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Color contrast sensitivity

Yuka Oishi, Toru Imamura, Tatsuo Shimomura, Kyoko Suzuki
BACKGROUND: Neuroimaging and some clinical studies have reported that the ventral visual pathway is relevant for visual texture recognition. Although a variety of visual deficits have been reported in patients with Alzheimer's disease (AD) and dementia with Lewy bodies (DLB), visual material identification and texture recognition have not been thoroughly examined. OBJECTIVES: To investigate visual texture recognition in patients with AD and DLB and to clarify the relationship between visual texture recognition and various visuoperceptual functions...
March 27, 2018: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
Stephanie Lin, Aleksandra Mihailovic, Sheila K West, Chris A Johnson, David S Friedman, Xiangrong Kong, Pradeep Y Ramulu
Purpose: We characterized vision in glaucoma using seven visual measures, with the goals of determining the dimensionality of vision, and how many and which visual measures best model activity limitation. Methods: We analyzed cross-sectional data from 150 older adults with glaucoma, collecting seven visual measures: integrated visual field (VF) sensitivity, visual acuity, contrast sensitivity (CS), area under the log CS function, color vision, stereoacuity, and visual acuity with noise...
April 2018: Translational Vision Science & Technology
Ethan Meltzer, Sashank Prasad
Optic neuritis remains a common diagnosis with controversial management. Although typical optic neuritis is often associated with "good" recovery of visual acuity, patients are often left with persistent impairments of contrast sensitivity, color vision, and visual field. These permanent visual deficits correlate with structural injury to the anterior visual pathway and are closely linked to visual quality of life. High dose corticosteroids are commonly used for patients with acute optic neuritis...
April 18, 2018: Asia-Pacific Journal of Ophthalmology
Christoph Witzel, Karl R Gegenfurtner
This study investigated categorical perception for unique hues in order to establish a relationship between color appearance, color discrimination, and low-level (second-stage) mechanisms. We tested whether pure red, yellow, green, and blue (unique hues) coincide with troughs, and their transitions (binary hues) with peaks of sensitivity in DKL-space. Results partially confirmed this idea: JNDs demarcated perceptual categories at the binary hues around green, blue and less clearly around yellow, when colors were isoluminant with the background and when accounting for the overall variation of sensitivity by fitting an ellipse...
April 10, 2018: Vision Research
Melanie Ailín Basnak, Verónica Pérez-Schuster, Gabriela Hermitte, Martín Berón de Astrada
Many animal species take advantage of polarization vision for vital tasks such as orientation, communication, and contrast enhancement. Previous studies have suggested that decapod crustaceans use a two-channel polarization system for contrast enhancement. Here, we characterize the polarization contrast sensitivity in a grapsid crab . We estimated the polarization contrast sensitivity of the animals by quantifying both their escape response and changes in heart rate when presented with polarized motion stimuli...
April 12, 2018: Journal of Experimental Biology
Laila Hugrass, Thomas Verhellen, Eleanore Morrall-Earney, Caitlin Mallon, David Philip Crewther
More than 50 years ago, Hubel and Wiesel identified a subpopulation of geniculate magnocellular (M) neurons that are suppressed by diffuse red light. Since then, many human psychophysical studies have used red and green backgrounds to study the effects of M suppression on visual task performance, as a means to better understand neurodevelopmental disorders such as dyslexia and schizophrenia. Few of these studies have explicitly assessed the relative effects of red backgrounds on the M and P (parvocellular) pathways...
April 1, 2018: Journal of Vision
Diya Wang, Zhe Su, Yu Zhang, Xiaoyan Zhao, Supin Wang, Mingxi Wan
PURPOSE: This study aimed to clarify the influences of composite dynamic contrast-enhanced ultrasound (DCEUS) on multi-parametric perfusion imaging (PPI) and to develop a novel PPI scheme through pulse-inversion Bubblet decorrelation (PIBD) to improve its contrast and detailed discriminability. METHOD: In in vivo perfusion experiments on rabbit kidneys, a pair of phase-inverted 'Bubblets' was constructed. Phase-inverted raw radiofrequency echoes were reconstructed by using the maximum coefficients obtained from Bubblet decorrelation analysis and summed to form DCEUS loops...
April 2, 2018: Medical Physics
John E Vanston, Michael A Crognale
Using near-threshold stimuli, human color sensitivity has been shown to decrease across the visual field, likely due in part to physiological differences between the fovea and periphery. It remains unclear to what extent this holds true for suprathreshold stimuli. The current study used suprathreshold contrast matching to examine how perceived contrast varies with eccentricity along the cardinal axes in a cone-opponent space. Our data show that, despite increasing stimulus size in the periphery, the LM axis stimuli were still perceived as reduced in contrast, whereas the S axis perceived contrast was observed to increase with eccentricity...
April 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Ray Chun-Fai Chan, Richard H Leung, Albert Posadas, Thomas S Lorey, Allison J Shaw
Flow cytometry is the gold standard in diagnosis of paroxysmal nocturnal hemoglobinuria (PNH) by detecting the absence of glycol-phosphatidyl inositol (GPI)-linked protein expression on granulocyte and monocyte surfaces. However, the current assays are not optimized and require improvement, particularly in reducing background fluorescence and optimizing sensitivity and specificity. With more fluorochromes available and with advances in instrument engineering, rare populations may be identified with high sensitivity...
March 2018: Biomedical Reports
Sriharsha Gummadi, John R Eisenbrey, Andrej Lyshchik
Endovascular repair of abdominal aortic aneurysms have been performed successfully since 1991. However, 20% to 50% of these patients may develop an endoleak or continued aneurysmal sac expansion or perfusion despite stent graft coverage. Current recommendations suggest lifelong surveillance with computed tomographic angiography (CTA) at least 1 month after intervention and yearly after that. In select patients with a stable aneurysm sac on computed tomography performed 1 year after treatment, future screening could be performed with ultrasonography...
March 29, 2018: Ultrasound Quarterly
Shamik Mascharak, Brandon J Baird, F Christopher Holsinger
OBJECTIVE: To determine if multispectral narrow-band imaging (mNBI) can be used for automated, quantitative detection of oropharyngeal carcinoma (OPC). STUDY DESIGN: Prospective cohort study. METHODS: Multispectral narrow-band imaging and white light endoscopy (WLE) were used to examine the lymphoepithelial tissues of the oropharynx in a preliminary cohort of 30 patients (20 with biopsy-proven OPC, 10 healthy). Low-level image features from five patients were then extracted to train naïve Bayesian classifiers for healthy and malignant tissue...
March 25, 2018: Laryngoscope
Michael Jackson Oliveira de Andrade, Armindo Campos Neto, Ana Raquel de Oliveira, Jessica Bruna Santana, Natanael Antonio Dos Santos
This study analyzed the fluctuation of the achromatic visual contrast sensitivity (CS) of adult males (M = 23.42 ± 2.6 years) during a daily period. Twenty-eight volunteers were divided into three groups according to circadian typology (CT): moderate morning (MM; n = 8); intermediate (I; n = 10) and moderate evening (ME; n = 10). The Pittsburgh Sleep Quality Index was used to evaluate sleep quality, and the Horne and Ostberg Morningness-Eveningness Questionnaire was used to measure CT. To measure CS, we used Metropsis software version 11...
March 22, 2018: Chronobiology International
Bo-Mi Song, Chi-Hon Lee
Many visual animals exploit spectral information for seeking food and mates, for identifying preys and predators, and for navigation. Animals use chromatic information in two ways. "True color vision," the ability to discriminate visual stimuli on the basis of their spectral content independent of brightness, is thought to play an important role in object identification. In contrast, "wavelength-specific behavior," which is strongly dependent on brightness, often associates with foraging, navigation, and other species-specific needs...
2018: Frontiers in Neural Circuits
Sunghwa Hong, Seungjo Park, Dahae Lee, Ahyoung Cha, Dongeun Kim, Jihye Choi
OBJECTIVE: This study was performed to evaluate ocular structures using contrast-enhanced ultrasonography (CEUS) in dogs to assess the feasibility of CEUS for investigating the blood perfusion of canine eyes. ANIMAL STUDIED: Eight purpose-bred beagles were used. PROCEDURES: Blood perfusion and vascularity of the right eye were evaluated using color Doppler, power Doppler, and CEUS with Sonazoid® . Vascular changes were quantitatively evaluated by measuring peak intensity, time to initial upslope, and time to peak from the ciliary body, iris, choroid, retina, and the retrobulbar region by CEUS...
March 9, 2018: Veterinary Ophthalmology
Cagri Ilhan, Mehmet Ali Sekeroglu, Sibel Doguizi, Pelin Yilmazbas
PURPOSE: To investigate the static and dynamic contrast sensitivity (CS) of patients with congenital red-green color vision deficiency (CVD) and to compare these values with those of healthy control subjects. METHODS: The study included 25 subjects with congenital CVD (10 with strong protan defect and 15 with strong deutan defect) and 20 age- and gender-matched healthy subjects. Following detailed ophthalmological examination, monocular static and dynamic CS measurements were taken with the Monpack3 device (Metrovision, Perenchies, France) on all subjects...
March 2, 2018: International Ophthalmology
Lorian E Schweikert, Robert R Fitak, Sönke Johnsen
Across diverse taxa, an increasing number of photoreceptive systems are being discovered in tissues outside of the eye, such as in the skin. Dermal photoreception is believed to serve a variety of functions, including rapid color change via specialized cells called chromatophores. In vitro studies of this system among color-changing fish have suggested the use of a phototransduction signaling cascade that fundamentally differs from that of the retina. Thus, the goal of this study was to identify phototransduction genes and compare their expression in the retina and skin of a color-changing fish, the hogfish Lachnolaimus maximus...
February 28, 2018: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
Marko Ilić, Andrej Meglič, Marko Kreft, Gregor Belušič
Microvillar photoreceptors are intrinsically capable of detecting the orientation of e-vector of linearly polarized light. They provide most invertebrates with an additional sensory channel to detect important features of their visual environment. However, polarization sensitivity (PS) of photoreceptors may lead to the detection of polarization-induced false colors and intensity contrasts. Most insect photoreceptors are thus adapted to have minimal PS. Flies have twisted rhabdomeres with microvilli rotated along the length of the ommatidia to reduce PS...
2018: Frontiers in Cellular Neuroscience
Muhammad Nasir, Muhammad Attique Khan, Muhammad Sharif, Ikram Ullah Lali, Tanzila Saba, Tassawar Iqbal
Melanoma is the deadliest type of skin cancer with highest mortality rate. However, the annihilation in early stage implies a high survival rate therefore, it demands early diagnosis. The accustomed diagnosis methods are costly and cumbersome due to the involvement of experienced experts as well as the requirements for highly equipped environment. The recent advancements in computerized solutions for these diagnoses are highly promising with improved accuracy and efficiency. In this article, we proposed a method for the classification of melanoma and benign skin lesions...
February 21, 2018: Microscopy Research and Technique
Konstantinos Lazaridis, Maria Lazaridou, Athanasios E Athanasiou
Introduction: Le Fort I and sagittal split ramus osteotomies are the most commonly performed orthognathic surgery procedures on the maxilla and mandible, respectively. Techniques: Despite progress in the techniques, these procedures may still be associated with morbidity, expressed as inflammation, inadequate bony union, periodontal damages or in extreme cases even total bone loss. Discussion: Through a comprehensive review of the literature, the influences of maxillary and mandibular surgery on Pulpal Blood Flow (PBF), pulp sensitivity and pulp vitality are examined...
2018: Open Dentistry Journal
Hongkai Cui, Ruifang Yan, Zhansheng Zhai, Jipeng Ren, Zheng Li, Qiang Li, Shouying Wang
The present study aimed to compare the diagnostic value of contrast-enhanced magnetic resonance angiography (CE MRA) with 3D time-resolved imaging of contrast kinetics, color Doppler ultrasound (CDUS) and digital subtraction angiography (DSA) in extracranial carotid stenosis (CS). A total of 54 patients with symptomatic CS were subjected to CDUS, CE MRA and DSA examination. Results of DSA were defined as the standard, and a total of 216 vessels were examined. In each patient four vessels were examined, namely the bilateral common carotid arteries and the bilateral internal carotid arteries...
February 2018: Experimental and Therapeutic Medicine
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