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1.
Visual Hallucinations and Impaired Conscious Visual Perception in Parkinson Disease.
Kurita, A, Koshikawa, H, Akiba, T, Seki, K, Ishikawa, H, Suzuki, M
Journal of geriatric psychiatry and neurology. 2020;(6):377-385
Abstract
Visual hallucinations (VHs) are common in patients with Parkinson disease (PD), especially those with dementia, whereas auditory hallucinations are quite rare. Recent studies have revealed the involvement of several regions along the visual information-processing system that contribute to the pathophysiological mechanism of VHs: the eyes and retina, retinofugal projection, lateral geniculate nucleus, striate cortex, ventral pathways in the temporal cortices, and frontal and parietal cortices. In addition, the concurrent involvement of other systems in the brainstem and basal forebrain further modify VHs in PD. In this review, we discuss the pathophysiological association between the regional involvement of these areas and VHs.
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2.
Wine psychology: basic & applied.
Spence, C
Cognitive research: principles and implications. 2020;(1):22
Abstract
Basic cognitive research can help to explain our response to wine, and the myriad factors that affect it. Wine is a complex, culture-laden, multisensory stimulus, and our perception/experience of its properties is influenced by everything from the packaging in which it is presented through the glassware in which it is served and evaluated. A growing body of experiential wine research now demonstrates that a number of contextual factors, including everything from the colour of the ambient lighting through to background music can exert a profound, and in some cases predictable, influence over the tasting experience. Sonic seasoning - that is, the matching of music or soundscapes with specific wines in order to accentuate or draw attention to certain qualities/attributes in the wine, such as sweetness, length, or body, also represents a rapidly growing area of empirical study. While such multisensory, experiential wine research undoubtedly has a number of practical applications, it also provides insights concerning multisensory perception that are relevant to basic scientists. Furthermore, the findings of the wine research are also often relevant to those marketers interested in understanding how the consumers' perception of any other food or beverage product can potentially be modified.
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3.
The effects of preterm birth on visual development.
Leung, MP, Thompson, B, Black, J, Dai, S, Alsweiler, JM
Clinical & experimental optometry. 2018;(1):4-12
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Abstract
Children born very preterm are at a greater risk of abnormal visual and neurological development when compared to children born at full term. Preterm birth is associated with retinopathy of prematurity (a proliferative retinal vascular disease) and can also affect the development of brain structures associated with post-retinal processing of visual information. Visual deficits common in children born preterm, such as reduced visual acuity, strabismus, abnormal stereopsis and refractive error, are likely to be detected through childhood vision screening programs, ophthalmological follow-up or optometric care. However, routine screening may not detect other vision problems, such as reduced visual fields, impaired contrast sensitivity and deficits in cortical visual processing, that may occur in children born preterm. For example, visual functions associated with the dorsal visual processing stream, such as global motion perception and visuomotor integration, may be impaired by preterm birth. These impairments can continue into adolescence and adulthood and may contribute to the difficulties in learning (particularly reading and mathematics), attention, behaviour and cognition that some children born preterm experience. Improvements in understanding the mechanisms by which preterm birth affects vision will inform future screening and interventions for children born preterm.
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4.
Corollary Discharge and Oculomotor Proprioception: Cortical Mechanisms for Spatially Accurate Vision.
Sun, LD, Goldberg, ME
Annual review of vision science. 2016;:61-84
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Abstract
A classic problem in psychology is understanding how the brain creates a stable and accurate representation of space for perception and action despite a constantly moving eye. Two mechanisms have been proposed to solve this problem: Herman von Helmholtz's idea that the brain uses a corollary discharge of the motor command that moves the eye to adjust the visual representation, and Sir Charles Sherrington's idea that the brain measures eye position to calculate a spatial representation. Here, we discuss the cognitive, neuropsychological, and physiological mechanisms that support each of these ideas. We propose that both are correct: A rapid corollary discharge signal remaps the visual representation before an impending saccade, computing accurate movement vectors; and an oculomotor proprioceptive signal enables the brain to construct a more accurate craniotopic representation of space that develops slowly after the saccade.
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5.
Fovea and foveation in Parkinson's disease.
Bodis-Wollner, I, Glazman, S, Yerram, S
Behavioral neuroscience. 2013;(2):139-50
Abstract
Nondemented Parkinson's disease (PD) patients report problems on nonmotor tasks that depend on visual or visuospatial abilities. In PD, foveal vision is impaired. Experimental studies in humans and monkeys established that foveal processing and visuospatial attention may be linked through saccadic eye movements. Saccadic eye movements "bring" eccentric targets to the direct sight line for closer scrutiny by foveal processing. This is called foveation. This review musters the arguments for impaired foveal vision and impaired cortical control of voluntary saccades in PD. Retinal impairment of spatial contrast vision is selective in PD. Thus, the reviewed literature includes a brief survey of the physiology of foveal pathways. This is necessary to understand the specificity of the retinopathy of PD, documented by clinical evidence, relying on psychophysical, electrophysiological, and imaging techniques. These have recently been supplanted by the results of retinal imaging using Optical Coherence Tomography (OCT). Studies of cortical mechanisms in PD reviewed here relied on neuropsychological, electrophysiological (EEG), and imaging techniques. Impaired functional anatomy and electrophysiology in PD are reviewed. The exact relationship of retinal foveal deficits and visuospatial attention and postural control impairment in PD remain challenging research questions. This review will hopefully will provide useful material for future studies.
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6.
Visual attention and stability.
Mathôt, S, Theeuwes, J
Philosophical transactions of the Royal Society of London. Series B, Biological sciences. 2011;(1564):516-27
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Abstract
In the present review, we address the relationship between attention and visual stability. Even though with each eye, head and body movement the retinal image changes dramatically, we perceive the world as stable and are able to perform visually guided actions. However, visual stability is not as complete as introspection would lead us to believe. We attend to only a few items at a time and stability is maintained only for those items. There appear to be two distinct mechanisms underlying visual stability. The first is a passive mechanism: the visual system assumes the world to be stable, unless there is a clear discrepancy between the pre- and post-saccadic image of the region surrounding the saccade target. This is related to the pre-saccadic shift of attention, which allows for an accurate preview of the saccade target. The second is an active mechanism: information about attended objects is remapped within retinotopic maps to compensate for eye movements. The locus of attention itself, which is also characterized by localized retinotopic activity, is remapped as well. We conclude that visual attention is crucial in our perception of a stable world.
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Visual development in infants: physiological and pathological mechanisms.
Brémond-Gignac, D, Copin, H, Lapillonne, A, Milazzo, S, ,
Current opinion in ophthalmology. 2011;:S1-8
Abstract
PURPOSE OF REVIEW This review summarizes current knowledge on ocular conditions related to abnormal visual development in infants, including prevalence, risk factors, causes, and mechanisms involved. We discuss the role of eyeball growth with pathologic mechanism of visual deprivation and development of amblyopia in infants, particular developmental issues in preterm neonates, methods of visual assessment and screening, diagnosis, treatment, and nutritional issues. RECENT FINDINGS Visual development is incomplete at birth, particularly in premature infants; maturation of the visual system--including neurological and ocular components--is influenced by many factors including prenatal and postnatal nutrition and postnatal visual stimulation. In early life, particularly during sensitive periods of development, abnormal visual input, for example caused by visual deprivation mechanism, amblyopia, or ocular misalignment, leads to abnormalities in visual development, including abnormal eyeball growth and neurological changes. Untreated anomalies or abnormal visual development can result in long-term or even permanent visual impairment. Nutrition plays a key role in visual development: infant formulas containing nutrients essential for normal visual development (specifically omega-3 fatty acid docosahexaenoic acid and omega-6 fatty acid arachidonic acid) may protect nonbreast-fed infants against visual development abnormalities. SUMMARY Problems related to visual anomalies are common among young children, particularly in preterm neonates. Screening to enable early diagnosis and correction of visual deficiency is important as abnormal visual input can lead to abnormalities in visual development, which can become permanent visual impairment if left untreated. Optimized nutrition can help to reduce the risk of abnormal visual development and prevent long-term or permanent visual deficits.
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Picture representation during REM dreams: a redox molecular hypothesis.
Bókkon, I, Dai, J, Antal, I
Bio Systems. 2010;(2):79-86
Abstract
A novel molecular hypothesis about visual perception and imagery has recently been proposed (Bókkon, 2009; BioSystems). Namely, external electromagnetic visible photons are converted into electrical signals in the retina and are then conveyed to V1. Next, these retinotopic electrical signals (spike-related electrical signals along classical axonal-dendritic pathways) can be converted into synchronized bioluminescent biophoton signals (inside the neurons) by neurocellular radical reactions (redox processes) in retinotopically organized V1 mitochondrial cytochrome oxidase-rich visual areas. The bioluminescent photonic signals (inside the neurons) generated by neurocellular redox/radical reactions in synchronized V1 neurons make it possible to produce computational biophysical pictures during visual perception and imagery. Our hypothesis is in line with the functional roles of reactive oxygen and nitrogen species in living cells and states that this is not a random process, but rather a strict mechanism used in signaling pathways. Here, we suggest that intrinsic biophysical pictures can also emerge during REM dreams.
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[Physiology and pathology of visual information processing].
Kitahara, K
Nippon Ganka Gakkai zasshi. 2007;(3):160-91; discussion 192
Abstract
(1) Human crystalline lens and vision In order to investigate the hue changes in eyes with UV-absorbing intraocular lenses (IOLs) and tinted IOLs, we simulated the changes in the chromaticity coordinates of the 16 colors of the Farnsworth dichotomous test-panel D-15 (panel D-15), considering the ratio of the spectral transmittance of the IOL and the human crystalline lens, and the results were plotted on a CIE chromaticity diagram. The chromaticity coordinates of each color for UV-absorbing IOLs shifted to close to the origin of coordinates while retaining their hue circle. However, the chromaticity coordinates for the eyes with tinted IOLs did not change much compared to the coordinates for phakic eyes. As a result, it was suggested that cyanopsia after UV-absorbing IOL implantation could be explained by this simulation. As far as the color perception is concerned, it was also felt that tinted IOLs were superior to UV-absorbing intraocular lenses. Next, in order to evaluate the hue changes after IOL implantation, the achromatic point settings were measured once before surgery and several times at intervals after surgery after taking off the eyepatch. Four subjects participated in the experiments. There was a large shift into the "yellowish" region of color space immediately after taking off the eyepatch after cataract surgery. Then, the achromatic point returned to the chromaticity near the achromaticpoint measured prior to the surgery, with the time course of a long time, compared to color constancy in our daily life, which takes as long as several hundreds of seconds to reach an asymptote. Therefore, the mechanism of achromatic point shifts after cataract surgery may be different from the color-constancy mechanism in everyday life. (2) Molecular genetics and vision We demonstrated new clinical and genetic aspects of congenital red-green color vision defects, congenital achromatopsia, enhanced s-cone syndrome (ESCS), and Oguchi disease in Japanese patients. We clinically diagnosed 88 male dichromats(31 protanopes, 56 deuteranopes, and one unclassified subject). This subject had a new form of X-linked pigment gene with a unique arrangement of exon 5(Y277 from the long-wavelength-sensitive gene and A 285 from the middle-wavelength-sensitive gene). Mutational analysis of patients with achromatopsia disclosed CNGA3 mutations (p.R 436 W, p.L633 P) in one of 14 patients, suggesting low frequency (7%, 1/14) of CNGA3 mutations in the Japanese population. Three novel NR2E3 mutations (p.R 104 Q, p.R 334 G, p.Q 350 X) were identified in both mild and severe forms of ESCS. A novel homozygous GRK1 mutation (p.P 391 H) was found in the Oguchi disease patient with reduced cone responses. This is the first reported Japanese patient with GRK1 -associated Oguchi disease. 3. Information processing of the visual cortex and vision Regarding information processing in the visual cortex, we developed the stimulus to improve identifying retinotopy of the human visual cortex. We performed two types of fMRI experiments. One provided a quick method of mapping retinotopy using a composite stimulus with both ring- and wedge-shaped stimuli. The other provided a method which can show the horizontal meridian clearer. We explored the activation of the visual cortex associated with color perception. In our studies of the color center, we first researched the symptoms and lesions of cerebral achromatopsia, and we next performed the fMRI experiments with a pseudoisochromatic plate test and with a color arrangement test. After this we also performed the fMRI experiments with a complex color painting. We realized objective perimetry with functional brain images. We first developed the software to depict a visual field from the signals of MR imaging. Next we performed the experiment with hemifield stimulation and showed the possibility of its clinical application. Then we showed its reproducibility, performing the experiment with more complicated letter-shaped masked visual stimulation. Finally, we applied the technique to patients with cerebral dysfunction. We performed diffusion tensor imaging (DTI) with a clinical 1.5 T MR machine to visualize optic radiation. With patients who were clinically expected to show disorder of optic radiation, these visualizations were consistent with their pathologies. It was suggested that this new DTI technique is useful for estimating functional disorder of optic radiation.
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Visual dysfunction, neurodegenerative diseases, and aging.
Jackson, GR, Owsley, C
Neurologic clinics. 2003;(3):709-28
Abstract
The four most common sight-threatening conditions in older adults in North America are cataract, ARM, glaucoma, and diabetic retinopathy. Even in their moderate stages, these conditions cause visual sensory impairments and reductions in health-related quality of life, including difficulties in daily tasks and psychosocial problems. Many older adults are free from these conditions, yet still experience a variety of visual perceptual problems resulting from aging-related changes in the optics of the eye and degeneration of the visual neural pathways. These problems consist of impairments in visual acuity, contrast sensitivity, color discrimination, temporal sensitivity, motion perception, peripheral visual field sensitivity, and visual processing speed. PD causes a progressive loss of dopaminergic cells predominantly in the retina and possibly in other areas of the visual system. This retinal dopamine deficiency produces selective spatial-temporal abnormalities in retinal ganglion cell function, probably arising from altered receptive field organization in the PD retina. The cortical degeneration characteristics of AD, including neurofibrillary tangles and neuritic plaques, also are present in the visual cortical areas, especially in the visual association areas. The most prominent electrophysiologic change in AD is a delay in the P2 component of the flash VEP. Deficits in higher-order visual abilities typically are compromised in AD, including problems with visual attention, perceiving structure from motion, visual memory, visual learning, reading, and object and face perception. There have been reports of a visual variant of AD in which these types of visual problems are the initial and most prominent signs of the disease. Visual sensory impairments (e.g., contrast sensitivity or achromatopsia) also have been reported but are believed more reflective of cortical disturbances than of AD-associated optic neuropathy.