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NeuroImage May 2018A neutral density filter placed before one eye will produce a dichoptic imbalance in luminance, which attenuates responses to visual stimuli and lags neural signals from...
A neutral density filter placed before one eye will produce a dichoptic imbalance in luminance, which attenuates responses to visual stimuli and lags neural signals from retina to cortex in the filtered eye. When stimuli are presented to both the filtered and unfiltered eye (i.e., binocularly), neural responses show little attenuation and no lag compared with their baseline counterpart. This suggests that binocular visual mechanisms must suppress the attenuated and delayed input from the filtered eye; however, the mechanisms involved remain unclear. Here, we used a Steady-State Visual Evoked Potential (SSVEP) technique to measure neural responses to monocularly and binocularly presented stimuli while observers wore an ND filter in front of their dominant eye. These data were well-described by a binocular summation model, which received the sinusoidal contrast modulation of the stimulus as input. We incorporated the influence of the ND filter with an impulse response function, which adjusted the input magnitude and phase in a biophysically plausible manner. The model captured the increase in attenuation and lag of neural signals for stimuli presented to the filtered eye as a function of filter strength, while also generating the filter phase-invariant responses from binocular presentation for EEG and psychophysical data. These results clarify how binocular visual mechanisms-specifically interocular suppression-can suppress the delayed and attenuated signals from the filtered eye and maintain normal neural signals under imbalanced luminance conditions.
Topics: Adult; Electroencephalography; Evoked Potentials, Visual; Female; Humans; Male; Photic Stimulation; Vision, Binocular; Vision, Monocular
PubMed: 29454106
DOI: 10.1016/j.neuroimage.2018.02.021 -
Journal of Vision Nov 2017We develop and test a new two-dimensional model for binocular combination of the two eyes' luminance profiles. For first-order stimuli, the model assumes that one eye's...
We develop and test a new two-dimensional model for binocular combination of the two eyes' luminance profiles. For first-order stimuli, the model assumes that one eye's luminance profile first goes through a luminance compressor, receives gain-control and gain-enhancement from the other eye, and then linearly combines the other eye's output profile. For second-order stimuli, rectification is added in the signal path of the model before the binocular combination site. Both the total contrast and luminance energies, weighted sums over both the space and spatial-frequency domains, were used in the interocular gain-control, while only the total contrast energy was used in the interocular gain-enhancement. To challenge the model, we performed a binocular brightness matching experiment over a large range of background and target luminances. The target stimulus was a dichoptic disc with a sharp edge that has an increment or decrement luminance from its background. The disk's interocular luminance ratio varied from trial to trial. To refine the model we tested three luminance compressors, five nested binocular combination models (including the Ding-Sperling and the DSKL models), and examined the presence or absence of total luminance energy in the model. We found that (1) installing a luminance compressor, either a logarithmic luminance function or luminance gain-control, (2) including both contrast and luminance energies, and (3) adding interocular gain-enhancement (the DSKL model) to a combined model significantly improved its performance. The combined model provides a systematic account of binocular luminance summation over a large range of luminance input levels. It gives a unified explanation of Fechner's paradox observed on a dark background, and a winner-take-all phenomenon observed on a light background. To further test the model, we conducted two additional experiments: luminance summation of discs with asymmetric contour information (Experiment 2), similar to Levelt (1965) and binocular combination of second-order contrast-modulated gratings (Experiment 3). We used the model obtained in Experiment 1 to predict the results of Experiments 2 and 3 and the results of our previous studies. Model simulations further refined the contrast space weight and contrast sensitivity functions that are installed in the model, and provide a reasonable account for rebalancing of imbalanced binocular vision by reducing the mean luminance in the dominant eye.
Topics: Contrast Sensitivity; Humans; Light; Models, Theoretical; Vision, Binocular; Vision, Ocular
PubMed: 29098293
DOI: 10.1167/17.13.4 -
Ophthalmic & Physiological Optics : the... Mar 2014Humans with amblyopia have an asymmetry in binocular vision: neural signals from the amblyopic eye are suppressed in the cortex by the fellow eye. The purpose of this...
PURPOSE
Humans with amblyopia have an asymmetry in binocular vision: neural signals from the amblyopic eye are suppressed in the cortex by the fellow eye. The purpose of this study was to develop new models and methods for rebalancing this asymmetric binocular vision by manipulating the contrast and luminance in the two eyes.
METHODS
We measured the perceived phase of a cyclopean sinewave by asking normal and amblyopic observers to indicate the apparent location (phase) of the dark trough in the horizontal cyclopean sine wave relative to a black horizontal reference line, and used the same stimuli to measure perceived contrast by matching the binocular combined contrast to a standard contrast presented to one eye. We varied both the relative contrast and luminance of the two eyes' inputs, in order to rebalance the asymmetric binocular vision.
RESULTS
Amblyopic binocular vision becomes more and more asymmetric the higher the stimulus contrast or spatial frequency. Reanalysing our previous data, we found that, at a given spatial frequency, the binocular asymmetry could be described by a log-linear formula with two parameters, one for the maximum asymmetry and one for the rate at which the binocular system becomes asymmetric as the contrast increases. Our new data demonstrates that reducing the dominant eye's mean luminance reduces its suppression of the non-dominant eye, and therefore rebalances the asymmetric binocular vision.
CONCLUSIONS
While the binocular asymmetry in amblyopic vision can be rebalanced by manipulating the relative contrast or luminance of the two eyes at a given spatial frequency and contrast, it is very difficult or even impossible to rebalance the asymmetry for all visual conditions. Nonetheless, wearing a neutral density filter before the dominant eye (or increasing the mean luminance in the non-dominant eye) may be more beneficial than the traditional method of patching the dominant eye for treating amblyopia.
Topics: Adult; Amblyopia; Female; Humans; Male; Middle Aged; Models, Theoretical; Photic Stimulation; Sensory Deprivation; Sensory Thresholds; Vision, Binocular
PubMed: 24417338
DOI: 10.1111/opo.12115 -
Journal of Vision Nov 2023Horizontal disparity has been recognized as the primary signal driving stereoscopic depth since the invention of the stereoscope in the 1830s. It has a unique status in...
Horizontal disparity has been recognized as the primary signal driving stereoscopic depth since the invention of the stereoscope in the 1830s. It has a unique status in our understanding of binocular vision. The direction of offset of the eyes gives the disparities of corresponding image point locations across the two retinas a strong horizontal bias. Beyond the retina, other factors give shape to the effective disparity direction used by visual mechanisms. The influence of orientation is examined here. I argue that horizontal disparity is an inflection point along a continuum of effective directions, and its role in stereo vision can be reinterpreted. The pointwise geometric justification for its special status neglects the oriented structural elements of spatial vision, its physiological support is equivocal, and psychophysical support of its special status may partially reflect biased stimulus sampling. The literature shows that horizontal disparity plays no particular role in the processing of one-dimensional stimuli, a reflection of the stereo aperture problem. The resulting depth is non-veridical, even non-transitive. Although one-dimensional components contribute to the stereo depth of visual objects generally, two-dimensional stimuli appear not to inherit the aperture problem. However, a look at the two-dimensional stimuli that predominate in experimental studies shows regularities in orientation that give a new perspective on horizontal disparity.
Topics: Humans; Retina; Vision, Binocular
PubMed: 37930689
DOI: 10.1167/jov.23.13.4 -
Journal of Optometry 2020The use of ophthalmic instruments requires increased effort on the accommodation and vergence system. This study aimed to understand the prevalence of binocular vision...
PURPOSE
The use of ophthalmic instruments requires increased effort on the accommodation and vergence system. This study aimed to understand the prevalence of binocular vision anomalies among ophthalmology trainees attending a surgical training program at a tertiary eye care center.
METHODS
This prospective cohort study was carried out between April and November 2017 at a tertiary eye care center in South India. All the ophthalmology trainees inducted for the training programs at the institution underwent a comprehensive ophthalmic and binocular vision assessment. Subjects with previous diagnosis of binocular vision dysfunction and vision therapy were excluded.
RESULTS
The mean (SD) age of the subjects was 29 (3) among which 48 were females. Out of the total 75 subjects, 66 had prior surgical experience [range: 1 to 17 years]. Thirty-eight subjects were asymptomatic and 37 were symptomatic. The most common asthenopic symptom was the presence of headache. Forty-one (55%) out of the 75 had a diagnosis of a non-strabismic binocular vision dysfunction. The range of phoria at distance was orthophoria to 14 Prism Diopter (PD) exophoria (mean +/- SD: -1 +/- 3), and at near 4PD esophoria to 25PD exophoria (mean +/- SD: -4 +/- 5). Based on standard diagnostic criteria, 15 subjects (20%) had convergence insufficiency, 14 (19%) had accommodative infacility, 9 (12%) had intermittent divergent squint (IDS), while 3 subjects (4%) had convergence excess.
CONCLUSIONS
This study shows the high frequency of binocular vision dysfunctions among ophthalmology trainees joining a tertiary eye care center.
Topics: Accommodation, Ocular; Adult; Education, Medical, Undergraduate; Female; Humans; India; Male; Middle Aged; Ophthalmology; Prevalence; Prospective Studies; Retinoscopy; Tertiary Care Centers; Vision Disorders; Vision, Binocular; Young Adult
PubMed: 32493674
DOI: 10.1016/j.optom.2020.01.003 -
Cell Reports Feb 2020The development of neuronal circuits requires both hard-wired gene expression and experience-dependent plasticity. Sensory processing, such as binocular vision, is...
The development of neuronal circuits requires both hard-wired gene expression and experience-dependent plasticity. Sensory processing, such as binocular vision, is especially sensitive to perturbations of experience. We investigated the experience-dependent development of the binocular visual cortex at single-cell resolution by using two-photon calcium imaging in awake mice. At eye-opening, the majority of visually responsive neurons are monocular. Binocular neurons emerge later with visual experience and acquire distinct visual response properties. Surprisingly, rather than mirroring the effects of visual deprivation, mice that lack the plasticity gene Arc show increased numbers of binocular neurons and a shift in ocular dominance during development. Strikingly, acutely removing Arc in the adult binocular visual cortex also increases the number of binocular neurons, suggesting that the maintenance of binocular circuits requires ongoing plasticity. Thus, experience-dependent plasticity is critical for the development and maintenance of circuits required to process binocular vision.
Topics: Animals; Mice; Neurons; Vision, Binocular; Visual Cortex
PubMed: 32049025
DOI: 10.1016/j.celrep.2020.01.031 -
Investigative Ophthalmology & Visual... Oct 2018Two core processes underlie 3-D binocular vision. The first, a binocular combination/summation process, integrates similar feature signals from the two eye channels to...
PURPOSE
Two core processes underlie 3-D binocular vision. The first, a binocular combination/summation process, integrates similar feature signals from the two eye channels to form a binocular representation. The second, a binocular inhibitory process, suppresses interocular conflicting signals or falsely matched binocular representations to establish single vision. Having an intrinsic interocular imbalance within one or both processes can cause sensory eye dominance (SED), related to imbalances of combination (SEDcombo) and/or inhibition (SEDinhibition). While much has recently been revealed about SEDcombo and SEDinhibition, the relationship between them is still unknown.
METHODS
We measured observers' foveal SEDcombo and SEDinhibition, respectively, with a pair of dichoptic horizontal sine wave gratings with different phases and binocular rivalry stimulus with vertical and horizontal gratings. We then measured horizontal and vertical monocular contrast thresholds using sinusoidal grating stimuli, and stereo thresholds using random-dot stereograms.
RESULTS
There exists a strong correlation between SEDcombo and SEDinhibition. An observer's interocular difference in contrast threshold was not always consistent with his/her SEDcombo and SEDinhihition, suggesting a partial binocular origin for the underlying imbalances. We also found stereo thresholds significantly increased with the magnitudes of SEDcombo, as well as with the magnitude of SEDinhibition.
CONCLUSIONS
Our findings suggest a common origin for interocular imbalance in the two different binocular processes and that both types of sensory eye dominance are significant factors in impeding stereopsis.
Topics: Adolescent; Adult; Contrast Sensitivity; Depth Perception; Dominance, Ocular; Female; Humans; Male; Photic Stimulation; Sensory Thresholds; Vision, Binocular; Visual Perception; Young Adult
PubMed: 30372739
DOI: 10.1167/iovs.18-24342 -
Investigative Ophthalmology & Visual... Apr 2021Infantile strabismus impedes the development of stereopsis. In optically strabismic monkeys, 2 continuous hours of normal binocular vision per day has been shown to...
PURPOSE
Infantile strabismus impedes the development of stereopsis. In optically strabismic monkeys, 2 continuous hours of normal binocular vision per day has been shown to preserve near-normal stereopsis. In this study, we investigated whether, as in learning, multiple shorter periods of intervention would further boost performance.
METHODS
To simulate infantile esotropia, infant monkeys were reared with 30 prism diopters base-in starting at 4 weeks of age. Daily periods of normal binocular vision were provided by replacing prisms with plano lenses. Altogether, 14 monkeys were prism reared: 2 with continuous prism, 2 with 2 continuous hours of normal binocular vision per day, 6 with 2 noncontinuous hours, and 4 with 1 noncontinuous hour of binocular vision each day. Seven normally reared monkeys provided control data. Behavioral methods were employed to measure spatial contrast sensitivity, eye alignment, and stereopsis.
RESULTS
One monkey reared with continuous prism had poor stereopsis, and the other had no stereopsis. Ten of the 12 monkeys reared with periods of normal binocular vision had stereopsis, and those with longer and more continuous periods of binocular vision had stereopsis approaching that of normally reared monkeys.
CONCLUSIONS
During early development, multiple short periods of binocular vision were effective in preserving clinically significant stereopsis in monkeys. These results suggest that by providing relatively short multiple daily intervention periods, stereopsis may be preserved in strabismic human children.
Topics: Animals; Circadian Rhythm; Contrast Sensitivity; Depth Perception; Disease Models, Animal; Macaca mulatta; Strabismus; Vision, Binocular; Visual Cortex
PubMed: 33891682
DOI: 10.1167/iovs.62.4.27 -
Vision Research Feb 2016We study geometric properties of horopters defined by the criterion of equality of angle. Our primary goal is to derive the precise geometry for anatomically correct...
We study geometric properties of horopters defined by the criterion of equality of angle. Our primary goal is to derive the precise geometry for anatomically correct horopters. When eyes fixate on points along a curve in the horizontal visual plane for which the vergence remains constant, this curve is the larger arc of a circle connecting the eyes' rotation centers. This isovergence circle is known as the Vieth-Müller circle. We show that, along the isovergence circular arc, there is an infinite family of horizontal horopters formed by circular arcs connecting the nodal points. These horopters intersect at the point of symmetric convergence. We prove that the family of 3D geometric horopters consists of two perpendicular components. The first component consists of the horizontal horopters parametrized by vergence, the point of the isovergence circle, and the choice of the nodal point location. The second component is formed by straight lines parametrized by vergence. Each of these straight lines is perpendicular to the visual plane and passes through the point of symmetric convergence. Finally, we evaluate the difference between the geometric horopter and the Vieth-Müller circle for typical near fixation distances and discuss its possible significance for depth discrimination and other related functions of vision that make use of disparity processing.
Topics: Convergence, Ocular; Eye Movements; Fixation, Ocular; Humans; Models, Theoretical; Vision, Binocular
PubMed: 26548811
DOI: 10.1016/j.visres.2015.11.001 -
Vision Research Oct 2018We study the "color weight" for a number of rather different paradigms. In well researched heterochromatic photometry methods we find that the "weights" determined by...
We study the "color weight" for a number of rather different paradigms. In well researched heterochromatic photometry methods we find that the "weights" determined by settings of naive observers are closely determined by the CIE luminance functional. This is very different for tasks that involve mid- and high-level aspects of perception. In several cases we find equipollence for the display red, green and blue channels. Moreover, in such cases the very nonlinear maximum-rule fits the data rather better than a linear functional. These findings are of interest when photometry needs to be applied for stimuli that are different from the high temporal and low spatial frequency gratings typical for flicker photometry. These results are relevant for science, ergonomics and art.
Topics: Color Perception Tests; Color Vision; Female; Humans; Light; Male; Photometry; Vision, Binocular; Young Adult
PubMed: 28705690
DOI: 10.1016/j.visres.2017.06.006