculopathies. There was a high degree of disease symmetry in reading performance in this BCM cohort. Reverse polarity showed better reading parameters than regular polarity in 82% of the patients. Conclusions MNREAD measures of reading performance in patients with BCM would be a worthy and robust secondary outcome in a clinical trial protocol, given its dual purpose of quantifying macular vision and addressing an important quality of life issue. Translational Relevance Assessment of an outcome for a clinical trial.
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Affiliation(s)
- Evelyn P Semenov
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Rebecca Sheplock
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Alejandro J Roman
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - David B McGuigan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Malgorzata Swider
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Artur V Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
| | - Samuel G Jacobson
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, USA
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Connectomic Identification and Three-Dimensional Color Tuning of S-OFF Midget Ganglion Cells in the Primate Retina. J Neurosci 2019; 39:7893-7909. [PMID: 31405926 DOI: 10.1523/jneurosci.0778-19.2019] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 06/27/2019] [Accepted: 08/06/2019] [Indexed: 11/21/2022] Open
Abstract
In the trichromatic primate retina, the "midget" retinal ganglion cell is the classical substrate for red-green color signaling, with a circuitry that enables antagonistic responses between long (L)- and medium (M)-wavelength-sensitive cone inputs. Previous physiological studies showed that some OFF midget ganglion cells may receive sparse input from short (S)-wavelength-sensitive cones, but the effect of S-cone inputs on the chromatic tuning properties of such cells has not been explored. Moreover, anatomical evidence for a synaptic pathway from S cones to OFF midget ganglion cells through OFF midget bipolar cells remains ambiguous. In this study, we address both questions for the macaque monkey retina. First, we used serial block-face electron microscopy to show that every S cone in the parafoveal retina synapses principally with a single OFF midget bipolar cell, which in turn forms a private-line connection with an OFF midget ganglion cell. Second, we used patch electrophysiology to characterize the chromatic tuning of OFF midget ganglion cells in the near peripheral retina that receive combined input from L, M, and S cones. These "S-OFF" midget cells have a characteristic S-cone spatial signature, but demonstrate heterogeneous color properties due to the variable strength of L, M, and S cone input across the receptive field. Together, these findings strongly support the hypothesis that the OFF midget pathway is the major conduit for S-OFF signals in primate retina and redefines the pathway as a chromatically complex substrate that encodes color signals beyond the classically recognized L versus M and S versus L+M cardinal mechanisms.SIGNIFICANCE STATEMENT The first step of color processing in the visual pathway of primates occurs when signals from short (S)-, middle (M)-, and long (L)-wavelength-sensitive cone types interact antagonistically within the retinal circuitry to create color-opponent pathways. The midget (L versus M or "red-green") and small bistratified (S vs L+M, or "blue-yellow") ganglion cell pathways appear to provide the physiological origin of the cardinal axes of human color vision. Here we confirm the presence of an additional S-OFF midget circuit in the macaque monkey fovea with scanning block-face electron microscopy and show physiologically that a subpopulation of S-OFF midget cells combine S, L, and M cone inputs along noncardinal directions of color space, expanding the retinal role in color coding.
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Huchzermeyer C, Kremers J. Perifoveal S-cone and rod-driven temporal contrast sensitivities at different retinal illuminances. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2017; 34:171-183. [PMID: 28157843 DOI: 10.1364/josaa.34.000171] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We evaluated a technique for measuring temporal contrast sensitivities to sine-wave modulation driven by S-cones and rods in the perifovea using triple silent substitution. Isolating stimuli for S-cones and rods were created using an eight-channel, four-primary LED stimulator that has been validated before. Sensitivities were measured at 10 different temporal frequencies between 1 and 28 Hz in three normal observers at 14 different retinal illuminances between 0.07 and 587 photopic troland (phot Td) and at three different retinal illuminances over the same range in one S-cone monochromat. The technique was further validated by measuring bleaching adaptation in two normal subjects, demonstrating sufficient isolation in rods. Good isolation was apparent from the differences in the temporal contrast sensitivity functions and the sensitivity-versus-retinal illuminance functions between S-cones and rods, and also from the results in the S-cone monochromats and the delayed recovery of rod sensitivities after bleaching. The results will help to determine optimal stimulus conditions in future studies. The results in the S-cone monochromat demonstrate the potential clinical value of our protocol.
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Smollon WE, Wooten BR, Hammond BR. Photopigment self-screening and the determination of macular pigment absorbance using heterochromatic flicker photometry. Exp Eye Res 2015; 140:10-18. [PMID: 26277581 DOI: 10.1016/j.exer.2015.07.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 07/23/2015] [Accepted: 07/28/2015] [Indexed: 11/25/2022]
Abstract
PURPOSE Heterochromatic flicker photometry (HFP) is commonly used to determine macular pigment optical density (MPOD). Since HFP in this application is a locus comparison method, an identical relative spectral response at each locus is required for a perfect measure. We know this requirement cannot be strictly true since the optical density of photopigments increases as the foveal center is approached. Thus, the self-screening effect would result in an underestimate of MPOD. An earlier study concluded that the underestimate is on the order of 30%. We examined this issue by manipulating photopigment optical density, and consequently the degree of selfscreening. METHODS A continuously exposed, 470 nm, background bleached cone photopigments over a range from 0 to 80%. MPOD was determined 10' and 30' from the foveal center. Two subjects were used in the main experiment. Five additional subjects were studied with just the 0% and 80% bleach levels. Spectral measures were obtained at 0% and 70% bleach levels for the two primary subjects. RESULTS Subjects in the main experiment showed MPOD estimates that increased with increasing bleaching. The effect, however, was small: one observer's MPOD increased 0.08 and 0.02 for the 10' and 30' loci, respectively; the other observer's values were 0.04 and 0.01 for the same loci. Comparable values were obtained for the other five subjects using the 0% and 80% bleach conditions. Spectral measures were consistent with the findings of the main experiment. CONCLUSIONS When self-screening is nearly abolished (80% bleach), a relatively small underestimation is revealed for the unbleached state. For the 1° target we show about 2-3% underestimation. Our 20' target reveals a larger underestimate (8-9%), consistent with longer photoreceptor outer-segments nearer the foveal center. We conclude that HFP yields values essentially independent of self-screening for targets of 1° diameter or greater. Smaller targets are less than 10% underestimated for near-zero bleach conditions.
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Affiliation(s)
- William E Smollon
- Department of Psychology, Brown University, Providence, RI 02906, USA.
| | - Billy R Wooten
- Department of Psychology, Brown University, Providence, RI 02906, USA.
| | - Billy R Hammond
- Brain and Behavioral Sciences, University of Georgia, Athens, GA 30602-3013, USA.
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Abstract
We review the features of the S-cone system that appeal to the psychophysicist and summarize the celebrated characteristics of S-cone mediated vision. Two factors are emphasized: First, the fine stimulus control that is required to isolate putative visual mechanisms and second, the relationship between physiological data and psychophysical approaches. We review convergent findings from physiology and psychophysics with respect to asymmetries in the retinal wiring of S-ON and S-OFF visual pathways, and the associated treatment of increments and decrements in the S-cone system. Beyond the retina, we consider the lack of S-cone projections to superior colliculus and the use of S-cone stimuli in experimental psychology, for example to address questions about the mechanisms of visually driven attention. Careful selection of stimulus parameters enables psychophysicists to produce entirely reversible, temporary, "lesions," and to assess behavior in the absence of specific neural subsystems.
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Johnson EN, Van Hooser SD, Fitzpatrick D. The representation of S-cone signals in primary visual cortex. J Neurosci 2010; 30:10337-50. [PMID: 20685977 PMCID: PMC2933431 DOI: 10.1523/jneurosci.1428-10.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 06/14/2010] [Accepted: 06/15/2010] [Indexed: 11/21/2022] Open
Abstract
Recent studies of middle-wavelength-sensitive and long-wavelength-sensitive cone responses in primate primary visual cortex (V1) have challenged the view that color and form are represented by distinct neuronal populations. Individual V1 neurons exhibit hallmarks of both color and form processing (cone opponency and orientation selectivity), and many display cone interactions that do not fit classic chromatic/achromatic classifications. Comparable analysis of short-wavelength-sensitive (S) cone responses has yet to be achieved and is of considerable interest because S-cones are the basis for the primordial mammalian chromatic pathway. Using intrinsic and two-photon imaging techniques in the tree shrew, we assessed the properties of V1 layer 2/3 neurons responsive to S-cone stimulation. These responses were orientation selective, exhibited distinct spatiotemporal properties, and reflected integration of S-cone inputs via opponent, summing, and intermediate configurations. Our observations support a common framework for the representation of cone signals in V1, one that endows orientation-selective neurons with a range of chromatic, achromatic, and mixed response properties.
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Affiliation(s)
- Elizabeth N Johnson
- Duke Institute for Brain Sciences, Duke University and Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
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Baraas RC, Kulikowski JJ, Muldoon MR. Bar-like S-cone stimuli reveal the importance of an intermediate temporal filter. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2010; 27:766-780. [PMID: 20360819 DOI: 10.1364/josaa.27.000766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The relative involvement of different temporal frequency-selective filters underlying detection of chromatic stimuli was studied. Diverse spectral stimuli were used, namely flashed blue and yellow light spots, wide bars, and narrow bars. The stimuli were temporally modulated in luminance having constant wavelength. Although the bar-like stimuli apparently reduced the sensitivity at short and long wavelengths, the cone-opponent mechanism still remained responsible for the actual stimulus detection at different temporal frequencies. The bar-like stimuli increased sensitivity for temporal frequencies around 3-6 Hz, revealing involvement of an intermediate temporal frequency-selective filter in detection, the so-called transient-1 filter. A probability summation model for the method of adjustment was developed that assumes that detection depends on the properties of the temporal filters underlying the temporal frequency-sensitivity curve. The model supports the notion that at least two temporal frequency-selective filters are necessary to account for the shape of the sensitivity curves obtained for blue bar-like stimuli.
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Affiliation(s)
- Rigmor C Baraas
- Department of Optometry and Visual Science, Buskerud University College, 3611 Kongsberg, Norway.
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Wade AR. Long-range suppressive interactions between S-cone and luminance channels. Vision Res 2009; 49:1554-62. [PMID: 19344735 DOI: 10.1016/j.visres.2009.03.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 03/04/2009] [Accepted: 03/12/2009] [Indexed: 11/26/2022]
Abstract
Surround suppression (SS) refers to a reduction in the effective stimulus contrast in one visual location produced by a stimulus presented in an adjacent location. This type of suppression is tuned for orientation and spatial frequency and is thought to be a cortical process. In this paper we used psychophysical measurements to determine whether S-cone-driven signals are affected by surround suppression and, if so, whether S-cone and achromatic signals interact at spatially-remote locations. Our results revealed three important aspects of surround suppression. Firstly, we show that S-cone probes are suppressed by simultaneous S-cone contrast surrounds and that this suppression has the characteristics of a cortical mechanism. Secondly, we show that when probes and surrounds are presented simultaneously, there are no suppressive interactions between S-cone and luminance stimuli. Finally, we demonstrate that this apparent independence is an artifact of signal timing: when the S-cone components of the stimuli precede the luminance components by approximately 40 ms, we find a significant interaction between the two pathways. The amplitude of this interaction depends critically upon the relative onset times of the two components. These results indicate that some component of surround suppression depends on neural computations that occur after the S- and luminance pathways are combined in striate cortex. In addition, the strong dependence of the magnitude of surround suppression on temporal ordering suggests that much of the effect is driven by transient signals.
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Affiliation(s)
- Alex R Wade
- Smith-Kettlewell Eye Research Institute, Brain Imaging, San Francisco, CA 94115, United States.
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How does the short-wavelength-sensitive contrast sensitivity function for detection and resolution change with age in the periphery? Vision Res 2008; 48:1894-901. [DOI: 10.1016/j.visres.2008.05.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Revised: 05/16/2008] [Accepted: 05/19/2008] [Indexed: 11/22/2022]
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Logvinenko AD, Hutchinson SJ. Evidence for the existence of colour mechanisms producing unique hues as derived from a colour illusion based on spatio-chromatic interactions. Vision Res 2007; 47:1315-34. [PMID: 17408717 DOI: 10.1016/j.visres.2006.10.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2004] [Revised: 10/13/2006] [Accepted: 10/18/2006] [Indexed: 11/20/2022]
Abstract
When its spatial frequency is high enough, a grid of grey horizontal strips presented on a coloured background may change its neutral colour. It was found that some background colours induce a strong illusion and some no illusion at all. The effect of the background colour on the illusion was studied for the spatial frequencies of 0.5, 2.5, 4, and 8 c/deg. Thirty chromaticities (evenly distributed across the colour gamut triangle) of the backgrounds in the equiluminant plane, and 24 in the ML plane (where S-contrast was zero), were tested. Five matches were made for each frequency and each background chromaticity. Viewing was binocular. For the low (0.5 c/deg) frequency strips, the backgrounds were found to induce the colour, if any, approximately complimentary to that of the background (i.e., chromatic simultaneous contrast). For the high (8 c/deg) frequency, most backgrounds induced only illusory colours close to unique hues (yellow, blue, and green), with a few backgrounds inducing a mixture of green with blue. Then, the method of adjustment was used to determine the unique hues for the same three observers. A remarkable similarity was found between unique hues and illusory loci, suggesting that the illusion is due to a difference in the spatial resolution of the post-receptor channels producing the unique hues.
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Abstract
Contrary to the general belief that the yellow-blue mechanism has lower spatial resolution than the red-green mechanism, it has been recently claimed that both mechanisms have similar spatial sensitivity (McKeefry et al, 2001 Vision Research 41 245-255). Studying high-spatial-frequency tritanopia (a colour illusion based on spatio-chromatic interactions in human vision), we found strong evidence for the existence of two blue mechanisms-with low and high spatial-frequency resolution. If confirmed, this may resolve the apparent paradox concerning spatial resolution of the yellow-blue mechanism.
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Affiliation(s)
- Alexander D Logvinenko
- Department of Vision Sciences, Glasgow Caledonian University, Glasgow G4 0BA, Scotland, UK.
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Kruger PB, Rucker FJ, Hu C, Rutman H, Schmidt NW, Roditis V. Accommodation with and without short-wavelength-sensitive cones and chromatic aberration. Vision Res 2004; 45:1265-74. [PMID: 15733959 DOI: 10.1016/j.visres.2004.11.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2004] [Revised: 11/08/2004] [Accepted: 11/15/2004] [Indexed: 11/28/2022]
Abstract
Accommodation was monitored while observers (23) viewed a square-wave grating (2.2 cycles/deg; 0.53 contrast) in a Badal optometer. The grating moved sinusoidally (0.2 Hz) to provide a stimulus between -1.00 D and -3.00 D during trials lasting 40.96 s. There were three illumination conditions: 1. Monochromatic 550 nm light to stimulate long-wavelength-sensitive cones (L-cones) and medium-wavelength-sensitive cones (M-cones) without chromatic aberration; 2. Monochromatic 550 nm light+420 nm light to stimulate long-, medium- and short-wavelength-sensitive cones (S-cones) with longitudinal chromatic aberration (LCA); 3. Monochromatic 550 nm light+420 nm light to stimulate L-, M- and S-cones viewed through an achromatizing lens. In the presence of LCA mean dynamic gain decreased (p=0.0003; ANOVA) and mean accommodation level was reduced (p=0.001; ANOVA). The reduction in gain and increased lag of accommodation in the presence of LCA could result from a blue-yellow chromatic signal or from a larger depth-of-focus.
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Affiliation(s)
- Philip B Kruger
- Schnurmacher Institute for Vision Research, State College of Optometry, State University of New York, 33 West 42nd Street, New York, NY 10036, USA.
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Rucker FJ, Kruger PB. The role of short-wavelength sensitive cones and chromatic aberration in the response to stationary and step accommodation stimuli. Vision Res 2004; 44:197-208. [PMID: 14637368 DOI: 10.1016/j.visres.2003.09.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The aim of the experiment was to test for a contribution from short-wavelength sensitive cones to the static and step accommodation response, to compare responses from short and long- plus middle-wavelength sensitive cone types, and to examine the contribution of a signal from longitudinal chromatic aberration to the accommodation response. Accommodation was monitored continuously (eight subjects) to a square-wave grating (2.2 c/d; 0.57 contrast) in a Badal optometer. The grating stepped (1.00 D) randomly towards or away from the eye from a starting position of 2.00 D. Five illumination conditions were used to isolate cone responses, and combine them with or without longitudinal chromatic aberration. Accuracy of the response before the step, step amplitude, latencies and time-constants, were compared between conditions using single factor ANOVA and t-test comparisons. Both S-cones and LM-cones mediated static and step accommodation responses. S-cone contrast drives "static" accommodation for near, but the S-cone response is too slow to influence step dynamics when LM-cones participate.
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Affiliation(s)
- Frances J Rucker
- Schnurmacher Institute for Vision Research, SUNY College of Optometry, Rm 1544b, 33 West 42nd St, New York, NY 10036-8003, USA.
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17
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Anderson RS, Coulter E, Zlatkova MB, Demirel S. Short-wavelength acuity: optical factors affecting detection and resolution of blue-yellow sinusoidal gratings in foveal and peripheral vision. Vision Res 2003; 43:101-7. [PMID: 12505609 DOI: 10.1016/s0042-6989(02)00410-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Previous studies have indicated that peripheral achromatic grating resolution is limited by the sampling density of the neural array (sampling limited), and largely unaffected by large amounts of optical defocus and significant changes in luminance. Under certain conditions, peripheral short-wavelength sensitive (SWS) grating acuity is also sampling limited. We wished to determine how the sampling-limited nature of SWS-driven grating resolution was affected by changing optical defocus and stimulus luminance. Using SWS-cone isolation techniques, detection and resolution acuity were measured for sinusoidal gratings under varying levels of stimulus mean luminance and optical defocus in the fovea and at 20 degrees eccentricity. From 1.4 down to 0.3 cd/m(2) peripheral detection acuity was superior to resolution acuity, accompanied by observations of aliasing: there was little change in resolution performance throughout this range. For defocus up to 3-4 dioptres, peripheral detection acuity was superior to resolution but fell steadily: resolution performance remained flat throughout the same range. Unlike achromatic acuity, foveal resolution performance displayed some robustness to defocus but to a lesser degree than the periphery. Peripheral SWS-driven resolution remains sampling limited for large changes in stimulus luminance and optical defocus, and should thus be useful as a clinical test of SWS-driven ganglion cell density.
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Affiliation(s)
- Roger S Anderson
- Vision Science Research Group, School of Biomedical Sciences, University of Ulster at Coleraine, Co Londonderry BT52 1SA, UK.
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18
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Anderson RS, Zlatkova MB, Beirne RO. The contrast sensitivity function for detection and resolution of blue-on-yellow gratings in foveal and peripheral vision. Ophthalmic Physiol Opt 2002; 22:420-6. [PMID: 12358313 DOI: 10.1046/j.1475-1313.2002.00068.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous studies using polychromatic gratings have shown that the peripheral grating contrast sensitivity function is significantly different when the task is resolution rather than detection. Specifically, in the middle frequency range, while resolution acuity drops suddenly to zero, detection performance continues up to much higher frequencies, accompanied by observations of aliasing. We wanted to determine if the same holds true for blue-cone isolating gratings in either foveal or peripheral vision. Contrast sensitivity function (CSFs) were measured at the fovea and 20 degrees eccentricity in the temporal retina under conditions of short-wavelength-sensitive (SWS)-cone pathway isolation using a two-alternative forced choice paradigm. The detection and resolution CSF were identical at the low frequency end but at higher frequencies resolution sensitivity falls abruptly while contrast detection remained possible till higher frequencies [cut-off frequencies: fovea detection 6.0 cycles (degree)(-1), resolution 4.6 cycles (degree)(-1); periphery detection 1.6 cycles (degree)(-1), resolution 1.05 cycles (degree)(-1)]. Aliasing was observable when spatial frequency exceeded the resolution limit. Medium/high contrast blue-cone-mediated resolution acuity is sampling limited in both the fovea and periphery. Previous studies of blue-cone contrast sensitivity which employed a detection task do not reflect the true resolution limit.
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Affiliation(s)
- R S Anderson
- Vision Science Research Group, School of Biomedical Sciences, University of Ulster at Coleraine, UK
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19
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Anderson RS, Zlatkova MB, Demirel S. What limits detection and resolution of short-wavelength sinusoidal gratings across the retina? Vision Res 2002; 42:981-90. [PMID: 11934450 DOI: 10.1016/s0042-6989(02)00013-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Peripheral resolution acuity for achromatic gratings is known to be limited by the density of the underlying ganglion cell sampling array. After confirming isolation of the short-wavelength sensitive (SWS) system using chromatic adaptation methods, we wished to determine if resolution is limited by blue/yellow ganglion cell sampling (evidenced by a superiority of detection over resolution acuity and the perception of aliasing) and thus directly related to SWS-driven ganglion cell density. We measured detection and resolution acuity between 0 degrees and 35 degrees, using blue sinusoidal gratings superimposed on a yellow adapting background which ranged in intensity from 2.5 to 4.7logTrolands. At all locations, a break could be observed in the acuity vs. illumination curves followed by a plateau. Detection and resolution acuity were the same for low background intensities, but resolution acuity was lower than detection at higher intensities, accompanied by observations of chromatic aliasing. SWS resolution is sampling-limited across the retina and agrees well with predicted performance based on anatomical estimates of small bistratified ganglion cell density.
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Affiliation(s)
- Roger S Anderson
- Vision Science Research Group, School of Biomedical Sciences, University of Ulster at Coleraine, Co. Londonderry, BT52 1SA, Northern Ireland, UK.
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20
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Abstract
The S cone is highly conserved across mammalian species, sampling the retinal image with less spatial frequency than other cone photoreceptors. In human and monkey retina, the S cone represents typically 5-10% of the cone mosaic and distributes in a quasi-regular fashion over most of the retina. In the fovea, the S cone mosaic recedes from a central "S-free" zone whose size depends on the optics of the eye for a particular primate species: the smaller the eye, the less extreme the blurring of short wavelengths, and the smaller the zone. In the human retina, the density of the S mosaic predicts well the spatial acuity for S-isolating targets across the retina. This acuity is likely supported by a bistratified retinal ganglion cell whose spatial density is about that of the S cone. The dendrites of this cell collect a depolarizing signal from S cones that opposes a summed signal from M and L cones. The source of this depolarizing signal is a specialized circuit that begins with expression of the L-AP4 or mGluR6 glutamate receptor at the S cone-->bipolar cell synapse. The pre-synaptic circuitry of this bistratified ganglion cell is consistent with its S-ON/(M+L)-OFF physiological receptive field and with a role for the ganglion cell in blue/yellow color discrimination. The S cone also provides synapses to other types of retinal circuit that may underlie a contribution to the cortical areas involved with motion discrimination.
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Affiliation(s)
- D J Calkins
- Departments of Ophthalmology, Neurobiology and Anatomy, and Neurology and the Center for Visual Science, University of Rochester Medical Center, Rochester, NY 14642, USA
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21
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Pearson P, Swanson WH, Fellman RL. Chromatic and achromatic defects in patients with progressing glaucoma. Vision Res 2001; 41:1215-27. [PMID: 11292509 DOI: 10.1016/s0042-6989(00)00311-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
To evaluate the pattern of losses associated with glaucomatous injury in patients with progressing glaucoma, functional losses were examined in 14 patients with progressing glaucoma using tests for which detection should be selectively mediated by one of three psychophysical mechanisms. Red-on-white increments, blue-on-white increments and critical flicker frequency were used to isolate the responses of the red-green chromatic mechanism, the blue-on chromatic mechanism, and the high-frequency flicker achromatic mechanism. For our 3.1 degrees circular stimuli, chromatic defects were found in a greater number of the patients with glaucoma than were achromatic defects. We evaluated these defects in terms of two existing hypotheses: preferential loss and reduced redundancy. The greater sensitivity to glaucomatous injury of chromatic tests, compared to achromatic tests, found in this and other studies and the apparent discrepancy between anatomical and psychophysical studies can be parsimoniously explained by differences in cortical summation of ganglion cell responses for the chromatic and achromatic pathways.
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Affiliation(s)
- P Pearson
- Retina Foundation of the Southwest, Dallas, TX 75231, USA
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22
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Rucker FJ, Kruger PB. Isolated short-wavelength sensitive cones can mediate a reflex accommodation response. Vision Res 2001; 41:911-22. [PMID: 11248276 DOI: 10.1016/s0042-6989(00)00303-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Both long- and middle-wavelength sensitive cones mediate the reflex accommodation signal but the contribution from the short-wavelength sensitive cones is unknown. A short-wavelength sensitive cone contribution could extend the range of the signed defocus signal from chromatic aberration. The aim was to determine whether isolated short-wavelength sensitive cones mediate reflex accommodation independently of long- and middle-wavelength sensitive cones. Accommodation was monitored continuously (eight subjects) to a sine-wave grating (3 cpd; 0.53 contrast) moving with a sum of sines motion in a Badal optometer. Two illumination conditions were used: a 'blue' condition that isolated short-wavelength sensitive cones, and a 'white' control condition that stimulated all three cone types. Of the eight subjects, two responded equally in the 'white' and 'blue' condition, four gave reduced responses in the 'blue' condition and two failed to respond in both conditions. The mean response in the 'blue' condition was reduced by 50% compared to the 'white' condition. Further analysis indicated that four of the eight subjects gave responses that were considerably greater than noise (S.D.>1.82) when short-wavelength sensitive cones were isolated. Some subjects can accommodate using only S-cones.
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Affiliation(s)
- F J Rucker
- Schnurmacher Institute for Vision Research, State College of Optometry, State University of New York, 33 West 42th Street, New York, NY 10010, USA
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23
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McKeefry DJ, Murray IJ, Kulikowski JJ. Red--green and blue--yellow mechanisms are matched in sensitivity for temporal and spatial modulation. Vision Res 2001; 41:245-55. [PMID: 11163858 DOI: 10.1016/s0042-6989(00)00247-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The spatial and temporal properties of human colour vision are examined using isoluminant, red--green and blue--yellow tritanopic gratings. Chromatic sensitivity is found to be low-pass as a function of both spatial and temporal frequency along all the chromatic axes investigated, including the tritanopic confusion lines employed to examine the properties of the S-cone driven mechanism. Comparison of sensitivity to on-off and contrast reversing stimuli indicates that transient mechanisms contribute to the detection of red--green patterns but that the detection of S-cone specific patterns is governed by sustained mechanisms. By compensating for transient contributions to red--green sensitivity, it is shown that sensitivity of chromatic mechanisms dominated by L- and M-cone input are closely matched to those with S-cone input.
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Affiliation(s)
- D J McKeefry
- School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, BT52 1SA, UK
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24
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Calkins DJ. Representation of cone signals in the primate retina. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2000; 17:597-606. [PMID: 10708041 DOI: 10.1364/josaa.17.000597] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Vision begins with specialized retinal circuits that encode diverse types of information. For Old World primates, these circuits sample three submosaics formed by cone photoreceptors sensitive to short, middle, and long wavelengths. For spatial acuity, the photon catch between any two cones is compared for discrimination of patterns as fine as the cone mosaic. For color vision, the photon catch between different cone types is compared for discrimination of fine spectral differences on the basis of hue. The retinal circuits for these two tasks differ at the synaptic level to form distinct representations of signals from the cone mosaic.
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Affiliation(s)
- D J Calkins
- Department of Ophthalmology, University of Rochester Medical Center, New York 14642, USA.
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25
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Calkins DJ, Sterling P. Evidence that circuits for spatial and color vision segregate at the first retinal synapse. Neuron 1999; 24:313-21. [PMID: 10571226 DOI: 10.1016/s0896-6273(00)80846-6] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- D J Calkins
- Department of Ophthalmology, University of Rochester Medical Center, New York 14642, USA.
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26
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Robson AG, Kulikowski JJ. Objective specification of tritanopic confusion lines using visual evoked potentials. Vision Res 1998; 38:3499-503. [PMID: 9893872 DOI: 10.1016/s0042-6989(98)00058-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The minimum distinct border (MDB) between different isoluminant hues of a bipartite field was set subjectively by adjustment and then according to a 3-point rating allowing determination of the S-cone specific (tritanopic) axis. This rating was compared with visual evoked potentials (VEPs) generated by coarse, isoluminant gratings, modulated along the same chromatic axes. Psychophysically determined tritanopic gratings elicited monophasic onset VEPs with the longest latency for each subject. Departure from this axis produced additional earlier negative components (reflecting additional response mechanisms). Colour-selective VEPs can, therefore, objectively specify tritanopic confusion lines with a comparable degree of accuracy to MDB judgements.
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Affiliation(s)
- A G Robson
- Visual Sciences Laboratory, UMIST, Manchester, UK.
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27
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Abstract
Short-wavelength-sensitive (S-) cone-mediated thresholds have been used to study the early stages of visual loss, but due to the effects of non-neural factors (pupil size, lenticular density, macular pigment density) S-cone thresholds are often of limited clinical utility. The current study evaluates four possible effects of non-neural factors on S-cone contrast sensitivity, and shows how these can be minimized by measuring sensitivity for 1-5 c/deg with a range of retinal illuminances for blue test gratings on yellow backgrounds. The data are fit well with a simple four-parameter model which indicates that S-cone contrast sensitivity can be relatively independent on non-neural factors. A simple control experiment is described for evaluating the independence in individual patients.
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Affiliation(s)
- W H Swanson
- Retina Foundation of the Southwest, Dallas, TX 75231-3303, USA.
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28
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Kulikowski JJ, Robson AG, McKeefry DJ. Specificity and selectivity of chromatic visual evoked potentials. Vision Res 1996; 36:3397-401. [PMID: 8977006 DOI: 10.1016/0042-6989(96)00055-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A paper by Rabin et al. (1994) Vision Research, 34, 2657-2671, claimed that spatially extensive grating stimuli could be used to generate chromatic-specific visual evoked potentials from subjects assumed to have standard spectral sensitivity and tritanopic confusion lines. Here we demonstrate that such spatially extensive stimuli may generate responses which are contaminated by luminance-contrast intrusions. Such intrusions are mainly due to chromatic aberrations and are compounded by the abovementioned assumptions. Claims regarding the chromatic selectivity of VEPs must, therefore, be substantiated by establishing correlations with the known properties of the chromatic system.
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29
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García-Pérez MA, Sierra-Vázquez V. Do channels shift their tuning towards lower spatial frequencies in the periphery? Vision Res 1996; 36:3339-72. [PMID: 8944292 DOI: 10.1016/0042-6989(96)00345-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Space-variant multichannel spatial vision models include either anchored channels whose units (sensors) share their tuning frequency, or shifting channels whose sensors shift their tuning towards lower frequencies in the periphery. Each type of model embodies a different type of structural organization across eccentricity. Anchored- and shifting-channel models are tested in this paper against empirical data from five types of relevant detection experiment: measurements of the local sine-wave contrast sensitivity function (CSF) at several eccentricities using (a) fixed apertures, (b) apertures scaled with eccentricity or (c) fixed number of cycles, (d) measurements of foveal sensitivity as a function of aperture size, and (e) measurements of the contrast sensitivity gradient across the visual field. Each type of model is shown to predict a different outcome in each type of experiment. A review of empirical research reveals that three of the five experiment types have yielded two distinct sets of results, each of which is consistent with the predictions from one of the types of model, while the two other types of experiment have always yielded similar results which support anchored-channel models. Further scrutiny of the models reveals that the distinction between anchored and shifting channels is more apparent than real, as model predictions are only determined by how sensor gain is assumed to change with eccentricity and tuning frequency. Two alternative sensor gain functions are identified and interpreted in terms of two versions of the cortical magnification theory of spatial vision. Altogether, these two functions account for all extant data on the five types of experiment, suggesting individual differences in the functional organization of the human visual system across eccentricity.
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Affiliation(s)
- M A García-Pérez
- Departamento de Metodología, Facultad de Psicología, Universidad Complutense, Madrid, Spain
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30
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Rabin J, Adams AJ. Lightness induction in the S-cone pathway. Vision Res 1992; 32:1771-4. [PMID: 1455748 DOI: 10.1016/0042-6989(92)90169-j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Lightness induction is classically regarded as a contrast phenomenon limited to pathways which process luminance information. To determine if lightness induction can also occur in the chromatic domain, this phenomenon was studied with stimuli visible only to the short wavelength sensitive (S)-cones which have post-receptoral connections limited to chromatic pathways. The lightness of an object visible only to S-cones was found to be dependent on the relative intensity of its background in a manner similar to achromatic, luminance stimuli. Less intense (dark) backgrounds made the object appear lighter, while more intense (light) backgrounds made the same object appear darker. These results indicate a commonality among lightness induction effect in the processing of chromatic and luminance information.
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Affiliation(s)
- J Rabin
- School of Optometry, University of California, Berkeley 94720
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31
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Kellner U, Foerster MH. Color electroretinography. A method for separation of dysfunctions of cones. Doc Ophthalmol 1992; 80:13-23. [PMID: 1505335 DOI: 10.1007/bf00161227] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Electroretinograms to white and color stimuli were recorded in four normal subjects and nine subjects with different cone dysfunctions, including protanopia, cone dystrophy, cone dystrophy with supernormal b-waves at dark adaptation, cone dystrophy with missing b-waves during light adaptation and rod-cone dystrophy with blue cone hypersensitivity. Color stimuli were obtained with Kodak Wratten filters in blue, blue-green, green, yellow and red. Electroretinograms to all stimuli were recorded during dark and light adaptation with different stimulus intensities and to 30-Hz flicker stimulation. In protanopia, responses to red during light adaptation and flicker stimulation were reduced. All cone dystrophies showed reduced amplitudes and prolonged implicit times to red when dark adapted. The light-adapted responses were equally reduced to all color stimuli in cone dystrophy and cone dystrophy with supernormal b-waves. Contrary to other cone dystrophies, in cone dystrophy with missing b-waves, responses to red were severely reduced and responses to green were preserved, indicating a predominantly red cone dysfunction. Blue cone hypersensitivity was clearly distinct from other dystrophies in having large response to blue and blue-green and much smaller responses to all other colors in all stimulus conditions. The electroretinogram with color stimuli allowed separation of different cone dysfunctions and identification of new retinal dysfunction syndromes.
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Affiliation(s)
- U Kellner
- FU Berlin, Klinikum Steglitz, Augenklinik und Poliklinik, Germany
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32
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Román AJ, Jacobson SG. S cone-driven but not S cone-type electroretinograms in the enhanced S cone syndrome. Exp Eye Res 1991; 53:685-90. [PMID: 1743268 DOI: 10.1016/0014-4835(91)90230-c] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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33
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Curcio CA, Allen KA, Sloan KR, Lerea CL, Hurley JB, Klock IB, Milam AH. Distribution and morphology of human cone photoreceptors stained with anti-blue opsin. J Comp Neurol 1991; 312:610-24. [PMID: 1722224 DOI: 10.1002/cne.903120411] [Citation(s) in RCA: 380] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Primate cones maximally sensitive to short wavelength light (blue cones) have been previously identified by using indirect methods. We stained 7 wholemounted human retinas obtained from 6 female donors, using an affinity purified antibody to a 19 amino acid peptide sequence at the N-terminus of blue opsin (Lerea et al., '89: Neuron 3:367-376), standard PAP immunocytochemistry, and controls. Cones were counted where all outer segments could be traced to inner segments and were measured where cells were well aligned vertically. We find that: (1) 7% of cones within 4 mm of the foveal center are labeled by antiblue opsin; (2) compared to neighboring red/green cones, blue cone inner segments are 10% taller, have a larger cross-sectional diameter near the junction with the outer segment, and a smaller diameter near the external limiting membrane, resulting in a more cylindrical shape, (3) foveal blue cones are sparse, irregularly spaced, and missing in a zone about 100 microns (0.35 degrees) in diameter near the site of peak cone density, (4) the highest densities of blue cones (greater than 2,000 cells/mm2) are found in a ring at 0.1-0.3 mm eccentricity, and (5) the shortest distances between neighboring cones are between blue and red/green cones, and the blue and red/green mosaics are statistically independent. These findings are consistent with psychophysical reports of foveal tritanopia and maximum sensitivity to blue light at 1 degree eccentricity. Blue cone spacing may limit resolution of the blue channel out to 20-30 degrees eccentricity. The blue and red/green mosaics appear to be formed by separate processes.
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Affiliation(s)
- C A Curcio
- Department of Ophthalmology, University of Alabama, Birmingham 35294
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34
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Anderson SJ, Mullen KT, Hess RF. Human peripheral spatial resolution for achromatic and chromatic stimuli: limits imposed by optical and retinal factors. J Physiol 1991; 442:47-64. [PMID: 1798037 PMCID: PMC1179877 DOI: 10.1113/jphysiol.1991.sp018781] [Citation(s) in RCA: 138] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
1. The aim of this study was to determine whether optical, receptoral or higher-order neural properties limit spatial resolution (acuity) in human vision, especially in the peripheral regions of the visual field. 2. Both achromatic and chromatic stimuli were used, and measures were taken to ensure that the resolution estimates were not contaminated by the detection of spatial sampling artifacts. Spatial contrast sensitivity functions were measured at retinal locations from 0 to 55 deg along the naso-temporal meridian for: (i) discriminating the direction of drift of luminance-modulated (black-white) sinusoidal stimuli drifting at 8 Hz (achromatic task); and (ii) for detecting isoluminant red-green sinusoidal stimuli drifting at 0.4 Hz (chromatic task). Achromatic contrast sensitivity functions were also measured along the vertical meridian for eccentricities of 8 and 40 deg. Each achromatic function was extrapolated to a contrast sensitivity of one (100% contrast) to estimate achromatic acuity. Chromatic acuities were obtained by expressing chromatic contrast in terms of cone contrasts and using the same method of extrapolation. We compared the results with recent data on human optical properties and retinal anatomy. 3. Both achromatic and chromatic acuity decline with distance from the fovea, but at a faster rate than that dictated by the known optical and/or receptoral properties of the human eye. We conclude that, for stimuli of either achromatic or chromatic contrast, peripheral spatial resolution is limited by post-receptoral mechanisms. Also, chromatic acuity declines more steeply than luminance acuity with eccentricity suggesting that there are additional post-receptoral limitations on colour resolution in the periphery. 4. A clear naso-temporal asymmetry is seen in the resolution whose dependence is qualitatively, but not quantitatively, similar to the Nyquist limits imposed by the asymmetric density of human retinal ganglion cells. We discuss the possibility that in peripheral vision (beyond the optic nerve head) the spacing of ganglion cells may pose a fundamental limit on the resolution of achromatic stimuli, but not chromatic stimuli.
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35
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Abstract
1. The receptoral mechanisms underlying the vision of two atypical achromats of the complete variety were studied with standard psychophysical procedures. 2. Under scotopic conditions the spectral sensitivity of each achromat was well described by the CIE (Commission Internationale de l'Eclairage) scotopic sensitivity function and the recovery of sensitivity after a retinal bleach showed characteristic duplex behaviour with the time constant of recovery of the slower phase matching that of normal rod vision for both foveal and peripheral stimulation. 3. Their spectral sensitivity was measured under conditions of chromatic adaptation in order to reveal any residual middle or long wavelength cone activity. Only one photopic spectral responses was found and this was adequately described by the spectral sensitivity function of Stiles pi 3 mechanism of normal vision. 4. Increment threshold measurements as a function of background intensity revealed a double-branched function in the fovea. The lower branch was found to have the spectral sensitivity of the rods; the upper branch that of Stiles' pi 3 mechanism. Stiles-Crawford measurements of directional sensitivity confirmed that the branch with the rhodopsin action spectrum had the directional sensitivity of rods and that the branch with the action spectrum of pi 3 had the directional sensitivity of cones. 5. These was no evidence for hue discrimination under photopic conditions. Regions of apparently normal performance on hue discrimination tests on more careful examination could be explained by luminosity judgements mediated by short wavelength-absorbing receptors. 6. We reject the notion of there being rhodopsin-filled cones in the fovea of these subjects. The foveal and peripheral vision of each of these achromats can be adequately described in terms of the participation of only two types of receptor, namely normally functional rods under scotopic conditions and normally functioning short wavelength-absorbing cones under photopic conditions. They are therefore functional blue mono-cone monochromats, an explanation which was originally proposed by Blackwell & Blackwell (1957) over thirty years ago.
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Affiliation(s)
- R F Hess
- Physiological Laboratory, University of Cambridge
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36
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Sharpe LT, Fach C, Nordby K, Stockman A. The incremental threshold of the rod visual system and Weber's law. Science 1989; 244:354-6. [PMID: 2711186 DOI: 10.1126/science.2711186] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The incremental threshold of the isolated rod visual system is believed, under certain conditions, to obey Weber's law (that is, to increase in direct proportion to the intensity of the background). This relation was tested at several background wavelengths, over an intensity range for which the target was seen only by the rods. Although the slope on long-wavelength background approximates unity (that is, Weber's law on log-log coordinates), it averages less than 0.8 on short- and middle-wavelength backgrounds. This is the same value as that found for the thresholds of a typical, complete achromat--who lacks cone vision--regardless of background wavelength. These results force the conclusion that Weber's law for incremental threshold detection is achieved not by the rods alone but only by the rods acting together with the cones.
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Affiliation(s)
- L T Sharpe
- Neurologische Universitätsklinik, Freiburg im Breisgau, Federal Republic of Germany
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