Achromatic luminance contrast sensitivity in X-linked color-deficient observers: An addition to the debate

AbstractIt is a matter of debate whether X-linked dichromacy is accompanied by enhanced achromatic processing. In the present study, we used sinusoidally modulated achromatic gratings under photopic conditions to compare the contrast sensitivity (CS) of protanopes, deuteranopes, and normal trichromats. 36 male volunteers were examined. CS was tested in static and dynamic conditions at nine different spatial frequencies. The results support the assumption that X-linked color-defective observers are at an advantage in terms of achromatic processing. Both protanopes and deuteranopes had significantly better CS than controls in both the static and the dynamic conditions. In the static condition, the advantage was observed especially at higher spatial frequencies, whereas in the dynamic condition, it was seen also at lower frequencies. The results are interpreted in terms of decreased chromatic modulation of the luminance channel and the early plasticity of the parvocellular system.

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Photopic and Mesopic Contrast Sensitivity Function in the Presence of Glare and the Effect of Filters in Young Healthy Adults

Frontiers in Psychology ◽

10.3389/fpsyg.2021.772661 ◽

2021 ◽

Vol 12 ◽

Author(s):

Alberto Domínguez-Vicent ◽

Emma Helghe ◽

Marika Wahlberg Ramsay ◽

Abinaya Priya Venkataraman

Keyword(s):

Contrast Sensitivity ◽

Light Transmission ◽

Luminance Contrast ◽

Sensitivity Function ◽

Contrast Sensitivity Function ◽

Selective Absorption ◽

Light Reduction ◽

Spatial Frequencies ◽

Significant Difference ◽

Young Subjects

Purpose: The aim of this study was to evaluate the effect of four different filters on contrast sensitivity under photopic and mesopic conditions with and without glare.Methods: A forced choice algorithm in a Bayesian psychophysical procedure was utilized to evaluate the spatial luminance contrast sensitivity. Five different spatial frequencies were evaluated: 1.5, 3, 6, 12, and 18 cycles per degree (cpd). The measurements were performed under 4 settings: photopic and mesopic luminance with glare and no glare. Two long pass filters (LED light reduction and 511nm filter) and two selective absorption filters (ML41 and emerald filter) and a no filter condition were evaluated. The measurements were performed in 9 young subjects with healthy eyes.Results: For the no filter condition, there was no difference between glare and no glare settings for the photopic contrast sensitivity measurements whereas in the mesopic setting, glare reduced the contrast sensitivity significantly at all spatial frequencies. There was no statistically significant difference between contrast sensitivity measurements obtained with different filters under both photopic conditions and the mesopic glare condition. In the mesopic no glare condition, the contrast sensitivity at 6 cpd with 511, ML41 and emerald filters was significantly reduced compared to no filter condition (p = 0.045, 0.045, and 0.071, respectively). Similarly, with these filters the area under the contrast sensitivity function in the mesopic no glare condition was also reduced. A significant positive correlation was seen between the filter light transmission and the average AULCSF in the mesopic non-glare condition.Conclusion: The contrast sensitivity measured with the filters was not significantly different than the no filter condition in photopic glare and no glare setting as well as in mesopic glare setting. In mesopic setting with no glare, filters reduced contrast sensitivity.

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Materials in action: The look and feel of soft

10.1101/2021.01.22.427730 ◽

2021 ◽

Author(s):

Müge Cavdan ◽

Knut Drewing ◽

Katja Doerschner

Keyword(s):

Dynamic Condition ◽

Prior Experience ◽

Static Condition ◽

Experimental Conditions ◽

Dynamic Conditions ◽

Similar Information ◽

The Senses ◽

The Look

AbstractThe softness of objects can be perceived through several senses. For instance, to judge the softness of our cat’s fur, we do not only look at it, we also run our fingers in idiosyncratic ways through its coat. Recently, we have shown that haptically perceived softness covaries with the compliance, viscosity, granularity, and furriness of materials (Dovencioglu et al.,2020). However, it is unknown whether vision can provide similar information about the various aspects of perceived softness. Here, we investigated this question in an experiment with three conditions: in the haptic condition, blindfolded participants explored materials with their hands, in the visual-static condition participants were presented with close-up photographs of the same materials, and in the visual-dynamic condition participants watched videos of the hand-material interactions that were recorded in the haptic condition. After haptically or visually exploring the materials participants rated them on various attributes. Our results show a high overall perceptual correspondence between the three experimental conditions. With a few exceptions, this correspondence tended to be strongest between haptic and visual-dynamic conditions. These results are discussed with respect to information potentially available through the senses, or through prior experience, when judging the softness of materials.

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Mixture of Sodium Hypochlorite and Hydrogen Peroxide on Adhered Aeromonas hydrophila to Solid Substrate in Water: Impact of Concentration and Assessment of the Synergistic Effect

International Journal of Bacteriology ◽

10.1155/2014/121367 ◽

2014 ◽

Vol 2014 ◽

pp. 1-13 ◽

Cited By ~ 4

Author(s):

Chrétien Lontsi Djimeli ◽

Antoine Tamsa Arfao ◽

Olive V. Noah Ewoti ◽

Mireille Ebiane Nougang ◽

Marlyse L. Moungang ◽

...

Keyword(s):

Growth Phase ◽

Dynamic Condition ◽

Synergistic Effects ◽

Freundlich Isotherm ◽

Static Condition ◽

Solid Substrate ◽

Exponential Growth Phase ◽

Static State ◽

Dynamic Conditions ◽

Significant Difference

The synergistic effects of the combined treatments of NaOCl and H2O2 on the elimination of A. hydrophila adhered to polythene under static and dynamic conditions were evaluated. The concentrations 0.1, 0.2, and 0.3‰ NaOCl and 0.5, 1, and 1.5‰ H2O2 were used. The contact periods were 180, 360, 540, and 720 minutes. The abundance of cells adhered reached 2.47 and 2.27 units (log (CFU/cm²)), respectively, under static and dynamic conditions after action of the mixture of disinfectants, whereas it reached 2.41 and 3.39 units (log (CFU/cm²)) after action of NaOCl and H2O2 alone, respectively. Increase in the incubation period resulted in a significant decrease in the abundance of cells adhered when the mixture of 0.3‰ NaOCl and 1.5‰ H2O2 was used (P<0.01). For each cell growth phase, there was a significant difference amongst the mean densities of cells adhered after action of the mixture of disinfectants (P<0.05). Although the Freundlich isotherm parameters relatively varied from one experimental condition to another, the Kf value registered in the exponential growth phase was relatively higher in static state than in dynamic regime; cells adhered under dynamic condition seem more sensitive to the synergistic action than those adhered under static condition.

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Stimulus-Locked Responses on Human Upper Limb Muscles and Corrective Reaches are Preferentially Evoked by Low Spatial Frequencies

10.1101/690354 ◽

2019 ◽

Cited By ~ 1

Author(s):

Rebecca A. Kozak ◽

Philipp Kreyenmeier ◽

Chao Gu ◽

Kevin Johnston ◽

Brian D. Corneil

Keyword(s):

Upper Limb ◽

Dynamic Condition ◽

Static Condition ◽

Emg Activity ◽

Limb Muscle ◽

Visually Guided ◽

Target Presentation ◽

Visuomotor Transformations ◽

Spatial Frequencies ◽

On Line

AbstractIn situations requiring immediate action, humans can generate visually-guided responses at remarkably short latencies. Here, to better understand the visual attributes that best evoke such rapid responses, we recorded upper limb muscle activity while participants performed visually-guided reaches towards Gabor patches composed of differing spatial frequencies. We studied reaches initiated from a stable posture (experiment 1, a static condition), or during on-line reach corrections to an abruptly displaced target (experiment 2, a dynamic condition). In both experiments, we detail the latency and prevalence of stimulus-locked responses (SLRs), which are brief bursts of EMG activity that are time-locked to target presentation rather than movement onset. SLRs represent the first wave of EMG recruitment influenced by target presentation, and enable quantification of rapid visuomotor transformations. In both experiments, reach targets composed of low spatial frequencies elicited the shortest latency and most prevalent SLRs, with SLR latency increasing and SLR prevalence decreasing for reach targets composed of progressively higher spatial frequencies. SLRs could be evoked in either the static or dynamic condition, and when present in experiment 2, were associated with shorter latency and larger magnitude corrections. Furthermore, SLRs evolved at shorter latencies (~20 ms) when the arm was already in motion. These results demonstrate that stimuli composed of low spatial frequencies preferentially evoke the most rapid visuomotor responses which, in the context of rapidly correcting an on-going reaching movement, are associated with earlier and larger on-line reach corrections.Significance StatementHumans have a remarkable capacity to respond quickly to changes in our visual environment. Although our visual world is composed of a range of spatial frequencies, surprisingly little is known about which frequencies preferentially evoke rapid reaching responses. Here, we systematically varied the spatial frequency of peripheral reach targets while measuring EMG activity on an upper limb muscle. We found that visual stimuli composed of low-spatial frequencies elicit the most rapid and robust EMG responses and corrective reaches. Thus, when time is of the essence, low spatial frequencies preferentially drive fast visuomotor responses.

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Postural Control Disturbances Induced by Virtual Reality in Stroke Patients

Applied Sciences ◽

10.3390/app11041510 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1510

Author(s):

Charles Morizio ◽

Maxime Billot ◽

Jean-Christophe Daviet ◽

Stéphane Baudry ◽

Christophe Barbanchon ◽

...

Keyword(s):

Virtual Reality ◽

Postural Control ◽

Virtual Environments ◽

Center Of Pressure ◽

Dynamic Condition ◽

Static Condition ◽

Stroke Patients ◽

Post Stroke ◽

Subacute Stroke

People who survive a stroke are often left with long-term neurologic deficits that induce, among other impairments, balance disorders. While virtual reality (VR) is growing in popularity for postural control rehabilitation in post-stroke patients, studies on the effect of challenging virtual environments, simulating common daily situations on postural control in post-stroke patients, are scarce. This study is a first step to document the postural response of stroke patients to different challenging virtual environments. Five subacute stroke patients and fifteen age-matched healthy adults were included. All participants underwent posturographic tests in control conditions (open and closed eyes) and virtual environment without (one static condition) and with avatars (four dynamic conditions) using a head-mounted device for VR. In dynamic environments, we modulated the density of the virtual crowd (dense and light crowd) and the avoidance space with the avatars (near or far). Center of pressure velocity was collected by trial throughout randomized 30-s periods. Results showed that more challenging conditions (dynamic condition) induced greater postural disturbances in stroke patients than in healthy counterparts. Our study suggests that virtual reality environments should be adjusted in light of obtaining more or less challenging conditions.

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Color and Luminance Contrast Sensitivity Changes in Early- and Late-Onset Strabismic Amblyopia

Journal of American Association for Pediatric Ophthalmology and Strabismus ◽

10.1016/j.jaapos.2006.01.125 ◽

2006 ◽

Vol 10 (1) ◽

pp. 81

Author(s):

John J. Sloper ◽

Alison R. Davis ◽

Majella M. Neveu ◽

Chris R. Hogg ◽

Michael J. Morgan ◽

...

Keyword(s):

Contrast Sensitivity ◽

Late Onset ◽

Luminance Contrast ◽

Strabismic Amblyopia ◽

Sensitivity Changes

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Aspheric Intraocular Lenses Implantation for Cataract Patients with Extreme Myopia

ISRN Ophthalmology ◽

10.1155/2014/403432 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

Yanwen Fang ◽

Yi Lu ◽

Aizhu Miao ◽

Yi Luo

Keyword(s):

Contrast Sensitivity ◽

Visual Quality ◽

Intraocular Lenses ◽

Wavefront Aberrations ◽

Spatial Frequencies ◽

Aspheric Iol ◽

Significant Difference ◽

Composite Scores ◽

Cataract Patients

Objective. To evaluate the postoperative visual quality of cataract patients with extreme myopia after implantation of aspheric intraocular lenses (IOLs). Methods. Thirty-three eyes were enrolled in this prospectivestudy. Eighteen eyes with an axial length longer than 28 mm were included in the extreme myopia group, and the other 15 eyes were included in the nonextreme myopia group. Phacoemulsification and aspheric IOL implantation were performed. Six months after cataract surgery, best-corrected visual acuity (BCVA), contrast sensitivity, and wavefront aberrations were measured, and subjective visual quality was assessed. Results. The BCVA improved significantly after surgery for both groups, and patients in the nonextreme myopia group achieved better postoperative BCVA due to better retinal status of the eyes. The evaluation of contrast sensitivity without glare was the same in both groups, whereas patients in the nonextreme myopia group performed better at intermediate spatial frequencies under glare conditions. The two groups did not show a significant difference in high-order aberrations. With regard to subjective visual quality, the composite scores of both groups did not differ significantly. Conclusions. Aspheric IOLs provided good visual outcomes in cataract patients with extreme myopia. These patients should undergo careful evaluation to determine the maculopathy severity level before surgery.

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Psychophysical Measurements of Luminance Contrast Sensitivity and Color Discrimination with Transparent and Blue-Light Filter Intraocular Lenses

Ophthalmology and Therapy ◽

10.1007/s40123-017-0101-y ◽

2017 ◽

Vol 6 (2) ◽

pp. 301-312 ◽

Cited By ~ 4

Author(s):

Marcelo Fernandes da Costa ◽

Augusto Paranhos Júnior ◽

Claudio Luiz Lottenberg ◽

Leonardo Cunha Castro ◽

Dora Fix Ventura

Keyword(s):

Contrast Sensitivity ◽

Blue Light ◽

Color Discrimination ◽

Luminance Contrast ◽

Light Filter ◽

Intraocular Lenses ◽

Blue Light Filter

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Effects of strabismus on responsivity, spatial resolution, and contrast sensitivity of cat lateral geniculate neurons

Journal of Neurophysiology ◽

10.1152/jn.1984.52.3.538 ◽

1984 ◽

Vol 52 (3) ◽

pp. 538-552 ◽

Cited By ~ 13

Author(s):

K. R. Jones ◽

R. E. Kalil ◽

P. D. Spear

Keyword(s):

Contrast Sensitivity ◽

Spatial Resolution ◽

Striate Cortex ◽

Receptive Fields ◽

Orienting Response ◽

Lateral Geniculate ◽

Spatial Frequencies ◽

Area Centralis ◽

X Cells ◽

Y Cells

Rearing cats with esotropia is known to cause a number of deficits in visual behavior tested through the deviated eye. These include a loss of orienting response to stimuli presented in the nasal visual field of the deviated eye, a reduction in visual acuity, and a general reduction in contrast sensitivity at all spatial frequencies. To assess the involvement of the lateral geniculate nucleus (LGN) in these deficits, we measured the following: 1) the visual responsiveness of lamina A1 cells with peripheral (more than 10 degrees from area centralis) receptive fields in three esotropic and three normal cats and 2) the spatial resolution and contrast sensitivity of lamina A X-cells with central (within 5 degrees of the area centralis) receptive fields in six esotropic and six normal cats. For comparison, we also measured LGN X-cell spatial resolutions in four exotropic cats and in two cats raised with an esotropia in one eye and the lids of the other eye sutured shut (MD-estropes). Recordings from the lateral portion of lamina A1 in esotropic cats yielded similar numbers of visually responsive cells with far nasal receptive fields as were seen in normal animals. Peak and mean response rates to a flashing spot also were normal. In addition, no differences were found between esotropes and normals in the percentages of X- and Y-cells encountered. These results suggest that the loss of orienting response to stimuli presented in the nasal field (12, 20) is not due to a loss of neural responses in the LGN of esotropic cats. In addition, they suggest that decreases in cell size in lamina A1 of esotropic cats (13, 36; R. E. Kalil, unpublished observations) are not accompanied by marked functional abnormalities of the cells and that cortical abnormalities ipsilateral to the deviated eye (22) are likely to have their origin within striate cortex itself. Recordings from lamina A cells with receptive fields near area centralis revealed that the average X-cell spatial resolution in esotropes (2.1 cycles/deg) was significantly lower than that in normal cats (3.1 cycles/deg). This reduction was seen in all esotropic cats tested and was due both to an increase in the proportion of X-cells with very low spatial resolution and to a loss of X-cells responding to high spatial frequencies (greater than 3.25 cycles/deg). The average spatial resolution of X-cells driven by the deviated eye in MD-esotropes fell midway between those of esotropes and normals. In exotropes, mean X-cell spatial resolution was normal.(ABSTRACT TRUNCATED AT 400 WORDS)

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Spatial Contrast Sensitivity of Migraine Patients Without Aura

Cephalalgia ◽

10.1046/j.1468-2982.2002.00351.x ◽

2002 ◽

Vol 22 (2) ◽

pp. 142-145 ◽

Cited By ~ 28

Author(s):

K Benedek ◽

J Tajti ◽

M Janáky ◽

L Vécsei ◽

G Benedek

Keyword(s):

Healthy Volunteers ◽

Contrast Sensitivity ◽

Migraine Without Aura ◽

Marked Decrease ◽

Primary Headache ◽

Visual Pathway ◽

Control Subjects ◽

Spatial Frequencies ◽

Spatial Contrast Sensitivity ◽

Visual Disturbances

Visual disturbances are frequent symptoms in migraine. Since there is a possibility of separate damage in the magno- or parvo-cellular visual pathway in migraine patients, we performed a study including the measurement of static and dynamic spatial contrast sensitivity on 15 patients suffering from migraine without aura under photopic and scotopic conditions. Fifteen healthy volunteers without primary headache served as controls. The results revealed a marked decrease in contrast sensitivity at low spatial frequencies in the migraine patients. Spatial contrast sensitivity demonstrated some lateralization, as the sensitivity to low spatial frequencies obtained through separate eyes showed significantly larger side-differences in migraine patients than in control subjects. These findings suggest that the mechanisms responsible for vision at low spatial frequencies are impaired in migraine patients. This might indicate impaired function of the magnocellular pathways in this condition.

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