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Sample records for visual field change

  1. Visual field

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    ... your visual field. How the Test is Performed Confrontation visual field exam. This is a quick and ... to achieve this important distinction for online health information and services. Learn more about A.D.A. ...

  2. Sparse coding can predict primary visual cortex receptive field changes induced by abnormal visual input.

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    Hunt, Jonathan J; Dayan, Peter; Goodhill, Geoffrey J

    2013-01-01

    Receptive fields acquired through unsupervised learning of sparse representations of natural scenes have similar properties to primary visual cortex (V1) simple cell receptive fields. However, what drives in vivo development of receptive fields remains controversial. The strongest evidence for the importance of sensory experience in visual development comes from receptive field changes in animals reared with abnormal visual input. However, most sparse coding accounts have considered only normal visual input and the development of monocular receptive fields. Here, we applied three sparse coding models to binocular receptive field development across six abnormal rearing conditions. In every condition, the changes in receptive field properties previously observed experimentally were matched to a similar and highly faithful degree by all the models, suggesting that early sensory development can indeed be understood in terms of an impetus towards sparsity. As previously predicted in the literature, we found that asymmetries in inter-ocular correlation across orientations lead to orientation-specific binocular receptive fields. Finally we used our models to design a novel stimulus that, if present during rearing, is predicted by the sparsity principle to lead robustly to radically abnormal receptive fields.

  3. Visual field changes after cataract extraction: the AGIS experience.

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    Koucheki, Behrooz; Nouri-Mahdavi, Kouros; Patel, Gitane; Gaasterland, Douglas; Caprioli, Joseph

    2004-12-01

    To test the hypothesis that cataract extraction in glaucomatous eyes improves overall sensitivity of visual function without affecting the size or depth of glaucomatous scotomas. Experimental study with no control group. One hundred fifty-eight eyes (of 140 patients) from the Advanced Glaucoma Intervention Study with at least two reliable visual fields within a year both before and after cataract surgery were included. Average mean deviation (MD), pattern standard deviation (PSD), and corrected pattern standard deviation (CPSD) were compared before and after cataract extraction. To evaluate changes in scotoma size, the number of abnormal points (P < .05) on the pattern deviation plot was compared before and after surgery. We described an index ("scotoma depth index") to investigate changes of scotoma depth after surgery. Mean values for MD, PSD, and CPSD were -13.2, 6.4, and 5.9 dB before and -11.9, 6.8, and 6.2 dB after cataract surgery (P < or = .001 for all comparisons). Mean (+/- SD) number of abnormal points on pattern deviation plot was 26.7 +/- 9.4 and 27.5 +/- 9.0 before and after cataract surgery, respectively (P = .02). Scotoma depth index did not change after cataract extraction (-19.3 vs -19.2 dB, P = .90). Cataract extraction caused generalized improvement of the visual field, which was most marked in eyes with less advanced glaucomatous damage. Although the enlargement of scotomas was statistically significant, it was not clinically meaningful. No improvement of sensitivity was observed in the deepest part of the scotomas.

  4. Visual cortex in aging and Alzheimer’s disease: Changes in visual field maps and population receptive fields

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    Alyssa A. Brewer

    2014-02-01

    Full Text Available Although several studies have suggested that cortical alterations underlie such age-related visual deficits as decreased acuity, little is known about what changes actually occur in visual cortex during healthy aging. Two recent studies showed changes in primary visual cortex (V1 during normal aging; however, no studies have characterized the effects of aging on visual cortex beyond V1, important measurements both for understanding the aging process and for comparison to changes in age-related diseases. Similarly, there is almost no information about changes in visual cortex in Alzheimer’s disease (AD, the most common form of dementia. Because visual deficits are often reported as one of the first symptoms of AD, measurements of such changes in the visual cortex of AD patients might improve our understanding of how the visual system is affected by neurodegeneration as well as aid early detection, accurate diagnosis and timely treatment of AD. Here we use fMRI to first compare the visual field map (VFM organization and population receptive fields (pRFs between young adults and healthy aging subjects for occipital VFMs V1, V2, V3, and hV4. Healthy aging subjects do not show major VFM organizational deficits, but do have reduced surface area and increased pRF sizes in the foveal representations of V1, V2, and hV4 relative to healthy young control subjects. These measurements are consistent with behavioral deficits seen in healthy aging. We then demonstrate the feasibility and first characterization of these measurements in two patients with mild AD, which reveal potential changes in visual cortex as part of the pathophysiology of AD. Our data aid in our understanding of the changes in the visual processing pathways in normal aging and provide the foundation for future research into earlier and more definitive detection of AD.

  5. O PHTHALMIC MANIFESTATIONS AND VISUAL FIELD CHANGES WITH SELLAR AND SUPRASELLAR TUMOURS

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    Arvind L.

    2015-08-01

    Full Text Available PURPOSE: To evaluate ocular manifestations and visual field changes in patients with Sellar and Suprasellar Tumours. METHODS: Fifty patients with Sellar and Suprasellar tumours underwent a complete ophthalmic assessment and visual field analysis using the Humphrey Field Analyzer 30 - 2 program. Visual acuity, duration of symptoms, optic nerve head changes, pattern of visual field defects was noted. RESULTS: 50 patients including 15 male and 35 female subjects with mean age of 35.1±9.9 years and CT/MRI proven Suprasellar tumours 70% pituitary adenoma and 30% craniopharyngiomas were included. 70% cases presented with headache 80% with diminution of vision only 10% with hypothyroidism 50% with abnormal pupillary reaction including RAPD and anisocoria. Mean visual acuity at presentation was 0.46 log MAR . Of 100 eyes, 45 patients (90% had visual field defects including temporal defects in 35 patients (70%, non - specific defects in 4 patients (20% and 1patient (10% without any defect. Optic nerve head changes note d and 5 patients (25% presented with partial optic atrophy and 10 presented with established papilloedema. Visual field outcomes are correlated with duration of symptoms, optic nerve head changes at presentation and CT/ MRI findings. CONCLUSION: Visual fi eld defects were present in two thirds of patients at presentation. An overall deterioration in vision and visual fields was noted before surgical resection. A correlation was found between the duration of symptoms, MRI/ CT scan reports and visual field, s ignifying the importance in early diagnosis of neurological lesions on the basis of ophthalmic examination .

  6. Learning to Recognize Patterns: Changes in the Visual Field with Familiarity

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    Bebko, James M.; Uchikawa, Keiji; Saida, Shinya; Ikeda, Mitsuo

    1995-01-01

    Two studies were conducted to investigate changes which take place in the visual information processing of novel stimuli as they become familiar. Japanese writing characters (Hiragana and Kanji) which were unfamiliar to two native English speaking subjects were presented using a moving window technique to restrict their visual fields. Study time for visual recognition was recorded across repeated sessions, and with varying visual field restrictions. The critical visual field was defined as the size of the visual field beyond which further increases did not improve the speed of recognition performance. In the first study, when the Hiragana patterns were novel, subjects needed to see about half of the entire pattern simultaneously to maintain optimal performance. However, the critical visual field size decreased as familiarity with the patterns increased. These results were replicated in the second study with more complex Kanji characters. In addition, the critical field size decreased as pattern complexity decreased. We propose a three component model of pattern perception. In the first stage a representation of the stimulus must be constructed by the subject, and restricting of the visual field interferes dramatically with this component when stimuli are unfamiliar. With increased familiarity, subjects become able to reconstruct a previous representation from very small, unique segments of the pattern, analogous to the informativeness areas hypothesized by Loftus and Mackworth [J. Exp. Psychol., 4 (1978) 565].

  7. Slow changing postural cues cancel visual field dependence on self-tilt detection.

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    Scotto Di Cesare, C; Macaluso, T; Mestre, D R; Bringoux, L

    2015-01-01

    Interindividual differences influence the multisensory integration process involved in spatial perception. Here, we assessed the effect of visual field dependence on self-tilt detection relative to upright, as a function of static vs. slow changing visual or postural cues. To that aim, we manipulated slow rotations (i.e., 0.05° s(-1)) of the body and/or the visual scene in pitch. Participants had to indicate whether they felt being tilted forward at successive angles. Results show that thresholds for self-tilt detection substantially differed between visual field dependent/independent subjects, when only the visual scene was rotated. This difference was no longer present when the body was actually rotated, whatever the visual scene condition (i.e., absent, static or rotated relative to the observer). These results suggest that the cancellation of visual field dependence by dynamic postural cues may rely on a multisensory reweighting process, where slow changing vestibular/somatosensory inputs may prevail over visual inputs. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Perceived change in orientation from optic flow in the central visual field

    Science.gov (United States)

    Dyre, Brian P.; Andersen, George J.

    1988-01-01

    The effects of internal depth within a simulation display on perceived changes in orientation have been studied. Subjects monocularly viewed displays simulating observer motion within a volume of randomly positioned points through a window which limited the field of view to 15 deg. Changes in perceived spatial orientation were measured by changes in posture. The extent of internal depth within the display, the presence or absence of visual information specifying change in orientation, and the frequency of motion supplied by the display were examined. It was found that increased sway occurred at frequencies equal to or below 0.375 Hz when motion at these frequencies was displayed. The extent of internal depth had no effect on the perception of changing orientation.

  9. Change in Visual Field Progression Following Treatment Escalation in Primary Open-angle Glaucoma.

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    Aptel, Florent; Bron, Alain M; Lachkar, Yves; Schweitzer, Cédric

    2017-10-01

    To evaluate the effect of treatment escalation on the rate of visual field progression in patients with primary open-angle glaucoma (POAG). Multicenter database study. We reviewed the electronic records of 171 patients with POAG under medical hypotensive treatment who underwent 5 consecutive visits 6 months apart before and after medical treatment escalation or additive laser trabeculoplasty. We calculated the rate of visual field progression (mean deviation change per year) before and after treatment escalation. The mean duration of follow-up was 5.1±0.5 years and the mean number of visual field examinations was 10.2±0.2. In 139 eyes with medical treatment escalation, the rate of progression was significantly reduced [from -0.57 to -0.29 dB/y; P=0.022; intraocular pressure (IOP) reduction 11.1%]. In detail, the rate of progression was significantly reduced after escalation from mono to dual therapy, dual to triple therapy, and from mono to triple therapy (-0.35 to -0.24 dB/y, P=0.018; -1.01 to -0.48 dB/y, P=0.038; -1.04 to -0.35 dB/y, P=0.020, respectively). In 32 eyes with additive laser trabeculoplasty, the rate of progression was significantly reduced (-0.60 to -0.24 dB/y; P=0.014; IOP reduction 9.4%). Medical treatment escalation or additive laser trabeculoplasty significantly reduced the rate of visual field progression in POAG. Larger IOP reduction has a greater probability of reducing glaucoma progression.

  10. Visual fields and eye morphology support color vision in a color-changing crab-spider.

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    Insausti, Teresita C; Defrize, Jérémy; Lazzari, Claudio R; Casas, Jérôme

    2012-03-01

    Vision plays a major role in many spiders, being involved in prey hunting, orientation or substrate choice, among others. In Misumena vatia, which experiences morphological color changes, vision has been reported to be involved in substrate color matching. Electrophysiological evidence reveals that at least two types of photoreceptors are present in this species, but these data are not backed up by morphological evidence. This work analyzes the functional structure of the eyes of this spider and relates it to its color-changing abilities. A broad superposition of the visual field of the different eyes was observed, even between binocular regions of principal and secondary eyes. The frontal space is simultaneously analyzed by four eyes. This superposition supports the integration of the visual information provided by the different eye types. The mobile retina of the principal eyes of this spider is organized in three layers of three different types of rhabdoms. The third and deepest layer is composed by just one large rhabdom surrounded by dark screening pigments that limit the light entry. The three pairs of secondary eyes have all a single layer of rhabdoms. Our findings provide strong support for an involvement of the visual system in color matching in this spider. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Human locomotion through a multiple obstacle environment : Strategy changes as a result of visual field limitation

    NARCIS (Netherlands)

    Jansen, S.E.M.; Toet, A.; Werkhoven, P.J.

    2011-01-01

    This study investigated how human locomotion through an obstacle environment is influenced by visual field limitation. Participants were asked to walk at a comfortable pace to a target location while avoiding multiple vertical objects. During this task, they wore goggles restricting their visual

  12. The Impact of Change in Visual Field on Health-Related Quality of Life: The Los Angeles Latino Eye Study

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    Patino, Cecilia M.; Varma, Rohit; Azen, Stanley P.; Conti, David V.; Nichol, Michael B.; McKean-Cowdin, Roberta

    2010-01-01

    Purpose To assess the impact of change in visual field (VF) on change in health related quality of life (HRQoL) at the population level. Design Prospective cohort study Participants 3,175 Los Angles Latino Eye Study (LALES) participants Methods Objective measures of VF and visual acuity and self-reported HRQoL were collected at baseline and 4-year follow-up. Analysis of covariance was used to evaluate mean differences in change of HRQoL across severity levels of change in VF and to test for effect modification by covariates. Main outcome measures General and vision-specific HRQoL. Results Of 3,175 participants, 1430 (46%) showed a change in VF (≥1 decibel [dB]) and 1651, 1715 (54%) reported a clinically important change (≥5 points) in vision-specific HRQoL. Progressive worsening and improvement in the VF were associated with increasing losses and gains in vision-specific HRQoL for the composite score and 10 of its 11 subscales (all Ptrends 5 dB and gains > 3 dB were associated with clinically meaningful losses and gains in vision-specific HRQoL, respectively. Areas of vision-specific HRQoL most affected by greater losses in VF were driving, dependency, role-functioning, and mental health. The effect of change in VF (loss or gain) on mean change in vision-specific HRQoL varied by level of baseline vision loss (in visual field and/or visual acuity) and by change in visual acuity (all P-interactions 5 dB loss in visual field during the study period had a mean loss of vision-specific HRQoL of 11.3 points, while those with no VF loss at baseline had a mean loss of 0.97 points Similarly, with a > 5 dB loss in VF and baseline visual acuity impairment (mild/severe) there was a loss in vision-specific HRQoL of 10.5 points, whereas with no visual acuity impairment at baseline there was a loss of vision-specific HRQoL of 3.7 points. Conclusion Both losses and gains in VF produce clinically meaningful changes in vision-specific HRQoL. In the presence of pre-existing vision

  13. Changes in Drivers’ Visual Performance during the Collision Avoidance Process as a Function of Different Field of Views at Intersections

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    Yan, Xuedong; Zhang, Xinran; Zhang, Yuting; Li, Xiaomeng; Yang, Zhuo

    2016-01-01

    The intersection field of view (IFOV) indicates an extent that the visual information can be observed by drivers. It has been found that further enhancing IFOV can significantly improve emergent collision avoidance performance at intersections, such as faster brake reaction time, smaller deceleration rate, and lower traffic crash involvement risk. However, it is not known how IFOV affects drivers’ eye movements, visual attention and the relationship between visual searching and traffic safety. In this study, a driving simulation experiment was conducted to uncover the changes in drivers’ visual performance during the collision avoidance process as a function of different field of views at an intersection by using an eye tracking system. The experimental results showed that drivers’ ability in identifying the potential hazard in terms of visual searching was significantly affected by different IFOV conditions. As the IFOVs increased, drivers had longer gaze duration (GD) and more number of gazes (NG) in the intersection surrounding areas and paid more visual attention to capture critical visual information on the emerging conflict vehicle, thus leading to a better collision avoidance performance and a lower crash risk. It was also found that female drivers had a better visual performance and a lower crash rate than male drivers. From the perspective of drivers’ visual performance, the results strengthened the evidence that further increasing intersection sight distance standards should be encouraged for enhancing traffic safety. PMID:27716824

  14. Baseline mean deviation and rates of visual field change in treated glaucoma patients.

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    Forchheimer, I; de Moraes, C G; Teng, C C; Folgar, F; Tello, C; Ritch, R; Liebmann, J M

    2011-05-01

    To evaluate the relationships between baseline visual field (VF) mean deviation (MD) and subsequent progression in treated glaucoma. Records of patients seen in a glaucoma practice between 1999 and 2009 were reviewed. Patients with glaucomatous optic neuropathy, baseline VF damage, and ≥8 SITA-standard 24-2 VF were included. Patients were divided into tertiles based upon baseline MD. Automated pointwise linear regression determined global and localized rates (decibels (dB) per year) of change. Progression was defined when two or more adjacent test locations in the same hemifield showed a sensitivity decline at a rate of >1.0  dB per year, P0.50) and global rates of VF change of progressing eyes were -1.3±1.2, -1.01±0.7, and -0.9±0.5 dB/year (P=0.09, analysis of variance). Within these groups, intraocular pressure (IOP) in stable vs progressing eyes were 15.5±3.3 vs 17.0±3.1 (P0.50) and multivariate (P=0.26) analyses adjusting for differences in follow-up IOP. After correcting for differences in IOP in treated glaucoma patients, we did not find a relationship between the rate of VF change (dB per year) and the severity of the baseline VF MD. This finding may have been due to more aggressive IOP lowering in eyes with more severe disease. Eyes with lower IOP progressed less frequently across the spectrum of VF loss.

  15. Comparison between visual half-field performance and cerebral blood flow changes as indicators of language dominance.

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    Krach, S; Chen, L M; Hartje, W

    2006-03-01

    The determination of hemispheric language dominance (HLD) can be accomplished in two ways. One approach relies on hemispheric differences in cerebral blood flow velocity (CBFV) changes during language activity, while the other approach makes use of performance differences between the left and right visual field when verbal stimuli are presented in a tachistoscopic visual field paradigm. Since both methodologically different approaches claim to assess functional HLD, it seems plausible to expect that the respective laterality indices (LI) would correspond. To test this expectation we measured language lateralisation in 58 healthy right-handed, left-handed, and ambidextrous subjects with both approaches. CBFV changes were recorded with functional transcranial Doppler sonography (fTCD). We applied a lexical decision task with bilateral visual field presentation of abstract nouns and, in addition, a task of mental word generation. In the lexical decision task, a highly significant right visual field advantage was observed for number of correct responses and reaction times, while at the same time and contrary to expectation the increase of CBFV was significantly higher in the right than left hemisphere. During mental word generation, the acceleration of CBF was significantly higher in the left hemisphere. A comparison between individual LI derived from CBF measurement during mental word generation and from visual field performances in the lexical decision task showed a moderate correspondence in classifying the subjects' HLD. However, the correlation between the corresponding individual LI was surprisingly low and not significant. The results are discussed with regard to the issue of a limited reliability of behavioural LI on the one hand and the possibility of a fundamental difference between the behavioural and the physiological indicators of laterality on the other hand.

  16. Short wavelength automated perimetry can detect visual field changes in diabetic patients without retinopathy

    Directory of Open Access Journals (Sweden)

    Othman Ali Zico

    2014-01-01

    Full Text Available Purpose: The purpose of the following study is to compare short wave automated perimetry (SWAP versus standard automated perimetry (SAP for early detection of diabetic retinopathy (DR. Materials and Methods: A total of 40 diabetic patients, divided into group I without DR (20 patients = 40 eyes and group II with mild non-proliferative DR (20 patients = 40 eyes were included. They were tested with central 24-2 threshold test with both shortwave and SAP to compare sensitivity values and local visual field indices in both of them. A total of 20 healthy age and gender matched subjects were assessed as a control group. Results: Control group showed no differences between SWAP and SAP regarding mean deviation (MD, corrected pattern standard deviation (CPSD or short fluctuations (SF. In group I, MD showed significant more deflection in SWAP (−4.44 ± 2.02 dB compared to SAP (−0.96 ± 1.81 dB (P = 0.000002. However, CPSD and SF were not different between SWAP and SAP. In group II, MD and SF showed significantly different values in SWAP (−5.75 ± 3.11 dB and 2.0 ± 0.95 compared to SAP (−3.91 ± 2.87 dB and 2.86 ± 1.23 (P = 0.01 and 0.006 respectively. There are no differences regarding CPSD between SWAP and SAP. The SWAP technique was significantly more sensitive than SAP in patients without retinopathy (p, but no difference exists between the two techniques in patients with non-proliferative DR. Conclusion: The SWAP technique has a higher yield and efficacy to pick up abnormal findings in diabetic patients without overt retinopathy rather than patients with clinical retinopathy.

  17. Visualizing the Computational Intelligence Field

    NARCIS (Netherlands)

    L. Waltman (Ludo); J.H. van den Berg (Jan); U. Kaymak (Uzay); N.J.P. van Eck (Nees Jan)

    2006-01-01

    textabstractIn this paper, we visualize the structure and the evolution of the computational intelligence (CI) field. Based on our visualizations, we analyze the way in which the CI field is divided into several subfields. The visualizations provide insight into the characteristics of each subfield

  18. Changes of visual-field global indices after cataract surgery in primary open-angle glaucoma patients.

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    Seol, Bo Ram; Jeoung, Jin Wook; Park, Ki Ho

    2016-11-01

    To determine changes of visual-field (VF) global indices after cataract surgery and the factors associated with the effect of cataracts on those indices in primary open-angle glaucoma (POAG) patients. A retrospective chart review of 60 POAG patients who had undergone phacoemulsification and intraocular lens insertion was conducted. All of the patients were evaluated with standard automated perimetry (SAP; 30-2 Swedish interactive threshold algorithm; Carl Zeiss Meditec Inc.) before and after surgery. VF global indices before surgery were compared with those after surgery. The best-corrected visual acuity, intraocular pressure (IOP), number of glaucoma medications before surgery, mean total deviation (TD) values, mean pattern deviation (PD) value, and mean TD-PD value were also compared with the corresponding postoperative values. Additionally, postoperative peak IOP and mean IOP were evaluated. Univariate and multivariate logistic regression analyses were performed to identify the factors associated with the effect of cataract on global indices. Mean deviation (MD) after cataract surgery was significantly improved compared with the preoperative MD. Pattern standard deviation (PSD) and visual-field index (VFI) after surgery were similar to those before surgery. Also, mean TD and mean TD-PD were significantly improved after surgery. The posterior subcapsular cataract (PSC) type showed greater MD changes than did the non-PSC type in both the univariate and multivariate logistic regression analyses. In the univariate logistic regression analysis, the preoperative TD-PD value and type of cataract were associated with MD change. However, in the multivariate logistic regression analysis, type of cataract was the only associated factor. None of the other factors was associated with MD change. MD was significantly affected by cataracts, whereas PSD and VFI were not. Most notably, the PSC type showed better MD improvement compared with the non-PSC type after cataract surgery

  19. Investigation of the metabolic changes in visual cortex due to visual stimulation using high field magnetic resonance spectroscopy at 7.0 T

    International Nuclear Information System (INIS)

    Lin Yan; Peter, M.; Wu Renhua

    2012-01-01

    Objective: To investigate the metabolic changes in the visual cortex due to visual stimulation using high field functional proton magnetic resonance spectroscopy at 7.0 T. A clear picture of brain metabolism and neurotransmitter activity during activation was expected to be established. Methods: Nine healthy subjects participated in this study. All MR measurements were acquired using a 7.0 T MR system and a 16-channel SENSE head coil. An initial fMRI scan was performed prior to spectroscopic acquisition in order to determine the activated region in the visual cortex. A cubic ROI of 2 cm× 2 cm × 2 cm was positioned inside the activated region for functional MRS acquisition. A short TE STEAM sequence was used for acquiring the MRS data. The functional paradigm comprised 6.6 min baseline followed by 13.2 min of visual stimulation and 19.8 min recovery. Summed averaged spectra for visual stimulus off and visual stimulus on were analyzed separately using LC Model and internal reference of water. A Wilcoxon signed rank test was conducted to compare the metabolite changes. Results During stimulation, concentration in Asp [(3.20 ± 0.28) μmol/g], Gln [(2.07 ± 0.10) μmol/g] and Gly [(1.65 ± 0.11)μmol/g] was found to be significantly decreased,compared with that of (3.52 ± 0.28), (2.25 ± 0.10) and (1.85 ± 0.11) μmol/g in rest (Z=-2.073, -2.073 and -2.429, respectively, P<0.05). The level in Glu [(11.50 ± 0.11) μmol/g], GSH [(2.45 ± 0.10) μmol/g] and Lac [(0.89 ± 0.05) μmol/g] due to neuronal activation was found to be significantly increased,versus resting concentration of (11.28 ± 0.11), (2.28 ± 0.10) and (0.79 ± 0.05) μmol/g,respectively (Z=2.521, 2.310, 2.016, respectively, P<0.05). Glc level [(1.54 ± 0.23)μmol/g] exhibited a tendency to decrease throughout the period of stimulation, compared with that of [(1.78 ± 0.28) μmol/g] in rest,but the decrease did not reach statistical significance (Z=-1.897, P>0.05). Conclusions: Using a novel visual

  20. The visual development of hand-centered receptive fields in a neural network model of the primate visual system trained with experimentally recorded human gaze changes.

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    Galeazzi, Juan M; Navajas, Joaquín; Mender, Bedeho M W; Quian Quiroga, Rodrigo; Minini, Loredana; Stringer, Simon M

    2016-01-01

    Neurons have been found in the primate brain that respond to objects in specific locations in hand-centered coordinates. A key theoretical challenge is to explain how such hand-centered neuronal responses may develop through visual experience. In this paper we show how hand-centered visual receptive fields can develop using an artificial neural network model, VisNet, of the primate visual system when driven by gaze changes recorded from human test subjects as they completed a jigsaw. A camera mounted on the head captured images of the hand and jigsaw, while eye movements were recorded using an eye-tracking device. This combination of data allowed us to reconstruct the retinal images seen as humans undertook the jigsaw task. These retinal images were then fed into the neural network model during self-organization of its synaptic connectivity using a biologically plausible trace learning rule. A trace learning mechanism encourages neurons in the model to learn to respond to input images that tend to occur in close temporal proximity. In the data recorded from human subjects, we found that the participant's gaze often shifted through a sequence of locations around a fixed spatial configuration of the hand and one of the jigsaw pieces. In this case, trace learning should bind these retinal images together onto the same subset of output neurons. The simulation results consequently confirmed that some cells learned to respond selectively to the hand and a jigsaw piece in a fixed spatial configuration across different retinal views.

  1. Can Probability Maps of Swept-Source Optical Coherence Tomography Predict Visual Field Changes in Preperimetric Glaucoma?

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    Lee, Won June; Kim, Young Kook; Jeoung, Jin Wook; Park, Ki Ho

    2017-12-01

    To determine the usefulness of swept-source optical coherence tomography (SS-OCT) probability maps in detecting locations with significant reduction in visual field (VF) sensitivity or predicting future VF changes, in patients with classically defined preperimetric glaucoma (PPG). Of 43 PPG patients, 43 eyes were followed-up on every 6 months for at least 2 years were analyzed in this longitudinal study. The patients underwent wide-field SS-OCT scanning and standard automated perimetry (SAP) at the time of enrollment. With this wide-scan protocol, probability maps originating from the corresponding thickness map and overlapped with SAP VF test points could be generated. We evaluated the vulnerable VF points with SS-OCT probability maps as well as the prevalence of locations with significant VF reduction or subsequent VF changes observed in the corresponding damaged areas of the probability maps. The vulnerable VF points were shown in superior and inferior arcuate patterns near the central fixation. In 19 of 43 PPG eyes (44.2%), significant reduction in baseline VF was detected within the areas of structural change on the SS-OCT probability maps. In 16 of 43 PPG eyes (37.2%), subsequent VF changes within the areas of SS-OCT probability map change were observed over the course of the follow-up. Structural changes on SS-OCT probability maps could detect or predict VF changes using SAP, in a considerable number of PPG eyes. Careful comparison of probability maps with SAP results could be useful in diagnosing and monitoring PPG patients in the clinical setting.

  2. Changes in glance behaviour when using a visual eco-driving system - A field study.

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    Ahlstrom, Christer; Kircher, Katja

    2017-01-01

    While in-vehicle eco-driving support systems have the potential to reduce greenhouse gas emissions and save fuel, they may also distract drivers, especially if the system makes use of a visual interface. The objective of this study is to investigate the visual behaviour of drivers interacting with such a system, implemented on a five-inch screen mounted above the middle console. Ten drivers participated in a real-world, on-road driving study where they drove a route nine times (2 pre-baseline drives, 5 treatment drives, 2 post-baseline drives). The route was 96 km long and consisted of rural roads, urban roads and a dual-lane motorway. The results show that drivers look at the system for 5-8% of the time, depending on road type, with a glance duration of about 0.6 s, and with 0.05% long glances (>2s) per kilometre. These figures are comparable to what was found for glances to the speedometer in this study. Glance behaviour away from the windscreen is slightly increased in treatment as compared to pre- and post-baseline, mirror glances decreased in treatment and post-baseline compared to pre-baseline, and speedometer glances increased compared to pre-baseline. The eco-driving support system provided continuous information interspersed with additional advice pop-ups (announced by a beep) and feedback pop-ups (no auditory cue). About 20% of sound initiated advice pop-ups were disregarded, and the remaining cases were usually looked at within the first two seconds. About 40% of the feedback pop-ups were disregarded. The amount of glances to the system immediately before the onset of a pop-up was clearly higher for feedback than for advice. All in all, the eco-driving support system under investigation is not likely to have a strong negative impact on glance behaviour. However, there is room for improvements. We recommend that eco-driving information is integrated with the speedometer, that optional activation of sound alerts for intermittent information is made

  3. Visual field measurement with motion sensitivity screening test

    African Journals Online (AJOL)

    has been shown that early ocular lesions which manifest as visual field defects or ... easy-to-understand computer perimetry that could be useful in monitoring visual field changes in onchocer- .... education with the equivalent of ordinary level.

  4. Introduction to Vector Field Visualization

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    Kao, David; Shen, Han-Wei

    2010-01-01

    Vector field visualization techniques are essential to help us understand the complex dynamics of flow fields. These can be found in a wide range of applications such as study of flows around an aircraft, the blood flow in our heart chambers, ocean circulation models, and severe weather predictions. The vector fields from these various applications can be visually depicted using a number of techniques such as particle traces and advecting textures. In this tutorial, we present several fundamental algorithms in flow visualization including particle integration, particle tracking in time-dependent flows, and seeding strategies. For flows near surfaces, a wide variety of synthetic texture-based algorithms have been developed to depict near-body flow features. The most common approach is based on the Line Integral Convolution (LIC) algorithm. There also exist extensions of LIC to support more flexible texture generations for 3D flow data. This tutorial reviews these algorithms. Tensor fields are found in several real-world applications and also require the aid of visualization to help users understand their data sets. Examples where one can find tensor fields include mechanics to see how material respond to external forces, civil engineering and geomechanics of roads and bridges, and the study of neural pathway via diffusion tensor imaging. This tutorial will provide an overview of the different tensor field visualization techniques, discuss basic tensor decompositions, and go into detail on glyph based methods, deformation based methods, and streamline based methods. Practical examples will be used when presenting the methods; and applications from some case studies will be used as part of the motivation.

  5. [Are Visual Field Defects Reversible? - Visual Rehabilitation with Brains].

    Science.gov (United States)

    Sabel, B A

    2017-02-01

    Visual field defects are considered irreversible because the retina and optic nerve do not regenerate. Nevertheless, there is some potential for recovery of the visual fields. This can be accomplished by the brain, which analyses and interprets visual information and is able to amplify residual signals through neuroplasticity. Neuroplasticity refers to the ability of the brain to change its own functional architecture by modulating synaptic efficacy. This is actually the neurobiological basis of normal learning. Plasticity is maintained throughout life and can be induced by repetitively stimulating (training) brain circuits. The question now arises as to how plasticity can be utilised to activate residual vision for the treatment of visual field loss. Just as in neurorehabilitation, visual field defects can be modulated by post-lesion plasticity to improve vision in glaucoma, diabetic retinopathy or optic neuropathy. Because almost all patients have some residual vision, the goal is to strengthen residual capacities by enhancing synaptic efficacy. New treatment paradigms have been tested in clinical studies, including vision restoration training and non-invasive alternating current stimulation. While vision training is a behavioural task to selectively stimulate "relative defects" with daily vision exercises for the duration of 6 months, treatment with alternating current stimulation (30 min. daily for 10 days) activates and synchronises the entire retina and brain. Though full restoration of vision is not possible, such treatments improve vision, both subjectively and objectively. This includes visual field enlargements, improved acuity and reaction time, improved orientation and vision related quality of life. About 70 % of the patients respond to the therapies and there are no serious adverse events. Physiological studies of the effect of alternating current stimulation using EEG and fMRI reveal massive local and global changes in the brain. These include

  6. 38 CFR 4.77 - Visual fields.

    Science.gov (United States)

    2010-07-01

    ... DISABILITIES Disability Ratings The Organs of Special Sense § 4.77 Visual fields. (a) Examination of visual... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Visual fields. 4.77... who are well adapted to intraocular lens implant or contact lens correction, visual field examinations...

  7. Prism therapy and visual rehabilitation in homonymous visual field loss.

    LENUS (Irish Health Repository)

    O'Neill, Evelyn C

    2011-02-01

    Homonymous visual field defects (HVFD) are common and frequently occur after cerebrovascular accidents. They significantly impair visual function and cause disability particularly with regard to visual exploration. The purpose of this study was to assess a novel interventional treatment of monocular prism therapy on visual functioning in patients with HVFD of varied etiology using vision targeted, health-related quality of life (QOL) questionnaires. Our secondary aim was to confirm monocular and binocular visual field expansion pre- and posttreatment.

  8. Visual field abnormalities in multiple sclerosis.

    OpenAIRE

    Patterson, V H; Heron, J R

    1980-01-01

    Visual fields were examined with a tangent screen in 54 patients with multiple sclerosis (MS) or optic neuritis (ON). Visual fields were abnormal in all patients with definite MS, 94% with probable MS and 81% with possible MS. Three-quarters of the MS patients with no history of visual symptoms had abnormal fields. The commonest defect found was an arcuate scotoma. As a diagnostic test of visual pathway involvement in MS, tangent screen examination compares favourably with more sophisticated ...

  9. A computational theory of visual receptive fields.

    Science.gov (United States)

    Lindeberg, Tony

    2013-12-01

    A receptive field constitutes a region in the visual field where a visual cell or a visual operator responds to visual stimuli. This paper presents a theory for what types of receptive field profiles can be regarded as natural for an idealized vision system, given a set of structural requirements on the first stages of visual processing that reflect symmetry properties of the surrounding world. These symmetry properties include (i) covariance properties under scale changes, affine image deformations, and Galilean transformations of space-time as occur for real-world image data as well as specific requirements of (ii) temporal causality implying that the future cannot be accessed and (iii) a time-recursive updating mechanism of a limited temporal buffer of the past as is necessary for a genuine real-time system. Fundamental structural requirements are also imposed to ensure (iv) mutual consistency and a proper handling of internal representations at different spatial and temporal scales. It is shown how a set of families of idealized receptive field profiles can be derived by necessity regarding spatial, spatio-chromatic, and spatio-temporal receptive fields in terms of Gaussian kernels, Gaussian derivatives, or closely related operators. Such image filters have been successfully used as a basis for expressing a large number of visual operations in computer vision, regarding feature detection, feature classification, motion estimation, object recognition, spatio-temporal recognition, and shape estimation. Hence, the associated so-called scale-space theory constitutes a both theoretically well-founded and general framework for expressing visual operations. There are very close similarities between receptive field profiles predicted from this scale-space theory and receptive field profiles found by cell recordings in biological vision. Among the family of receptive field profiles derived by necessity from the assumptions, idealized models with very good qualitative

  10. COMPARISON OF RNFL THICKNESS AND VISUAL FIELD CHANGES BETWEEN DIABETIC WITHOUT RETINOPATHY AND NONDIABETIC CONTROLS- A CROSS-SECTIONAL STUDY

    Directory of Open Access Journals (Sweden)

    Soumya Swarup Chattopadhyay

    2017-10-01

    Full Text Available BACKGROUND Diabetes mellitus is one of the major component of metabolic syndrome and a leading cause of ocular morbidity in modern era and India will be considered to be the diabetes capital of the world. Before the onset of diabetic retinopathy, other structural and functional changes may predict the visual diminution of the individual. MATERIALS AND METHODS In this cross-sectional study in a tertiary care hospital, after inclusion and exclusion, the age-gender matched groups (diagnosed type 2 diabetes patients without diabetic retinopathy and controls without diabetes were thoroughly examined clinically and by noninvasive and invasive examination (after proper counselling of the patient and informed consent. Then, they are tested for functional loss of retina by Humphrey FDT, GDx VCC. Comparison done between cases and controls as well as poorly-controlled and well-controlled diabetic groups. RESULTS It was found that the average RNFL thickness was significantly reduced in diabetics (mean 53.48, SD 2.69 compared to controls (mean 60.21, SD 1.87 (p7%, the RNFL thickness was significantly reduced (mean 52.23, SD 1.31 compared to diabetics with good metabolic control (mean 56.38, SD 2.92 (p<0.05. In retinal functional testing, it was found that the Humphrey FDT mean deviation (FDT MD and pattern standard deviation (FDT PSD were significantly worse in diabetics (FDT MD- 1.478, SD 0.386, (FDT PSD- 3.485, SD 0.403 compared to normal controls (FDT MD- 0.442, SD 0.536, (FDT PSD- 1.438, SD 0.404. The parameters were also found to be significantly worse in uncontrolled diabetics (p<0.05. CONCLUSION To conclude, without diabetic retinopathy, functional and structural loss in retina in diabetes patients compared to age-sex matched individual and especially in poorly-controlled diabetes should be of concern as there are no detectable vasculopathy. So, early diagnosis and control of diabetes is advocated to control this functional loss

  11. Visual acuity and visual field impairment in Usher syndrome.

    Science.gov (United States)

    Edwards, A; Fishman, G A; Anderson, R J; Grover, S; Derlacki, D J

    1998-02-01

    To determine the extent of visual acuity and visual field impairment in patients with types 1 and 2 Usher syndrome. The records of 53 patients with type 1 and 120 patients with type 2 Usher syndrome were reviewed for visual acuity and visual field area at their most recent visit. Visual field areas were determined by planimetry of the II4e and V4e isopters obtained with a Goldmann perimeter. Both ordinary and logistic regression models were used to evaluate differences in visual acuity and visual field impairment between patients with type 1 and type 2 Usher syndrome. The difference in visual acuity of the better eye between patients with type 1 and type 2 varied by patient age (P=.01, based on a multiple regression model). The maximum difference in visual acuity between the 2 groups occurred during the third and fourth decades of life (with the type 1 patients being more impaired), while more similar acuities were seen in both younger and older patients. Fifty-one percent (n=27) of the type 1 patients had a visual acuity of 20/40 or better in at least 1 eye compared with 72% (n=87) of the type 2 patients (age-adjusted odds ratio, 3.9). Visual field area to both the II4e (P=.001) and V4e (Ptype 1 patients than type 2 patients. A concentric central visual field greater than 20 degrees in at least 1 eye was present in 20 (59%) of the available 34 visual fields of type 1 patients compared with 70 (67%) of the available 104 visual fields of type 2 patients (age-adjusted odds ratio, 2.9) with the V4e target and in 6 (21%) of the available 29 visual fields of type 1 patients compared with 36 (38%) of the available 94 visual fields of type 2 patients (age-adjusted odds ratio, 4.9) with the II4e target. The fraction of patients who had a visual acuity of 20/40 or better and a concentric central visual field greater than 20 degrees to the II4e target in at least 1 eye was 17% (n=5) in the type 1 patients and 35% (n=33) in the type 2 patients (age-adjusted odds ratio, 3

  12. Contralateral eye comparison on changes in visual field following laser in situ keratomileusis vs photorefractive keratectomy for myopia: a randomized clinical trial.

    Science.gov (United States)

    Mostafaei, A; Sedgipour, M R; Sadeghi-Bazargani, H

    2009-12-01

    Study purpose was to compare the changes of Visual Field (VF) during laser in situ Keratomileusis (LASIK) VS photorefractive keratectomy (PRK). This randomized, double blind, study involved 54 eyes of 27 Myopia patients who underwent LASIK or PRK procedures for contralateral eyes in each patient. Using Humphrey 30-2 SITA standard, the Mean Defect (MD) and Pattern Standard Deviation (PSD) were evaluated preoperatively and three months after surgery. At the same examination optical zone size, papillary and corneal diameters were also evaluated. There was no clinically significant difference in PSD and MD measurements between treated eyes with LASIK or PRK in any zone pre and postoperatively. VF may not be affected by corneal changes induced by LASIK or PRK three months after surgery.

  13. Visual Field Asymmetry in Attentional Capture

    Science.gov (United States)

    Du, Feng; Abrams, Richard A.

    2010-01-01

    The present study examined the spatial distribution of involuntary attentional capture over the two visual hemi-fields. A new experiment, and an analysis of three previous experiments showed that distractors in the left visual field that matched a sought-for target in color produced a much larger capture effect than identical distractors in the…

  14. Prism therapy and visual rehabilitation in homonymous visual field loss.

    LENUS (Irish Health Repository)

    O'Neill, Evelyn C

    2012-02-01

    PURPOSE: Homonymous visual field defects (HVFD) are common and frequently occur after cerebrovascular accidents. They significantly impair visual function and cause disability particularly with regard to visual exploration. The purpose of this study was to assess a novel interventional treatment of monocular prism therapy on visual functioning in patients with HVFD of varied etiology using vision targeted, health-related quality of life (QOL) questionnaires. Our secondary aim was to confirm monocular and binocular visual field expansion pre- and posttreatment. METHODS: Twelve patients with acquired, documented HVFD were eligible to be included. All patients underwent specific vision-targeted, health-related QOL questionnaire and monocular and binocular Goldmann perimetry before commencing prism therapy. Patients were fitted with monocular prisms on the side of the HVFD with the base-in the direction of the field defect creating a peripheral optical exotropia and field expansion. After the treatment period, QOL questionnaires and perimetry were repeated. RESULTS: Twelve patients were included in the treatment group, 10 of whom were included in data analysis. Overall, there was significant improvement within multiple vision-related, QOL functioning parameters, specifically within the domains of general health (p < 0.01), general vision (p < 0.05), distance vision (p < 0.01), peripheral vision (p < 0.05), role difficulties (p < 0.05), dependency (p < 0.05), and social functioning (p < 0.05). Visual field expansion was shown when measured monocularly and binocularly during the study period in comparison with pretreatment baselines. CONCLUSIONS: Patients with HVFD demonstrate decreased QOL. Monocular sector prisms can improve the QOL and expand the visual field in these patients.

  15. Visualizing vector field topology in fluid flows

    Science.gov (United States)

    Helman, James L.; Hesselink, Lambertus

    1991-01-01

    Methods of automating the analysis and display of vector field topology in general and flow topology in particular are discussed. Two-dimensional vector field topology is reviewed as the basis for the examination of topology in three-dimensional separated flows. The use of tangent surfaces and clipping in visualizing vector field topology in fluid flows is addressed.

  16. Visualization of induced electric fields

    NARCIS (Netherlands)

    Deursen, van A.P.J.

    2005-01-01

    A cylindrical electrolytic tank between a set of Helmholtz coils provides a classroom demonstration of induced, nonconservative electric fields. The field strength is measured by a sensor consisting of a pair of tiny spheres immersed in the liquid. The sensor signal depends on position, frequency,

  17. Dynamic change of ERPs related to selective attention to signals from left and right visual field during head-down tilt

    Science.gov (United States)

    Wei, Jinhe; Zhao, Lun; Van, Gongdong; Chen, Wenjuan; Ren, Wei; Duan, Ran

    To study further the effect of head-down tilt(HDT) on slow positive potential in the event-related potentials(ERPs), the temporal and spatial features of visual ERPs changes during 2 hour HDT(-10 °) were compared with that during HUT(+20°) in 15 normal subjects. The stimuli were consisted of two color LED flashes appeared randomly in left or right visual field(LVF or RVF) with same probability. The subjects were asked to make switch response to target signals(T) differentially: switching to left for T in LVF and to right for T in RVF, ignoring non-target signals(N). Five sets of tests were made during HUT and HDT. ERPs were obtained from 9 locations on scalp. The mean value of the ERPs in the period from 0.32-0.55 s was taken as the amplitude of slow positive potential(P400). The main results were as follows. 1)The mean amplitude of P400 decreased during HDT which was more significant at the 2nd, 3rd and 5th set of tests; 2)spatially, the reduction of mean P400 amplitude during HDT was more significant for signals from RVF and was more significant at posterior and central brain regions than that on frontal locations. As that the positive potential probably reflects the active inhibition activity in the brain during attention process, these data provide further evidence showing that the higher brain function was affected by the simulated weightlessness and that this effect was not only transient but also with interesting spatial characteristics.

  18. Visualization of numerically simulated aerodynamic flow fields

    International Nuclear Information System (INIS)

    Hian, Q.L.; Damodaran, M.

    1991-01-01

    The focus of this paper is to describe the development and the application of an interactive integrated software to visualize numerically simulated aerodynamic flow fields so as to enable the practitioner of computational fluid dynamics to diagnose the numerical simulation and to elucidate essential flow physics from the simulation. The input to the software is the numerical database crunched by a supercomputer and typically consists of flow variables and computational grid geometry. This flow visualization system (FVS), written in C language is targetted at the Personal IRIS Workstations. In order to demonstrate the various visualization modules, the paper also describes the application of this software to visualize two- and three-dimensional flow fields past aerodynamic configurations which have been numerically simulated on the NEC-SXIA Supercomputer. 6 refs

  19. Visual Discomfort and Depth-of-Field

    Directory of Open Access Journals (Sweden)

    Louise O'Hare

    2013-05-01

    Full Text Available Visual discomfort has been reported for certain visual stimuli and under particular viewing conditions, such as stereoscopic viewing. In stereoscopic viewing, visual discomfort can be caused by a conflict between accommodation and convergence cues that may specify different distances in depth. Earlier research has shown that depth-of-field, which is the distance range in depth in the scene that is perceived to be sharp, influences both the perception of egocentric distance to the focal plane, and the distance range in depth between objects in the scene. Because depth-of-field may also be in conflict with convergence and the accommodative state of the eyes, we raised the question of whether depth-of-field affects discomfort when viewing stereoscopic photographs. The first experiment assessed whether discomfort increases when depth-of-field is in conflict with coherent accommodation–convergence cues to distance in depth. The second experiment assessed whether depth-of-field influences discomfort from a pre-existing accommodation–convergence conflict. Results showed no effect of depth-of-field on visual discomfort. These results suggest therefore that depth-of-field can be used as a cue to depth without inducing discomfort in the viewer, even when cue conflicts are large.

  20. Functional visual fields: relationship of visual field areas to self-reported function.

    Science.gov (United States)

    Subhi, Hikmat; Latham, Keziah; Myint, Joy; Crossland, Michael D

    2017-07-01

    The aim of this study is to relate areas of the visual field to functional difficulties to inform the development of a binocular visual field assessment that can reflect the functional consequences of visual field loss. Fifty-two participants with peripheral visual field loss undertook binocular assessment of visual fields using the 30-2 and 60-4 SITA Fast programs on the Humphrey Field Analyser, and mean thresholds were derived. Binocular visual acuity, contrast sensitivity and near reading performance were also determined. Self-reported overall and mobility function were assessed using the Dutch ICF Activity Inventory. Greater visual field loss (0-60°) was associated with worse self-reported function both overall (R 2 = 0.50; p function (R 2 = 0.61, p function in multiple regression analyses. Superior and inferior visual field areas related similarly to mobility function (R 2 = 0.56, p function in multiple regression analysis. Mean threshold of the binocular visual field to 60° eccentricity is a good predictor of self-reported function overall, and particularly of mobility function. Both the central (0-30°) and peripheral (30-60°) mean threshold are good predictors of self-reported function, but the peripheral (30-0°) field is a slightly better predictor of mobility function, and should not be ignored when considering functional consequences of field loss. The inferior visual field is a slightly stronger predictor of perceived overall and mobility function than the superior field. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

  1. Change in vision, visual disability, and health after cataract surgery.

    Science.gov (United States)

    Helbostad, Jorunn L; Oedegaard, Maria; Lamb, Sarah E; Delbaere, Kim; Lord, Stephen R; Sletvold, Olav

    2013-04-01

    Cataract surgery improves vision and visual functioning; the effect on general health is not established. We investigated if vision, visual functioning, and general health follow the same trajectory of change the year after cataract surgery and if changes in vision explain changes in visual disability and general health. One-hundred forty-eight persons, with a mean (SD) age of 78.9 (5.0) years (70% bilateral surgery), were assessed before and 6 weeks and 12 months after surgery. Visual disability and general health were assessed by the CatQuest-9SF and the Short Formular-36. Corrected binocular visual acuity, visual field, stereo acuity, and contrast vision improved (P visual acuity evident up to 12 months (P = 0.034). Cataract surgery had an effect on visual disability 1 year later (P visual disability and general health 6 weeks after surgery. Vision improved and visual disability decreased in the year after surgery, whereas changes in general health and visual functioning were short-term effects. Lack of associations between changes in vision and self-reported disability and general health suggests that the degree of vision changes and self-reported health do not have a linear relationship.

  2. Comparison of optical coherence tomography findings and visual field changes in patients with primary open-angle glaucoma and amyotrophic lateral sclerosis.

    Science.gov (United States)

    Liu, Ziyuan; Wang, Hongli; Fan, Dongsheng; Wang, Wei

    2018-02-01

    Recent studies revealing genetic connection of primary open angle glaucoma (POAG) and amyotrophic lateral sclerosis (ALS) have received particular attention. Exploring the evidence for common pathogenesis of these two progressive neurological disorders may assist in understanding the mechanism and searching for new treatment. Retinal nerve fiber layer (RNFL) defect and corresponding visual field (VF) impairment are well known neuropathy signs in glaucoma. In our study, thickness of certain retinal layer in ALS patients was analyzed to detect ganglion cell's soma and axon, and for first time visual field was examined for ALS. The correlation of retinal involvement and ALS progression were also investigated. The results were compared with those of POAG. The study may provide new knowledge for these two neurodegenerative diseases. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Visualization and processing of tensor fields

    CERN Document Server

    Weickert, Joachim

    2007-01-01

    Presents information on the visualization and processing of tensor fields. This book serves as an overview for the inquiring scientist, as a basic foundation for developers and practitioners, and as a textbook for specialized classes and seminars for graduate and doctoral students.

  4. Interventions for visual field defects in patients with stroke.

    Science.gov (United States)

    Pollock, Alex; Hazelton, Christine; Henderson, Clair A; Angilley, Jayne; Dhillon, Baljean; Langhorne, Peter; Livingstone, Katrina; Munro, Frank A; Orr, Heather; Rowe, Fiona J; Shahani, Uma

    2011-10-05

    Visual field defects are estimated to affect 20% to 57% of people who have had a stroke. Visual field defects can affect functional ability in activities of daily living (commonly affecting mobility, reading and driving), quality of life, ability to participate in rehabilitation, and depression, anxiety and social isolation following stroke. There are many interventions for visual field defects, which are proposed to work by restoring the visual field (restitution); compensating for the visual field defect by changing behaviour or activity (compensation); substituting for the visual field defect by using a device or extraneous modification (substitution); or ensuring appropriate diagnosis, referral and treatment prescription through standardised assessment or screening, or both. To determine the effects of interventions for people with visual field defects after stroke. We searched the Cochrane Stroke Group Trials Register (February 2011), the Cochrane Eyes and Vision Group Trials Register (December 2009) and nine electronic bibliographic databases including CENTRAL (The Cochrane Library 2009, Issue 4), MEDLINE (1950 to December 2009), EMBASE (1980 to December 2009), CINAHL (1982 to December 2009), AMED (1985 to December 2009), and PsycINFO (1967 to December 2009). We also searched reference lists and trials registers, handsearched journals and conference proceedings and contacted experts. Randomised trials in adults after stroke, where the intervention was specifically targeted at improving the visual field defect or improving the ability of the participant to cope with the visual field loss. The primary outcome was functional ability in activities of daily living and secondary outcomes included functional ability in extended activities of daily living, reading ability, visual field measures, balance, falls, depression and anxiety, discharge destination or residence after stroke, quality of life and social isolation, visual scanning, adverse events and death. Two

  5. Performance of the visual field index in glaucoma patients with moderately advanced visual field loss.

    Science.gov (United States)

    Lee, Jun Mo; Cirineo, Nila; Ramanathan, Meera; Nouri-Mahdavi, Kouros; Morales, Esteban; Coleman, Anne L; Caprioli, Joseph

    2014-01-01

    To explore the relationship between the visual field index (VFI) and the visual field mean deviation (MD) in glaucoma patients with moderately advanced perimetric damage and to identify the magnitude of the boundary effect of VFI that occurred when the VFI estimation strategy changed from pattern deviation probability value to total deviation probability value as the MD crossed -20 dB in longitudinal visual field (VF) series. A retrospective cohort study of longitudinal data analysis. The MD and VFI values obtained from VF tests conducted on 148 eyes of 148 glaucoma patients having an MD around -20 dB were studied. A total of 1286 VFs with MD values within the range of -16 dB to -24 dB were included. The eyes were divided into 2 groups, with the first having serial MDs all better than or all worse than -20 dB and the second with serial MDs crossing the -20 dB value. Change in MD (ΔMD) was defined as the absolute difference between the MD values of 2 consecutive VFs. Based on the 2 VFI values of the same VFs, the absolute value of change in VFI (ΔVFI) was calculated. The means (± standard deviation) for the ΔVFI were 4.17% (± 3.3%) in the group of eyes with MDs on either side of -20 dB, and were 15.8% (± 8.4%) in the group with MDs crossing -20 dB (P values were 6.8%/dB (± 10.5%) when the range of MD falls on either side of -20 dB, and 7.9%/dB (± 6.2%) when the range of MD crosses the -20 dB values (P = .042). The values of the VFI become highly variable in serial VFs of eyes with MDs crossing -20 dB, in comparison to those VFIs associated with MDs on either side of -20 dB. The likelihood for this effect is the change from use of pattern deviation probability value to total deviation probability value in the points included in the calculation of VFI at -20 dB of MD. The development of indices to measure VF rates that are free from this boundary effect in moderately advanced glaucoma is desirable. Copyright © 2014. Published by Elsevier Inc.

  6. Unpredictable visual changes cause temporal memory averaging.

    Science.gov (United States)

    Ohyama, Junji; Watanabe, Katsumi

    2007-09-01

    Various factors influence the perceived timing of visual events. Yet, little is known about the ways in which transient visual stimuli affect the estimation of the timing of other visual events. In the present study, we examined how a sudden color change of an object would influence the remembered timing of another transient event. In each trial, subjects saw a green or red disk travel in circular motion. A visual flash (white frame) occurred at random times during the motion sequence. The color of the disk changed either at random times (unpredictable condition), at a fixed time relative to the motion sequence (predictable condition), or it did not change (no-change condition). The subjects' temporal memory of the visual flash in the predictable condition was as veridical as that in the no-change condition. In the unpredictable condition, however, the flash was reported to occur closer to the timing of the color change than actual timing. Thus, an unpredictable visual change distorts the temporal memory of another visual event such that the remembered moment of the event is closer to the timing of the unpredictable visual change.

  7. Testing of Visual Field with Virtual Reality Goggles in Manual and Visual Grasp Modes

    Directory of Open Access Journals (Sweden)

    Dariusz Wroblewski

    2014-01-01

    Full Text Available Automated perimetry is used for the assessment of visual function in a variety of ophthalmic and neurologic diseases. We report development and clinical testing of a compact, head-mounted, and eye-tracking perimeter (VirtualEye that provides a more comfortable test environment than the standard instrumentation. VirtualEye performs the equivalent of a full threshold 24-2 visual field in two modes: (1 manual, with patient response registered with a mouse click, and (2 visual grasp, where the eye tracker senses change in gaze direction as evidence of target acquisition. 59 patients successfully completed the test in manual mode and 40 in visual grasp mode, with 59 undergoing the standard Humphrey field analyzer (HFA testing. Large visual field defects were reliably detected by VirtualEye. Point-by-point comparison between the results obtained with the different modalities indicates: (1 minimal systematic differences between measurements taken in visual grasp and manual modes, (2 the average standard deviation of the difference distributions of about 5 dB, and (3 a systematic shift (of 4–6 dB to lower sensitivities for VirtualEye device, observed mostly in high dB range. The usability survey suggested patients’ acceptance of the head-mounted device. The study appears to validate the concepts of a head-mounted perimeter and the visual grasp mode.

  8. Testing of visual field with virtual reality goggles in manual and visual grasp modes.

    Science.gov (United States)

    Wroblewski, Dariusz; Francis, Brian A; Sadun, Alfredo; Vakili, Ghazal; Chopra, Vikas

    2014-01-01

    Automated perimetry is used for the assessment of visual function in a variety of ophthalmic and neurologic diseases. We report development and clinical testing of a compact, head-mounted, and eye-tracking perimeter (VirtualEye) that provides a more comfortable test environment than the standard instrumentation. VirtualEye performs the equivalent of a full threshold 24-2 visual field in two modes: (1) manual, with patient response registered with a mouse click, and (2) visual grasp, where the eye tracker senses change in gaze direction as evidence of target acquisition. 59 patients successfully completed the test in manual mode and 40 in visual grasp mode, with 59 undergoing the standard Humphrey field analyzer (HFA) testing. Large visual field defects were reliably detected by VirtualEye. Point-by-point comparison between the results obtained with the different modalities indicates: (1) minimal systematic differences between measurements taken in visual grasp and manual modes, (2) the average standard deviation of the difference distributions of about 5 dB, and (3) a systematic shift (of 4-6 dB) to lower sensitivities for VirtualEye device, observed mostly in high dB range. The usability survey suggested patients' acceptance of the head-mounted device. The study appears to validate the concepts of a head-mounted perimeter and the visual grasp mode.

  9. Adaptive Gaze Strategies for Locomotion with Constricted Visual Field

    Directory of Open Access Journals (Sweden)

    Colas N. Authié

    2017-07-01

    Full Text Available In retinitis pigmentosa (RP, loss of peripheral visual field accounts for most difficulties encountered in visuo-motor coordination during locomotion. The purpose of this study was to accurately assess the impact of peripheral visual field loss on gaze strategies during locomotion, and identify compensatory mechanisms. Nine RP subjects presenting a central visual field limited to 10–25° in diameter, and nine healthy subjects were asked to walk in one of three directions—straight ahead to a visual target, leftward and rightward through a door frame, with or without obstacle on the way. Whole body kinematics were recorded by motion capture, and gaze direction in space was reconstructed using an eye-tracker. Changes in gaze strategies were identified in RP subjects, including extensive exploration prior to walking, frequent fixations of the ground (even knowing no obstacle was present, of door edges, essentially of the proximal one, of obstacle edge/corner, and alternating door edges fixations when approaching the door. This was associated with more frequent, sometimes larger rapid-eye-movements, larger movements, and forward tilting of the head. Despite the visual handicap, the trajectory geometry was identical between groups, with a small decrease in walking speed in RPs. These findings identify the adaptive changes in sensory-motor coordination, in order to ensure visual awareness of the surrounding, detect changes in spatial configuration, collect information for self-motion, update the postural reference frame, and update egocentric distances to environmental objects. They are of crucial importance for the design of optimized rehabilitation procedures.

  10. Adaptive Gaze Strategies for Locomotion with Constricted Visual Field

    Science.gov (United States)

    Authié, Colas N.; Berthoz, Alain; Sahel, José-Alain; Safran, Avinoam B.

    2017-01-01

    In retinitis pigmentosa (RP), loss of peripheral visual field accounts for most difficulties encountered in visuo-motor coordination during locomotion. The purpose of this study was to accurately assess the impact of peripheral visual field loss on gaze strategies during locomotion, and identify compensatory mechanisms. Nine RP subjects presenting a central visual field limited to 10–25° in diameter, and nine healthy subjects were asked to walk in one of three directions—straight ahead to a visual target, leftward and rightward through a door frame, with or without obstacle on the way. Whole body kinematics were recorded by motion capture, and gaze direction in space was reconstructed using an eye-tracker. Changes in gaze strategies were identified in RP subjects, including extensive exploration prior to walking, frequent fixations of the ground (even knowing no obstacle was present), of door edges, essentially of the proximal one, of obstacle edge/corner, and alternating door edges fixations when approaching the door. This was associated with more frequent, sometimes larger rapid-eye-movements, larger movements, and forward tilting of the head. Despite the visual handicap, the trajectory geometry was identical between groups, with a small decrease in walking speed in RPs. These findings identify the adaptive changes in sensory-motor coordination, in order to ensure visual awareness of the surrounding, detect changes in spatial configuration, collect information for self-motion, update the postural reference frame, and update egocentric distances to environmental objects. They are of crucial importance for the design of optimized rehabilitation procedures. PMID:28798674

  11. MODELLING SYNERGISTIC EYE MOVEMENTS IN THE VISUAL FIELD

    Directory of Open Access Journals (Sweden)

    BARITZ Mihaela

    2015-06-01

    Full Text Available Some theoretical and practical considerations about eye movements in visual field are presented in the first part of this paper. These movements are developed into human body to be synergistic and are allowed to obtain the visual perception in 3D space. The theoretical background of the eye movements’ analysis is founded on the establishment of movement equations of the eyeball, as they consider it a solid body with a fixed point. The exterior actions, the order and execution of the movements are ensured by the neural and muscular external system and thus the position, stability and movements of the eye can be quantified through the method of reverse kinematic. The purpose of these researches is the development of a simulation model of human binocular visual system, an acquisition methodology and an experimental setup for data processing and recording regarding the eye movements, presented in the second part of the paper. The modeling system of ocular movements aims to establish the binocular synergy and limits of visual field changes in condition of ocular motor dysfunctions. By biomechanical movements of eyeball is established a modeling strategy for different sort of processes parameters like convergence, fixation and eye lens accommodation to obtain responses from binocular balance. The results of modelling processes and the positions of eye ball and axis in visual field are presented in the final part of the paper.

  12. Visual Fields at Presentation and after Trans-sphenoidal Resection of Pituitary Adenomas

    Directory of Open Access Journals (Sweden)

    Renu Dhasmana

    2011-01-01

    Full Text Available Purpose: To evaluate visual field changes in patients with pituitary adenomas following trans-sphenoidal surgery. Methods: Eighteen patients with pituitary adenomas underwent a complete ophthalmic assessment and visual field analysis using the Humphrey Field Analyzer 30-2 program before and after trans-sphenoidal surgical resection at the Himalayan Institute of Medical Sciences over a one year period. Visual acuity, duration of symptoms, optic nerve head changes, pattern of visual field defects, and variables such as mean deviation and visual field index were compared. Results: Thirty-six eyes of 18 patients including 10 male and 8 female subjects with mean age of 35.1±9.9 years and histologically proven pituitary adenoma were included. Mean visual acuity at presentation was 0.29 logMAR which improved to 0.21 logMAR postoperatively (P = 0.305. Of 36 eyes, 24 (66.7% had visual field defects including temporal defects in 12 eyes (33.3%, non-specific defects in 10 eyes (27.8%, and peripheral field constriction in 2 eyes (5.6%. Mean deviation of visual fields at presentation was -14.28 dB which improved to -11.32 dB postoperatively. The visual field index improved from 63.5% to 75% postoperatively. Favorable visual field outcomes were correlated with shorter duration of symptoms and absence of optic nerve head changes at presentation. Conclusion: Visual field defects were present in two thirds of patients at presentation. An overall improvement in vision and visual fields was noted after surgical resection. An inverse correlation was found between the duration of symptoms and postoperative visual field recovery, signifying the importance of early surgical intervention.

  13. Visualizing electromagnetic fields in metals by MRI

    Directory of Open Access Journals (Sweden)

    Chandrika Sefcikova Chandrashekar

    2017-02-01

    Full Text Available Based upon Maxwell’s equations, it has long been established that oscillating electromagnetic (EM fields incident upon a metal surface, decay exponentially inside the conductor, leading to a virtual absence of EM fields at sufficient depths. Magnetic resonance imaging (MRI utilizes radiofrequency (r.f. EM fields to produce images. Here we present a visualization of a virtual EM vacuum inside a bulk metal strip by MRI, amongst several findings. At its simplest, an MRI image is an intensity map of density variations across voxels (pixels of identical size (=Δx Δy Δz. By contrast in bulk metal MRI, we uncover that despite uniform density, intensity variations arise from differing effective elemental volumes (voxels from different parts of the bulk metal. Further, we furnish chemical shift imaging (CSI results that discriminate different faces (surfaces of a metal block according to their distinct nuclear magnetic resonance (NMR chemical shifts, which holds much promise for monitoring surface chemical reactions noninvasively. Bulk metals are ubiquitous, and MRI is a premier noninvasive diagnostic tool. Combining the two, the emerging field of bulk metal MRI can be expected to grow in importance. The findings here may impact further development of bulk metal MRI and CSI.

  14. Assessment of visual function by optical coherence tomography and visual field for craniopharyngioma patients

    Directory of Open Access Journals (Sweden)

    Yang Tang

    2015-09-01

    Full Text Available AIM:To analyze the differences and correlations between ganglion cell complex(GCC, peripapillary retinal nerve fiber layer(pRNFLand mean defect(MD, mean sensitivity(MSof visual field(VFin craniopharyngioma patients, to evaluate the feasibility of optical coherence tomography(OCTin diagnosis of the visual pathway damage of craniopharyngioma patients.METHODS:Ninety-five craniopharyngioma patients treated in Beijing Tiantan Hospital, from September 2014 to April 2015 received the VF test by Octopus 900 automated perimeter with the central 30 degree program and the mean thickness measurements of GCC and pRNFL by RTVue OCT. Spearman rank correlation coefficient(rswas used to assess the correlation between GCC, pRNFL and MD, MS. The changes of VF and optic disc were analyzed. RESULTS: Abnormal pRNFL findings occurred in 53.1%(93/175, which included optic disk edema 3.4%(6/175, atrophic changes of optic nerve 47.4%(83/175and glaucoma-like optic neuropathy 7.4%(13/175. Various visual field defect was 71.4%(125/175. The average thickness of binocular pRNFL(rsOD=-0.411, rsOS=-0.354and GCC(rsOD=-0.400, rsOS=-0.314had correlation with MD(PrsOD=0.412, rsOS=0.342and GCC(rsOD=0.414, rsOS=0.299had correlation with MS(PCONCLUSION: The average thickness of pRNFL and GCC has correlation with VF damage, can evaluate the optic nerve damage of craniopharyngioma patients quantitatively. The thinner the thickness of pRNFL and GCC is, the serious damage of visual function is. During the clinical work, visual field test combined with OCT are helpful to find and assess the damage of visual pathway and prognosis.

  15. Anosognosia for obvious visual field defects in stroke patients.

    Science.gov (United States)

    Baier, Bernhard; Geber, Christian; Müller-Forell, Wiebke; Müller, Notger; Dieterich, Marianne; Karnath, Hans-Otto

    2015-01-01

    Patients with anosognosia for visual field defect (AVFD) fail to recognize consciously their visual field defect. There is still unclarity whether specific neural correlates are associated with AVFD. We studied AVFD in 54 patients with acute stroke and a visual field defect. Nineteen percent of this unselected sample showed AVFD. By using modern voxelwise lesion-behaviour mapping techniques we found an association between AVFD and parts of the lingual gyrus, the cuneus as well as the posterior cingulate and corpus callosum. Damage to these regions appears to induce unawareness of visual field defects and thus may play a significant role for conscious visual perception.

  16. New techniques in 3D scalar and vector field visualization

    International Nuclear Information System (INIS)

    Max, N.; Crawfis, R.; Becker, B.

    1993-01-01

    At Lawrence Livermore National Laboratory (LLNL) we have recently developed several techniques for volume visualization of scalar and vector fields, all of which use back-to-front compositing. The first renders volume density clouds by compositing polyhedral volume cells or their faces. The second is a ''splatting'' scheme which composites textures used to reconstruct the scalar or vector fields. One version calculates the necessary texture values in software, and another takes advantage of hardware texture mapping. The next technique renders contour surface polygons using semi-transparent textures, which adjust appropriately when the surfaces deform in a flow, or change topology. The final one renders the ''flow volume'' of smoke or dye tracer swept out by a fluid flowing through a small generating polygon. All of these techniques are applied to a climate model data set, to visualize cloud density and wind velocity

  17. New techniques in 3D scalar and vector field visualization

    Energy Technology Data Exchange (ETDEWEB)

    Max, N.; Crawfis, R.; Becker, B.

    1993-05-05

    At Lawrence Livermore National Laboratory (LLNL) we have recently developed several techniques for volume visualization of scalar and vector fields, all of which use back-to-front compositing. The first renders volume density clouds by compositing polyhedral volume cells or their faces. The second is a ``splatting`` scheme which composites textures used to reconstruct the scalar or vector fields. One version calculates the necessary texture values in software, and another takes advantage of hardware texture mapping. The next technique renders contour surface polygons using semi-transparent textures, which adjust appropriately when the surfaces deform in a flow, or change topology. The final one renders the ``flow volume`` of smoke or dye tracer swept out by a fluid flowing through a small generating polygon. All of these techniques are applied to a climate model data set, to visualize cloud density and wind velocity.

  18. Enhancement and suppression in the visual field under perceptual load.

    Science.gov (United States)

    Parks, Nathan A; Beck, Diane M; Kramer, Arthur F

    2013-01-01

    The perceptual load theory of attention proposes that the degree to which visual distractors are processed is a function of the attentional demands of a task-greater demands increase filtering of irrelevant distractors. The spatial configuration of such filtering is unknown. Here, we used steady-state visual evoked potentials (SSVEPs) in conjunction with time-domain event-related potentials (ERPs) to investigate the distribution of load-induced distractor suppression and task-relevant enhancement in the visual field. Electroencephalogram (EEG) was recorded while subjects performed a foveal go/no-go task that varied in perceptual load. Load-dependent distractor suppression was assessed by presenting a contrast reversing ring at one of three eccentricities (2, 6, or 11°) during performance of the go/no-go task. Rings contrast reversed at 8.3 Hz, allowing load-dependent changes in distractor processing to be tracked in the frequency-domain. ERPs were calculated to the onset of stimuli in the load task to examine load-dependent modulation of task-relevant processing. Results showed that the amplitude of the distractor SSVEP (8.3 Hz) was attenuated under high perceptual load (relative to low load) at the most proximal (2°) eccentricity but not at more eccentric locations (6 or 11°). Task-relevant ERPs revealed a significant increase in N1 amplitude under high load. These results are consistent with a center-surround configuration of load-induced enhancement and suppression in the visual field.

  19. Visual discomfort and depth-of-field

    NARCIS (Netherlands)

    O'Hare, L.; Zhang, T.; Nefs, H.T.; Hibbard, P.B.

    2013-01-01

    Visual discomfort has been reported for certain visual stimuli and under particular viewing conditions, such as stereoscopic viewing. In stereoscopic viewing, visual discomfort can be caused by a conflict between accommodation and convergence cues that may specify different distances in depth.

  20. Lateralized occipital degeneration in posterior cortical atrophy predicts visual field deficits

    Directory of Open Access Journals (Sweden)

    Rebecca S Millington

    2017-01-01

    Conclusions: Detailed brain imaging shows that the asymmetric visual field deficits in patients with PCA reflect the pattern of degeneration of both white and gray matter in the occipital lobe. Understanding the nature of both visual field deficits and the neurodegenerative brain changes in PCA may improve diagnosis and understanding of this disease.

  1. Brain correlates of automatic visual change detection.

    Science.gov (United States)

    Cléry, H; Andersson, F; Fonlupt, P; Gomot, M

    2013-07-15

    A number of studies support the presence of visual automatic detection of change, but little is known about the brain generators involved in such processing and about the modulation of brain activity according to the salience of the stimulus. The study presented here was designed to locate the brain activity elicited by unattended visual deviant and novel stimuli using fMRI. Seventeen adult participants were presented with a passive visual oddball sequence while performing a concurrent visual task. Variations in BOLD signal were observed in the modality-specific sensory cortex, but also in non-specific areas involved in preattentional processing of changing events. A degree-of-deviance effect was observed, since novel stimuli elicited more activity in the sensory occipital regions and at the medial frontal site than small changes. These findings could be compared to those obtained in the auditory modality and might suggest a "general" change detection process operating in several sensory modalities. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Visual advantage in deaf adults linked to retinal changes.

    Directory of Open Access Journals (Sweden)

    Charlotte Codina

    Full Text Available The altered sensory experience of profound early onset deafness provokes sometimes large scale neural reorganisations. In particular, auditory-visual cross-modal plasticity occurs, wherein redundant auditory cortex becomes recruited to vision. However, the effect of human deafness on neural structures involved in visual processing prior to the visual cortex has never been investigated, either in humans or animals. We investigated neural changes at the retina and optic nerve head in profoundly deaf (N = 14 and hearing (N = 15 adults using Optical Coherence Tomography (OCT, an in-vivo light interference method of quantifying retinal micro-structure. We compared retinal changes with behavioural results from the same deaf and hearing adults, measuring sensitivity in the peripheral visual field using Goldmann perimetry. Deaf adults had significantly larger neural rim areas, within the optic nerve head in comparison to hearing controls suggesting greater retinal ganglion cell number. Deaf adults also demonstrated significantly larger visual field areas (indicating greater peripheral sensitivity than controls. Furthermore, neural rim area was significantly correlated with visual field area in both deaf and hearing adults. Deaf adults also showed a significantly different pattern of retinal nerve fibre layer (RNFL distribution compared to controls. Significant correlations between the depth of the RNFL at the inferior-nasal peripapillary retina and the corresponding far temporal and superior temporal visual field areas (sensitivity were found. Our results show that cross-modal plasticity after early onset deafness may not be limited to the sensory cortices, noting specific retinal adaptations in early onset deaf adults which are significantly correlated with peripheral vision sensitivity.

  3. The four-meter confrontation visual field test.

    OpenAIRE

    Kodsi, S R; Younge, B R

    1992-01-01

    The 4-m confrontation visual field test has been successfully used at the Mayo Clinic for many years in addition to the standard 0.5-m confrontation visual field test. The 4-m confrontation visual field test is a test of macular function and can identify small central or paracentral scotomas that the examiner may not find when the patient is tested only at 0.5 m. Also, macular sparing in homonymous hemianopias and quadrantanopias may be identified with the 4-m confrontation visual field test....

  4. Early auditory change detection implicitly facilitated by ignored concurrent visual change during a Braille reading task.

    Science.gov (United States)

    Aoyama, Atsushi; Haruyama, Tomohiro; Kuriki, Shinya

    2013-09-01

    Unconscious monitoring of multimodal stimulus changes enables humans to effectively sense the external environment. Such automatic change detection is thought to be reflected in auditory and visual mismatch negativity (MMN) and mismatch negativity fields (MMFs). These are event-related potentials and magnetic fields, respectively, evoked by deviant stimuli within a sequence of standard stimuli, and both are typically studied during irrelevant visual tasks that cause the stimuli to be ignored. Due to the sensitivity of MMN/MMF to potential effects of explicit attention to vision, however, it is unclear whether multisensory co-occurring changes can purely facilitate early sensory change detection reciprocally across modalities. We adopted a tactile task involving the reading of Braille patterns as a neutral ignore condition, while measuring magnetoencephalographic responses to concurrent audiovisual stimuli that were infrequently deviated either in auditory, visual, or audiovisual dimensions; 1000-Hz standard tones were switched to 1050-Hz deviant tones and/or two-by-two standard check patterns displayed on both sides of visual fields were switched to deviant reversed patterns. The check patterns were set to be faint enough so that the reversals could be easily ignored even during Braille reading. While visual MMFs were virtually undetectable even for visual and audiovisual deviants, significant auditory MMFs were observed for auditory and audiovisual deviants, originating from bilateral supratemporal auditory areas. Notably, auditory MMFs were significantly enhanced for audiovisual deviants from about 100 ms post-stimulus, as compared with the summation responses for auditory and visual deviants or for each of the unisensory deviants recorded in separate sessions. Evidenced by high tactile task performance with unawareness of visual changes, we conclude that Braille reading can successfully suppress explicit attention and that simultaneous multisensory changes can

  5. 21 CFR 886.1360 - Visual field laser instrument.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Visual field laser instrument. 886.1360 Section 886.1360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1360 Visual field laser instrument...

  6. Cortico-Cortical Receptive Field Estimates in Human Visual Cortex

    Directory of Open Access Journals (Sweden)

    Koen V Haak

    2012-05-01

    Full Text Available Human visual cortex comprises many visual areas that contain a map of the visual field (Wandell et al 2007, Neuron 56, 366–383. These visual field maps can be identified readily in individual subjects with functional magnetic resonance imaging (fMRI during experimental sessions that last less than an hour (Wandell and Winawer 2011, Vis Res 718–737. Hence, visual field mapping with fMRI has been, and still is, a heavily used technique to examine the organisation of both normal and abnormal human visual cortex (Haak et al 2011, ACNR, 11(3, 20–21. However, visual field mapping cannot reveal every aspect of human visual cortex organisation. For example, the information processed within a visual field map arrives from somewhere and is sent to somewhere, and visual field mapping does not derive these input/output relationships. Here, we describe a new, model-based analysis for estimating the dependence between signals in distinct cortical regions using functional magnetic resonance imaging (fMRI data. Just as a stimulus-referred receptive field predicts the neural response as a function of the stimulus contrast, the neural-referred receptive field predicts the neural response as a function of responses elsewhere in the nervous system. When applied to two cortical regions, this function can be called the cortico-cortical receptive field (CCRF. We model the CCRF as a Gaussian-weighted region on the cortical surface and apply the model to data from both stimulus-driven and resting-state experimental conditions in visual cortex.

  7. Lateralized occipital degeneration in posterior cortical atrophy predicts visual field deficits.

    Science.gov (United States)

    Millington, Rebecca S; James-Galton, Merle; Maia Da Silva, Mari N; Plant, Gordon T; Bridge, Holly

    2017-01-01

    Posterior cortical atrophy (PCA), the visual variant of Alzheimer's disease, leads to high-level visual deficits such as alexia or agnosia. Visual field deficits have also been identified, but often inconsistently reported. Little is known about the pattern of visual field deficits or the underlying cortical changes leading to this visual loss. Multi-modal magnetic resonance imaging was used to investigate differences in gray matter volume, cortical thickness, white matter microstructure and functional activity in patients with PCA compared to age-matched controls. Additional analyses investigated hemispheric asymmetries in these metrics according to the visual field most affected by the disease. Analysis of structural data indicated considerable loss of gray matter in the occipital and parietal cortices, lateralized to the hemisphere contralateral to the visual loss. This lateralized pattern of gray matter loss was also evident in the hippocampus and parahippocampal gyrus. Diffusion-weighted imaging showed considerable effects of PCA on white matter microstructure in the occipital cortex, and in the corpus callosum. The change in white matter was only lateralized in the occipital lobe, however, with greatest change in the optic radiation contralateral to the visual field deficit. Indeed, there was a significant correlation between the laterality of the optic radiation microstructure and visual field loss. Detailed brain imaging shows that the asymmetric visual field deficits in patients with PCA reflect the pattern of degeneration of both white and gray matter in the occipital lobe. Understanding the nature of both visual field deficits and the neurodegenerative brain changes in PCA may improve diagnosis and understanding of this disease.

  8. Auditory-visual integration in fields of the auditory cortex.

    Science.gov (United States)

    Kubota, Michinori; Sugimoto, Shunji; Hosokawa, Yutaka; Ojima, Hisayuki; Horikawa, Junsei

    2017-03-01

    While multimodal interactions have been known to exist in the early sensory cortices, the response properties and spatiotemporal organization of these interactions are poorly understood. To elucidate the characteristics of multimodal sensory interactions in the cerebral cortex, neuronal responses to visual stimuli with or without auditory stimuli were investigated in core and belt fields of guinea pig auditory cortex using real-time optical imaging with a voltage-sensitive dye. On average, visual responses consisted of short excitation followed by long inhibition. Although visual responses were observed in core and belt fields, there were regional and temporal differences in responses. The most salient visual responses were observed in the caudal belt fields, especially posterior (P) and dorsocaudal belt (DCB) fields. Visual responses emerged first in fields P and DCB and then spread rostroventrally to core and ventrocaudal belt (VCB) fields. Absolute values of positive and negative peak amplitudes of visual responses were both larger in fields P and DCB than in core and VCB fields. When combined visual and auditory stimuli were applied, fields P and DCB were more inhibited than core and VCB fields beginning approximately 110 ms after stimuli. Correspondingly, differences between responses to auditory stimuli alone and combined audiovisual stimuli became larger in fields P and DCB than in core and VCB fields after approximately 110 ms after stimuli. These data indicate that visual influences are most salient in fields P and DCB, which manifest mainly as inhibition, and that they enhance differences in auditory responses among fields. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Enhancement and Suppression in the Visual Field under Perceptual Load

    Directory of Open Access Journals (Sweden)

    Nathan A Parks

    2013-05-01

    Full Text Available The perceptual load theory of attention proposes that the degree to which visual distractors are processed is a function of the attentional demands of a task – greater demands increase filtering of irrelevant distractors. The spatial configuration of such filtering is unknown. Here, we used steady-state visual evoked potentials (SSVEPs in conjunction with time-domain event-related potentials (ERPs to investigate the distribution of load-induced distractor suppression and task-relevant enhancement in the visual field. Electroencephalogram (EEG was recorded while subjects performed a foveal go/no-go task that varied in perceptual load. Load-dependent distractor suppression was assessed by presenting a contrast reversing ring at one of three eccentricities (2°, 6°, or 11° during performance of the go/no-go task. Rings contrast reversed at 8.3 Hz, allowing load-dependent changes in distractor processing to be tracked in the frequency-domain. ERPs were calculated to the onset of stimuli in the load task to examine load-dependent modulation of task-relevant processing. Results showed that the amplitude of the distractor SSVEP (8.3Hz was attenuated under high perceptual load (relative to low load at the most proximal (2° eccentricity but not at more eccentric locations (6˚ or 11˚. Task-relevant ERPs revealed a significant increase in N1 amplitude under high load. These results are consistent with a center-surround configuration of load-induced enhancement and suppression in the visual field.

  10. The Tölz Temporal Topography Study: mapping the visual field across the life span. Part II: cognitive factors shaping visual field maps.

    Science.gov (United States)

    Poggel, Dorothe A; Treutwein, Bernhard; Calmanti, Claudia; Strasburger, Hans

    2012-08-01

    Part I described the topography of visual performance over the life span. Performance decline was explained only partly by deterioration of the optical apparatus. Part II therefore examines the influence of higher visual and cognitive functions. Visual field maps for 95 healthy observers of static perimetry, double-pulse resolution (DPR), reaction times, and contrast thresholds, were correlated with measures of visual attention (alertness, divided attention, spatial cueing), visual search, and the size of the attention focus. Correlations with the attentional variables were substantial, particularly for variables of temporal processing. DPR thresholds depended on the size of the attention focus. The extraction of cognitive variables from the correlations between topographical variables and participant age substantially reduced those correlations. There is a systematic top-down influence on the aging of visual functions, particularly of temporal variables, that largely explains performance decline and the change of the topography over the life span.

  11. Preoperative visual field deficits in temporal lobe epilepsy

    Directory of Open Access Journals (Sweden)

    Sanjeet S. Grewal

    2017-01-01

    Full Text Available Surgical resection and laser thermoablation have been used to treat drug resistant epilepsy with good results. However, they are not without risk. One of the most commonly reported complications of temporal lobe surgery is contralateral superior homonymous quadrantanopsia. We describe a patient with asymptomatic preoperative quadrantanopsia fortuitously discovered as part of our recently modified protocol to evaluate patients prior to temporal lobe epilepsy surgery. This visual field deficit was subtle and not detected on routine clinical neurological examination. While we understand that this is a single case, we advocate further study for more detailed preoperative visual field examinations to characterize the true incidence of postoperative visual field lesions.

  12. Large Field Visualization with Demand-Driven Calculation

    Science.gov (United States)

    Moran, Patrick J.; Henze, Chris

    1999-01-01

    We present a system designed for the interactive definition and visualization of fields derived from large data sets: the Demand-Driven Visualizer (DDV). The system allows the user to write arbitrary expressions to define new fields, and then apply a variety of visualization techniques to the result. Expressions can include differential operators and numerous other built-in functions, ail of which are evaluated at specific field locations completely on demand. The payoff of following a demand-driven design philosophy throughout becomes particularly evident when working with large time-series data, where the costs of eager evaluation alternatives can be prohibitive.

  13. Visual field impairment captures disease burden in multiple sclerosis.

    Science.gov (United States)

    Ortiz-Perez, Santiago; Andorra, Magí; Sanchez-Dalmau, Bernardo; Torres-Torres, Rubén; Calbet, David; Lampert, Erika J; Alba-Arbalat, Salut; Guerrero-Zamora, Ana M; Zubizarreta, Irati; Sola-Valls, Nuria; Llufriu, Sara; Sepúlveda, María; Saiz, Albert; Villoslada, Pablo; Martinez-Lapiscina, Elena H

    2016-04-01

    Monitoring disease burden is an unmeet need in multiple sclerosis (MS). Identifying patients at high risk of disability progression will be useful for improving clinical-therapeutic decisions in clinical routine. To evaluate the role of visual field testing in non-optic neuritis eyes (non-ON eyes) as a biomarker of disability progression in MS. In 109 patients of the MS-VisualPath cohort, we evaluated the association between visual field abnormalities and global and cognitive disability markers and brain and retinal imaging markers of neuroaxonal injury using linear regression models adjusted for sex, age, disease duration and use of disease-modifying therapies. We evaluated the risk of disability progression associated to have baseline impaired visual field after 3 years of follow-up. Sixty-two percent of patients showed visual field defects in non-ON eyes. Visual field mean deviation was statistically associated with global disability; brain (normalized brain parenchymal, gray matter volume and lesion load) and retinal (peripapillary retinal nerve fiber layer thickness and macular ganglion cell complex thickness) markers of neuroaxonal damage. Patients with impaired visual field had statistically significative greater disability, lower normalized brain parenchymal volume and higher lesion volume than patients with normal visual field testing. MS patients with baseline impaired VF tripled the risk of disability progression during follow-up [OR = 3.35; 95 % CI (1.10-10.19); p = 0.033]. The association of visual field impairment with greater disability and neuroaxonal injury and higher risk of disability progression suggest that VF could be used to monitor MS disease burden.

  14. Visual verification of linac light and radiation fields coincidence

    International Nuclear Information System (INIS)

    Monti, Angelo F.; Frigerio, Milena; Frigerio, Giovanna

    2003-01-01

    X-ray and light field alignment evaluation is carried out during linac quality assurance programs. In this paper, we compare the size of the light field measured by a photodiode and by a more traditional visual observation with the size of the x-ray field. The comparison between actual light field size, measured with the photodiode, and light field size measured by human eye allow us to verify the reliability of human eye in the evaluation of this parameter. The visual field is always larger than real light field; however, it agrees better with the x-ray field. It matches the light field if we take into account the 25% (± 1%) of the decrement line of the maximum central lightening; however, this method simulates better the actual field employed in radiation treatments

  15. A computerised screening for visual field defects in brain injury patients

    DEFF Research Database (Denmark)

    Nordfang, Maria; Uhre, Valdemar H.B.; Robotham, Ro Julia

    The c-VFT is a computer program written in open source Python using Psychopy and can be installed without a license. The program tests 48 points in the visual field, covering the visual field from 1 degree to 10 degrees in each hemifield. A colour change detection task controls fixation. Several...... parameters like the number of stimulus repetitions, the colour of stimuli and background, and the orientation of the layout can be individually set. The c-VFT probes all four quadrants and probes along the horizontal midline, making it particularly sensitive for visual field deficits that affect reading...

  16. Long Term Results of Visual Field Progression Analysis in Open Angle Glaucoma Patients Under Treatment.

    Science.gov (United States)

    Kocatürk, Tolga; Bekmez, Sinan; Katrancı, Merve; Çakmak, Harun; Dayanır, Volkan

    2015-01-01

    To evaluate visual field progression with trend and event analysis in open angle glaucoma patients under treatment. Fifteen year follow-up results of 408 eyes of 217 glaucoma patients who were followed at Adnan Menderes University, Department of Ophthalmology between 1998 and 2013 were analyzed retrospectively. Visual field data were collected for Mean Deviation (MD), Visual Field Index (VFI), and event occurrence. There were 146 primary open-angle glaucoma (POAG), 123 pseudoexfoliative glaucoma (XFG) and 139 normal tension glaucoma (NTG) eyes. MD showed significant change in all diagnostic groups (pfield indices. We herein report our fifteen year follow-up results in open angle glaucoma.

  17. Visual Field Measurement with Motion Sensitivity Screening Test in ...

    African Journals Online (AJOL)

    Eye disease is a frequent complication of onchocerciasis in countrise where the disease is highly endemic. It has been shown that early ocular lesions which manifest as visual field defects or reduction in visual acuity can be reversed following treatment with ivermectin. At the community level, it is important to detect ...

  18. Getting a grip on affordances, attention and visual fields

    OpenAIRE

    Linden, Lotje van der; Theeuwes, Jan; Ellis, Rob

    2013-01-01

    van der Linden, L., Theeuwes, J., & Ellis, R. (2012). Getting a grip on affordances, attention, and visual fields. Poster presented at the 2012 William James Graduate School Symposium, Amsterdam, The Netherlands.

  19. Visualization of Flow Field: Application of PLIF Technique

    Directory of Open Access Journals (Sweden)

    Jiang Bo Peng

    2018-01-01

    Full Text Available The objective of this paper is to apply planar laser-induced fluorescence (PLIF technology to flow field visualization. This experiment was carried out in a one-meter wind tunnel to study the wake flow field around a circular cylinder. This experiment studied the method of injecting tracer into the flow field; the frequency of the vortex in the wake field and the vortex speed are quantitatively analyzed. This paper gives the correspondence between the speed of the flow field and the frequency of the laser, which could be used as a rough reference standard for future wind tunnel visualization experiments. The result shows that PLIF diagnostic technology has great potential in visualization of flow field.

  20. Sunglasses with thick temples and frame constrict temporal visual field.

    Science.gov (United States)

    Denion, Eric; Dugué, Audrey Emmanuelle; Augy, Sylvain; Coffin-Pichonnet, Sophie; Mouriaux, Frédéric

    2013-12-01

    Our aim was to compare the impact of two types of sunglasses on visual field and glare: one ("thick sunglasses") with a thick plastic frame and wide temples and one ("thin sunglasses") with a thin metal frame and thin temples. Using the Goldmann perimeter, visual field surface areas (cm²) were calculated as projections on a 30-cm virtual cupola. A V4 test object was used, from seen to unseen, in 15 healthy volunteers in the primary position of gaze ("base visual field"), then allowing eye motion ("eye motion visual field") without glasses, then with "thin sunglasses," followed by "thick sunglasses." Visual field surface area differences greater than the 14% reproducibility error of the method and having a p thick sunglasses." This decrease was most severe in the temporal quadrant (-33%; p thick sunglasses" than with the "thin sunglasses" (p thick sunglasses" is offset by the much poorer ability to use lateral space exploration; this results in a loss of most, if not all, of the additional visual field gained through eye motion.

  1. Visual field shape and foraging ecology in diurnal raptors.

    Science.gov (United States)

    Potier, Simon; Duriez, Olivier; Cunningham, Gregory B; Bonhomme, Vincent; O'Rourke, Colleen; Fernández-Juricic, Esteban; Bonadonna, Francesco

    2018-05-18

    Birds, particularly raptors, are believed to forage primarily using visual cues. However, raptor foraging tactics are highly diverse - from chasing mobile prey to scavenging - which may reflect adaptations of their visual systems. To investigate this, we studied the visual field configuration of 15 species of diurnal Accipitriformes that differ in such tactics, first focusing on the binocular field and blind area by using a single traits approach, and then exploring the shape of the binocular field with morphometric approaches. While the maximum binocular field width did not differ in species of different foraging tactics, the overall shape of their binocular fields did. In particular, raptors chasing terrestrial prey (ground predators) had a more protruding binocular field and a wider blind area above the head than did raptors chasing aerial or aquatic prey and obligate scavengers. Ground predators that forage on mammals from above have a wide but short bill - which increases ingestion rate - and large suborbital ridge to avoid sun glare. This may explain the protruding binocular field and the wide blind area above the head. By contrast, species from the two other groups have long but narrow bills used to pluck, flake or tear food and may need large visual coverage (and reduced suborbital ridges) to increase their foraging efficiency ( e.g. using large visual coverage to follow the escaping prey in three dimensions or detect conspecifics). We propose that binocular field shape is associated with bill and suborbital ridge shape and, ultimately, foraging strategies. © 2018. Published by The Company of Biologists Ltd.

  2. Visual Sample Plan (VSP) - FIELDS Integration

    Energy Technology Data Exchange (ETDEWEB)

    Pulsipher, Brent A.; Wilson, John E.; Gilbert, Richard O.; Hassig, Nancy L.; Carlson, Deborah K.; Bing-Canar, John; Cooper, Brian; Roth, Chuck

    2003-04-19

    Two software packages, VSP 2.1 and FIELDS 3.5, are being used by environmental scientists to plan the number and type of samples required to meet project objectives, display those samples on maps, query a database of past sample results, produce spatial models of the data, and analyze the data in order to arrive at defensible decisions. VSP 2.0 is an interactive tool to calculate optimal sample size and optimal sample location based on user goals, risk tolerance, and variability in the environment and in lab methods. FIELDS 3.0 is a set of tools to explore the sample results in a variety of ways to make defensible decisions with quantified levels of risk and uncertainty. However, FIELDS 3.0 has a small sample design module. VSP 2.0, on the other hand, has over 20 sampling goals, allowing the user to input site-specific assumptions such as non-normality of sample results, separate variability between field and laboratory measurements, make two-sample comparisons, perform confidence interval estimation, use sequential search sampling methods, and much more. Over 1,000 copies of VSP are in use today. FIELDS is used in nine of the ten U.S. EPA regions, by state regulatory agencies, and most recently by several international countries. Both software packages have been peer-reviewed, enjoy broad usage, and have been accepted by regulatory agencies as well as site project managers as key tools to help collect data and make environmental cleanup decisions. Recently, the two software packages were integrated, allowing the user to take advantage of the many design options of VSP, and the analysis and modeling options of FIELDS. The transition between the two is simple for the user – VSP can be called from within FIELDS, automatically passing a map to VSP and automatically retrieving sample locations and design information when the user returns to FIELDS. This paper will describe the integration, give a demonstration of the integrated package, and give users download

  3. Effect of Cognitive Demand on Functional Visual Field Performance in Senior Drivers with Glaucoma

    Directory of Open Access Journals (Sweden)

    Viswa Gangeddula

    2017-08-01

    Full Text Available Purpose: To investigate the effect of cognitive demand on functional visual field performance in drivers with glaucoma.Method: This study included 20 drivers with open-angle glaucoma and 13 age- and sex-matched controls. Visual field performance was evaluated under different degrees of cognitive demand: a static visual field condition (C1, dynamic visual field condition (C2, and dynamic visual field condition with active driving (C3 using an interactive, desktop driving simulator. The number of correct responses (accuracy and response times on the visual field task were compared between groups and between conditions using Kruskal–Wallis tests. General linear models were employed to compare cognitive workload, recorded in real-time through pupillometry, between groups and conditions.Results: Adding cognitive demand (C2 and C3 to the static visual field test (C1 adversely affected accuracy and response times, in both groups (p < 0.05. However, drivers with glaucoma performed worse than did control drivers when the static condition changed to a dynamic condition [C2 vs. C1 accuracy; glaucoma: median difference (Q1–Q3 3 (2–6.50 vs. controls: 2 (0.50–2.50; p = 0.05] and to a dynamic condition with active driving [C3 vs. C1 accuracy; glaucoma: 2 (2–6 vs. controls: 1 (0.50–2; p = 0.02]. Overall, drivers with glaucoma exhibited greater cognitive workload than controls (p = 0.02.Conclusion: Cognitive demand disproportionately affects functional visual field performance in drivers with glaucoma. Our results may inform the development of a performance-based visual field test for drivers with glaucoma.

  4. Mass conservative fluid flow visualization for CFD velocity fields

    International Nuclear Information System (INIS)

    Li, Zhenquan; Mallinson, Gordon D.

    2001-01-01

    Mass conservation is a key issue for accurate streamline and stream surface visualization of flow fields. This paper complements an existing method (Feng et al., 1997) for CFD velocity fields defined at discrete locations in space that uses dual stream functions to generate streamlines and stream surfaces. Conditions for using the method have been examined and its limitations defined. A complete set of dual stream functions for all possible cases of the linear fields on which the method relies are presented. The results in this paper are important for developing new methods for mass conservative streamline visualization from CFD data and using the existing method

  5. Behavior of visual field index in advanced glaucoma.

    Science.gov (United States)

    Rao, Harsha L; Senthil, Sirisha; Choudhari, Nikhil S; Mandal, Anil K; Garudadri, Chandra S

    2013-01-14

    To evaluate the magnitude of Visual Field Index (VFI) change attributable to change in the estimation algorithm from the pattern deviation probability plot (PDPP) to the total deviation probability plot (TDPP) when the mean deviation (MD) crosses -20 decibels (dB). In a retrospective study, 37 stable glaucoma eyes in which MD of the VFs crossed -20 dB were identified. For each eye, a pair of VFs was selected so that one VF of the pair had a MD better than but close to -20 dB and the other had a MD worse than but again close to -20 dB. The change in VFI in the VF pairs and its associations with the number of points in probability plots with normal threshold sensitivities were evaluated. Similar pairs of VFs from 28 stable glaucoma eyes where the MD crossed -10 dB were chosen as controls. The change in VFI in VF pairs when the MD crossed 20 dB ranged from 3% to 33% (median: 15%), while the change when MD crossed -10 dB ranged from 1% to 8% (median: 4%). Difference in the number of points with normal threshold sensitivities in PDPP when MD was better than -20 dB compared to those in TDPP when MD crossed -20 dB significantly influenced the VFI change (R(2) = 0.65). Considering the eccentricity of these points further explained the VFI change (R(2) = 0.81). The decrease in VFI when MD crosses -20 dB can be highly variable. This has to be considered with the use of VFI in clinical and research settings.

  6. Lateralized visual behavior in bottlenose dolphins (Tursiops truncatus) performing audio-visual tasks: the right visual field advantage.

    Science.gov (United States)

    Delfour, F; Marten, K

    2006-01-10

    Analyzing cerebral asymmetries in various species helps in understanding brain organization. The left and right sides of the brain (lateralization) are involved in different cognitive and sensory functions. This study focuses on dolphin visual lateralization as expressed by spontaneous eye preference when performing a complex cognitive task; we examine lateralization when processing different visual stimuli displayed on an underwater touch-screen (two-dimensional figures, three-dimensional figures and dolphin/human video sequences). Three female bottlenose dolphins (Tursiops truncatus) were submitted to a 2-, 3- or 4-, choice visual/auditory discrimination problem, without any food reward: the subjects had to correctly match visual and acoustic stimuli together. In order to visualize and to touch the underwater target, the dolphins had to come close to the touch-screen and to position themselves using monocular vision (left or right eye) and/or binocular naso-ventral vision. The results showed an ability to associate simple visual forms and auditory information using an underwater touch-screen. Moreover, the subjects showed a spontaneous tendency to use monocular vision. Contrary to previous findings, our results did not clearly demonstrate right eye preference in spontaneous choice. However, the individuals' scores of correct answers were correlated with right eye vision, demonstrating the advantage of this visual field in visual information processing and suggesting a left hemispheric dominance. We also demonstrated that the nature of the presented visual stimulus does not seem to have any influence on the animals' monocular vision choice.

  7. Sensitivity to the visual field origin of natural image patches in human low-level visual cortex

    Directory of Open Access Journals (Sweden)

    Damien J. Mannion

    2015-06-01

    Full Text Available Asymmetries in the response to visual patterns in the upper and lower visual fields (above and below the centre of gaze have been associated with ecological factors relating to the structure of typical visual environments. Here, we investigated whether the content of the upper and lower visual field representations in low-level regions of human visual cortex are specialised for visual patterns that arise from the upper and lower visual fields in natural images. We presented image patches, drawn from above or below the centre of gaze of an observer navigating a natural environment, to either the upper or lower visual fields of human participants (n = 7 while we used functional magnetic resonance imaging (fMRI to measure the magnitude of evoked activity in the visual areas V1, V2, and V3. We found a significant interaction between the presentation location (upper or lower visual field and the image patch source location (above or below fixation; the responses to lower visual field presentation were significantly greater for image patches sourced from below than above fixation, while the responses in the upper visual field were not significantly different for image patches sourced from above and below fixation. This finding demonstrates an association between the representation of the lower visual field in human visual cortex and the structure of the visual input that is likely to be encountered below the centre of gaze.

  8. Timing, timing, timing: Fast decoding of object information from intracranial field potentials in human visual cortex

    Science.gov (United States)

    Liu, Hesheng; Agam, Yigal; Madsen, Joseph R.; Kreiman, Gabriel

    2010-01-01

    Summary The difficulty of visual recognition stems from the need to achieve high selectivity while maintaining robustness to object transformations within hundreds of milliseconds. Theories of visual recognition differ in whether the neuronal circuits invoke recurrent feedback connections or not. The timing of neurophysiological responses in visual cortex plays a key role in distinguishing between bottom-up and top-down theories. Here we quantified at millisecond resolution the amount of visual information conveyed by intracranial field potentials from 912 electrodes in 11 human subjects. We could decode object category information from human visual cortex in single trials as early as 100 ms post-stimulus. Decoding performance was robust to depth rotation and scale changes. The results suggest that physiological activity in the temporal lobe can account for key properties of visual recognition. The fast decoding in single trials is compatible with feed-forward theories and provides strong constraints for computational models of human vision. PMID:19409272

  9. Glyph-Based Comparative Visualization for Diffusion Tensor Fields.

    Science.gov (United States)

    Zhang, Changgong; Schultz, Thomas; Lawonn, Kai; Eisemann, Elmar; Vilanova, Anna

    2016-01-01

    Diffusion Tensor Imaging (DTI) is a magnetic resonance imaging modality that enables the in-vivo reconstruction and visualization of fibrous structures. To inspect the local and individual diffusion tensors, glyph-based visualizations are commonly used since they are able to effectively convey full aspects of the diffusion tensor. For several applications it is necessary to compare tensor fields, e.g., to study the effects of acquisition parameters, or to investigate the influence of pathologies on white matter structures. This comparison is commonly done by extracting scalar information out of the tensor fields and then comparing these scalar fields, which leads to a loss of information. If the glyph representation is kept, simple juxtaposition or superposition can be used. However, neither facilitates the identification and interpretation of the differences between the tensor fields. Inspired by the checkerboard style visualization and the superquadric tensor glyph, we design a new glyph to locally visualize differences between two diffusion tensors by combining juxtaposition and explicit encoding. Because tensor scale, anisotropy type, and orientation are related to anatomical information relevant for DTI applications, we focus on visualizing tensor differences in these three aspects. As demonstrated in a user study, our new glyph design allows users to efficiently and effectively identify the tensor differences. We also apply our new glyphs to investigate the differences between DTI datasets of the human brain in two different contexts using different b-values, and to compare datasets from a healthy and HIV-infected subject.

  10. Visual field defects after temporal lobe resection for epilepsy.

    Science.gov (United States)

    Steensberg, Alvilda T; Olsen, Ane Sophie; Litman, Minna; Jespersen, Bo; Kolko, Miriam; Pinborg, Lars H

    2018-01-01

    To determine visual field defects (VFDs) using methods of varying complexity and compare results with subjective symptoms in a population of newly operated temporal lobe epilepsy patients. Forty patients were included in the study. Two patients failed to perform VFD testing. Humphrey Field Analyzer (HFA) perimetry was used as the gold standard test to detect VFDs. All patients performed a web-based visual field test called Damato Multifixation Campimetry Online (DMCO). A bedside confrontation visual field examination ad modum Donders was extracted from the medical records in 27/38 patients. All participants had a consultation by an ophthalmologist. A questionnaire described the subjective complaints. A VFD in the upper quadrant was demonstrated with HFA in 29 (76%) of the 38 patients after surgery. In 27 patients tested ad modum Donders, the sensitivity of detecting a VFD was 13%. Eight patients (21%) had a severe VFD similar to a quadrant anopia, thus, questioning their permission to drive a car. In this group of patients, a VFD was demonstrated in one of five (sensitivity=20%) ad modum Donders and in seven of eight (sensitivity=88%) with DMCO. Subjective symptoms were only reported by 28% of the patients with a VFD and in two of eight (sensitivity=25%) with a severe VFD. Most patients (86%) considered VFD information mandatory. VFD continue to be a frequent adverse event after epilepsy surgery in the medial temporal lobe and may affect the permission to drive a car in at least one in five patients. Subjective symptoms and bedside visual field testing ad modum Donders are not sensitive to detect even a severe VFD. Newly developed web-based visual field test methods appear sensitive to detect a severe VFD but perimetry remains the golden standard for determining if visual standards for driving is fulfilled. Patients consider VFD information as mandatory. Copyright © 2017. Published by Elsevier Ltd.

  11. Prevention of visual field defects after macular hole surgery.

    LENUS (Irish Health Repository)

    Cullinane, A B

    2012-02-03

    BACKGROUND\\/AIM: The pathogenesis of visual field loss associated with macular hole surgery is uncertain but a number of explanations have been proposed, the most convincing of which is the effect of peeling of the posterior hyaloid, causing either direct damage to the nerve fibre layer or to its blood supply at the optic nerve head. The purpose of this preliminary prospective study was to determine the incidence of visual field defects following macular hole surgery in cases in which peeling of the posterior hyaloid was confined only to the area of the macula. METHODS: 102 consecutive eyes that had macular hole surgery had preoperative and postoperative visual field examination using a Humphrey\\'s perimeter. A comparison was made between two groups: I, those treated with vitrectomy with complete posterior cortical vitreous peeling; and II, those treated with a vitrectomy with peeling of the posterior hyaloid in the area of the macula but without attempting a complete posterior vitreous detachment. Specifically, no attempt was made to separate the posterior hyaloid from the optic nerve head. Eyes with stage II or III macular holes were operated. Autologous platelet concentrate and non-expansile gas tamponade was used. Patients were postured prone for 1 week. RESULTS: In group I, 22% of patients were found to have visual field defects. In group II, it was possible to separate the posterior hyaloid from the macula without stripping it from the optic nerve head and in these eyes no pattern of postoperative visual field loss emerged. There were no significant vision threatening complications in this group. The difference in the incidence of visual field loss between group I and group II was significant (p=0.02). The anatomical and visual success rates were comparable between both groups. CONCLUSION: The results from this preliminary study suggest that the complication of visual field loss after macular surgery may be reduced if peeling of the posterior hyaloid is

  12. The advanced glaucoma intervention study, 6: effect of cataract on visual field and visual acuity. The AGIS Investigators.

    Science.gov (United States)

    2000-12-01

    To investigate the effect of cataract on visual function and the role of cataract in explaining a race-treatment interaction in outcomes of glaucoma surgery. The Advanced Glaucoma Intervention Study (AGIS) enrolled 332 black patients (451 eyes) and 249 white patients (325 eyes) with advanced glaucoma. Eyes were randomly assigned to an argon laser trabeculoplasty (ALT)-trabeculectomy-trabeculectomy sequence or a trabeculectomy-ALT-trabeculectomy sequence. From the AGIS experience with cataract surgery during follow-up, we estimated the expected change in visual function scores from before cataract surgery to after cataract surgery. Then, for eyes with cataract not removed, we used these estimates of expected change to adjust visual function scores for the presumed effects of cataract. In turn, we used the adjusted scores to obtain cataract-adjusted main outcome measures. Average percent of eyes with decrease of visual field (APDVF) and average percent of eyes with decrease of visual acuity (APDVA). Within the 2 months before cataract surgery, visual acuity was better in eyes of white patients than of black patients by an average of approximately 2 lines on the visual acuity test chart. Cataract surgery improved visual acuity and visual field defect scores, with the amounts of improvement greater when preoperative visual acuity was lower. Adjustments for cataract brought about the following relative reductions: for APDVF, a relative reduction of 5% to 11% in black patients and 9% to 11% in white patients; for APDVA, a relative reduction of 45% to 49% in black patients and 31% to 38% in white patients; and for the APDVF and APDVA race-treatment interactions, relative reductions of 25% and 45%, respectively. On average, visual function scores improved after cataract surgery. The findings of reduced race-treatment interactions after adjustment for cataract do not alter our earlier conclusion that the AGIS 7-year results support use of the ALT

  13. Wide-field fundus autofluorescence corresponds to visual fields in chorioretinitis patients

    Directory of Open Access Journals (Sweden)

    Seidensticker F

    2011-11-01

    Full Text Available Florian Seidensticker1, Aljoscha S Neubauer1, Tamer Wasfy1,2, Carmen Stumpf1, Stephan R Thurau1,*, Anselm Kampik1, Marcus Kernt1,*1Department of Ophthalmology, Ludwig-Maximilians-University, Munich, Germany; 2Department of Ophthalmology, Tanta University, Tanta, Egypt *Both authors contributed equally to this workBackground and objectives: Detection of peripheral fundus autofluorescence (FAF using conventional scanning laser ophthalmoscopes (SLOs is difficult and requires pupil dilation. Here we evaluated the diagnostic properties of wide-field FAF detected by a two-laser wavelength wide-field SLO in uveitis patients.Study design/materials and methods: Observational case series of four patients suffering from different types of posterior uveitis/chorioretinitis. Wide-field FAF images were compared to visual fields. Panretinal FAF was detected by a newly developed SLO, which allows FAF imaging of up to 200° of the retina in one scan without the need for pupil dilation. Visual fields were obtained by Goldmann manual perimetry.Results: Findings from wide-field FAF imaging showed correspondence to visual field defects in all cases.Conclusion: Wide-field FAF allowed the detection of visual field defect-related alterations of the retinal pigment epithelium in all four uveitis cases.Keywords: fundus autofluorescence (FAF, Optomap, wide-field scanning laser ophthalmoscopy, imaging, uveitis, visual field

  14. Multiresolution and Explicit Methods for Vector Field Analysis and Visualization

    Science.gov (United States)

    Nielson, Gregory M.

    1997-01-01

    This is a request for a second renewal (3d year of funding) of a research project on the topic of multiresolution and explicit methods for vector field analysis and visualization. In this report, we describe the progress made on this research project during the second year and give a statement of the planned research for the third year. There are two aspects to this research project. The first is concerned with the development of techniques for computing tangent curves for use in visualizing flow fields. The second aspect of the research project is concerned with the development of multiresolution methods for curvilinear grids and their use as tools for visualization, analysis and archiving of flow data. We report on our work on the development of numerical methods for tangent curve computation first.

  15. The risk of pedestrian collisions with peripheral visual field loss

    OpenAIRE

    Peli, Eli; Apfelbaum, Henry; Berson, Eliot L.; Goldstein, Robert B.

    2016-01-01

    Patients with peripheral field loss complain of colliding with other pedestrians in open-space environments such as shopping malls. Field expansion devices (e.g., prisms) can create artificial peripheral islands of vision. We investigated the visual angle at which these islands can be most effective for avoiding pedestrian collisions, by modeling the collision risk density as a function of bearing angle of pedestrians relative to the patient. Pedestrians at all possible locations were assumed...

  16. Visual field examination in children with brain disorders

    NARCIS (Netherlands)

    Koenraads, Y

    2016-01-01

    The aim of this thesis is to gain more insight in the diagnostic and prognostic implications of visual field (VF) examination in children with brain disorders. Several aspects of VF examination in children with brain disorders were evaluated: All VF examinations that were performed with the

  17. RelEx: Visualization for Actively Changing Overlay Network Specifications.

    Science.gov (United States)

    Sedlmair, M; Frank, A; Munzner, T; Butz, A

    2012-12-01

    We present a network visualization design study focused on supporting automotive engineers who need to specify and optimize traffic patterns for in-car communication networks. The task and data abstractions that we derived support actively making changes to an overlay network, where logical communication specifications must be mapped to an underlying physical network. These abstractions are very different from the dominant use case in visual network analysis, namely identifying clusters and central nodes, that stems from the domain of social network analysis. Our visualization tool RelEx was created and iteratively refined through a full user-centered design process that included a full problem characterization phase before tool design began, paper prototyping, iterative refinement in close collaboration with expert users for formative evaluation, deployment in the field with real analysts using their own data, usability testing with non-expert users, and summative evaluation at the end of the deployment. In the summative post-deployment study, which entailed domain experts using the tool over several weeks in their daily practice, we documented many examples where the use of RelEx simplified or sped up their work compared to previous practices.

  18. Visual teaching and learning in the fields of engineering

    Directory of Open Access Journals (Sweden)

    Kyvete S. Shatri

    2015-11-01

    Full Text Available Engineering education today is faced with numerous demands that are closely connected with a globalized economy. One of these requirements is to draw the engineers of the future, who are characterized with: strong analytical skills, creativity, ingenuity, professionalism, intercultural communication and leadership. To achieve this effective teaching methods should be used to facilitate and enhance the learning of students and their performance in general, making them able to cope with market demands of a globalized economy. One of these methods is the visualization as a very important method that increases the learning of students. A visual approach in science and in engineering also increases communication, critical thinking and provides analytical approach to various problems. Therefore, this research is aimed to investigate the effect of the use of visualization in the process of teaching and learning in engineering fields and encourage teachers and students to use visual methods for teaching and learning. The results of this research highlight the positive effect that the use of visualization has in the learning process of students and their overall performance. In addition, innovative teaching methods have a good effect in the improvement of the situation. Visualization motivates students to learn, making them more cooperative and developing their communication skills.

  19. Neural Circuit to Integrate Opposing Motions in the Visual Field.

    Science.gov (United States)

    Mauss, Alex S; Pankova, Katarina; Arenz, Alexander; Nern, Aljoscha; Rubin, Gerald M; Borst, Alexander

    2015-07-16

    When navigating in their environment, animals use visual motion cues as feedback signals that are elicited by their own motion. Such signals are provided by wide-field neurons sampling motion directions at multiple image points as the animal maneuvers. Each one of these neurons responds selectively to a specific optic flow-field representing the spatial distribution of motion vectors on the retina. Here, we describe the discovery of a group of local, inhibitory interneurons in the fruit fly Drosophila key for filtering these cues. Using anatomy, molecular characterization, activity manipulation, and physiological recordings, we demonstrate that these interneurons convey direction-selective inhibition to wide-field neurons with opposite preferred direction and provide evidence for how their connectivity enables the computation required for integrating opposing motions. Our results indicate that, rather than sharpening directional selectivity per se, these circuit elements reduce noise by eliminating non-specific responses to complex visual information. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. [New visual field testing possibilities (a preliminary report)].

    Science.gov (United States)

    Erichev, V P; Ermolaev, A P; Antonov, A A; Grigoryan, G L; Kosova, D V

    2018-01-01

    There are currently no portable mobile perimeters that allow visual field testing outside ophthalmologist's examination rooms. To develop a mobile perimetry technique based on use of a virtual reality headset (VR). The study involved 26 patients (30 eyes) with II-III stage primary open-angle glaucoma (POAG) with compensated IOP. Perimetry was performed for each patient twice - on Humphrey analyzer (test 30-2, 76 points) and employing similar strategy on a perimeter integrated into VR headset (Total Vision, Russia). Visual field testing was performed with an interval from 1 hour to 3 days. The results were comparatively analyzed. Patients tolerated the examination well. Comparative analysis of preliminary perimetry results obtained with both methods showed high degree of identity, so the results were concluded to be comparable. By visually isolating the wearer, VR headset achieves elimination of distractions and stable light conditions for visual field testing. The headset-perimeter is compact, mobile, easily transportable, can be used in the work of visiting medical teams and for examination at home.

  1. Decoding complex flow-field patterns in visual working memory.

    Science.gov (United States)

    Christophel, Thomas B; Haynes, John-Dylan

    2014-05-01

    There has been a long history of research on visual working memory. Whereas early studies have focused on the role of lateral prefrontal cortex in the storage of sensory information, this has been challenged by research in humans that has directly assessed the encoding of perceptual contents, pointing towards a role of visual and parietal regions during storage. In a previous study we used pattern classification to investigate the storage of complex visual color patterns across delay periods. This revealed coding of such contents in early visual and parietal brain regions. Here we aim to investigate whether the involvement of visual and parietal cortex is also observable for other types of complex, visuo-spatial pattern stimuli. Specifically, we used a combination of fMRI and multivariate classification to investigate the retention of complex flow-field stimuli defined by the spatial patterning of motion trajectories of random dots. Subjects were trained to memorize the precise spatial layout of these stimuli and to retain this information during an extended delay. We used a multivariate decoding approach to identify brain regions where spatial patterns of activity encoded the memorized stimuli. Content-specific memory signals were observable in motion sensitive visual area MT+ and in posterior parietal cortex that might encode spatial information in a modality independent manner. Interestingly, we also found information about the memorized visual stimulus in somatosensory cortex, suggesting a potential crossmodal contribution to memory. Our findings thus indicate that working memory storage of visual percepts might be distributed across unimodal, multimodal and even crossmodal brain regions. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Visualizing Vector Fields Using Line Integral Convolution and Dye Advection

    Science.gov (United States)

    Shen, Han-Wei; Johnson, Christopher R.; Ma, Kwan-Liu

    1996-01-01

    We present local and global techniques to visualize three-dimensional vector field data. Using the Line Integral Convolution (LIC) method to image the global vector field, our new algorithm allows the user to introduce colored 'dye' into the vector field to highlight local flow features. A fast algorithm is proposed that quickly recomputes the dyed LIC images. In addition, we introduce volume rendering methods that can map the LIC texture on any contour surface and/or translucent region defined by additional scalar quantities, and can follow the advection of colored dye throughout the volume.

  3. The effect of visual training for patients with visual field defects due to brain damage : a systematic review

    NARCIS (Netherlands)

    Bouwmeester, Lies; Heutink, Joost; Lucas, Cees

    The objective of this review was to evaluate whether systematic visual training leads to ( 1) a restitution of the visual field ( restoration), ( 2) an increase in the visual search field size or an improvement in scanning strategies (compensation) and ( 3) a transfer of training-related

  4. The effect of visual training for patients with visual field defects due to brain damage: a systematic review

    NARCIS (Netherlands)

    Bouwmeester, Lies; Heutink, Joost; Lucas, Cees

    2007-01-01

    The objective of this review was to evaluate whether systematic visual training leads to (1) a restitution of the visual field (restoration), (2) an increase in the visual search field size or an improvement in scanning strategies (compensation) and (3) a transfer of training-related improvements in

  5. Semantic Data And Visualization Techniques Applied To Geologic Field Mapping

    Science.gov (United States)

    Houser, P. I. Q.; Royo-Leon, M.; Munoz, R.; Estrada, E.; Villanueva-Rosales, N.; Pennington, D. D.

    2015-12-01

    Geologic field mapping involves the use of technology before, during, and after visiting a site. Geologists utilize hardware such as Global Positioning Systems (GPS) connected to mobile computing platforms such as tablets that include software such as ESRI's ArcPad and other software to produce maps and figures for a final analysis and report. Hand written field notes contain important information and drawings or sketches of specific areas within the field study. Our goal is to collect and geo-tag final and raw field data into a cyber-infrastructure environment with an ontology that allows for large data processing, visualization, sharing, and searching, aiding in connecting field research with prior research in the same area and/or aid with experiment replication. Online searches of a specific field area return results such as weather data from NOAA and QuakeML seismic data from USGS. These results that can then be saved to a field mobile device and searched while in the field where there is no Internet connection. To accomplish this we created the GeoField ontology service using the Web Ontology Language (OWL) and Protégé software. Advanced queries on the dataset can be made using reasoning capabilities can be supported that go beyond a standard database service. These improvements include the automated discovery of data relevant to a specific field site and visualization techniques aimed at enhancing analysis and collaboration while in the field by draping data over mobile views of the site using augmented reality. A case study is being performed at University of Texas at El Paso's Indio Mountains Research Station located near Van Horn, Texas, an active multi-disciplinary field study site. The user can interactively move the camera around the study site and view their data digitally. Geologist's can check their data against the site in real-time and improve collaboration with another person as both parties have the same interactive view of the data.

  6. Reducing Visual Discomfort with HMDs Using Dynamic Depth of Field.

    Science.gov (United States)

    Carnegie, Kieran; Rhee, Taehyun

    2015-01-01

    Although head-mounted displays (HMDs) are ideal devices for personal viewing of immersive stereoscopic content, exposure to VR applications on them results in significant discomfort for the majority of people, with symptoms including eye fatigue, headaches, nausea, and sweating. A conflict between accommodation and vergence depth cues on stereoscopic displays is a significant cause of visual discomfort. This article describes the results of an evaluation used to judge the effectiveness of dynamic depth-of-field (DoF) blur in an effort to reduce discomfort caused by exposure to stereoscopic content on HMDs. Using a commercial game engine implementation, study participants report a reduction of visual discomfort on a simulator sickness questionnaire when DoF blurring is enabled. The study participants reported a decrease in symptom severity caused by HMD exposure, indicating that dynamic DoF can effectively reduce visual discomfort.

  7. Connectivity changes underlying neurofeedback training of visual cortex activity.

    Directory of Open Access Journals (Sweden)

    Frank Scharnowski

    Full Text Available Neurofeedback based on real-time functional magnetic resonance imaging (fMRI is a new approach that allows training of voluntary control over regionally specific brain activity. However, the neural basis of successful neurofeedback learning remains poorly understood. Here, we assessed changes in effective brain connectivity associated with neurofeedback training of visual cortex activity. Using dynamic causal modeling (DCM, we found that training participants to increase visual cortex activity was associated with increased effective connectivity between the visual cortex and the superior parietal lobe. Specifically, participants who learned to control activity in their visual cortex showed increased top-down control of the superior parietal lobe over the visual cortex, and at the same time reduced bottom-up processing. These results are consistent with efficient employment of top-down visual attention and imagery, which were the cognitive strategies used by participants to increase their visual cortex activity.

  8. Change blindness and visual memory: visual representations get rich and act poor.

    Science.gov (United States)

    Varakin, D Alexander; Levin, Daniel T

    2006-02-01

    Change blindness is often taken as evidence that visual representations are impoverished, while successful recognition of specific objects is taken as evidence that they are richly detailed. In the current experiments, participants performed cover tasks that required each object in a display to be attended. Change detection trials were unexpectedly introduced and surprise recognition tests were given for nonchanging displays. For both change detection and recognition, participants had to distinguish objects from the same basic-level category, making it likely that specific visual information had to be used for successful performance. Although recognition was above chance, incidental change detection usually remained at floor. These results help reconcile demonstrations of poor change detection with demonstrations of good memory because they suggest that the capability to store visual information in memory is not reflected by the visual system's tendency to utilize these representations for purposes of detecting unexpected changes.

  9. Visualizing the blind brain: brain imaging of visual field defects from early recovery to rehabilitation techniques

    Directory of Open Access Journals (Sweden)

    Marika eUrbanski

    2014-09-01

    Full Text Available Visual field defects (VFDs are one of the most common consequences observed after brain injury, especially after a stroke in the posterior cerebral artery territory. Less frequently, tumours, traumatic brain injury, brain surgery or demyelination can also determine various visual disabilities, from a decrease in visual acuity to cerebral blindness. VFD is a factor of bad functional prognosis as it compromises many daily life activities (e.g., obstacle avoidance, driving, and reading and therefore the patient’s quality of life. Spontaneous recovery seems to be limited and restricted to the first six months, with the best chance of improvement at one month. The possible mechanisms at work could be partly due to cortical reorganization in the visual areas (plasticity and/or partly to the use of intact alternative visual routes, first identified in animal studies and possibly underlying the phenomenon of blindsight. Despite processes of early recovery, which is rarely complete, and learning of compensatory strategies, the patient’s autonomy may still be compromised at more chronic stages. Therefore, various rehabilitation therapies based on neuroanatomical knowledge have been developed to improve VFDs. These use eye-movement training techniques (e.g., visual search, saccadic eye movements, reading training, visual field restitution (the Vision Restoration Therapy, VRT, or perceptual learning. In this review, we will focus on studies of human adults with acquired VFDs, which have used different imaging techniques (Positron Emission Tomography: PET, Diffusion Tensor Imaging: DTI, functional Magnetic Resonance Imaging: fMRI, MagnetoEncephalography: MEG or neurostimulation techniques (Transcranial Magnetic Stimulation: TMS; transcranial Direct Current Stimulation, tDCS to show brain activations in the course of spontaneous recovery or after specific rehabilitation techniques.

  10. Visualization of the chains of risks under global climate change

    Science.gov (United States)

    Yokohata, T.; Nishina, K.; Takahashi, K.; Kiguchi, M.; Iseri, Y.; Sueyoshi, T.; Yoshimori, M.; Iwase, K.; Yamamoto, A.; Shigemitsu, M.; Honda, Y.; Hanasaki, N.; Masaki, Y.; Ito, A.; Iizumi, T.; Sakurai, G.; Okada, M.; Emori, S.; Oki, T.

    2014-12-01

    Anthropogenic climate change possibly causes various impacts on human society and ecosystem. Here, we call possible damages or benefits caused by the future climate change as "climate risks". Many climate risks are closely interconnected with each other by direct cause-effect relationship. In this study, the major climate risks are comprehensively summarized based on the survey of studies in the literature using IPCC AR5 etc, and their cause-effect relationship are visualized by a "network diagram". This research is conducted by the collaboration between the experts of various fields, such as water, energy, agriculture, health, society, and eco-system under the project called ICA-RUS (Integrated Climate Assessment - Risks, Uncertainties and Society). First, the climate risks are classified into 9 categories (water, energy, food, health, disaster, industry, society, ecosystem, and tipping elements). Second, researchers of these fields in our project survey the research articles, and pick up items of climate risks, and possible cause-effect relationship between the risk items. A long list of the climate risks is summarized into ~130, and that of possible cause-effect relationship between the risk items is summarized into ~300, because the network diagram would be illegible if the number of the risk items and cause-effect relationship is too large. Here, we only consider the risks that could occur if climate mitigation policies are not conducted. Finally, the chain of climate risks is visualized by creating a "network diagram" based on a network graph theory (Fruchtman & Reingold algorithm). Through the analysis of network diagram, we find that climate risks at various sectors are closely related. For example, the decrease in the precipitation under the global climate change possibly causes the decrease in river runoff and the decrease in soil moisture, which causes the changes in crop production. The changes in crop production can have an impact on society by

  11. Neural attractor network for application in visual field data classification

    International Nuclear Information System (INIS)

    Fink, Wolfgang

    2004-01-01

    The purpose was to introduce a novel method for computer-based classification of visual field data derived from perimetric examination, that may act as a ' counsellor', providing an independent 'second opinion' to the diagnosing physician. The classification system consists of a Hopfield-type neural attractor network that obtains its input data from perimetric examination results. An iterative relaxation process determines the states of the neurons dynamically. Therefore, even 'noisy' perimetric output, e.g., early stages of a disease, may eventually be classified correctly according to the predefined idealized visual field defect (scotoma) patterns, stored as attractors of the network, that are found with diseases of the eye, optic nerve and the central nervous system. Preliminary tests of the classification system on real visual field data derived from perimetric examinations have shown a classification success of over 80%. Some of the main advantages of the Hopfield-attractor-network-based approach over feed-forward type neural networks are: (1) network architecture is defined by the classification problem; (2) no training is required to determine the neural coupling strengths; (3) assignment of an auto-diagnosis confidence level is possible by means of an overlap parameter and the Hamming distance. In conclusion, the novel method for computer-based classification of visual field data, presented here, furnishes a valuable first overview and an independent 'second opinion' in judging perimetric examination results, pointing towards a final diagnosis by a physician. It should not be considered a substitute for the diagnosing physician. Thanks to the worldwide accessibility of the Internet, the classification system offers a promising perspective towards modern computer-assisted diagnosis in both medicine and tele-medicine, for example and in particular, with respect to non-ophthalmic clinics or in communities where perimetric expertise is not readily available

  12. Getting the picture and changing the picture: visual methodologies ...

    African Journals Online (AJOL)

    ... photo-voice, photo-elicitation, researcher as photographer, working with family photos, cinematic texts, video production, material culture, advertising campaigns as nine key areas within visual methodologies. Keywords: educational research; social change; visual methodologies. South African Journal of Education Vol.

  13. Practical landmarks for visual field disability in glaucoma.

    Science.gov (United States)

    Saunders, Luke J; Russell, Richard A; Crabb, David P

    2012-09-01

    To assess whether mean deviation (MD) from automated perimetry is related to the visual field (VF) component for legal fitness to drive (LFTD) in glaucoma patients. Monocular 24-2 VFs of 2604 patients with bilateral VF damage were retrospectively investigated. Integrated visual fields were calculated and used as a surrogate to assess LFTD according to current UK driving licence criteria. The better eye MD (BEMD), worse eye MD (WEMD) and a measure utilising MD of both eyes were compared, to assess respective diagnostic capabilities to predict LFTD (using the integrated visual field surrogate test as the gold standard) and a 'Probability of Failure' (PoF) for various defect levels was calculated. BEMD appears to be a good predictor of the VF component for a patient's LFTD (receiver operating characteristic area under the curve: 96.2%); MDs from both eyes offered no significant extra diagnostic power (area under the curve: 96.4%). PoF for BEMD thresholds of ≤-10 dB and ≤-14 dB were 70 (95% CI 66% to 74%) and 92% (87% to 95%), respectively. There is a strong relationship between BEMD and a patient's LFTD. PoF values for LFTD associated with readily available MD values provide practical landmarks for VF disability in glaucoma.

  14. The T?lz Temporal Topography Study: Mapping the visual field across the life span. Part II: Cognitive factors shaping visual field maps

    OpenAIRE

    Poggel, Dorothe A.; Treutwein, Bernhard; Calmanti, Claudia; Strasburger, Hans

    2012-01-01

    Part I described the topography of visual performance over the life span. Performance decline was explained only partly by deterioration of the optical apparatus. Part II therefore examines the influence of higher visual and cognitive functions. Visual field maps for 95 healthy observers of static perimetry, double-pulse resolution (DPR), reaction times, and contrast thresholds, were correlated with measures of visual attention (alertness, divided attention, spatial cueing), visual search, an...

  15. Binocular glaucomatous visual field loss and its impact on visual exploration--a supermarket study.

    Directory of Open Access Journals (Sweden)

    Katrin Sippel

    Full Text Available Advanced glaucomatous visual field loss may critically interfere with quality of life. The purpose of this study was to (i assess the impact of binocular glaucomatous visual field loss on a supermarket search task as an example of everyday living activities, (ii to identify factors influencing the performance, and (iii to investigate the related compensatory mechanisms. Ten patients with binocular glaucoma (GP, and ten healthy-sighted control subjects (GC were asked to collect twenty different products chosen randomly in two supermarket racks as quickly as possible. The task performance was rated as "passed" or "failed" with regard to the time per correctly collected item. Based on the performance of control subjects, the threshold value for failing the task was defined as μ+3σ (in seconds per correctly collected item. Eye movements were recorded by means of a mobile eye tracker. Eight out of ten patients with glaucoma and all control subjects passed the task. Patients who failed the task needed significantly longer time (111.47 s ±12.12 s to complete the task than patients who passed (64.45 s ±13.36 s, t-test, p < 0.001. Furthermore, patients who passed the task showed a significantly higher number of glances towards the visual field defect (VFD area than patients who failed (t-test, p < 0.05. According to these results, glaucoma patients with defects in the binocular visual field display on average longer search times in a naturalistic supermarket task. However, a considerable number of patients, who compensate by frequent glancing towards the VFD, showed successful task performance. Therefore, systematic exploration of the VFD area seems to be a "time-effective" compensatory mechanism during the present supermarket task.

  16. The risk of pedestrian collisions with peripheral visual field loss.

    Science.gov (United States)

    Peli, Eli; Apfelbaum, Henry; Berson, Eliot L; Goldstein, Robert B

    2016-12-01

    Patients with peripheral field loss complain of colliding with other pedestrians in open-space environments such as shopping malls. Field expansion devices (e.g., prisms) can create artificial peripheral islands of vision. We investigated the visual angle at which these islands can be most effective for avoiding pedestrian collisions, by modeling the collision risk density as a function of bearing angle of pedestrians relative to the patient. Pedestrians at all possible locations were assumed to be moving in all directions with equal probability within a reasonable range of walking speeds. The risk density was found to be highly anisotropic. It peaked at ≈45° eccentricity. Increasing pedestrian speed range shifted the risk to higher eccentricities. The risk density is independent of time to collision. The model results were compared to the binocular residual peripheral island locations of 42 patients with forms of retinitis pigmentosa. The natural residual island prevalence also peaked nasally at about 45° but temporally at about 75°. This asymmetry resulted in a complementary coverage of the binocular field of view. Natural residual binocular island eccentricities seem well matched to the collision-risk density function, optimizing detection of other walking pedestrians (nasally) and of faster hazards (temporally). Field expansion prism devices will be most effective if they can create artificial peripheral islands at about 45° eccentricities. The collision risk and residual island findings raise interesting questions about normal visual development.

  17. Three-dimensional imaging in degraded visual field

    International Nuclear Information System (INIS)

    Oran, A.; Ozdur, I.; Ozharar, S.

    2016-01-01

    Imaging at degraded visual environments is one of the biggest challenges in today’s imaging technologies. Especially military and commercial rotary wing aviation is suffering from impaired visual field in sandy, dusty, marine and snowy environments. For example during landing the rotor churns up the particles and creates dense clouds of highly scattering medium, which limits the vision of the pilot and may result in an uncontrolled landing. The vision in such environments is limited because of the high ratio of scattered photons over the ballistic photons which have the image information. We propose to use optical spatial filtering (OSF) method in order to eliminate the scattered photons and only collect the ballistic photons at the receiver. OSF is widely used in microscopy, to the best of our knowledge this will be the first application of OSF for macroscopic imaging. Our experimental results show that most of the scattered photons are eliminated using the spatial filtering in a highly scattering impaired visual field. The results are compared with a standard broad area photo detector which shows the effectiveness of spatial filtering. (paper)

  18. A hierarchy of timescales explains distinct effects of local inhibition of primary visual cortex and frontal eye fields.

    Science.gov (United States)

    Cocchi, Luca; Sale, Martin V; L Gollo, Leonardo; Bell, Peter T; Nguyen, Vinh T; Zalesky, Andrew; Breakspear, Michael; Mattingley, Jason B

    2016-09-06

    Within the primate visual system, areas at lower levels of the cortical hierarchy process basic visual features, whereas those at higher levels, such as the frontal eye fields (FEF), are thought to modulate sensory processes via feedback connections. Despite these functional exchanges during perception, there is little shared activity between early and late visual regions at rest. How interactions emerge between regions encompassing distinct levels of the visual hierarchy remains unknown. Here we combined neuroimaging, non-invasive cortical stimulation and computational modelling to characterize changes in functional interactions across widespread neural networks before and after local inhibition of primary visual cortex or FEF. We found that stimulation of early visual cortex selectively increased feedforward interactions with FEF and extrastriate visual areas, whereas identical stimulation of the FEF decreased feedback interactions with early visual areas. Computational modelling suggests that these opposing effects reflect a fast-slow timescale hierarchy from sensory to association areas.

  19. Spatial Scaling of the Profile of Selective Attention in the Visual Field.

    Science.gov (United States)

    Gannon, Matthew A; Knapp, Ashley A; Adams, Thomas G; Long, Stephanie M; Parks, Nathan A

    2016-01-01

    Neural mechanisms of selective attention must be capable of adapting to variation in the absolute size of an attended stimulus in the ever-changing visual environment. To date, little is known regarding how attentional selection interacts with fluctuations in the spatial expanse of an attended object. Here, we use event-related potentials (ERPs) to investigate the scaling of attentional enhancement and suppression across the visual field. We measured ERPs while participants performed a task at fixation that varied in its attentional demands (attentional load) and visual angle (1.0° or 2.5°). Observers were presented with a stream of task-relevant stimuli while foveal, parafoveal, and peripheral visual locations were probed by irrelevant distractor stimuli. We found two important effects in the N1 component of visual ERPs. First, N1 modulations to task-relevant stimuli indexed attentional selection of stimuli during the load task and further correlated with task performance. Second, with increased task size, attentional modulation of the N1 to distractor stimuli showed a differential pattern that was consistent with a scaling of attentional selection. Together, these results demonstrate that the size of an attended stimulus scales the profile of attentional selection across the visual field and provides insights into the attentional mechanisms associated with such spatial scaling.

  20. Spatial Scaling of the Profile of Selective Attention in the Visual Field.

    Directory of Open Access Journals (Sweden)

    Matthew A Gannon

    Full Text Available Neural mechanisms of selective attention must be capable of adapting to variation in the absolute size of an attended stimulus in the ever-changing visual environment. To date, little is known regarding how attentional selection interacts with fluctuations in the spatial expanse of an attended object. Here, we use event-related potentials (ERPs to investigate the scaling of attentional enhancement and suppression across the visual field. We measured ERPs while participants performed a task at fixation that varied in its attentional demands (attentional load and visual angle (1.0° or 2.5°. Observers were presented with a stream of task-relevant stimuli while foveal, parafoveal, and peripheral visual locations were probed by irrelevant distractor stimuli. We found two important effects in the N1 component of visual ERPs. First, N1 modulations to task-relevant stimuli indexed attentional selection of stimuli during the load task and further correlated with task performance. Second, with increased task size, attentional modulation of the N1 to distractor stimuli showed a differential pattern that was consistent with a scaling of attentional selection. Together, these results demonstrate that the size of an attended stimulus scales the profile of attentional selection across the visual field and provides insights into the attentional mechanisms associated with such spatial scaling.

  1. A Prospective Profile of Visual Field Loss following Stroke: Prevalence, Type, Rehabilitation, and Outcome

    Directory of Open Access Journals (Sweden)

    Fiona J. Rowe

    2013-01-01

    Full Text Available Aims. To profile site of stroke/cerebrovascular accident, type and extent of field loss, treatment options, and outcome. Methods. Prospective multicentre cohort trial. Standardised referral and investigation protocol of visual parameters. Results. 915 patients were recruited with a mean age of 69 years (SD 14. 479 patients (52% had visual field loss. 51 patients (10% had no visual symptoms. Almost half of symptomatic patients (n=226 complained only of visual field loss: almost half (n=226 also had reading difficulty, blurred vision, diplopia, and perceptual difficulties. 31% (n=151 had visual field loss as their only visual impairment: 69% (n=328 had low vision, eye movement deficits, or visual perceptual difficulties. Occipital and parietal lobe strokes most commonly caused visual field loss. Treatment options included visual search training, visual awareness, typoscopes, substitutive prisms, low vision aids, refraction, and occlusive patches. At followup 15 patients (7.5% had full recovery, 78 (39% had improvement, and 104 (52% had no recovery. Two patients (1% had further decline of visual field. Patients with visual field loss had lower quality of life scores than stroke patients without visual impairment. Conclusions. Stroke survivors with visual field loss require assessment to accurately define type and extent of loss, diagnose coexistent visual impairments, and offer targeted treatment.

  2. Visual field defects after temporal lobe resection for epilepsy

    DEFF Research Database (Denmark)

    Steensberg, Alvilda T; Olsen, Ane Sophie; Litman, Minna

    2018-01-01

    PURPOSE: To determine visual field defects (VFDs) using methods of varying complexity and compare results with subjective symptoms in a population of newly operated temporal lobe epilepsy patients. METHODS: Forty patients were included in the study. Two patients failed to perform VFD testing...... symptoms were only reported by 28% of the patients with a VFD and in two of eight (sensitivity=25%) with a severe VFD. Most patients (86%) considered VFD information mandatory. CONCLUSION: VFD continue to be a frequent adverse event after epilepsy surgery in the medial temporal lobe and may affect...

  3. How does glaucoma look?: patient perception of visual field loss.

    Science.gov (United States)

    Crabb, David P; Smith, Nicholas D; Glen, Fiona C; Burton, Robyn; Garway-Heath, David F

    2013-06-01

    To explore patient perception of vision loss in glaucoma and, specifically, to test the hypothesis that patients do not recognize their impairment as a black tunnel effect or as black patches in their field of view. Clinic-based cross-sectional study. Fifty patients (age range, 52-82 years) with visual acuity better than 20/30 and with a range of glaucomatous visual field (VF) defects in both eyes, excluding those with very advanced disease (perimetrically blind). Participants underwent monocular VF testing in both eyes using a Humphrey Field Analyzer (HFA; Carl Zeiss Meditec, Dublin, CA; 24-2 Swedish interactive threshold algorithm standard tests) and other tests of visual function. Participants took part in a recorded interview during which they were asked if they were aware of their VF loss; if so, there were encouraged to describe it in their own words. Participants were shown 6 images modified in a variety of ways on a computer monitor and were asked to select the image that most closely represented their perception of their VF loss. Forced choice of an image best representing glaucomatous vision impairment. Participants had a range of VF defect severity: average HFA mean deviation was -8.7 dB (standard deviation [SD], 5.8 dB) and -10.5 dB (SD, 7.1 dB) in the right and left eyes, respectively. Thirteen patients (26%; 95% confidence interval [CI], 15%-40%) reported being completely unaware of their vision loss. None of the patients chose the images with a distinct black tunnel effect or black patches. Only 2 patients (4%; 95% CI, 0%-14%) chose the image with a tunnel effect with blurred edges. An image depicting blurred patches and another with missing patches was chosen by 54% (95% CI, 39%-68%) and 16% (95% CI, 7%-29%) of the patients, respectively. Content analysis of the transcripts from the recorded interviews indicated a frequent use of descriptors of visual symptoms associated with reported blur and missing features. Patients with glaucoma do not perceive

  4. Segregation of Spontaneous and Training Induced Recovery from Visual Field Defects in Subacute Stroke Patients

    Directory of Open Access Journals (Sweden)

    Douwe P. Bergsma

    2017-12-01

    Full Text Available Whether rehabilitation after stroke profits from an early start is difficult to establish as the contributions of spontaneous recovery and treatment are difficult to tease apart. Here, we use a novel training design to dissociate these components for visual rehabilitation of subacute stroke patients with visual field defects such as hemianopia. Visual discrimination training was started within 6 weeks after stroke in 17 patients. Spontaneous and training-induced recoveries were distinguished by training one-half of the defect for 8 weeks, while monitoring spontaneous recovery in the other (control half of the defect. Next, trained and control regions were swapped, and training continued for another 8 weeks. The same paradigm was also applied to seven chronic patients for whom spontaneous recovery can be excluded and changes in the control half of the defect point to a spillover effect of training. In both groups, field stability was assessed during a no-intervention period. Defect reduction was significantly greater in the trained part of the defect than in the simultaneously untrained part of the defect irrespective of training onset (p = 0.001. In subacute patients, training contributed about twice as much to their defect reduction as the spontaneous recovery. Goal Attainment Scores were significantly and positively correlated with the total defect reduction (p = 0.01, percentage increase reading speed was significantly and positively correlated with the defect reduction induced by training (epoch 1: p = 0.0044; epoch 2: p = 0.023. Visual training adds significantly to the spontaneous recovery of visual field defects, both during training in the early and the chronic stroke phase. However, field recovery as a result of training in this subacute phase was as large as in the chronic phase. This suggests that patients benefited primarily of early onset training by gaining access to a larger visual field sooner.

  5. Leadership Shifts in Changing Field

    Science.gov (United States)

    Zubrzycki, Jaclyn

    2013-01-01

    As groups representing local and state education players struggle to remain relevant in a policy conversation often dominated by foundations, think tanks, new advocacy groups, and political and business figures, a shift in leadership has been under way at major associations. Most of the changes have come as part of the natural churn; former…

  6. Cortical dynamics of visual change detection based on sensory memory.

    Science.gov (United States)

    Urakawa, Tomokazu; Inui, Koji; Yamashiro, Koya; Tanaka, Emi; Kakigi, Ryusuke

    2010-08-01

    Detecting a visual change was suggested to relate closely to the visual sensory memory formed by visual stimuli before the occurrence of the change, because change detection involves identifying a difference between ongoing and preceding sensory conditions. Previous neuroimaging studies showed that an abrupt visual change activates the middle occipital gyrus (MOG). However, it still remains to be elucidated whether the MOG is related to visual change detection based on sensory memory. Here we tried to settle this issue using a new method of stimulation with blue and red LEDs to emphasize a memory-based change detection process. There were two stimuli, a standard trial stimulus and a deviant trial stimulus. The former was a red light lasting 500 ms, and the latter was a red light lasting 250 ms immediately followed by a blue light lasting 250 ms. Effects of the trial-trial interval, 250 approximately 2000 ms, were investigated to know how cortical responses to the abrupt change (from red to blue) were affected by preceding conditions. The brain response to the deviant trial stimulus was recorded by magnetoencephalography. Results of a multi-dipole analysis showed that the activity in the MOG, peaking at around 150 ms after the change onset, decreased in amplitude as the interval increased, but the earlier activity in BA 17/18 was not affected by the interval. These results suggested that the MOG is an important cortical area relating to the sensory memory-based visual change-detecting system. Copyright 2010 Elsevier Inc. All rights reserved.

  7. Emotional facial expression detection in the peripheral visual field.

    Directory of Open Access Journals (Sweden)

    Dimitri J Bayle

    Full Text Available BACKGROUND: In everyday life, signals of danger, such as aversive facial expressions, usually appear in the peripheral visual field. Although facial expression processing in central vision has been extensively studied, this processing in peripheral vision has been poorly studied. METHODOLOGY/PRINCIPAL FINDINGS: Using behavioral measures, we explored the human ability to detect fear and disgust vs. neutral expressions and compared it to the ability to discriminate between genders at eccentricities up to 40°. Responses were faster for the detection of emotion compared to gender. Emotion was detected from fearful faces up to 40° of eccentricity. CONCLUSIONS: Our results demonstrate the human ability to detect facial expressions presented in the far periphery up to 40° of eccentricity. The increasing advantage of emotion compared to gender processing with increasing eccentricity might reflect a major implication of the magnocellular visual pathway in facial expression processing. This advantage may suggest that emotion detection, relative to gender identification, is less impacted by visual acuity and within-face crowding in the periphery. These results are consistent with specific and automatic processing of danger-related information, which may drive attention to those messages and allow for a fast behavioral reaction.

  8. Effect of word familiarity on visually evoked magnetic fields.

    Science.gov (United States)

    Harada, N; Iwaki, S; Nakagawa, S; Yamaguchi, M; Tonoike, M

    2004-11-30

    This study investigated the effect of word familiarity of visual stimuli on the word recognizing function of the human brain. Word familiarity is an index of the relative ease of word perception, and is characterized by facilitation and accuracy on word recognition. We studied the effect of word familiarity, using "Hiragana" (phonetic characters in Japanese orthography) characters as visual stimuli, on the elicitation of visually evoked magnetic fields with a word-naming task. The words were selected from a database of lexical properties of Japanese. The four "Hiragana" characters used were grouped and presented in 4 classes of degree of familiarity. The three components were observed in averaged waveforms of the root mean square (RMS) value on latencies at about 100 ms, 150 ms and 220 ms. The RMS value of the 220 ms component showed a significant positive correlation (F=(3/36); 5.501; p=0.035) with the value of familiarity. ECDs of the 220 ms component were observed in the intraparietal sulcus (IPS). Increments in the RMS value of the 220 ms component, which might reflect ideographical word recognition, retrieving "as a whole" were enhanced with increments of the value of familiarity. The interaction of characters, which increased with the value of familiarity, might function "as a large symbol"; and enhance a "pop-out" function with an escaping character inhibiting other characters and enhancing the segmentation of the character (as a figure) from the ground.

  9. Structural and functional changes across the visual cortex of a patient with visual form agnosia.

    Science.gov (United States)

    Bridge, Holly; Thomas, Owen M; Minini, Loredana; Cavina-Pratesi, Cristiana; Milner, A David; Parker, Andrew J

    2013-07-31

    Loss of shape recognition in visual-form agnosia occurs without equivalent losses in the use of vision to guide actions, providing support for the hypothesis of two visual systems (for "perception" and "action"). The human individual DF received a toxic exposure to carbon monoxide some years ago, which resulted in a persisting visual-form agnosia that has been extensively characterized at the behavioral level. We conducted a detailed high-resolution MRI study of DF's cortex, combining structural and functional measurements. We present the first accurate quantification of the changes in thickness across DF's occipital cortex, finding the most substantial loss in the lateral occipital cortex (LOC). There are reduced white matter connections between LOC and other areas. Functional measures show pockets of activity that survive within structurally damaged areas. The topographic mapping of visual areas showed that ordered retinotopic maps were evident for DF in the ventral portions of visual cortical areas V1, V2, V3, and hV4. Although V1 shows evidence of topographic order in its dorsal portion, such maps could not be found in the dorsal parts of V2 and V3. We conclude that it is not possible to understand fully the deficits in object perception in visual-form agnosia without the exploitation of both structural and functional measurements. Our results also highlight for DF the cortical routes through which visual information is able to pass to support her well-documented abilities to use visual information to guide actions.

  10. Visualizing the Entropy Change of a Thermal Reservoir

    Science.gov (United States)

    Langbeheim, Elon; Safran, Samuel A.; Yerushalmi, Edit

    2014-01-01

    When a system exchanges energy with a constant-temperature environment, the entropy of the surroundings changes. A lattice model of a fluid thermal reservoir can provide a visualization of the microscopic changes that occur in the surroundings upon energy transfer from the system. This model can be used to clarify the consistency of phenomena such…

  11. GABAA receptors in visual and auditory cortex and neural activity changes during basic visual stimulation

    Directory of Open Access Journals (Sweden)

    Pengmin eQin

    2012-12-01

    Full Text Available Recent imaging studies have demonstrated that levels of resting GABA in the visual cortex predict the degree of stimulus-induced activity in the same region. These studies have used the presentation of discrete visual stimulus; the change from closed eyes to open also represents a simple visual stimulus, however, and has been shown to induce changes in local brain activity and in functional connectivity between regions. We thus aimed to investigate the role of the GABA system, specifically GABAA receptors, in the changes in brain activity between the eyes closed (EC and eyes open (EO state in order to provide detail at the receptor level to complement previous studies of GABA concentrations. We conducted an fMRI study involving two different modes of the change from EC to EO: An EO and EC block design, allowing the modelling of the haemodynamic response, followed by longer periods of EC and EO to allow the measuring of functional connectivity. The same subjects also underwent [18F]Flumazenil PET measure GABAA receptor binding potentials. It was demonstrated that the local-to-global ratio of GABAA receptor binding potential in the visual cortex predicted the degree of changes in neural activity from EC to EO. This same relationship was also shown in the auditory cortex. Furthermore, the local-to-global ratio of GABAA receptor binding potential in the visual cortex also predicts the change of functional connectivity between visual and auditory cortex from EC to EO. These findings contribute to our understanding of the role of GABAA receptors in stimulus-induced neural activity in local regions and in inter-regional functional connectivity.

  12. Mass Charge Interactions for Visualizing the Quantum Field

    Science.gov (United States)

    Baer, Wolfgang

    Our goal is to integrate the objective and subjective aspects of our personal experience into a single complete theory of reality. To further this endeavor we replace elementary particles with elementary events as the building blocks of an event oriented description of that reality. The simplest event in such a conception is an adaptation of A. Wheeler's primitive explanatory--measurement cycle between internal observations experienced by an observer and their assumed physical causes. We will show how internal forces between charge and mass are required to complete the cyclic sequence of activity. This new formulation of internal material is easier to visualize and map to cognitive experiences than current formulations of sub-atomic physics. In our formulation, called Cognitive Action Theory, such internal forces balance the external forces of gravity-inertia and electricity-magnetism. They thereby accommodate outside influences by adjusting the internal structure of material from which all things are composed. Such accommodation is interpreted as the physical implementation of a model of the external physical world in the brain of a cognitive being or alternatively the response mechanism to external influences in the material of inanimate objects. We adopt the deBroglie-Bohm causal interpretation of QT to show that the nature of space in our model is mathematically equivalent to a field of clocks. Within this field small oscillations form deBroglie waves. This interpretation allows us to visualize the underlying structure of empty space with a charge-mass separation field in equilibrium, and objects appearing in space with quantum wave disturbances to that equilibrium occurring inside material. Space is thereby associated with the internal structure of material and quantum mechanics is shown to be, paraphrasing Heisenberg, the physics of the material that knows the world.

  13. Long-term visual changes following pituitary irradiation

    International Nuclear Information System (INIS)

    Movsas, Benjamin; Movsas, Tammy Z.; Steinberg, Seth M.; Okunieff, Paul

    1995-01-01

    Purpose: To analyze possible long-term effects of pituitary irradiation on visual fields and acuity. Methods and Materials: Eighty-six patients were treated with radiotherapy for pituitary tumors at the National Cancer Institute between 1980 and 1991. Twenty-one patients had baseline preradiation and long-term follow-up visual fields. Eyes were followed with serial Goldmann or Humphrey visual field testing. Neuroradiologic correlation was made with the available brain scans. There were 12 females and 9 males with an median age of 44. Eighteen patients had hormone-secreting tumors and three had chromophobe adenomas. All but one patient with an inoperable invasive macroadenoma were irradiated after one or more transphenoidal resections or a craniotomy. The indications for radiation in the operable patients were: nine patients, partial tumor resection; nine patients, tumor recurrence; and two patients, persistent hormonal elevation after surgery. The median dose delivered was 50 Gy (45-59.4 Gy). The average field size was 6 x 6 cm (5 x 5 cm to 10 x 12.5 cm). Results: With a median follow-up of 48 months (14-128) after radiotherapy, 1 out of 21 patients has recurred (at 8 months) and all patients are alive. Of the 38 sighted eyes, 27 had normal visual fields before and after radiation, 7 eyes showed improvement, and 4 eyes had a stable defect, mostly in the superior temporal region. There were no cases of radiation-induced visual field or acuity deterioration. Six out of 21 patients (29%) had neurologic symptoms in follow-up, most of which appeared vascular in nature. Four patients complained of atypical migranous-like headaches that first began 1.5-3 years following treatment. One patient complained of recurrent vertical diplopia and one patient had a cerebral vascular accident 7 years following therapy. A dose-related association with these neurovascular symptoms approached statistical significance. Only 1 out of 11 (9%) patients who received doses less than or equal

  14. Effect of dorzolamide/timolol combination on the visual field in glaucoma

    Directory of Open Access Journals (Sweden)

    Takeda S

    2014-08-01

    Full Text Available Sakurako Takeda,1,2 Tatsuya Mimura,1 Masao Matsubara1,2 1Department of Ophthalmology, Tokyo Women’s Medical University Medical Center East, Tokyo, Japan; 2Department of Ophthalmology, Nippori Clinic, Medical Center East, Tokyo Women’s Medical University, Tokyo, Japan Purpose: To evaluate the effect of treatment for 3 years with a dorzolamide/timolol (1%/0.5% fixed combination (DTFC on visual field progression in patients with open-angle glaucoma.Participants: A total of 14 consecutive patients were enrolled who had been previously treated with monotherapy or any combination of a beta blocker, carbonic anhydrase inhibitor, and/or prostaglandin analog for primary open-angle glaucoma (POAG; n=4 or normal-tension glaucoma (NTG; n=10.Methods: Patients were switched to DTFC from their prior glaucoma therapy. The IOP was measured at intervals of 4–6 weeks, and the visual fields were examined at least twice a year for 3 years. The annual change of mean deviation (MD slope was used to quantify visual field loss. Results: The mean MD value was –5.9±5.0 dB at baseline; it was –5.6±4.8 dB at 12 months, –5.9±5.0 dB at 24 months, and –5.6±5.1 dB at 36 months after switching. The mean MD slope was –0.2±0.8 dB/year before switching and 0.3±1.3 dB/year from baseline to 1 year, –0.3±1.1 dB/year from 1–2 years, and 0.3±0.9 dB/year from 2–3 years after switching. The mean MD slope from baseline to 36 months was correlated with the IOP reduction rate at 36 months after switching. Visual field progression was associated with the IOP reduction rate at 12 months after switching.Conclusion: Switching to DTFC from prior glaucoma therapy improved the MD slope for at least 3 years. Reduction of the IOP after switching to DTFC was effective for delaying visual field progression. Although our study was not nonrandomized and was small in scale, the findings suggest that DTFC might have a beneficial effect on the visual fields in patients with

  15. Binocular glaucomatous visual field loss and its impact on visual exploration--a supermarket study.

    Science.gov (United States)

    Sippel, Katrin; Kasneci, Enkelejda; Aehling, Kathrin; Heister, Martin; Rosenstiel, Wolfgang; Schiefer, Ulrich; Papageorgiou, Elena

    2014-01-01

    Advanced glaucomatous visual field loss may critically interfere with quality of life. The purpose of this study was to (i) assess the impact of binocular glaucomatous visual field loss on a supermarket search task as an example of everyday living activities, (ii) to identify factors influencing the performance, and (iii) to investigate the related compensatory mechanisms. Ten patients with binocular glaucoma (GP), and ten healthy-sighted control subjects (GC) were asked to collect twenty different products chosen randomly in two supermarket racks as quickly as possible. The task performance was rated as "passed" or "failed" with regard to the time per correctly collected item. Based on the performance of control subjects, the threshold value for failing the task was defined as μ+3σ (in seconds per correctly collected item). Eye movements were recorded by means of a mobile eye tracker. Eight out of ten patients with glaucoma and all control subjects passed the task. Patients who failed the task needed significantly longer time (111.47 s ±12.12 s) to complete the task than patients who passed (64.45 s ±13.36 s, t-test, p supermarket task. However, a considerable number of patients, who compensate by frequent glancing towards the VFD, showed successful task performance. Therefore, systematic exploration of the VFD area seems to be a "time-effective" compensatory mechanism during the present supermarket task.

  16. Sensor for detecting changes in magnetic fields

    Science.gov (United States)

    Praeg, Walter F.

    1981-01-01

    A sensor for detecting changes in the magnetic field of the equilibrium-field coil of a Tokamak plasma device comprises a pair of bifilar wires disposed circumferentially, one inside and one outside the equilibrium-field coil. Each is shorted at one end. The difference between the voltages detected at the other ends of the bifilar wires provides a measure of changing flux in the equilibrium-field coil. This difference can be used to detect faults in the coil in time to take action to protect the coil.

  17. Visual Field Preferences of Object Analysis for Grasping with One Hand

    Directory of Open Access Journals (Sweden)

    Ada eLe

    2014-10-01

    Full Text Available When we grasp an object using one hand, the opposite hemisphere predominantly guides the motor control of grasp movements (Davare et al. 2007; Rice et al. 2007. However, it is unclear whether visual object analysis for grasp control relies more on inputs (a from the contralateral than the ipsilateral visual field, (b from one dominant visual field regardless of the grasping hand, or (c from both visual fields equally. For bimanual grasping of a single object we have recently demonstrated a visual field preference for the left visual field (Le and Niemeier 2013a, 2013b, consistent with a general right-hemisphere dominance for sensorimotor control of bimanual grasps (Le et al., 2013. But visual field differences have never been tested for unimanual grasping. Therefore, here we asked right-handed participants to fixate to the left or right of an object and then grasp the object either with their right or left hand using a precision grip. We found that participants grasping with their right hand performed better with objects in the right visual field: maximum grip apertures (MGAs were more closely matched to the object width and were smaller than for objects in the left visual field. In contrast, when people grasped with their left hand, preferences switched to the left visual field. What is more, MGA scaling showed greater visual field differences compared to right-hand grasping. Our data suggest that, visual object analysis for unimanual grasping shows a preference for visual information from the ipsilateral visual field, and that the left hemisphere is better equipped to control grasps in both visual fields.

  18. The Association of Glaucomatous Visual Field Loss and Balance

    Science.gov (United States)

    de Luna, Regina A.; Mihailovic, Aleksandra; Nguyen, Angeline M.; Friedman, David S.; Gitlin, Laura N.; Ramulu, Pradeep Y.

    2017-01-01

    Purpose To relate balance measures to visual field (VF) damage from glaucoma. Methods The OPAL kinematic system measured balance, as root mean square (RMS) sway, on 236 patients with suspect/diagnosed glaucoma. Balance was measured with feet shoulder width apart while standing on a firm/foam surface with eyes opened/closed (Instrumental Clinical Test of Sensory Integration and Balance [ICTSIB] conditions), and eyes open on a firm surface under feet together, semi-tandem, or tandem positions (standing balance conditions). Integrated VF (IVF) sensitivities were calculated by merging right and left eye 24-2 VF data. Results Mean age was 71 years (range, 57–93) and mean IVF sensitivity was 27.1 dB (normal = 31 dB). Lower IVF sensitivity was associated with greater RMS sway during eyes-open foam-surface testing (β = 0.23 z-score units/5 dB IVF sensitivity decrement, P = 0.001), but not during other ICTSIB conditions. Lower IVF sensitivity also was associated with greater RMS sway during feet together standing balance testing (0.10 z-score units/5 dB IVF sensitivity decrement, P = 0.049), but not during other standing balance conditions. Visual dependence of balance was lower in patients with worse IVF sensitivity (β = −21%/5 dB IVF sensitivity decrement, P falls and patients with VF loss from glaucoma may be at higher risk of falls because of poor balance. PMID:28553562

  19. Disinhibition outside receptive fields in the visual cortex.

    Science.gov (United States)

    Walker, Gary A; Ohzawa, Izumi; Freeman, Ralph D

    2002-07-01

    By definition, the region outside the classical receptive field (CRF) of a neuron in the visual cortex does not directly activate the cell. However, the response of a neuron can be influenced by stimulation of the surrounding area. In previous work, we showed that this influence is mainly suppressive and that it is generally limited to a local region outside the CRF. In the experiments reported here, we investigate the mechanisms of the suppressive effect. Our approach is to find the position of a grating patch that is most effective in suppressing the response of a cell. We then use a masking stimulus at different contrasts over the grating patch in an attempt to disinhibit the response. We find that suppressive effects may be partially or completely reversed by use of the masking stimulus. This disinhibition suggests that effects from outside the CRF may be local. Although they do not necessarily underlie the perceptual analysis of a figure-ground visual scene, they may provide a substrate for this process.

  20. 38 CFR 4.76a - Computation of average concentric contraction of visual fields.

    Science.gov (United States)

    2010-07-01

    ... concentric contraction of visual fields. 4.76a Section 4.76a Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS SCHEDULE FOR RATING DISABILITIES Disability Ratings The Organs of Special Sense § 4.76a Computation of average concentric contraction of visual fields. Table III—Normal Visual...

  1. Distillation and Visualization of Spatiotemporal Structures in Turbulent Flow Fields

    International Nuclear Information System (INIS)

    Hege, Hans-Christian; Hotz, Ingrid; Kasten, Jens

    2011-01-01

    Although turbulence suggests randomness and disorder, organized motions that cause spatiotemporal 'coherent structures' are of particular interest. Revealing such structures in numerically given turbulent or semi-turbulent flows is of interest both for practically working engineers and theoretically oriented physicists. However, as long as there is no common agreement about the mathematical definition of coherent structures, extracting such structures is a vaguely defined task. Instead of searching for a general definition, the data visualization community takes a pragmatic approach and provides various tool chains implemented in flexible software frameworks that allow the user to extract distinct flow field structures. Thus physicists or engineers can select those flow structures which might advance their insight best. We present different approaches to distill important features from turbulent flows and discuss the necessary steps to be taken on the example of Lagrangian coherent structures.

  2. Prior rates of visual field loss and lifetime risk of blindness in glaucomatous patients undergoing trabeculectomy.

    Science.gov (United States)

    Foulsham, W S; Fu, L; Tatham, A J

    2015-10-01

    Trend-based analyses examining rates of visual field (VF) loss in glaucoma are useful for predicting risk of vision-related morbidity. Although patients with faster losses are likely to require treatment escalation, little is known about rates that might trigger a decision to intervene surgically. The aims of this study were to investigate prior rates of VF loss in patients attending for trabeculectomy and to estimate, in the absence of surgical intervention, lifetime risk of visual impairment, and blindness. A retrospective analysis of 117 eyes of 86 consecutive patients with glaucoma attending for trabeculectomy, including 53 patients referred from general ophthalmology clinics and 33 patients from specialist glaucoma clinics. Rates of change in standard automated perimetry mean deviation were examined using linear regression and random coefficient models. Risk of lifetime visual impairment and blindness was calculated using life expectancy data. Mean age at surgery was 71.0±9.7 years. Patients were followed for 10.7±7.5 years prior to surgery with an average of seven useable fields per eye. On average patients referred from general clinics lost 1.04 dB/year compared with 0.77 dB/year in those referred from glaucoma clinics (P=0.070). Patients referred from general clinics had more medication changes prior to surgery (3.4 and 2.6 changes, respectively; P=0.004). Given Scottish life expectancy data, untreated, 61 eyes (52%) would have passed the threshold for visual impairment, whereas 40 (34%) would have passed the threshold demarcating blindness. Patients attending for trabeculectomy had faster average rates of field loss prior to surgery than published values for the general glaucoma population with over one-third of eyes studied predicted to have become blind without intervention. Those managed by glaucoma specialists had fewer changes in medication and tended to slower rates of VF loss, although the latter did not reach statistical significance.

  3. Nonuniform Changes in the Distribution of Visual Attention from Visual Complexity and Action: A Driving Simulation Study.

    Science.gov (United States)

    Park, George D; Reed, Catherine L

    2015-02-01

    Researchers acknowledge the interplay between action and attention, but typically consider action as a response to successful attentional selection or the correlation of performance on separate action and attention tasks. We investigated how concurrent action with spatial monitoring affects the distribution of attention across the visual field. We embedded a functional field of view (FFOV) paradigm with concurrent central object recognition and peripheral target localization tasks in a simulated driving environment. Peripheral targets varied across 20-60 deg eccentricity at 11 radial spokes. Three conditions assessed the effects of visual complexity and concurrent action on the size and shape of the FFOV: (1) with no background, (2) with driving background, and (3) with driving background and vehicle steering. The addition of visual complexity slowed task performance and reduced the FFOV size but did not change the baseline shape. In contrast, the addition of steering produced not only shrinkage of the FFOV, but also changes in the FFOV shape. Nonuniform performance decrements occurred in proximal regions used for the central task and for steering, independent of interference from context elements. Multifocal attention models should consider the role of action and account for nonhomogeneities in the distribution of attention. © 2015 SAGE Publications.

  4. Transient magnetic field changes in flares

    International Nuclear Information System (INIS)

    Patterson, A.; Zirin, H.

    1981-01-01

    Magnetic changes have been detected with the videomagnetograph (VMG) at Big Bear during two large flares on 1979 November 5. Two kinds of changes were detected in both flares: a decrease in satellite field strength near the locus of the flare and the appearance of strong transient fields during the peak of the flare. We explain why we believe that the observed effects are real and not instrumental and discuss their significance for flare studies

  5. Sustained change blindness to incremental scene rotation: a dissociation between explicit change detection and visual memory.

    Science.gov (United States)

    Hollingworth, Andrew; Henderson, John M

    2004-07-01

    In a change detection paradigm, the global orientation of a natural scene was incrementally changed in 1 degree intervals. In Experiments 1 and 2, participants demonstrated sustained change blindness to incremental rotation, often coming to consider a significantly different scene viewpoint as an unchanged continuation of the original view. Experiment 3 showed that participants who failed to detect the incremental rotation nevertheless reliably detected a single-step rotation back to the initial view. Together, these results demonstrate an important dissociation between explicit change detection and visual memory. Following a change, visual memory is updated to reflect the changed state of the environment, even if the change was not detected.

  6. Visual field bias in hearing and deaf adults during judgments of facial expression and identity.

    Directory of Open Access Journals (Sweden)

    Susan M Letourneau

    2013-06-01

    Full Text Available The dominance of the right hemisphere during face perception is associated with more accurate judgments of faces presented in the left rather than the right visual field. Previous research suggests that the left visual field bias typically observed during face perception tasks is reduced in deaf adults who use sign language, for whom facial expressions convey important linguistic information. The current study examined whether visual field biases were altered in deaf adults whenever they viewed expressive faces, or only when attention was explicitly directed to expression. Twelve hearing adults and 12 deaf signers were trained to recognize a set of novel faces posing various emotional expressions. They then judged the familiarity or emotion of faces presented in the left or right visual field, or both visual fields simultaneously. The same familiar and unfamiliar faces posing neutral and happy expressions were presented in the two tasks. Both groups were most accurate when faces were presented in both visual fields. Across tasks, the hearing group demonstrated a bias toward the left visual field. In contrast, the deaf group showed a bias toward the left visual field during identity judgments that shifted marginally toward the right visual field during emotion judgments. Two secondary conditions tested whether these effects generalized to angry faces and famous faces and similar effects were observed. These results suggest that attention to facial expression, not merely the presence of emotional expression, reduces a typical left visual field bias for face processing in deaf signers.

  7. Visual working memory load-related changes in neural activity and functional connectivity.

    Directory of Open Access Journals (Sweden)

    Ling Li

    Full Text Available BACKGROUND: Visual working memory (VWM helps us store visual information to prepare for subsequent behavior. The neuronal mechanisms for sustaining coherent visual information and the mechanisms for limited VWM capacity have remained uncharacterized. Although numerous studies have utilized behavioral accuracy, neural activity, and connectivity to explore the mechanism of VWM retention, little is known about the load-related changes in functional connectivity for hemi-field VWM retention. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we recorded electroencephalography (EEG from 14 normal young adults while they performed a bilateral visual field memory task. Subjects had more rapid and accurate responses to the left visual field (LVF memory condition. The difference in mean amplitude between the ipsilateral and contralateral event-related potential (ERP at parietal-occipital electrodes in retention interval period was obtained with six different memory loads. Functional connectivity between 128 scalp regions was measured by EEG phase synchronization in the theta- (4-8 Hz, alpha- (8-12 Hz, beta- (12-32 Hz, and gamma- (32-40 Hz frequency bands. The resulting matrices were converted to graphs, and mean degree, clustering coefficient and shortest path length was computed as a function of memory load. The results showed that brain networks of theta-, alpha-, beta-, and gamma- frequency bands were load-dependent and visual-field dependent. The networks of theta- and alpha- bands phase synchrony were most predominant in retention period for right visual field (RVF WM than for LVF WM. Furthermore, only for RVF memory condition, brain network density of theta-band during the retention interval were linked to the delay of behavior reaction time, and the topological property of alpha-band network was negative correlation with behavior accuracy. CONCLUSIONS/SIGNIFICANCE: We suggest that the differences in theta- and alpha- bands between LVF and RVF

  8. Visual Working Memory Load-Related Changes in Neural Activity and Functional Connectivity

    Science.gov (United States)

    Li, Ling; Zhang, Jin-Xiang; Jiang, Tao

    2011-01-01

    Background Visual working memory (VWM) helps us store visual information to prepare for subsequent behavior. The neuronal mechanisms for sustaining coherent visual information and the mechanisms for limited VWM capacity have remained uncharacterized. Although numerous studies have utilized behavioral accuracy, neural activity, and connectivity to explore the mechanism of VWM retention, little is known about the load-related changes in functional connectivity for hemi-field VWM retention. Methodology/Principal Findings In this study, we recorded electroencephalography (EEG) from 14 normal young adults while they performed a bilateral visual field memory task. Subjects had more rapid and accurate responses to the left visual field (LVF) memory condition. The difference in mean amplitude between the ipsilateral and contralateral event-related potential (ERP) at parietal-occipital electrodes in retention interval period was obtained with six different memory loads. Functional connectivity between 128 scalp regions was measured by EEG phase synchronization in the theta- (4–8 Hz), alpha- (8–12 Hz), beta- (12–32 Hz), and gamma- (32–40 Hz) frequency bands. The resulting matrices were converted to graphs, and mean degree, clustering coefficient and shortest path length was computed as a function of memory load. The results showed that brain networks of theta-, alpha-, beta-, and gamma- frequency bands were load-dependent and visual-field dependent. The networks of theta- and alpha- bands phase synchrony were most predominant in retention period for right visual field (RVF) WM than for LVF WM. Furthermore, only for RVF memory condition, brain network density of theta-band during the retention interval were linked to the delay of behavior reaction time, and the topological property of alpha-band network was negative correlation with behavior accuracy. Conclusions/Significance We suggest that the differences in theta- and alpha- bands between LVF and RVF conditions in

  9. High ionization radiation field remote visualization device - shielding requirements

    International Nuclear Information System (INIS)

    Fernandez, Antonio P. Rodrigues; Omi, Nelson M.; Silveira, Carlos Gaia da; Calvo, Wilson A. Pajero

    2011-01-01

    The high activity sources manipulation hot-cells use special and very thick leaded glass windows. This window provides a single sight of what is being manipulated inside the hot-cell. The use of surveillance cameras would replace the leaded glass window, provide other sights and show more details of the manipulated pieces, using the zoom capacity. Online distant manipulation may be implemented, too. The limitation is their low ionizing radiation resistance. This low resistance also limited the useful time of robots made to explore or even fix problematic nuclear reactor core, industrial gamma irradiators and high radioactive leaks. This work is a part of the development of a high gamma field remote visualization device using commercial surveillance cameras. These cameras are cheap enough to be discarded after the use for some hours of use in an emergency application, some days or some months in routine applications. A radiation shield can be used but it cannot block the camera sight which is the shield weakness. Estimates of the camera and its electronics resistance may be made knowing each component behavior. This knowledge is also used to determine the optical sensor type and the lens material, too. A better approach will be obtained with the commercial cameras working inside a high gamma field, like the one inside of the IPEN Multipurpose Irradiator. The goal of this work is to establish the radiation shielding needed to extend the camera's useful time to hours, days or months, depending on the application needs. (author)

  10. Changing fields of rationality - a policy for change?

    Energy Technology Data Exchange (ETDEWEB)

    Strumse, Einar; Westskog, Hege; Winther, Tanja

    2010-07-01

    Work objective: To analyze effective strategies for changing households' energy consumption based on an interdisciplinary model for understanding change. Methodology: In this paper we develop a conceptual model for understanding individuals' energy consumption. We synthesize insights from anthropology, social psychology and economics grasping perspectives from behaviour to practice and from the Bourdieu's fields to rationality thinking in economics. We use this insight to analyze strategies for change. Abstract: In this paper we analyze effective strategies for changing households' energy consumption based on an interdisciplinary model for understanding change. The model focuses on four main categories for understanding individual consumption: a. Material constraints b. Values and identity c. Norms d. Ability These are the main influencing factors of the individual's consumption level, but in interaction with the corresponding group and the societal levels for the same factors. The model can be illustrated. One combination of factors on all levels constitutes a field of rationality. We claim that an important strategy for changing energy consumption towards sustainability is changing the field of rationality of the individual. Changing of rationality fields would from our point of view initiate reflection which is an important condition for changed behavior. One example of changing of fields is information measures that relates energy consumption to the 'citizen' field rather than the 'consumer' field. Hence, according to our conceptual framework - how policy should be framed (information measures for instance ) would be an important knowledge area for design of effective policy measures. (Author)

  11. The relationship between better-eye and integrated visual field mean deviation and visual disability.

    Science.gov (United States)

    Arora, Karun S; Boland, Michael V; Friedman, David S; Jefferys, Joan L; West, Sheila K; Ramulu, Pradeep Y

    2013-12-01

    To determine the extent of difference between better-eye visual field (VF) mean deviation (MD) and integrated VF (IVF) MD among Salisbury Eye Evaluation (SEE) subjects and a larger group of glaucoma clinic subjects and to assess how those measures relate to objective and subjective measures of ability/performance in SEE subjects. Retrospective analysis of population- and clinic-based samples of adults. A total of 490 SEE and 7053 glaucoma clinic subjects with VF loss (MD ≤-3 decibels [dB] in at least 1 eye). Visual field testing was performed in each eye, and IVF MD was calculated. Differences between better-eye and IVF MD were calculated for SEE and clinic-based subjects. In SEE subjects with VF loss, models were constructed to compare the relative impact of better-eye and IVF MD on driving habits, mobility, self-reported vision-related function, and reading speed. Difference between better-eye and IVF MD and relationship of better-eye and IVF MD with performance measures. The median difference between better-eye and IVF MD was 0.41 dB (interquartile range [IQR], -0.21 to 1.04 dB) and 0.72 dB (IQR, 0.04-1.45 dB) for SEE subjects and clinic-based patients with glaucoma, respectively, with differences of ≥ 2 dB between the 2 MDs observed in 9% and 18% of the groups, respectively. Among SEE subjects with VF loss, both MDs demonstrated similar associations with multiple ability and performance metrics as judged by the presence/absence of a statistically significant association between the MD and the metric, the magnitude of observed associations (odds ratios, rate ratios, or regression coefficients associated with 5-dB decrements in MD), and the extent of variability in the metric explained by the model (R(2)). Similar associations of similar magnitude also were noted for the subgroup of subjects with glaucoma and subjects in whom better-eye and IVF MD differed by ≥ 2 dB. The IVF MD rarely differs from better-eye MD, and similar associations between VF loss and

  12. Changing viewer perspectives reveals constraints to implicit visual statistical learning.

    Science.gov (United States)

    Jiang, Yuhong V; Swallow, Khena M

    2014-10-07

    Statistical learning-learning environmental regularities to guide behavior-likely plays an important role in natural human behavior. One potential use is in search for valuable items. Because visual statistical learning can be acquired quickly and without intention or awareness, it could optimize search and thereby conserve energy. For this to be true, however, visual statistical learning needs to be viewpoint invariant, facilitating search even when people walk around. To test whether implicit visual statistical learning of spatial information is viewpoint independent, we asked participants to perform a visual search task from variable locations around a monitor placed flat on a stand. Unbeknownst to participants, the target was more often in some locations than others. In contrast to previous research on stationary observers, visual statistical learning failed to produce a search advantage for targets in high-probable regions that were stable within the environment but variable relative to the viewer. This failure was observed even when conditions for spatial updating were optimized. However, learning was successful when the rich locations were referenced relative to the viewer. We conclude that changing viewer perspective disrupts implicit learning of the target's location probability. This form of learning shows limited integration with spatial updating or spatiotopic representations. © 2014 ARVO.

  13. Effect of Retinal Nerve Fibre Layer Injury on Visual Field After LASIK for Correction of Myopia

    International Nuclear Information System (INIS)

    Saif, S.E.H.; Bahgat, M.; El'emary, A.T.; Naguib, N.I.; Lotfy, A.A.

    2006-01-01

    This work aimed at clinical assessment of the damage to the retinal nerve fibre layer (RNFL) due to the suction time during LASIK on the visual field of the patients. forty-five patients were subjected to LASIk followed by optic coherence tomography (OCT) and visual field (VF) in this study in the research institute of ophthalmology. clinical assessment will be achieved by using visual perimetry. we concluded that LASIK did not cause visual field defects in the study. actually we were expecting a field defect in the upper, and to a lesser extent, in the lower quadrant but this could be detected by more sophisticated technology

  14. Effect of Retinal Nerve Fibre Layer Injury on Visual Field After LASIK for Correction of Myopia

    Energy Technology Data Exchange (ETDEWEB)

    Saif, S E.H.; Bahgat, M [Ophthalmology dept, Cairo University, Cairo (Egypt); El' emary, A T [Research Institute of Ophthalmology (Egypt); Naguib, N I; Lotfy, A A [National Centre for Rdiation Research and Tecnology (NCRRT), Atomic Energy Authority (AEA), Cairo (Egypt)

    2006-05-15

    This work aimed at clinical assessment of the damage to the retinal nerve fibre layer (RNFL) due to the suction time during LASIK on the visual field of the patients. forty-five patients were subjected to LASIk followed by optic coherence tomography (OCT) and visual field (VF) in this study in the research institute of ophthalmology. clinical assessment will be achieved by using visual perimetry. we concluded that LASIK did not cause visual field defects in the study. actually we were expecting a field defect in the upper, and to a lesser extent, in the lower quadrant but this could be detected by more sophisticated technology.

  15. Visualization system for grid environment in the nuclear field

    International Nuclear Information System (INIS)

    Suzuki, Yoshio; Matsumoto, Nobuko; Idomura, Yasuhiro; Tani, Masayuki

    2006-01-01

    An innovative scientific visualization system is needed to integratedly visualize large amount of data which are distributedly generated in remote locations as a result of a large-scale numerical simulation using a grid environment. One of the important functions in such a visualization system is a parallel visualization which enables to visualize data using multiple CPUs of a supercomputer. The other is a distributed visualization which enables to execute visualization processes using a local client computer and remote computers. We have developed a toolkit including these functions in cooperation with the commercial visualization software AVS/Express, called Parallel Support Toolkit (PST). PST can execute visualization processes with three kinds of parallelism (data parallelism, task parallelism and pipeline parallelism) using local and remote computers. We have evaluated PST for large amount of data generated by a nuclear fusion simulation. Here, two supercomputers Altix3700Bx2 and Prism installed in JAEA are used. From the evaluation, it can be seen that PST has a potential to efficiently visualize large amount of data in a grid environment. (author)

  16. Temporal modulation visual fields, normal aging, Parkinson's disease and methyl-mercury in the James Bay Cree: a feasibility study

    Directory of Open Access Journals (Sweden)

    Jocelyn Faubert

    2003-01-01

    Full Text Available We assessed temporal modulation visual fields (TMFs for 91 observers including controls, Parkinson patients and members of the James Bay Cree community of Northern Québec suspected of being chronically exposed to relatively low levels of methyl-mercury. The main goal was to establish the feasibility of using such procedures to rapidly evaluate visual function in a large field study with the James Bay Cree community. The results show clear normal aging effects on TMFs and the pattern of loss differed depending on the flicker rates used. Group data comparisons between the controls and the experimental groups showed significant effects only between the Cree and normal controls in the 40 to 49 year-old age category for the low temporal frequency condition (2 Hz. Examples of individual analysis shows a Cree observer with severe visual field constriction at the 2 Hz condition with a normal visual field at the 16 Hz condition and a reverse pattern was demonstrated for a Parkinson's patient where a visual field constriction was evident only for the 16 Hz condition. The general conclusions are: Such a technique can be used to evaluate the visual consequences of neuropathological disorders and it may lead to dissociation between certain neurotoxic and neurodegenerative effects depending on the parameters used; this technique can be used for a large field study because it is rapid and easily understood and performed by the subjects; the TMF procedure used showed good test-retest correlations; normal aging causes changes in TMF profiles but the changes will show different patterns throughout the visual field depending on the parameters used.

  17. Lifespan changes in attention revisited: Everyday visual search.

    Science.gov (United States)

    Brennan, Allison A; Bruderer, Alison J; Liu-Ambrose, Teresa; Handy, Todd C; Enns, James T

    2017-06-01

    This study compared visual search under everyday conditions among participants across the life span (healthy participants in 4 groups, with average age of 6 years, 8 years, 22 years, and 75 years, and 1 group averaging 73 years with a history of falling). The task involved opening a door and stepping into a room find 1 of 4 everyday objects (apple, golf ball, coffee can, toy penguin) visible on shelves. The background for this study included 2 well-cited laboratory studies that pointed to different cognitive mechanisms underlying each end of the U-shaped pattern of visual search over the life span (Hommel et al., 2004; Trick & Enns, 1998). The results recapitulated some of the main findings of the laboratory study (e.g., a U-shaped function, dissociable factors for maturation and aging), but there were several unique findings. These included large differences in the baseline salience of common objects at different ages, visual eccentricity effects that were unique to aging, and visual field effects that interacted strongly with age. These findings highlight the importance of studying cognitive processes in more natural settings, where factors such as personal relevance, life history, and bodily contributions to cognition (e.g., limb, head, and body movements) are more readily revealed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  18. Adaptive Kalman filtering for real-time mapping of the visual field

    Science.gov (United States)

    Ward, B. Douglas; Janik, John; Mazaheri, Yousef; Ma, Yan; DeYoe, Edgar A.

    2013-01-01

    This paper demonstrates the feasibility of real-time mapping of the visual field for clinical applications. Specifically, three aspects of this problem were considered: (1) experimental design, (2) statistical analysis, and (3) display of results. Proper experimental design is essential to achieving a successful outcome, particularly for real-time applications. A random-block experimental design was shown to have less sensitivity to measurement noise, as well as greater robustness to error in modeling of the hemodynamic impulse response function (IRF) and greater flexibility than common alternatives. In addition, random encoding of the visual field allows for the detection of voxels that are responsive to multiple, not necessarily contiguous, regions of the visual field. Due to its recursive nature, the Kalman filter is ideally suited for real-time statistical analysis of visual field mapping data. An important feature of the Kalman filter is that it can be used for nonstationary time series analysis. The capability of the Kalman filter to adapt, in real time, to abrupt changes in the baseline arising from subject motion inside the scanner and other external system disturbances is important for the success of clinical applications. The clinician needs real-time information to evaluate the success or failure of the imaging run and to decide whether to extend, modify, or terminate the run. Accordingly, the analytical software provides real-time displays of (1) brain activation maps for each stimulus segment, (2) voxel-wise spatial tuning profiles, (3) time plots of the variability of response parameters, and (4) time plots of activated volume. PMID:22100663

  19. Early event related fields during visually evoked pain anticipation.

    Science.gov (United States)

    Gopalakrishnan, Raghavan; Burgess, Richard C; Plow, Ela B; Floden, Darlene P; Machado, Andre G

    2016-03-01

    Pain experience is not only a function of somatosensory inputs. Rather, it is strongly influenced by cognitive and affective pathways. Pain anticipatory phenomena, an important limitation to rehabilitative efforts in the chronic state, are processed by associative and limbic networks, along with primary sensory cortices. Characterization of neurophysiological correlates of pain anticipation, particularly during very early stages of neural processing is critical for development of therapeutic interventions. Here, we utilized magnetoencephalography to study early event-related fields (ERFs) in healthy subjects exposed to a 3 s visual countdown task that preceded a painful stimulus, a non-painful stimulus or no stimulus. We found that the first countdown cue, but not the last cue, evoked critical ERFs signaling anticipation, attention and alertness to the noxious stimuli. Further, we found that P2 and N2 components were significantly different in response to first-cues that signaled incoming painful stimuli when compared to non-painful or no stimuli. The findings indicate that early ERFs are relevant neural substrates of pain anticipatory phenomena and could be potentially serve as biomarkers. These measures could assist in the development of neurostimulation approaches aimed at curbing the negative effects of pain anticipation during rehabilitation. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  20. Splitting Attention across the Two Visual Fields in Visual Short-Term Memory

    Science.gov (United States)

    Delvenne, Jean-Francois; Holt, Jessica L.

    2012-01-01

    Humans have the ability to attentionally select the most relevant visual information from their extrapersonal world and to retain it in a temporary buffer, known as visual short-term memory (VSTM). Research suggests that at least two non-contiguous items can be selected simultaneously when they are distributed across the two visual hemifields. In…

  1. Homonymous Visual Field Loss and Its Impact on Visual Exploration: A Supermarket Study.

    Science.gov (United States)

    Kasneci, Enkelejda; Sippel, Katrin; Heister, Martin; Aehling, Katrin; Rosenstiel, Wolfgang; Schiefer, Ulrich; Papageorgiou, Elena

    2014-10-01

    Homonymous visual field defects (HVFDs) may critically interfere with quality of life. The aim of this study was to assess the impact of HVFDs on a supermarket search task and to investigate the influence of visual search on task performance. Ten patients with HVFDs (four with a right-sided [HR] and six with a left-sided defect [HL]), and 10 healthy-sighted, sex-, and age-matched control subjects were asked to collect 20 products placed on two supermarket shelves as quickly as possible. Task performance was rated as "passed" or "failed" with regard to the time per correctly collected item ( T C -failed = 4.84 seconds based on the performance of healthy subjects). Eye movements were analyzed regarding the horizontal gaze activity, glance frequency, and glance proportion for different VF areas. Seven of 10 HVFD patients (three HR, four HL) passed the supermarket search task. Patients who passed needed significantly less time per correctly collected item and looked more frequently toward the VFD area than patients who failed. HL patients who passed the test showed a higher percentage of glances beyond the 60° VF ( P < 0.05). A considerable number of HVFD patients performed successfully and could compensate for the HVFD by shifting the gaze toward the peripheral VF and the VFD area. These findings provide new insights on gaze adaptations in patients with HVFDs during activities of daily living and will enhance the design and development of realistic examination tools for use in the clinical setting to improve daily functioning. (http://www.clinicaltrials.gov, NCT01372319, NCT01372332).

  2. Action video game players and deaf observers have larger Goldmann visual fields.

    Science.gov (United States)

    Buckley, David; Codina, Charlotte; Bhardwaj, Palvi; Pascalis, Olivier

    2010-03-05

    We used Goldmann kinetic perimetry to compare how training and congenital auditory deprivation may affect the size of the visual field. We measured the ability of action video game players and deaf observers to detect small moving lights at various locations in the central (around 30 degrees from fixation) and peripheral (around 60 degrees ) visual fields. Experiment 1 found that 10 habitual video game players showed significantly larger central and peripheral field areas than 10 controls. In Experiment 2 we found that 13 congenitally deaf observers had significantly larger visual fields than 13 hearing controls for both the peripheral and central fields. Here the greatest differences were found in the lower parts of the fields. Comparison of the two groups showed that whereas VGP players have a more uniform increase in field size in both central and peripheral fields deaf observers show non-uniform increases with greatest increases in lower parts of the visual field.

  3. MAGNETIC FIELD MEASUREMENTS FOR FAST-CHANGING MAGNETIC FIELDS

    International Nuclear Information System (INIS)

    2004-01-01

    Several recent applications for fast ramped magnets have been found that require rapid measurement of the field quality during the ramp. (In one instance, accelerator dipoles will be ramped at 1 T/sec, with measurements needed to the accuracy typically required for accelerators.) We have built and tested a new type of magnetic field measuring system to meet this need. The system consists of 16 stationary pickup windings mounted on a cylinder. The signals induced in the windings in a changing magnetic field are sampled and analyzed to obtain the field harmonics. To minimize costs, printed circuit boards were used for the pickup windings and a combination of amplifiers and ADPs used for the voltage readout system. New software was developed for the analysis. Magnetic field measurements of a model dipole developed for the SIS200 accelerator at GSI are presented. The measurements are needed to insure that eddy currents induced by the fast ramps do not impact the field quality needed for successful accelerator operation

  4. Callosal Influence on Visual Receptive Fields Has an Ocular, an Orientation-and Direction Bias

    Directory of Open Access Journals (Sweden)

    Sergio A. Conde-Ocazionez

    2018-04-01

    Full Text Available One leading hypothesis on the nature of visual callosal connections (CC is that they replicate features of intrahemispheric lateral connections. However, CC act also in the central part of the binocular visual field. In agreement, early experiments in cats indicated that they provide the ipsilateral eye part of binocular receptive fields (RFs at the vertical midline (Berlucchi and Rizzolatti, 1968, and play a key role in stereoscopic function. But until today callosal inputs to receptive fields activated by one or both eyes were never compared simultaneously, because callosal function has been often studied by cutting or lesioning either corpus callosum or optic chiasm not allowing such a comparison. To investigate the functional contribution of CC in the intact cat visual system we recorded both monocular and binocular neuronal spiking responses and receptive fields in the 17/18 transition zone during reversible deactivation of the contralateral hemisphere. Unexpectedly from many of the previous reports, we observe no change in ocular dominance during CC deactivation. Throughout the transition zone, a majority of RFs shrink, but several also increase in size. RFs are significantly more affected for ipsi- as opposed to contralateral stimulation, but changes are also observed with binocular stimulation. Noteworthy, RF shrinkages are tiny and not correlated to the profound decreases of monocular and binocular firing rates. They depend more on orientation and direction preference than on eccentricity or ocular dominance of the receiving neuron's RF. Our findings confirm that in binocularly viewing mammals, binocular RFs near the midline are constructed via the direct geniculo-cortical pathway. They also support the idea that input from the two eyes complement each other through CC: Rather than linking parts of RFs separated by the vertical meridian, CC convey a modulatory influence, reflecting the feature selectivity of lateral circuits, with a

  5. Confrontation visual field testing in routine ophthalmic practice ...

    African Journals Online (AJOL)

    Results: Two patients had symptoms of headache and visual blurring, galactorrhea and amenorrhea. A right homonymous hemianopia and bitemporal hemianopia respectively were detected on CVF. The 3rd patient complained of visual blurring and bumping into objects following an assault to the head. CVF detected ...

  6. Visual business ecosystem intelligence: lessons from the field.

    Science.gov (United States)

    Basole, Rahul C

    2014-01-01

    Macroscopic insight into business ecosystems is becoming increasingly important. With the emergence of new digital business data, opportunities exist to develop rich, interactive visual-analytics tools. Georgia Institute of Technology researchers have been developing and implementing visual business ecosystem intelligence tools in corporate settings. This article discusses the challenges they faced, the lessons learned, and opportunities for future research.

  7. Gait Implications of Visual Field Damage from Glaucoma.

    Science.gov (United States)

    Mihailovic, Aleksandra; Swenor, Bonnielin K; Friedman, David S; West, Sheila K; Gitlin, Laura N; Ramulu, Pradeep Y

    2017-06-01

    To evaluate fall-relevant gait features in older glaucoma patients. The GAITRite Electronic Walkway was used to define fall-related gait parameters in 239 patients with suspected or manifest glaucoma under normal usual-pace walking conditions and while carrying a cup or tray. Multiple linear regression models assessed the association between gait parameters and integrated visual field (IVF) sensitivity after controlling for age, race, sex, medications, and comorbid illness. Under normal walking conditions, worse IVF sensitivity was associated with a wider base of support (β = 0.60 cm/5 dB IVF sensitivity decrement, 95% confidence interval [CI] = 0.12-1.09, P = 0.016). Worse IVF sensitivity was not associated with slower gait speed, shorter step or stride length, or greater left-right drift under normal walking conditions ( P > 0.05 for all), but was during cup and/or tray carrying conditions ( P < 0.05 for all). Worse IVF sensitivity was positively associated with greater stride-to-stride variability in step length, stride length, and stride velocity ( P < 0.005 for all). Inferior and superior IVF sensitivity demonstrated associations with each of the above gait parameters as well, though these associations were consistently similar to, or weaker than, the associations noted for overall IVF sensitivity. Glaucoma severity was associated with several gait parameters predictive of higher fall risk in prior studies, particularly measures of stride-to-stride variability. Gait may be useful in identifying glaucoma patients at higher risk of falls, and in designing and testing interventions to prevent falls in this high-risk group. These findings could serve to inform the development of the interventions for falls prevention in glaucoma patients.

  8. Visualizing spatial and temporal heterogeneity of single molecule rotational diffusion in a glassy polymer by defocused wide-field imaging

    NARCIS (Netherlands)

    Uji-i, Hiroshi; Melnikov, Sergey M.; Deres, Ania; Bergamini, Giacomo; Schryver, Frans De; Herrmann, Andreas; Müllen, Klaus; Enderlein, Jörg; Hofkens, Johan

    2006-01-01

    Defocused wide-field fluorescence microscopy was used to follow the 3D molecular rotational diffusion of a fluorescent probe molecule in a polymer thin film. The technique allows for visualizing the molecular reorientation both in-plane and out-of-plane. The local environmental change driven by

  9. Perimetric demonstration of spontaneous visual field recovery following occipital lobe haemorrhage.

    Science.gov (United States)

    Lin, Siying; George, Badie Z; Wilson-Holt, Nicholas J

    2013-08-29

    A 45-year-old patient on lifelong warfarin therapy after a metal aortic valve replacement developed a homonymous visual field defect following an occipital lobe haemorrhage. The patient received only conservative management and yet described continued improvement in her visual field defect for up to 20 months following the initial cerebral insult. We present the first conclusive illustrative documentation of visual recovery in a patient with an occipital lobe haemorrhage with sequential automated perimetric assessments over an extended period of time.

  10. Effect of Visual Field Presentation on Action Planning (Estimating Reach) in Children

    Science.gov (United States)

    Gabbard, Carl; Cordova, Alberto

    2012-01-01

    In this article, the authors examined the effects of target information presented in different visual fields (lower, upper, central) on estimates of reach via use of motor imagery in children (5-11 years old) and young adults. Results indicated an advantage for estimating reach movements for targets placed in lower visual field (LoVF), with all…

  11. Active Learning in Neuroscience: A Manipulative to Simulate Visual Field Defects

    Science.gov (United States)

    Li, Andrew Yue-Lin; Carvalho, Helena

    2016-01-01

    Prevalent in 20-57% of stroke patients, visual field defects have been shown to impact quality of life. Studies have shown increased risk of falling, ambulatory difficulties, impaired reading ability, and feelings of panic in crowded or unfamiliar places in patients with visual field defects. Rehabilitation, independence, and mental health may…

  12. Different developmental trajectories across feature types support a dynamic field model of visual working memory development.

    Science.gov (United States)

    Simmering, Vanessa R; Miller, Hilary E; Bohache, Kevin

    2015-05-01

    Research on visual working memory has focused on characterizing the nature of capacity limits as "slots" or "resources" based almost exclusively on adults' performance with little consideration for developmental change. Here we argue that understanding how visual working memory develops can shed new light onto the nature of representations. We present an alternative model, the Dynamic Field Theory (DFT), which can capture effects that have been previously attributed either to "slot" or "resource" explanations. The DFT includes a specific developmental mechanism to account for improvements in both resolution and capacity of visual working memory throughout childhood. Here we show how development in the DFT can account for different capacity estimates across feature types (i.e., color and shape). The current paper tests this account by comparing children's (3, 5, and 7 years of age) performance across different feature types. Results showed that capacity for colors increased faster over development than capacity for shapes. A second experiment confirmed this difference across feature types within subjects, but also showed that the difference can be attenuated by testing memory for less familiar colors. Model simulations demonstrate how developmental changes in connectivity within the model-purportedly arising through experience-can capture differences across feature types.

  13. Comparison of Diagnostic Accuracy between Octopus 900 and Goldmann Kinetic Visual Fields

    Directory of Open Access Journals (Sweden)

    Fiona J. Rowe

    2014-01-01

    Full Text Available Purpose. To determine diagnostic accuracy of kinetic visual field assessment by Octopus 900 perimetry compared with Goldmann perimetry. Methods. Prospective cross section evaluation of 40 control subjects with full visual fields and 50 patients with known visual field loss. Comparison of test duration and area measurement of isopters for Octopus 3, 5, and 10°/sec stimulus speeds. Comparison of test duration and type of visual field classification for Octopus versus Goldmann perimetry. Results were independently graded for presence/absence of field defect and for type and location of defect. Statistical evaluation comprised of ANOVA and paired t test for evaluation of parametric data with Bonferroni adjustment. Bland Altman and Kappa tests were used for measurement of agreement between data. Results. Octopus 5°/sec perimetry had comparable test duration to Goldmann perimetry. Octopus perimetry reliably detected type and location of visual field loss with visual fields matched to Goldmann results in 88.8% of results (K=0.775. Conclusions. Kinetic perimetry requires individual tailoring to ensure accuracy. Octopus perimetry was reproducible for presence/absence of visual field defect. Our screening protocol when using Octopus perimetry is 5°/sec for determining boundaries of peripheral isopters and 3°/sec for blind spot mapping with further evaluation of area of field loss for defect depth and size.

  14. Attention changes perceived size of moving visual patterns.

    Science.gov (United States)

    Anton-Erxleben, Katharina; Henrich, Christian; Treue, Stefan

    2007-08-23

    Spatial attention shifts receptive fields in monkey extrastriate visual cortex toward the focus of attention (S. Ben Hamed, J. R. Duhamel, F. Bremmer, & W. Graf, 2002; C. E. Connor, J. L. Gallant, D. C. Preddie, & D. C. Van Essen, 1996; C. E. Connor, D. C. Preddie, J. L. Gallant, & D. C. Van Essen, 1997; T. Womelsdorf, K. Anton-Erxleben, F. Pieper, & S. Treue, 2006). This distortion in the retinotopic distribution of receptive fields might cause distortions in spatial perception such as an increase of the perceived size of attended stimuli. Here we test for such an effect in human subjects by measuring the point of subjective equality (PSE) for the perceived size of a neutral and an attended stimulus when drawing automatic attention to one of two spatial locations. We found a significant increase in perceived size of attended stimuli. Depending on the absolute stimulus size, this effect ranged from 4% to 12% and was more pronounced for smaller than for larger stimuli. In our experimental design, an attentional effect on task difficulty or a cue bias might influence the PSE measure. We performed control experiments and indeed found such effects, but they could only account for part of the observed results. Our findings demonstrate that the allocation of transient spatial attention onto a visual stimulus increases its perceived size and additionally biases subjects to select this stimulus for a perceptual judgment.

  15. Medical review licensing outcomes in drivers with visual field loss in Victoria, Australia

    Science.gov (United States)

    Muir, Carlyn; Charlton, Judith L; Odell, Morris; Keeffe, Jill; Wood, Joanne; Bohensky, Megan; Fildes, Brian; Oxley, Jennifer; Bentley, Sharon; Rizzo, Matthew

    2017-01-01

    Background Good vision is essential for safe driving and studies have associated visual impairment with an increased crash risk. Currently, there is little information about the medical review of drivers with visual field loss. This study examines the prevalence of visual field loss among drivers referred for medical review in one Australian jurisdiction and investigates factors associated with licence outcome in this group. Methods A random sample of 10,000 (31.25 per cent) medical review cases was extracted for analysis from the Victorian licensing authority. Files were screened for the presence of six visual field-related medical conditions. Data were captured on a range of variables, including referral source, age, gender, health status, crash history and licence outcome. Prevalence analyses were univariate and descriptive. Logistic regression was used to assess factors associated with licence outcomes in the visual field loss group. Results Approximately 1.9 per cent of the 10,000 medical review cases screened had a visual field loss condition identified (n=194). Among the visual field loss group, 57.2 per cent were permitted to continue driving (conditional/unconditional licence). Primary referral sources were the police, self-referrals and general medical practitioners. Key factors associated with licence test outcomes were visual field condition, age group, crash involvement and referral to the Driver Licensing Authority’s Medical Advisors. Those who were younger had a crash involvement triggering referral and those who were referred to the Medical Advisors were more likely to have a positive licensing outcome. Conclusion The evidence base for making licensing decisions is complicated by the variable causes, patterns, progressions and measuring technologies for visual field loss. This study highlighted that the involvement of an expert medical advisory service in Victoria resulted in an increased likelihood that drivers with visual field loss will be

  16. The efficacy of a novel mobile phone application for goldmann ptosis visual field interpretation.

    Science.gov (United States)

    Maamari, Robi N; D'Ambrosio, Michael V; Joseph, Jeffrey M; Tao, Jeremiah P

    2014-01-01

    To evaluate the efficacy of a novel mobile phone application that calculates superior visual field defects on Goldmann visual field charts. Experimental study in which the mobile phone application and 14 oculoplastic surgeons interpreted the superior visual field defect in 10 Goldmann charts. Percent error of the mobile phone application and the oculoplastic surgeons' estimates were calculated compared with computer software computation of the actual defects. Precision and time efficiency of the application were evaluated by processing the same Goldmann visual field chart 10 repeated times. The mobile phone application was associated with a mean percent error of 1.98% (95% confidence interval[CI], 0.87%-3.10%) in superior visual field defect calculation. The average mean percent error of the oculoplastic surgeons' visual estimates was 19.75% (95% CI, 14.39%-25.11%). Oculoplastic surgeons, on average, underestimated the defect in all 10 Goldmann charts. There was high interobserver variance among oculoplastic surgeons. The percent error of the 10 repeated measurements on a single chart was 0.93% (95% CI, 0.40%-1.46%). The average time to process 1 chart was 12.9 seconds (95% CI, 10.9-15.0 seconds). The mobile phone application was highly accurate, precise, and time-efficient in calculating the percent superior visual field defect using Goldmann charts. Oculoplastic surgeon visual interpretations were highly inaccurate, highly variable, and usually underestimated the field vision loss.

  17. MRI of optic tract lesions: Review and correlation with visual field defects

    International Nuclear Information System (INIS)

    Fadzli, F.; Ramli, N.; Ramli, N.M.

    2013-01-01

    Visual field defects are a conglomerate of patterns of visual impairment derived from diseases affecting the optic nerve as it extends from the globe to the visual cortex. They are complex signs requiring perimetry or visual confrontation for delineation and are associated with diverse aetiologies. This review considers the chiasmatic and post-chiasmatic causes of visual disturbances, with an emphasis on magnetic resonance imaging (MRI) techniques. Newer MRI sequences are considered, such as diffusion-tensor imaging. MRI images are correlated with perimetric findings in order to demonstrate localization of lesions in the visual pathway. This may serve as a valuable reference tool to clinicians and radiologists in the early diagnostic process of differentiating causes of various visual field defects in daily practice

  18. Developmental changes in cytosolic coupling between epidermis cells as visualized by photoactivation of fluorescein

    DEFF Research Database (Denmark)

    Liu, Xiangdong; Martens, Helle; Schulz, Alexander

    Developmental changes in cytosolic coupling between epidermis cells as visualized by photoactivation of fluorescein.......Developmental changes in cytosolic coupling between epidermis cells as visualized by photoactivation of fluorescein....

  19. Visualization research of 3D radiation field based on Delaunay triangulation

    International Nuclear Information System (INIS)

    Xie Changji; Chen Yuqing; Li Shiting; Zhu Bo

    2011-01-01

    Based on the characteristics of the three dimensional partition, the triangulation of discrete date sets is improved by the method of point-by-point insertion. The discrete data for the radiation field by theoretical calculation or actual measurement is restructured, and the continuous distribution of the radiation field data is obtained. Finally, the 3D virtual scene of the nuclear facilities is built with the VR simulation techniques, and the visualization of the 3D radiation field is also achieved by the visualization mapping techniques. It is shown that the method combined VR and Delaunay triangulation could greatly improve the quality and efficiency of 3D radiation field visualization. (authors)

  20. Changes of Transient Visual Evoked Potentials in Dyslexic Children

    Directory of Open Access Journals (Sweden)

    Ka Yan Leung

    2011-05-01

    Full Text Available Objectives: To investigate the characteristics of Visual Evoked Potentials (VEP in dyslexics. Methods: Fourteen children, 7 dyslexics and 7 control, aged 7 to 8 years were recruited. All dyslexic subjects were diagnosed by clinical psychologist. All subjects are from mainstream primary schools in Hong Kong, using Chinese and Cantonese as their primary written and spoken language, having normal visual acuity and IQ. Children with reported emotional or behavioral problems or binocular vision problem were excluded. All the subjects participated in pattern-reversal VEP measurements binocularly with 1000msec recording time. Four conditions of stimulations (checkersize: 180 min of arc were applied. (15-Hz at 15% contrast (25-Hz at 1% contrast (315-Hz at 15% contrast (415-Hz at 1% contrast Results: At 15% contrast stimulus, dyslexic subjects showed smaller amplitudes in both frequencies compared with the control group, especially in higher frequency. At 1% contrast stimulus, dyslexic subjects also showed smaller amplitudes in both frequencies and obvious reduction was observed at the later part of the recording period. No observable difference was showed in the latency of both contrast conditions. Conclusion: The attenuated VEP responses in higher frequency at low contrast condition in dyslexic group showed the changes of the transient visual response and this implies an abnormality in magnocellular pathway in dyslexia.

  1. Improved data visualization techniques for analyzing macromolecule structural changes.

    Science.gov (United States)

    Kim, Jae Hyun; Iyer, Vidyashankara; Joshi, Sangeeta B; Volkin, David B; Middaugh, C Russell

    2012-10-01

    The empirical phase diagram (EPD) is a colored representation of overall structural integrity and conformational stability of macromolecules in response to various environmental perturbations. Numerous proteins and macromolecular complexes have been analyzed by EPDs to summarize results from large data sets from multiple biophysical techniques. The current EPD method suffers from a number of deficiencies including lack of a meaningful relationship between color and actual molecular features, difficulties in identifying contributions from individual techniques, and a limited ability to be interpreted by color-blind individuals. In this work, three improved data visualization approaches are proposed as techniques complementary to the EPD. The secondary, tertiary, and quaternary structural changes of multiple proteins as a function of environmental stress were first measured using circular dichroism, intrinsic fluorescence spectroscopy, and static light scattering, respectively. Data sets were then visualized as (1) RGB colors using three-index EPDs, (2) equiangular polygons using radar charts, and (3) human facial features using Chernoff face diagrams. Data as a function of temperature and pH for bovine serum albumin, aldolase, and chymotrypsin as well as candidate protein vaccine antigens including a serine threonine kinase protein (SP1732) and surface antigen A (SP1650) from S. pneumoniae and hemagglutinin from an H1N1 influenza virus are used to illustrate the advantages and disadvantages of each type of data visualization technique. Copyright © 2012 The Protein Society.

  2. The role of hemifield sector analysis in multifocal visual evoked potential objective perimetry in the early detection of glaucomatous visual field defects

    Directory of Open Access Journals (Sweden)

    Mousa MF

    2013-05-01

    % respectively and 89% and 79% in glaucoma suspects. These results showed that the new analysis protocol was able to confirm existing visual field defects detected by standard perimetry, was able to differentiate between the three study groups with a clear distinction between normal patients and those with suspected glaucoma, and was able to detect early visual field changes not detected by standard perimetry. In addition, the distinction between normal and glaucoma patients was especially clear and significant using this analysis.Conclusion: The new hemifield sector analysis protocol used in mfVEP testing can be used to detect glaucomatous visual field defects in both glaucoma and glaucoma suspect patients. Using this protocol, it can provide information about focal visual field differences across the horizontal midline, which can be utilized to differentiate between glaucoma and normal subjects. The sensitivity and specificity of the mfVEP test showed very promising results and correlated with other anatomical changes in glaucomatous visual field loss. The intersector analysis protocol can detect early field changes not detected by the standard Humphrey Field Analyzer test.Keywords: objective perimetry, multifocal VEP, visual field testing, glaucomatous field loss, glaucoma suspect, SAP, HFA

  3. Direct Visualization of Local Electromagnetic Field Structures by Scanning Transmission Electron Microscopy.

    Science.gov (United States)

    Shibata, Naoya; Findlay, Scott D; Matsumoto, Takao; Kohno, Yuji; Seki, Takehito; Sánchez-Santolino, Gabriel; Ikuhara, Yuichi

    2017-07-18

    The functional properties of materials and devices are critically determined by the electromagnetic field structures formed inside them, especially at nanointerface and surface regions, because such structures are strongly associated with the dynamics of electrons, holes and ions. To understand the fundamental origin of many exotic properties in modern materials and devices, it is essential to directly characterize local electromagnetic field structures at such defect regions, even down to atomic dimensions. In recent years, rapid progress in the development of high-speed area detectors for aberration-corrected scanning transmission electron microscopy (STEM) with sub-angstrom spatial resolution has opened new possibilities to directly image such electromagnetic field structures at very high-resolution. In this Account, we give an overview of our recent development of differential phase contrast (DPC) microscopy for aberration-corrected STEM and its application to many materials problems. In recent years, we have developed segmented-type STEM detectors which divide the detector plane into 16 segments and enable simultaneous imaging of 16 STEM images which are sensitive to the positions and angles of transmitted/scattered electrons on the detector plane. These detectors also have atomic-resolution imaging capability. Using these segmented-type STEM detectors, we show DPC STEM imaging to be a very powerful tool for directly imaging local electromagnetic field structures in materials and devices in real space. For example, DPC STEM can clearly visualize the local electric field variation due to the abrupt potential change across a p-n junction in a GaAs semiconductor, which cannot be observed by normal in-focus bright-field or annular type dark-field STEM imaging modes. DPC STEM is also very effective for imaging magnetic field structures in magnetic materials, such as magnetic domains and skyrmions. Moreover, real-time imaging of electromagnetic field structures can

  4. Relationship between progression of visual field defect and intraocular pressure in primary open-angle glaucoma.

    Science.gov (United States)

    Naito, Tomoko; Yoshikawa, Keiji; Mizoue, Shiro; Nanno, Mami; Kimura, Tairo; Suzumura, Hirotaka; Shiraga, Fumio

    2015-01-01

    To analyze the relationship between intraocular pressure (IOP) and the progression of visual field defects in Japanese primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG) patients. The subjects of the study were patients undergoing treatment for POAG or NTG who had performed visual field tests at least ten times with a Humphrey field analyzer (Swedish interactive thresholding algorithm standard, C30-2 program). The progression of visual field defects was defined by a significantly negative value of the mean deviation slope at the final visual field test during the follow-up period. The relationships between the progression of visual field defects and IOP, as well as other clinical factors, were retrospectively analyzed. A total of 156 eyes of 156 patients were included in the analysis. Significant progression of visual field defects was observed in 70 eyes of 70 patients (44.9%), while no significant progression was evident in 86 eyes of 86 patients (55.1%). The eyes with visual field defect progression had significantly lower baseline IOP (Pfield defect progression than in eyes without (Pfield defects. In NTG, IOP management should take into account not only achieving the target IOP, but also minimizing the fluctuation of IOP during follow-up period.

  5. Occipital lobe lesions result in a displacement of magnetoencephalography visual evoked field dipoles.

    Science.gov (United States)

    Pang, Elizabeth W; Chu, Bill H W; Otsubo, Hiroshi

    2014-10-01

    The pattern-reversal visual evoked potential measured electrically from scalp electrodes is known to be decreased, or absent, in patients with occipital lobe lesions. We questioned whether the measurement and source analysis of the neuromagnetic visual evoked field (VEF) might offer additional information regarding visual cortex relative to the occipital lesion. We retrospectively examined 12 children (6-18 years) with occipital lesions on MRI, who underwent magnetoencephalography and ophthalmology as part of their presurgical assessment. Binocular half-field pattern-reversal VEFs were obtained in a 151-channel whole-head magnetoencephalography. Data were averaged and dipole source analyses were performed for each half-field stimulation. A significant lateral shift (P occipital lesions. Magnetoencephalography may be useful as a screening test of visual function in young patients. We discuss potential explanations for this lateral shift and emphasize the utility of adding the magnetoencephalography pattern-reversal visual evoked field protocol to the neurologic work-up.

  6. Visual field tunneling in aviators induced by memory demands.

    Science.gov (United States)

    Williams, L J

    1995-04-01

    Aviators are required rapidly and accurately to process enormous amounts of visual information located foveally and peripherally. The present study, expanding upon an earlier study (Williams, 1988), required young aviators to process within the framework of a single eye fixation a briefly displayed foveally presented memory load while simultaneously trying to identify common peripheral targets presented on the same display at locations up to 4.5 degrees of visual angle from the fixation point. This task, as well as a character classification task (Williams, 1985, 1988), has been shown to be very difficult for nonaviators: It results in a tendency toward tunnel vision. Limited preliminary measurements of peripheral accuracy suggested that aviators might be less susceptible than nonaviators to this visual tunneling. The present study demonstrated moderate susceptibility to cognitively induced tunneling in aviators when the foveal task was sufficiently difficult and reaction time was the principal dependent measure.

  7. Visual marking and change blindness : moving occluders and transient masks neutralize shape changes to ignored objects

    OpenAIRE

    Watson, Derrick G.; Kunar, Melina A.

    2010-01-01

    Visual search efficiency improves by presenting (previewing) one set of distractors before the target and remaining distractor items (D. G. Watson & G. W. Humphreys, 1997). Previous work has shown that this preview benefit is abolished if the old items change their shape when the new items are added (e.g., D. G. Watson & G. W. Humphreys, 2002). Here we present 5 experiments that examined whether such object changes are still effective in recapturing attention if the changes occur while the pr...

  8. Natural course of visual field loss in patients with Type 2 Usher syndrome.

    Science.gov (United States)

    Fishman, Gerald A; Bozbeyoglu, Simge; Massof, Robert W; Kimberling, William

    2007-06-01

    To evaluate the natural course of visual field loss in patients with Type 2 Usher syndrome and different patterns of visual field loss. Fifty-eight patients with Type 2 Usher syndrome who had at least three visual field measurements during a period of at least 3 years were studied. Kinetic visual fields measured on a standard calibrated Goldmann perimeter with II4e and V4e targets were analyzed. The visual field areas in both eyes were determined by planimetry with the use of a digitalizing tablet and computer software and expressed in square inches. The data for each visual field area measurement were transformed to a natural log unit. Using a mixed model regression analysis, values for the half-life of field loss (time during which half of the remaining field area is lost) were estimated. Three different patterns of visual field loss were identified, and the half-life time for each pattern of loss was calculated. Of the 58 patients, 11 were classified as having pattern type I, 12 with pattern type II, and 14 with pattern type III. Of 21 patients whose visual field loss was so advanced that they could not be classified, 15 showed only a small residual central field (Group A) and 6 showed a residual central field with a peripheral island (Group B). The average half-life times varied between 3.85 and 7.37 for the II4e test target and 4.59 to 6.42 for the V4e target. There was no statistically significant difference in the half-life times between the various patterns of field loss or for the test targets. The average half-life times for visual field loss in patients with Usher syndrome Type 2 were statistically similar among those patients with different patterns of visual field loss. These findings will be useful for counseling patients with Type 2 Usher syndrome as to their prognosis for anticipated visual field loss.

  9. A self-organizing model of perisaccadic visual receptive field dynamics in primate visual and oculomotor system.

    Science.gov (United States)

    Mender, Bedeho M W; Stringer, Simon M

    2015-01-01

    We propose and examine a model for how perisaccadic visual receptive field dynamics, observed in a range of primate brain areas such as LIP, FEF, SC, V3, V3A, V2, and V1, may develop through a biologically plausible process of unsupervised visually guided learning. These dynamics are associated with remapping, which is the phenomenon where receptive fields anticipate the consequences of saccadic eye movements. We find that a neural network model using a local associative synaptic learning rule, when exposed to visual scenes in conjunction with saccades, can account for a range of associated phenomena. In particular, our model demonstrates predictive and pre-saccadic remapping, responsiveness shifts around the time of saccades, and remapping from multiple directions.

  10. Recovery of visual-field defects after occipital lobe infarction: a perimetric study.

    Science.gov (United States)

    Çelebisoy, Mehmet; Çelebisoy, Neşe; Bayam, Ece; Köse, Timur

    2011-06-01

    To assess the temporal course of homonymous visual-field defects due to occipital lobe infarction, by using automated perimetry. 32 patients with ischaemic infarction of the occipital lobe were studied prospectively, using a Humphrey Visual Field Analyser II. The visual field of each eye was divided into central, paracentral and peripheral zones. The mean visual sensitivity of each zone was calculated and used for the statistical analysis. The results of the initial examination, performed within 2 weeks of stroke, were compared with the results of the sixth-month control. The lesions were assigned to the localisations, optic radiation, striate cortex, occipital pole and occipital convexity, by MRI. A statistically significant improvement was noted, especially for the lower quadrants. Lesions of the occipital pole and convexity were not significantly associated with visual-field recovery. However, involvement of the striate cortex and extensive lesions involving all the areas studied was significantly associated with poor prognosis. Homonymous visual-field defects in our patients improved within 6 months. Restoration of the lower quadrants and especially the peripheral zones was noted. Incomplete damage to the striate cortex, which has a varying pattern of vascular supply, could explain this finding. Magnification factor theory, which is the increment of the receptive-field size of striate cortex cells with visual-field eccentricity, may explain the more significant improvement in the peripheral zones.

  11. Visual field examination method using virtual reality glasses compared with the Humphrey perimeter

    Directory of Open Access Journals (Sweden)

    Tsapakis S

    2017-08-01

    Full Text Available Stylianos Tsapakis, Dimitrios Papaconstantinou, Andreas Diagourtas, Konstantinos Droutsas, Konstantinos Andreanos, Marilita M Moschos, Dimitrios Brouzas 1st Department of Ophthalmology, National and Kapodistrian University of Athens, Athens, Greece Purpose: To present a visual field examination method using virtual reality glasses and evaluate the reliability of the method by comparing the results with those of the Humphrey perimeter.Materials and methods: Virtual reality glasses, a smartphone with a 6 inch display, and software that implements a fast-threshold 3 dB step staircase algorithm for the central 24° of visual field (52 points were used to test 20 eyes of 10 patients, who were tested in a random and consecutive order as they appeared in our glaucoma department. The results were compared with those obtained from the same patients using the Humphrey perimeter.Results: High correlation coefficient (r=0.808, P<0.0001 was found between the virtual reality visual field test and the Humphrey perimeter visual field.Conclusion: Visual field examination results using virtual reality glasses have a high correlation with the Humphrey perimeter allowing the method to be suitable for probable clinical use. Keywords: visual fields, virtual reality glasses, perimetry, visual fields software, smartphone

  12. Can DMCO Detect Visual Field Loss in Neurological Patients? A Secondary Validation Study

    DEFF Research Database (Denmark)

    Olsen, Ane Sophie; Steensberg, Alvilda Thougaard; la Cour, Morten

    2017-01-01

    Unrecognized visual field loss is caused by a range of blinding eye conditions as well as serious brain diseases. The commonest cause of asymptomatic visual field loss is glaucoma. No screening tools have been proven cost-effective. Damato Multifixation Campimetry Online (DMCO), an inexpensive...... online test, has been evaluated as a future cost-beneficial tool to detect glaucoma. To further validate DMCO, this study aimed to test DMCO in a preselected population with neurological visual field loss. Methods : The study design was an evaluation of a diagnostic test. Patients were included...... if they had undergone surgery for epilepsy during 2011-2014, resulting in visual field loss. They were examined with DMCO and results were compared with those obtained with the Humphrey Field Analyzer (30:2 SITA-Fast). DMCO sensitivity and specificity were estimated with 95% confidence intervals. Results...

  13. Pupillary anomaly masquerading as a glaucomatous visual field defect: a case report

    Directory of Open Access Journals (Sweden)

    Tey Adrian

    2004-06-01

    Full Text Available Abstract Background Patients are often referred to ophthalmologists with focal visual field defects on routine testing, possibly related to a potential diagnosis of glaucoma. However, examination of the individual patient's ocular characteristics as well as facial characteristics may often reveal a cause of the visual field defect. Case presentation We describe a patient who was found to have a superior visual field defect on routine testing by the optician. Repeat perimetry with pharmacological dilatation of the pupil revealed that the cause of the field defect was related to an eccentric inferiorly displaced pupil, secondary to trauma some years previously. Discussion Individual patient characteristics, including both ocular, as well as facial, need to be considered, when interpreting any visual field defect.

  14. TMS over the right precuneus reduces the bilateral field advantage in visual short term memory capacity.

    Science.gov (United States)

    Kraft, Antje; Dyrholm, Mads; Kehrer, Stefanie; Kaufmann, Christian; Bruening, Jovita; Kathmann, Norbert; Bundesen, Claus; Irlbacher, Kerstin; Brandt, Stephan A

    2015-01-01

    Several studies have demonstrated a bilateral field advantage (BFA) in early visual attentional processing, that is, enhanced visual processing when stimuli are spread across both visual hemifields. The results are reminiscent of a hemispheric resource model of parallel visual attentional processing, suggesting more attentional resources on an early level of visual processing for bilateral displays [e.g. Sereno AB, Kosslyn SM. Discrimination within and between hemifields: a new constraint on theories of attention. Neuropsychologia 1991;29(7):659-75.]. Several studies have shown that the BFA extends beyond early stages of visual attentional processing, demonstrating that visual short term memory (VSTM) capacity is higher when stimuli are distributed bilaterally rather than unilaterally. Here we examine whether hemisphere-specific resources are also evident on later stages of visual attentional processing. Based on the Theory of Visual Attention (TVA) [Bundesen C. A theory of visual attention. Psychol Rev 1990;97(4):523-47.] we used a whole report paradigm that allows investigating visual attention capacity variability in unilateral and bilateral displays during navigated repetitive transcranial magnetic stimulation (rTMS) of the precuneus region. A robust BFA in VSTM storage capacity was apparent after rTMS over the left precuneus and in the control condition without rTMS. In contrast, the BFA diminished with rTMS over the right precuneus. This finding indicates that the right precuneus plays a causal role in VSTM capacity, particularly in bilateral visual displays. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Visualizing projected Climate Changes - the CMIP5 Multi-Model Ensemble

    Science.gov (United States)

    Böttinger, Michael; Eyring, Veronika; Lauer, Axel; Meier-Fleischer, Karin

    2017-04-01

    Large ensembles add an additional dimension to climate model simulations. Internal variability of the climate system can be assessed for example by multiple climate model simulations with small variations in the initial conditions or by analyzing the spread in large ensembles made by multiple climate models under common protocols. This spread is often used as a measure of uncertainty in climate projections. In the context of the fifth phase of the WCRP's Coupled Model Intercomparison Project (CMIP5), more than 40 different coupled climate models were employed to carry out a coordinated set of experiments. Time series of the development of integral quantities such as the global mean temperature change for all models visualize the spread in the multi-model ensemble. A similar approach can be applied to 2D-visualizations of projected climate changes such as latitude-longitude maps showing the multi-model mean of the ensemble by adding a graphical representation of the uncertainty information. This has been demonstrated for example with static figures in chapter 12 of the last IPCC report (AR5) using different so-called stippling and hatching techniques. In this work, we focus on animated visualizations of multi-model ensemble climate projections carried out within CMIP5 as a way of communicating climate change results to the scientific community as well as to the public. We take a closer look at measures of robustness or uncertainty used in recent publications suitable for animated visualizations. Specifically, we use the ESMValTool [1] to process and prepare the CMIP5 multi-model data in combination with standard visualization tools such as NCL and the commercial 3D visualization software Avizo to create the animations. We compare different visualization techniques such as height fields or shading with transparency for creating animated visualization of ensemble mean changes in temperature and precipitation including corresponding robustness measures. [1] Eyring, V

  16. Accessibility of shared space for visually impaired persons : A comparative field study

    NARCIS (Netherlands)

    Havik, Else; Steyvers, Franciscus J.J.M.; Kooijman, Aart; Melis, Bart

    Shared Space is a concept that comprises the design and planning process of a public space. There are concerns about the accessibility of Shared Spaces for people who are visually impaired. In a comparative field study, the wayfinding performance of 25 visually impaired persons (VIPs) was observed

  17. Long-term occupational exposure to organic solvents affects color vision, contrast sensitivity and visual fields.

    Directory of Open Access Journals (Sweden)

    Thiago Leiros Costa

    Full Text Available The purpose of this study was to evaluate the visual outcome of chronic occupational exposure to a mixture of organic solvents by measuring color discrimination, achromatic contrast sensitivity and visual fields in a group of gas station workers. We tested 25 workers (20 males and 25 controls with no history of chronic exposure to solvents (10 males. All participants had normal ophthalmologic exams. Subjects had worked in gas stations on an average of 9.6 ± 6.2 years. Color vision was evaluated with the Lanthony D15d and Cambridge Colour Test (CCT. Visual field assessment consisted of white-on-white 24-2 automatic perimetry (Humphrey II-750i. Contrast sensitivity was measured for sinusoidal gratings of 0.2, 0.5, 1.0, 2.0, 5.0, 10.0 and 20.0 cycles per degree (cpd. Results from both groups were compared using the Mann-Whitney U test. The number of errors in the D15d was higher for workers relative to controls (p<0.01. Their CCT color discrimination thresholds were elevated compared to the control group along the protan, deutan and tritan confusion axes (p<0.01, and their ellipse area and ellipticity were higher (p<0.01. Genetic analysis of subjects with very elevated color discrimination thresholds excluded congenital causes for the visual losses. Automated perimetry thresholds showed elevation in the 9°, 15° and 21° of eccentricity (p<0.01 and in MD and PSD indexes (p<0.01. Contrast sensitivity losses were found for all spatial frequencies measured (p<0.01 except for 0.5 cpd. Significant correlation was found between previous working years and deutan axis thresholds (rho = 0.59; p<0.05, indexes of the Lanthony D15d (rho=0.52; p<0.05, perimetry results in the fovea (rho= -0.51; p<0.05 and at 3, 9 and 15 degrees of eccentricity (rho= -0.46; p<0.05. Extensive and diffuse visual changes were found, suggesting that specific occupational limits should be created.

  18. Developmental changes in GABAergic mechanisms in human visual cortex across the lifespan

    Directory of Open Access Journals (Sweden)

    Joshua G A Pinto

    2010-06-01

    Full Text Available Functional maturation of visual cortex is linked with dynamic changes in synaptic expression of GABAergic mechanisms. These include setting the excitation-inhibition balance required for experience-dependent plasticity, as well as, intracortical inhibition underlying development and aging of receptive field properties. Animal studies have shown developmental regulation of GABAergic mechanisms in visual cortex. In this study, we show for the first time how these mechanisms develop in the human visual cortex across the lifespan. We used Western blot analysis of postmortem tissue from human primary visual cortex (n=30, range: 20 days to 80 years to quantify expression of 8 pre- and post-synaptic GABAergic markers. We quantified the inhibitory modulating cannabinoid receptor (CB1, GABA vesicular transporter (VGAT, GABA synthesizing enzymes (GAD65/GAD67, GABAA receptor anchoring protein (Gephyrin, and GABAA receptor subunits (GABAA∝1, GABAA∝2, GABAA∝3. We found a complex pattern of changes, many of which were prolonged and continued well into into the teen, young adult, and even older adult years. These included a monotonic increase or decrease (GABAA∝1, GABAA∝2, a biphasic increase then decrease (GAD65, Gephyrin, or multiple increases and decreases (VGAT, CB1 across the lifespan. Comparing the balances between the pre- and post-synaptic markers we found 3 main transitions (early childhood, early teen years, aging when there were rapid switches in the composition of the GABAergic signaling system, indicating that functioning of the GABAergic system must change as the visual cortex develops and ages. Furthermore, these results provide key information for translating therapies developed in animal models into effective treatments for amblyopia in humans.

  19. The subtlety of simple eyes: the tuning of visual fields to perceptual challenges in birds

    Science.gov (United States)

    Martin, Graham R.

    2014-01-01

    Birds show interspecific variation both in the size of the fields of individual eyes and in the ways that these fields are brought together to produce the total visual field. Variation is found in the dimensions of all main parameters: binocular region, cyclopean field and blind areas. There is a phylogenetic signal with respect to maximum width of the binocular field in that passerine species have significantly broader field widths than non-passerines; broadest fields are found among crows (Corvidae). Among non-passerines, visual fields show considerable variation within families and even within some genera. It is argued that (i) the main drivers of differences in visual fields are associated with perceptual challenges that arise through different modes of foraging, and (ii) the primary function of binocularity in birds lies in the control of bill position rather than in the control of locomotion. The informational function of binocular vision does not lie in binocularity per se (two eyes receiving slightly different information simultaneously about the same objects from which higher-order depth information is extracted), but in the contralateral projection of the visual field of each eye. Contralateral projection ensures that each eye receives information from a symmetrically expanding optic flow-field from which direction of travel and time to contact targets can be extracted, particularly with respect to the control of bill position. PMID:24395967

  20. Enhanced flow field visualization using a flexible animation procedure

    International Nuclear Information System (INIS)

    Marconi, F.; Moretti, G.; Englund, D.C.

    1989-01-01

    A flexible and powerful procedure for transposing computer-generated images onto video tape is used in flowfield visualization. The result is animated sequences which can be used very effectively in the study of both steady and unsteady flows. The key to the procedure is the fact that the images (i.e., frames) of the animated sequence are recorded on the video tapes one at a time after they are created. Thus, the need for a mass storage system is eliminated because after a frame is recorded it is discarded. 7 references

  1. Preschool teaching staff 's opinions on the importance of preschool curricular fields of activities, art genres and visual arts fields

    OpenAIRE

    Zupančič, Tomaž; Mulej, Matjaž; Čagran, Branka

    2017-01-01

    This article presents preschool teachers’ and assistant teachers’ opinions on the importance of selected fields of educational work in kindergartens. The article first highlights the importance of activities expressing artistic creativity within modern curriculums. Then, it presents an empirical study that examines the preschool teachers’ and assistant teachers’ opinions on the importance of the educational fields, art genres, and visual arts fields. In research hypotheses, we presumed that p...

  2. Flow visualization of a low density hypersonic flow field

    International Nuclear Information System (INIS)

    Masson, B.S.; Jumper, E.J.; Walters, E.; Segalman, T.Y.; Founds, N.D.

    1989-01-01

    Characteristics of laser induced iodine fluorescence (LIIF) in low density hypersonic flows are being investigated for use as a diagnostic technique. At low pressures, doppler broadening dominates the iodine absorption profile producing a fluorescence signal that is primarily temperature and velocity dependent. From this dependency, a low pressure flow field has the potential to be mapped for its velocity and temperature fields. The theory for relating iodine emission to the velocity and temperature fields of a hypersonic flow is discussed in this paper. Experimental observations are made of a fluorescencing free expansion and qualitatively related to the theory. 7 refs

  3. Specvis: Free and open-source software for visual field examination.

    Science.gov (United States)

    Dzwiniel, Piotr; Gola, Mateusz; Wójcik-Gryciuk, Anna; Waleszczyk, Wioletta J

    2017-01-01

    Visual field impairment affects more than 100 million people globally. However, due to the lack of the access to appropriate ophthalmic healthcare in undeveloped regions as a result of associated costs and expertise this number may be an underestimate. Improved access to affordable diagnostic software designed for visual field examination could slow the progression of diseases, such as glaucoma, allowing for early diagnosis and intervention. We have developed Specvis, a free and open-source application written in Java programming language that can run on any personal computer to meet this requirement (http://www.specvis.pl/). Specvis was tested on glaucomatous, retinitis pigmentosa and stroke patients and the results were compared to results using the Medmont M700 Automated Static Perimeter. The application was also tested for inter-test intrapersonal variability. The results from both validation studies indicated low inter-test intrapersonal variability, and suitable reliability for a fast and simple assessment of visual field impairment. Specvis easily identifies visual field areas of zero sensitivity and allows for evaluation of its levels throughout the visual field. Thus, Specvis is a new, reliable application that can be successfully used for visual field examination and can fill the gap between confrontation and perimetry tests. The main advantages of Specvis over existing methods are its availability (free), affordability (runs on any personal computer), and reliability (comparable to high-cost solutions).

  4. Normal Threshold Size of Stimuli in Children Using a Game-Based Visual Field Test.

    Science.gov (United States)

    Wang, Yanfang; Ali, Zaria; Subramani, Siddharth; Biswas, Susmito; Fenerty, Cecilia; Henson, David B; Aslam, Tariq

    2017-06-01

    The aim of this study was to demonstrate and explore the ability of novel game-based perimetry to establish normal visual field thresholds in children. One hundred and eighteen children (aged 8.0 ± 2.8 years old) with no history of visual field loss or significant medical history were recruited. Each child had one eye tested using a game-based visual field test 'Caspar's Castle' at four retinal locations 12.7° (N = 118) from fixation. Thresholds were established repeatedly using up/down staircase algorithms with stimuli of varying diameter (luminance 20 cd/m 2 , duration 200 ms, background luminance 10 cd/m 2 ). Relationships between threshold and age were determined along with measures of intra- and intersubject variability. The Game-based visual field test was able to establish threshold estimates in the full range of children tested. Threshold size reduced with increasing age in children. Intrasubject variability and intersubject variability were inversely related to age in children. Normal visual field thresholds were established for specific locations in children using a novel game-based visual field test. These could be used as a foundation for developing a game-based perimetry screening test for children.

  5. Volume of visual field assessed with kinetic perimetry and its application to static perimetry

    Directory of Open Access Journals (Sweden)

    Christoforidis JB

    2011-04-01

    Full Text Available John B ChristoforidisCollege of Medicine, The Ohio State University, Columbus, OH, USABackground: The purpose of this study was to quantify the volume of the kinetic visual field with a single unit that accounts for visual field area and differential luminance sensitivity.Methods: Kinetic visual field perimetry was performed with a Goldmann perimeter using I4e, I3e, I2e, and I1e targets. The visual fields of 25 normal volunteers (17 women, eight men of mean age 33.9 ± 10.1 (range 17–64 years were obtained and digitized. Isopter areas were measured with a method devised to correct cartographic distortion due to polar projection inherent in perimetry and are expressed in steradians. The third dimension of each isopter represents sensitivity to target luminance and was calculated as log (target luminance-1. If luminance is expressed in cd/m2, the values for the third dimension are 0.5 for I4e, 1.0 for I3e, 1.5 for I2e, and 2.0 for I1e. The resulting unit is a steradian (log 103 (cd/m2-1 which is referred to as a Goldmann. In addition, the visual fields of four patients with representative visual defect patterns were examined and compared with normal subjects.Results: Mean isopter areas for normal subjects were 3.092 ± 0.242 steradians for I4e, 2.349 ± 0.280 steradians for I3e, 1.242 ± 0.263 steradians for I2e, and 0.251 ± 0.114 steradians for the I1e target. Isopter volumes were 1.546 ± 0.121 Goldmanns for the I4e target, 1.174 ± 0.140 Goldmanns for I3e, 0.621 ± 0.131 Goldmanns for I2e, and 0.126 ± 0.057 Goldmanns for I1e. The total mean visual field volume in our study for the I target was 3.467 ± 0.371 Goldmanns.Conclusion: The volume of the island of vision may be used to quantify a visual field with a single value which contains information about both visual field extension and differential luminance sensitivity. This technique may be used to assess the progression or stability of visual field defects over time. A similar method may

  6. Tactile search for change has less memory than visual search for change.

    Science.gov (United States)

    Yoshida, Takako; Yamaguchi, Ayumi; Tsutsui, Hideomi; Wake, Tenji

    2015-05-01

    Haptic perception of a 2D image is thought to make heavy demands on working memory. During active exploration, humans need to store the latest local sensory information and integrate it with kinesthetic information from hand and finger locations in order to generate a coherent perception. This tactile integration has not been studied as extensively as visual shape integration. In the current study, we compared working-memory capacity for tactile exploration to that of visual exploration as measured in change-detection tasks. We found smaller memory capacity during tactile exploration (approximately 1 item) compared with visual exploration (2-10 items). These differences generalized to position memory and could not be attributed to insufficient stimulus-exposure durations, acuity differences between modalities, or uncertainty over the position of items. This low capacity for tactile memory suggests that the haptic system is almost amnesic when outside the fingertips and that there is little or no cross-position integration.

  7. Development of Techniques for Visualization of Scalar and Vector Fields in the Immersive Environment

    Science.gov (United States)

    Bidasaria, Hari B.; Wilson, John W.; Nealy, John E.

    2005-01-01

    Visualization of scalar and vector fields in the immersive environment (CAVE - Cave Automated Virtual Environment) is important for its application to radiation shielding research at NASA Langley Research Center. A complete methodology and the underlying software for this purpose have been developed. The developed software has been put to use for the visualization of the earth s magnetic field, and in particular for the study of the South Atlantic Anomaly. The methodology has also been put to use for the visualization of geomagnetically trapped protons and electrons within Earth's magnetosphere.

  8. Comparing artistic and geometrical perspective depictions of space in the visual field.

    Science.gov (United States)

    Baldwin, Joseph; Burleigh, Alistair; Pepperell, Robert

    2014-01-01

    Which is the most accurate way to depict space in our visual field? Linear perspective, a form of geometrical perspective, has traditionally been regarded as the correct method of depicting visual space. But artists have often found it is limited in the angle of view it can depict; wide-angle scenes require uncomfortably close picture viewing distances or impractical degrees of enlargement to be seen properly. Other forms of geometrical perspective, such as fisheye projections, can represent wider views but typically produce pictures in which objects appear distorted. In this study we created an artistic rendering of a hemispherical visual space that encompassed the full visual field. We compared it to a number of geometrical perspective projections of the same space by asking participants to rate which best matched their visual experience. We found the artistic rendering performed significantly better than the geometrically generated projections.

  9. Age-related changes in visual exploratory behavior in a natural scene setting

    Directory of Open Access Journals (Sweden)

    Johanna eHamel

    2013-06-01

    Full Text Available Diverse cognitive functions decline with increasing age, including the ability to process central and peripheral visual information in a laboratory testing situation (useful visual field of view. To investigate whether and how this influences activities of daily life, we studied age-related changes in visual exploratory behavior in a natural scene setting: a driving simulator paradigm of variable complexity was tested in subjects of varying ages with simultaneous eye- and head-movement recordings via a head-mounted camera. Detection and reaction times were also measured by visual fixation and manual reaction. We considered video computer game experience as a possible influence on performance. Data of 73 participants of varying ages were analyzed, driving two different courses. We analyzed the influence of route difficulty level, age and eccentricity of test stimuli on oculomotor and driving behavior parameters. No significant age effects were found regarding saccadic parameters. In the older subjects head-movements increasingly contributed to gaze amplitude. More demanding courses and more peripheral stimuli locations, induced longer reaction times in all age groups. Deterioration of the functionally useful visual field of view with increasing age was not suggested in our study group. However, video game-experienced subjects revealed larger saccade amplitudes and a broader distribution of fixations on the screen. They reacted faster to peripheral objects suggesting the notion of a general detection task rather than perceiving driving as a central task. As the video game experienced population consisted of younger subjects, our study indicates that effects due to video game experience can easily be misinterpreted as age effects if not accounted for. We therefore view it as essential to consider video game experience in all testing methods using virtual media.

  10. Age-related changes in visual exploratory behavior in a natural scene setting.

    Science.gov (United States)

    Hamel, Johanna; De Beukelaer, Sophie; Kraft, Antje; Ohl, Sven; Audebert, Heinrich J; Brandt, Stephan A

    2013-01-01

    Diverse cognitive functions decline with increasing age, including the ability to process central and peripheral visual information in a laboratory testing situation (useful visual field of view). To investigate whether and how this influences activities of daily life, we studied age-related changes in visual exploratory behavior in a natural scene setting: a driving simulator paradigm of variable complexity was tested in subjects of varying ages with simultaneous eye- and head-movement recordings via a head-mounted camera. Detection and reaction times were also measured by visual fixation and manual reaction. We considered video computer game experience as a possible influence on performance. Data of 73 participants of varying ages were analyzed, driving two different courses. We analyzed the influence of route difficulty level, age, and eccentricity of test stimuli on oculomotor and driving behavior parameters. No significant age effects were found regarding saccadic parameters. In the older subjects head-movements increasingly contributed to gaze amplitude. More demanding courses and more peripheral stimuli locations induced longer reaction times in all age groups. Deterioration of the functionally useful visual field of view with increasing age was not suggested in our study group. However, video game-experienced subjects revealed larger saccade amplitudes and a broader distribution of fixations on the screen. They reacted faster to peripheral objects suggesting the notion of a general detection task rather than perceiving driving as a central task. As the video game-experienced population consisted of younger subjects, our study indicates that effects due to video game experience can easily be misinterpreted as age effects if not accounted for. We therefore view it as essential to consider video game experience in all testing methods using virtual media.

  11. Temporal visual field defects are associated with monocular inattention in chiasmal pathology.

    Science.gov (United States)

    Fledelius, Hans C

    2009-11-01

    Chiasmal lesions have been shown to give rise occasionally to uni-ocular temporal inattention, which cannot be compensated for by volitional eye movement. This article describes the assessments of 46 such patients with chiasmal pathology. It aims to determine the clinical spectrum of this disorder, including interference with reading. Retrospective consecutive observational clinical case study over a 7-year period comprising 46 patients with chiasmal field loss of varying degrees. Observation of reading behaviour during monocular visual acuity testing ascertained from consecutive patients who appeared unable to read optotypes on the temporal side of the chart. Visual fields were evaluated by kinetic (Goldmann) and static (Octopus) techniques. Five patients who clearly manifested this condition are presented in more detail. The results of visual field testing were related to absence or presence of uni-ocular visual inattentive behaviour for distance visual acuity testing and/or reading printed text. Despite normal eye movements, the 46 patients making up the clinical series perceived only optotypes in the nasal part of the chart, in one eye or in both, when tested for each eye in turn. The temporal optotypes were ignored, and this behaviour persisted despite instruction to search for any additional letters temporal to those, which had been seen. This phenomenon of unilateral visual inattention held for both eyes in 18 and was unilateral in the remaining 28 patients. Partial or full reversibility after treatment was recorded in 21 of the 39 for whom reliable follow-up data were available. Reading a text was affected in 24 individuals, and permanently so in six. A neglect-like spatial unawareness and a lack of cognitive compensation for varying degrees of temporal visual field loss were present in all the patients observed. Not only is visual field loss a feature of chiasmal pathology, but the higher visual function of affording attention within the temporal visual

  12. The left visual-field advantage in rapid visual presentation is amplified rather than reduced by posterior-parietal rTMS

    DEFF Research Database (Denmark)

    Verleger, Rolf; Möller, Friderike; Kuniecki, Michal

    2010-01-01

    ) either as effective or as sham stimulation. In two experiments, either one of these two factors, hemisphere and effectiveness of rTMS, was varied within or between participants. Again, T2 was much better identified in the left than in the right visual field. This advantage of the left visual field......In the present task, series of visual stimuli are rapidly presented left and right, containing two target stimuli, T1 and T2. In previous studies, T2 was better identified in the left than in the right visual field. This advantage of the left visual field might reflect dominance exerted...... by the right over the left hemisphere. If so, then repetitive transcranial magnetic stimulation (rTMS) to the right parietal cortex might release the left hemisphere from right-hemispheric control, thereby improving T2 identification in the right visual field. Alternatively or additionally, the asymmetry in T2...

  13. Visualizing thesauri in the field of information retrieval

    International Nuclear Information System (INIS)

    Riemer, J.

    2007-01-01

    This thesis was written in the course of an International Atomic Energy Agency (IAEA) project aimed at visualizing the thesaurus used in the International Nuclear Information System (INIS) online database. The first part of the paper comprises a brief historical review of the development of thesauri, providing an overview of tools for categorizing knowledge and covering a spectrum from wordnets to folksonomies. The second part discusses existing strategies for displaying thesauri and explores basic considerations concerning the technical realization of visualizing a thesaurus as a Web application. A problem experienced by users when navigating through hierarchical thesauri is the quasi-standard to display word blocks in tabular form. Starting from a top term all word block terms (e.g. narrower, broader, related, forbidden terms, etc.) are listed vertically. Human perception however is much better suited to grasp relationships by spatial clustering of items within a context. The shortcoming of the tabular approach is further amplified by the widespread practise of putting the top term in alphabetical context to other top terms in order to assist navigation. However, using an alphabetical index for this purpose contradicts the paradigm of hierarchical thesauri in most cases. It is only in the domain of linguistic thesauri where the visualisation deviates from the classical tabular data view in favour of more intuitive visualisation paradigms. Yet in those cases applications always fall back on additional software that needs to be installed into the Web browser. The approach chosen in the present project tries to solve both problem areas and provides an intuitively usable visualisation technique for hierarchical thesauri which runs on any current web browser natively i.e. without any additional software needed. A considerable portion of the publication is devoted to the concrete implementation of the INIS project. Special attention is given to the methodologies and

  14. Research on Visualization Design Method in the Field of New Media Software Engineering

    Science.gov (United States)

    Deqiang, Hu

    2018-03-01

    In the new period of increasingly developed science and technology, with the increasingly fierce competition in the market and the increasing demand of the masses, new design and application methods have emerged in the field of new media software engineering, that is, the visualization design method. Applying the visualization design method to the field of new media software engineering can not only improve the actual operation efficiency of new media software engineering but more importantly the quality of software development can be enhanced by means of certain media of communication and transformation; on this basis, the progress and development of new media software engineering in China are also continuously promoted. Therefore, the application of visualization design method in the field of new media software engineering is analysed concretely in this article from the perspective of the overview of visualization design methods and on the basis of systematic analysis of the basic technology.

  15. High-sensitivity visualization of localized electric fields using low-energy electron beam deflection

    Science.gov (United States)

    Jeong, Samuel; Ito, Yoshikazu; Edwards, Gary; Fujita, Jun-ichi

    2018-06-01

    The visualization of localized electronic charges on nanocatalysts is expected to yield fundamental information about catalytic reaction mechanisms. We have developed a high-sensitivity detection technique for the visualization of localized charges on a catalyst and their corresponding electric field distribution, using a low-energy beam of 1 to 5 keV electrons and a high-sensitivity scanning transmission electron microscope (STEM) detector. The highest sensitivity for visualizing a localized electric field was ∼0.08 V/µm at a distance of ∼17 µm from a localized charge at 1 keV of the primary electron energy, and a weak local electric field produced by 200 electrons accumulated on the carbon nanotube (CNT) apex can be visualized. We also observed that Au nanoparticles distributed on a CNT forest tended to accumulate a certain amount of charges, about 150 electrons, at a ‑2 V bias.

  16. Changing the Learning Curve in Novice Laparoscopists: Incorporating Direct Visualization into the Simulation Training Program.

    Science.gov (United States)

    Dawidek, Mark T; Roach, Victoria A; Ott, Michael C; Wilson, Timothy D

    A major challenge in laparoscopic surgery is the lack of depth perception. With the development and continued improvement of 3D video technology, the potential benefit of restoring 3D vision to laparoscopy has received substantial attention from the surgical community. Despite this, procedures conducted under 2D vision remain the standard of care, and trainees must become proficient in 2D laparoscopy. This study aims to determine whether incorporating 3D vision into a 2D laparoscopic simulation curriculum accelerates skill acquisition in novices. Postgraduate year-1 surgical specialty residents (n = 15) at the Schulich School of Medicine and Dentistry, at Western University were randomized into 1 of 2 groups. The control group practiced the Fundamentals of Laparoscopic Surgery peg-transfer task to proficiency exclusively under standard 2D laparoscopy conditions. The experimental group first practiced peg transfer under 3D direct visualization, with direct visualization of the working field. Upon reaching proficiency, this group underwent a perceptual switch, changing to standard 2D laparoscopy conditions, and once again trained to proficiency. Incorporating 3D direct visualization before training under standard 2D conditions significantly (p learning curves for each respective training protocol. An adaptive learning approach, which incorporates 3D direct visualization into a 2D laparoscopic simulation curriculum, accelerates skill acquisition. This is in contrast to previous work, possibly owing to the proficiency-based methodology employed, and has implications for resource savings in surgical training. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

  17. Clinical study of the visual field defects caused by occipital lobe lesions.

    Science.gov (United States)

    Ogawa, Katsuhiko; Ishikawa, Hiroshi; Suzuki, Yutaka; Oishi, Minoru; Kamei, Satoshi

    2014-01-01

    The central visual field is projected to the region from the occipital tip to the posterior portion of the medial area in the striate cortex. However, central visual field disturbances have not been compared with the location of the lesions in the striate cortex. Thirteen patients with visual field defects caused by partial involvement of the striate cortex were enrolled. The lesions were classified according to their location into the anterior portion, the posterior portion of the medial area, and the occipital tip. Visual field defects were examined by the Goldmann perimetry, the Humphrey perimetry and the auto-plot tangent screen. We defined a defect within the central 10° of vision as a central visual field disturbance. The visual field defects in 13 patients were compared with the location of their lesions in the striate cortex. The medial area was involved in 7 patients with no involvement of the occipital tip. In 2 of them, peripheral homonymous hemianopia without central visual field disturbance was shown, and their lesions were located only in the anterior portion. One patient with a lesion in the posterior portion alone showed incomplete central homonymous hemianopia. Three of 4 patients with lesions located in both the anterior and posterior portions of the medial area showed incomplete central homonymous hemianopia and peripheral homonymous hemianopia. The occipital tip was involved in 6 patients. Five of them had small lesions in the occipital tip alone and showed complete central homonymous hemianopia or quadrantanopia. The other patient with a lesion in the lateral posterior portion and bilateral occipital tip lesions showed bilateral slight peripheral visual field disturbance in addition to complete central homonymous hemianopia on both sides. Lesions in the posterior portion of the medial area as well as the occipital tip caused central visual field disturbance in our study, as indicated in previous reports. Central homonymous hemianopia tended to

  18. Interactive exploratory visualization of 2D vector fields

    NARCIS (Netherlands)

    Isenberg, Tobias; Everts, Maarten H.; Grubert, Jens; Carpendale, Sheelagh

    In this paper we present several techniques to interactively explore representations of 2D vector fields. Through a set of simple hand postures used on large, touch-sensitive displays, our approach allows individuals to custom design glyphs (arrows, lines, etc.) that best reveal patterns of the

  19. The Advanced Glaucoma Intervention Study (AGIS): 12. Baseline risk factors for sustained loss of visual field and visual acuity in patients with advanced glaucoma.

    Science.gov (United States)

    2002-10-01

    To examine the relationships between baseline risk factors and sustained decrease of visual field (SDVF) and sustained decrease of visual acuity (SDVA). Cohort study of participants in the Advanced Glaucoma Intervention Study (AGIS). This multicenter study enrolled patients between 1988 and 1992 and followed them until 2001; 789 eyes of 591 patients with advanced glaucoma were randomly assigned to one of two surgical sequences, argon laser trabeculoplasty (ALT)-trabeculectomy-trabeculectomy (ATT) or trabeculectomy-ALT-trabeculectomy (TAT). This report is based on data from 747 eyes. Eyes were offered the next intervention in the sequence upon failure of the previous intervention. Failure was based on recurrent intraocular pressure elevation, visual field defect, and disk rim criteria. Study visits occurred every 6 months; potential follow-up ranged from 8 to 13 years. For each intervention sequence, Cox multiple regression analyses were used to examine the baseline characteristics for association with two vision outcomes: SDVF and SDVA. The magnitude of the association is measured by the hazard ratio (HR), where HR for binary variables is the relative change in the hazard (or risk) of the outcome in eyes with the factor divided by the hazard in eyes without the factor, and HR for continuous variables is the relative change in the hazard (or risk) of the outcome in eyes with a unit increase in the factor. Characteristics associated with increased SDVF risk in the ATT sequence are: less baseline visual field defect (hazard ratio [HR] = 0.86, P <.001, 95% CI = 0.82-0.90), male gender (HR = 2.23, P <.001, 1.54-3.23), and worse baseline visual acuity (HR = 0.96, P =.001, 0.94-0.98); in the TAT sequence: less baseline visual field defect (HR = 0.93, P =.001, 0.89-0.97) and diabetes (HR = 1.87, P =.007, 1.18-2.97). Characteristics associated with increased SDVA risk in both treatment sequences are better baseline acuity (ATT: HR = 1.05, P <.001, 1.02-1.09; TAT: HR = 1

  20. Visualizing Robustness of Critical Points for 2D Time-Varying Vector Fields

    KAUST Repository

    Wang, B.

    2013-06-01

    Analyzing critical points and their temporal evolutions plays a crucial role in understanding the behavior of vector fields. A key challenge is to quantify the stability of critical points: more stable points may represent more important phenomena or vice versa. The topological notion of robustness is a tool which allows us to quantify rigorously the stability of each critical point. Intuitively, the robustness of a critical point is the minimum amount of perturbation necessary to cancel it within a local neighborhood, measured under an appropriate metric. In this paper, we introduce a new analysis and visualization framework which enables interactive exploration of robustness of critical points for both stationary and time-varying 2D vector fields. This framework allows the end-users, for the first time, to investigate how the stability of a critical point evolves over time. We show that this depends heavily on the global properties of the vector field and that structural changes can correspond to interesting behavior. We demonstrate the practicality of our theories and techniques on several datasets involving combustion and oceanic eddy simulations and obtain some key insights regarding their stable and unstable features. © 2013 The Author(s) Computer Graphics Forum © 2013 The Eurographics Association and Blackwell Publishing Ltd.

  1. Visualizing Robustness of Critical Points for 2D Time-Varying Vector Fields

    KAUST Repository

    Wang, B.; Rosen, P.; Skraba, P.; Bhatia, H.; Pascucci, V.

    2013-01-01

    Analyzing critical points and their temporal evolutions plays a crucial role in understanding the behavior of vector fields. A key challenge is to quantify the stability of critical points: more stable points may represent more important phenomena or vice versa. The topological notion of robustness is a tool which allows us to quantify rigorously the stability of each critical point. Intuitively, the robustness of a critical point is the minimum amount of perturbation necessary to cancel it within a local neighborhood, measured under an appropriate metric. In this paper, we introduce a new analysis and visualization framework which enables interactive exploration of robustness of critical points for both stationary and time-varying 2D vector fields. This framework allows the end-users, for the first time, to investigate how the stability of a critical point evolves over time. We show that this depends heavily on the global properties of the vector field and that structural changes can correspond to interesting behavior. We demonstrate the practicality of our theories and techniques on several datasets involving combustion and oceanic eddy simulations and obtain some key insights regarding their stable and unstable features. © 2013 The Author(s) Computer Graphics Forum © 2013 The Eurographics Association and Blackwell Publishing Ltd.

  2. Characteristics of eye-position gain field populations determine geometry of visual space

    Directory of Open Access Journals (Sweden)

    Sidney R Lehky

    2016-01-01

    Full Text Available We have previously demonstrated differences in eye-position spatial maps for anterior inferotemporal cortex (AIT in the ventral stream and lateral intraparietal cortex (LIP in the dorsal stream, based on population decoding of gaze angle modulations of neural visual responses (i.e., eye-position gain fields. Here we explore the basis of such spatial encoding differences through modeling of gain field characteristics. We created a population of model neurons, each having a different eye-position gain field. This population was used to reconstruct eye-position visual space using multidimensional scaling. As gain field shapes have never been well established experimentally, we examined different functions, including planar, sigmoidal, elliptical, hyperbolic, and mixtures of those functions. All functions successfully recovered positions, indicating weak constraints on allowable gain field shapes. We then used a genetic algorithm to modify the characteristics of model gain field populations until the recovered spatial maps closely matched those derived from monkey neurophysiological data in AIT and LIP. The primary differences found between model AIT and LIP gain fields were that AIT gain fields were more foveally dominated. That is, gain fields in AIT operated on smaller spatial scales and smaller dispersions than in LIP. Thus we show that the geometry of eye-position visual space depends on the population characteristics of gain fields, and that differences in gain field characteristics for different cortical areas may underlie differences in the representation of space.

  3. Using a free software tool for the visualization of complicated electromagnetic fields

    International Nuclear Information System (INIS)

    Murello, A; Milotti, E

    2014-01-01

    Here, we show how a readily available and free scientific visualization program—ParaView—can be used to display electric fields in interesting situations. We give a few examples and specify the individual steps that lead to highly educational representations of the fields. (paper)

  4. Design Improvements on Graded Insulation of Power Transformers Using Transient Electric Field Analysis and Visualization Technique

    OpenAIRE

    Yamashita, Hideo; Nakamae, Eihachiro; Namera, Akihiro; Cingoski, Vlatko; Kitamura, Hideo

    1998-01-01

    This paper deals with design improvements on graded insulation of power transformers using transient electric field analysis and a visualization technique. The calculation method for transient electric field analysis inside a power transformer impressed with impulse voltage is presented: Initially, the concentrated electric network for the power transformer is concentrated by dividing transformer windings into several blocks and by computing the electric circuit parameters.

  5. Visualizing Special Relativity: The Field of An Electric Dipole Moving at Relativistic Speed

    Science.gov (United States)

    Smith, Glenn S.

    2011-01-01

    The electromagnetic field is determined for a time-varying electric dipole moving with a constant velocity that is parallel to its moment. Graphics are used to visualize this field in the rest frame of the dipole and in the laboratory frame when the dipole is moving at relativistic speed. Various phenomena from special relativity are clearly…

  6. Visualizing intramyocardial steam formation with a radiofrequency ablation catheter incorporating near-field ultrasound.

    Science.gov (United States)

    Wright, Matthew; Harks, Erik; Deladi, Szabolcs; Fokkenrood, Steven; Zuo, Fei; Van Dusschoten, Anneke; Kolen, Alexander F; Belt, Harm; Sacher, Frederic; Hocini, Mélèze; Haïssaguerre, Michel; Jaïs, Pierre

    2013-12-01

    Steam pops are a risk of irrigated RF ablation even when limiting power delivery. There is currently no way to predict gas formation during ablation. It would be useful to visualize intramyocardial gas formation prior to a steam pop occurring using near-field ultrasound integrated into a RF ablation catheter. In an in vivo open-chest ovine model (n = 9), 86 lesions were delivered to the epicardial surface of the ventricles. Energy was delivered for 15-60 seconds, to achieve lesions with and without steam pops, based on modeling data. The ultrasound image was compared to a digital audio recording from within the pericardium by a blinded observer. Of 86 lesions, 28 resulted in an audible steam pop. For lesions that resulted in a steam pop compared to those that did not (n = 58), the mean power delivered was 8.0 ± 1.8 W versus 6.7 ± 2.0 W, P = 0.006. A change in US contrast due to gas formation in the tissue occurred in all lesions that resulted in a steam pop. In 4 ablations, a similar change in US contrast was observed in the tissue and RF delivery was stopped; in these cases, no pop occurred. The mean depth of gas formation was 0.9 ± 0.8 mm, which correlated with maximal temperature predicted by modeling. Changes in US contrast occurred 7.6 ± 7.2 seconds before the impedance rise and 7.9 ± 6.2 seconds (0.1-17.0) before an audible pop. Integrated US in an RF ablation catheter is able to visualize gas formation intramyocardially several seconds prior to a steam pop occurring. This technology may help prevent complications arising from steam pops. © 2013 Wiley Periodicals, Inc.

  7. Hawk eyes I: diurnal raptors differ in visual fields and degree of eye movement.

    Directory of Open Access Journals (Sweden)

    Colleen T O'Rourke

    Full Text Available BACKGROUND: Different strategies to search and detect prey may place specific demands on sensory modalities. We studied visual field configuration, degree of eye movement, and orbit orientation in three diurnal raptors belonging to the Accipitridae and Falconidae families. METHODOLOGY/PRINCIPAL FINDINGS: We used an ophthalmoscopic reflex technique and an integrated 3D digitizer system. We found inter-specific variation in visual field configuration and degree of eye movement, but not in orbit orientation. Red-tailed Hawks have relatively small binocular areas (∼33° and wide blind areas (∼82°, but intermediate degree of eye movement (∼5°, which underscores the importance of lateral vision rather than binocular vision to scan for distant prey in open areas. Cooper's Hawks' have relatively wide binocular fields (∼36°, small blind areas (∼60°, and high degree of eye movement (∼8°, which may increase visual coverage and enhance prey detection in closed habitats. Additionally, we found that Cooper's Hawks can visually inspect the items held in the tip of the bill, which may facilitate food handling. American Kestrels have intermediate-sized binocular and lateral areas that may be used in prey detection at different distances through stereopsis and motion parallax; whereas the low degree eye movement (∼1° may help stabilize the image when hovering above prey before an attack. CONCLUSIONS: We conclude that: (a there are between-species differences in visual field configuration in these diurnal raptors; (b these differences are consistent with prey searching strategies and degree of visual obstruction in the environment (e.g., open and closed habitats; (c variations in the degree of eye movement between species appear associated with foraging strategies; and (d the size of the binocular and blind areas in hawks can vary substantially due to eye movements. Inter-specific variation in visual fields and eye movements can influence

  8. Hawk eyes I: diurnal raptors differ in visual fields and degree of eye movement.

    Science.gov (United States)

    O'Rourke, Colleen T; Hall, Margaret I; Pitlik, Todd; Fernández-Juricic, Esteban

    2010-09-22

    Different strategies to search and detect prey may place specific demands on sensory modalities. We studied visual field configuration, degree of eye movement, and orbit orientation in three diurnal raptors belonging to the Accipitridae and Falconidae families. We used an ophthalmoscopic reflex technique and an integrated 3D digitizer system. We found inter-specific variation in visual field configuration and degree of eye movement, but not in orbit orientation. Red-tailed Hawks have relatively small binocular areas (∼33°) and wide blind areas (∼82°), but intermediate degree of eye movement (∼5°), which underscores the importance of lateral vision rather than binocular vision to scan for distant prey in open areas. Cooper's Hawks' have relatively wide binocular fields (∼36°), small blind areas (∼60°), and high degree of eye movement (∼8°), which may increase visual coverage and enhance prey detection in closed habitats. Additionally, we found that Cooper's Hawks can visually inspect the items held in the tip of the bill, which may facilitate food handling. American Kestrels have intermediate-sized binocular and lateral areas that may be used in prey detection at different distances through stereopsis and motion parallax; whereas the low degree eye movement (∼1°) may help stabilize the image when hovering above prey before an attack. We conclude that: (a) there are between-species differences in visual field configuration in these diurnal raptors; (b) these differences are consistent with prey searching strategies and degree of visual obstruction in the environment (e.g., open and closed habitats); (c) variations in the degree of eye movement between species appear associated with foraging strategies; and (d) the size of the binocular and blind areas in hawks can vary substantially due to eye movements. Inter-specific variation in visual fields and eye movements can influence behavioral strategies to visually search for and track prey while

  9. Field visual perspective during autobiographical memory recall is less frequent among patients with schizophrenia.

    Science.gov (United States)

    Potheegadoo, Jevita; Berna, Fabrice; Cuervo-Lombard, Christine; Danion, Jean-Marie

    2013-10-01

    There is growing interest in clinical research regarding the visual perspective adopted during memory retrieval, because it reflects individuals' self-attitude towards their memories of past personal events. Several autobiographical memory deficits, including low specificity of personal memories, have been identified in schizophrenia, but visual perspective during autobiographical memory retrieval has not yet been investigated in patients. The aim of this study was therefore to investigate the visual perspective with which patients visualize themselves when recalling autobiographical memories and to assess the specificity of their memories which is a major determinant of visual perspective. Thirty patients with schizophrenia and 30 matched controls recalled personal events from 4 life periods. After each recall, they were asked to report their visual perspective (Field or Observer) associated with the event. The specificity of their memories was assessed by independent raters. Our results showed that patients reported significantly fewer Field perspectives than comparison participants. Patients' memories, whether recalled with Field or Observer perspectives, were less specific and less detailed. Our results indicate that patients with schizophrenia adopt Field perspectives less frequently than comparison participants, and that this may contribute to a weakened sense of the individual of being an actor of his past events, and hence to a reduced sense of self. They suggest that this may be related to low specificity of memories and that all the important aspects involved in re-experiencing autobiographical events are impaired in patients with schizophrenia. © 2013 Elsevier B.V. All rights reserved.

  10. The Tölz Temporal Topography Study: mapping the visual field across the life span. Part I: the topography of light detection and temporal-information processing.

    Science.gov (United States)

    Poggel, Dorothe A; Treutwein, Bernhard; Calmanti, Claudia; Strasburger, Hans

    2012-08-01

    Temporal performance parameters vary across the visual field. Their topographical distributions relative to each other and relative to basic visual performance measures and their relative change over the life span are unknown. Our goal was to characterize the topography and age-related change of temporal performance. We acquired visual field maps in 95 healthy participants (age: 10-90 years): perimetric thresholds, double-pulse resolution (DPR), reaction times (RTs), and letter contrast thresholds. DPR and perimetric thresholds increased with eccentricity and age; the periphery showed a more pronounced age-related increase than the center. RT increased only slightly and uniformly with eccentricity. It remained almost constant up to the age of 60, a marked change occurring only above 80. Overall, age was a poor predictor of functionality. Performance decline could be explained only in part by the aging of the retina and optic media. In Part II, we therefore examine higher visual and cognitive functions.

  11. [Change settings for visual analyzer of child users of mobile communication: longitudinal study].

    Science.gov (United States)

    Khorseva, N I; Grigor'ev, Iu G; Gorbunova, N V

    2014-01-01

    The paper represents theresults of longitudinal monitoring of the changes in the parameters of simple visual-motor reaction, the visual acuity and the rate of the visual discrimination in the child users of mobile communication, which indicate the multivariability of the possible effects of radiation from mobile phones on the auditory system of children.

  12. Effects of Visual Speech on Early Auditory Evoked Fields - From the Viewpoint of Individual Variance

    Science.gov (United States)

    Yahata, Izumi; Kanno, Akitake; Hidaka, Hiroshi; Sakamoto, Shuichi; Nakasato, Nobukazu; Kawashima, Ryuta; Katori, Yukio

    2017-01-01

    The effects of visual speech (the moving image of the speaker’s face uttering speech sound) on early auditory evoked fields (AEFs) were examined using a helmet-shaped magnetoencephalography system in 12 healthy volunteers (9 males, mean age 35.5 years). AEFs (N100m) in response to the monosyllabic sound /be/ were recorded and analyzed under three different visual stimulus conditions, the moving image of the same speaker’s face uttering /be/ (congruent visual stimuli) or uttering /ge/ (incongruent visual stimuli), and visual noise (still image processed from speaker’s face using a strong Gaussian filter: control condition). On average, latency of N100m was significantly shortened in the bilateral hemispheres for both congruent and incongruent auditory/visual (A/V) stimuli, compared to the control A/V condition. However, the degree of N100m shortening was not significantly different between the congruent and incongruent A/V conditions, despite the significant differences in psychophysical responses between these two A/V conditions. Moreover, analysis of the magnitudes of these visual effects on AEFs in individuals showed that the lip-reading effects on AEFs tended to be well correlated between the two different audio-visual conditions (congruent vs. incongruent visual stimuli) in the bilateral hemispheres but were not significantly correlated between right and left hemisphere. On the other hand, no significant correlation was observed between the magnitudes of visual speech effects and psychophysical responses. These results may indicate that the auditory-visual interaction observed on the N100m is a fundamental process which does not depend on the congruency of the visual information. PMID:28141836

  13. Occipital Proton Magnetic Resonance Spectroscopy ((1)H-MRS) Reveals Normal Metabolite Concentrations in Retinal Visual Field Defects

    NARCIS (Netherlands)

    Boucard, Christine C.; Hoogduin, Johannes M.; van der Grond, Jeroen; Cornelissen, Frans W.

    2007-01-01

    Background. Progressive visual field defects, such as age-related macular degeneration and glaucoma, prevent normal stimulation of visual cortex. We investigated whether in the case of visual field defects, concentrations of metabolites such as N-acetylaspartate (NAA), a marker for degenerative

  14. Effect of Size Change and Brightness Change of Visual Stimuli on Loudness Perception and Pitch Perception of Auditory Stimuli

    Directory of Open Access Journals (Sweden)

    Syouya Tanabe

    2011-10-01

    Full Text Available People obtain a lot of information from visual and auditory sensation on daily life. Regarding the effect of visual stimuli on perception of auditory stimuli, studies of phonological perception and sound localization have been made in great numbers. This study examined the effect of visual stimuli on perception in loudness and pitch of auditory stimuli. We used the image of figures whose size or brightness was changed as visual stimuli, and the sound of pure tone whose loudness or pitch was changed as auditory stimuli. Those visual and auditory stimuli were combined independently to make four types of audio-visual multisensory stimuli for psychophysical experiments. In the experiments, participants judged change in loudness or pitch of auditory stimuli, while they judged the direction of size change or the kind of a presented figure in visual stimuli. Therefore they cannot neglect visual stimuli while they judged auditory stimuli. As a result, perception in loudness and pitch were promoted significantly around their difference limen, when the image was getting bigger or brighter, compared with the case in which the image had no changes. This indicates that perception in loudness and pitch were affected by change in size and brightness of visual stimuli.

  15. Overview of long-term field experiments in Germany - metadata visualization

    Science.gov (United States)

    Muqit Zoarder, Md Abdul; Heinrich, Uwe; Svoboda, Nikolai; Grosse, Meike; Hierold, Wilfried

    2017-04-01

    BonaRes ("soil as a sustainable resource for the bioeconomy") is conducting to collect data and metadata of agricultural long-term field experiments (LTFE) of Germany. It is funded by the German Federal Ministry of Education and Research (BMBF) under the umbrella of the National Research Strategy BioEconomy 2030. BonaRes consists of ten interdisciplinary research project consortia and the 'BonaRes - Centre for Soil Research'. BonaRes Data Centre is responsible for collecting all LTFE data and regarding metadata into an enterprise database upon higher level of security and visualization of the data and metadata through data portal. In the frame of the BonaRes project, we are compiling an overview of long-term field experiments in Germany that is based on a literature review, the results of the online survey and direct contacts with LTFE operators. Information about research topic, contact person, website, experiment setup and analyzed parameters are collected. Based on the collected LTFE data, an enterprise geodatabase is developed and a GIS-based web-information system about LTFE in Germany is also settled. Various aspects of the LTFE, like experiment type, land-use type, agricultural category and duration of experiment, are presented in thematic maps. This information system is dynamically linked to the database, which means changes in the data directly affect the presentation. An easy data searching option using LTFE name, -location or -operators and the dynamic layer selection ensure a user-friendly web application. Dispersion and visualization of the overlapping LTFE points on the overview map are also challenging and we make it automatized at very zoom level which is also a consistent part of this application. The application provides both, spatial location and meta-information of LTFEs, which is backed-up by an enterprise geodatabase, GIS server for hosting map services and Java script API for web application development.

  16. [Correlation of intraocular pressure variation after visual field examination with 24-hour intraocular pressure variations in primary open-angle glaucoma].

    Science.gov (United States)

    Noro, Takahiko; Nakamoto, Kenji; Sato, Makoto; Yasuda, Noriko; Ito, Yoshinori; Ogawa, Shumpei; Nakano, Tadashi; Tsuneoka, Hiroshi

    2014-10-01

    We retrospectively examined intraocular pressure variations after visual field examination in primary open angle glaucoma (POAG), together with its influencing factors and its association with 24-hour intraocular pressure variations. Subjects were 94 eyes (52 POAG patients) subjected to measurements of 24-hour intraocular pressure and of changes in intraocular pressure after visual field examination using a Humphrey Visual Field Analyzer. Subjects were classified into three groups according to the magnitude of variation (large, intermediate and small), and 24-hour intraocular pressure variations were compared among the three groups. Factors influencing intraocular pressure variations after visual field examination and those associated with the large variation group were investigated. Average intraocular pressure variation after visual field examination was -0.28 ± 1.90 (range - 6.0(-) + 5.0) mmHg. No significant influencing factors were identified. The intraocular pressure at 3 a.m. was significantly higher in the large variation group than other two groups (p field examination. Increases in intraocular pressure during the night might be associated with large intraocular pressure variations after visual field examination.

  17. Auditory and visual reaction time and peripheral field of vision in helmet users

    Directory of Open Access Journals (Sweden)

    Abbupillai Adhilakshmi

    2016-12-01

    Full Text Available Background: The incidence of fatal accidents are more in two wheeler drivers compared to four wheeler drivers. Head injury is of serious concern when recovery and prognosis of the patients are warranted, helmets are being used for safety purposes by moped, scooters and motorcycle drivers. Although, helmets are designed with cushioning effect to prevent head injuries but there are evidences of increase risk of neck injuries and reduced peripheral vision and hearing in helmet users. A complete full coverage helmets provide about less than 3 percent restrictions in horizontal peripheral visual field compared to rider without helmet. The standard company patented ergonomically designed helmets which does not affect the peripheral vision neither auditory reaction time. Objective: This pilot study aimed to evaluate the peripheral field of vision and auditory and visual reaction time in a hypertensive, diabetic and healthy male and female in order to have a better insight of protective characteristics of helmet in health and disease. Method: This pilot study carried out on age matched male of one healthy, one hypertensive and one diabetic and female subject of one healthy, one hypertensive and one diabetics. The field of vision was assessed by Lister’s perimeter whereas auditory and visual reaction time was recorded with response analyser. Result : Gender difference was not noted in peripheral field of vision but mild difference was found in auditory reaction time for high frequency and visual reaction time for both red and green colour in healthy control. But lateral and downward peripheral visual field was found reduced whereas auditory and visual reaction time was found increased in both hypertensive and diabetic subject in both sexes. Conclusion: Peripheral vision, auditory reaction time and visual reaction time in hypertensive and diabetics may lead to vulnerable accident. Helmet use has proven to reduce extent of injury in motorcyclist and

  18. GABA(A) receptors in visual and auditory cortex and neural activity changes during basic visual stimulation.

    Science.gov (United States)

    Qin, Pengmin; Duncan, Niall W; Wiebking, Christine; Gravel, Paul; Lyttelton, Oliver; Hayes, Dave J; Verhaeghe, Jeroen; Kostikov, Alexey; Schirrmacher, Ralf; Reader, Andrew J; Northoff, Georg

    2012-01-01

    Recent imaging studies have demonstrated that levels of resting γ-aminobutyric acid (GABA) in the visual cortex predict the degree of stimulus-induced activity in the same region. These studies have used the presentation of discrete visual stimulus; the change from closed eyes to open also represents a simple visual stimulus, however, and has been shown to induce changes in local brain activity and in functional connectivity between regions. We thus aimed to investigate the role of the GABA system, specifically GABA(A) receptors, in the changes in brain activity between the eyes closed (EC) and eyes open (EO) state in order to provide detail at the receptor level to complement previous studies of GABA concentrations. We conducted an fMRI study involving two different modes of the change from EC to EO: an EO and EC block design, allowing the modeling of the haemodynamic response, followed by longer periods of EC and EO to allow the measuring of functional connectivity. The same subjects also underwent [(18)F]Flumazenil PET to measure GABA(A) receptor binding potentials. It was demonstrated that the local-to-global ratio of GABA(A) receptor binding potential in the visual cortex predicted the degree of changes in neural activity from EC to EO. This same relationship was also shown in the auditory cortex. Furthermore, the local-to-global ratio of GABA(A) receptor binding potential in the visual cortex also predicted the change in functional connectivity between the visual and auditory cortex from EC to EO. These findings contribute to our understanding of the role of GABA(A) receptors in stimulus-induced neural activity in local regions and in inter-regional functional connectivity.

  19. Differences between Non-arteritic Anterior Ischemic Optic Neuropathy and Open Angle Glaucoma with Altitudinal Visual Field Defect.

    Science.gov (United States)

    Han, Sangyoun; Jung, Jong Jin; Kim, Ungsoo Samuel

    2015-12-01

    To investigate the differences in retinal nerve fiber layer (RNFL) change and optic nerve head parameters between non-arteritic anterior ischemic optic neuropathy (NAION) and open angle glaucoma (OAG) with altitudinal visual field defect. Seventeen NAION patients and 26 OAG patients were enrolled prospectively. The standard visual field indices (mean deviation, pattern standard deviation) were obtained from the Humphrey visual field test and differences between the two groups were analyzed. Cirrus HD-OCT parameters were used, including optic disc head analysis, average RNFL thickness, and RNFL thickness of each quadrant. The mean deviation and pattern standard deviation were not significantly different between the groups. In the affected eye, although the disc area was similar between the two groups (2.00 ± 0.32 and 1.99 ± 0.33 mm(2), p = 0.586), the rim area of the OAG group was smaller than that of the NAION group (1.26 ± 0.56 and 0.61 ± 0.15 mm(2), respectively, p field defects, optic disc head analysis of not only the affected eye, but also the unaffected eye, by using spectral domain optical coherence tomography may be helpful.

  20. Recognition of emotion in hemifaces presented to the left and right visual fields.

    Science.gov (United States)

    Wedding, D; Cyrus, P

    1986-09-01

    Thirty-two right-handed subjects (16 males and 16 females) participated in a choice reaction time experiment replicating two previous studies which demonstrated the superiority of the left hemisphere in rapidly identifying facial emotion as either positive or negative. Slides of hemifaces split along the vertical axis, showing either positive (happiness, surprise) or negative (anger, disgust, or sadness) affect were presented tachistoscopically to either the left or right visual field. A 2 X 2 X 2 mixed ANOVA revealed main effects for visual field and type of affect. In contrast to earlier studies which presented full face stimuli, presentation of hemifaces produced a strong left visual field advantage and, as expected, positive faces produced faster reaction times than negative faces.

  1. Thickness and clearance visualization based on distance field of 3D objects

    Directory of Open Access Journals (Sweden)

    Masatomo Inui

    2015-07-01

    Full Text Available This paper proposes a novel method for visualizing the thickness and clearance of 3D objects in a polyhedral representation. The proposed method uses the distance field of the objects in the visualization. A parallel algorithm is developed for constructing the distance field of polyhedral objects using the GPU. The distance between a voxel and the surface polygons of the model is computed many times in the distance field construction. Similar sets of polygons are usually selected as close polygons for close voxels. By using this spatial coherence, a parallel algorithm is designed to compute the distances between a cluster of close voxels and the polygons selected by the culling operation so that the fast shared memory mechanism of the GPU can be fully utilized. The thickness/clearance of the objects is visualized by distributing points on the visible surfaces of the objects and painting them with a unique color corresponding to the thickness/clearance values at those points. A modified ray casting method is developed for computing the thickness/clearance using the distance field of the objects. A system based on these algorithms can compute the distance field of complex objects within a few minutes for most cases. After the distance field construction, thickness/clearance visualization at a near interactive rate is achieved.

  2. At technique for visualizing electrostatic fields based on their topological structures

    International Nuclear Information System (INIS)

    Handa, Susumu

    2004-01-01

    In molecular science, visualization techniques based on computer graphics are now well established as a tool to interpret simulation results, since molecules are complicated in the structures and mutual interactions. As a probe to study such molecular interactions, electrostatic fields are considered to be useful. However, since they are given as 3D vector fields having complicated distributions, conventional drawing techniques are inadequate. In this article, a new approach based on topological structures in vector fields is presented to visualize the electrostatic fields of molecules. The scheme is to select regions of interest only from the topological structures of the fields. An example in applications to chemical reactions of an amino acid complex is presented to show how the scheme is used. (author)

  3. Repetitive Transcranial Direct Current Stimulation Induced Excitability Changes of Primary Visual Cortex and Visual Learning Effects-A Pilot Study.

    Science.gov (United States)

    Sczesny-Kaiser, Matthias; Beckhaus, Katharina; Dinse, Hubert R; Schwenkreis, Peter; Tegenthoff, Martin; Höffken, Oliver

    2016-01-01

    Studies on noninvasive motor cortex stimulation and motor learning demonstrated cortical excitability as a marker for a learning effect. Transcranial direct current stimulation (tDCS) is a non-invasive tool to modulate cortical excitability. It is as yet unknown how tDCS-induced excitability changes and perceptual learning in visual cortex correlate. Our study aimed to examine the influence of tDCS on visual perceptual learning in healthy humans. Additionally, we measured excitability in primary visual cortex (V1). We hypothesized that anodal tDCS would improve and cathodal tDCS would have minor or no effects on visual learning. Anodal, cathodal or sham tDCS were applied over V1 in a randomized, double-blinded design over four consecutive days (n = 30). During 20 min of tDCS, subjects had to learn a visual orientation-discrimination task (ODT). Excitability parameters were measured by analyzing paired-stimulation behavior of visual-evoked potentials (ps-VEP) and by measuring phosphene thresholds (PTs) before and after the stimulation period of 4 days. Compared with sham-tDCS, anodal tDCS led to an improvement of visual discrimination learning (p learning effect. For cathodal tDCS, no significant effects on learning or on excitability could be seen. Our results showed that anodal tDCS over V1 resulted in improved visual perceptual learning and increased cortical excitability. tDCS is a promising tool to alter V1 excitability and, hence, perceptual visual learning.

  4. Autonomous visual exploration creates developmental change in familiarity and novelty seeking behaviors

    Directory of Open Access Journals (Sweden)

    Sammy ePerone

    2013-09-01

    Full Text Available What motivates children to radically transform themselves during early development? We addressed this question in the domain of infant visual exploration. Over the first year, infants’ exploration shifts from familiarity to novelty seeking. This shift is delayed in preterm relative to term infants and is stable within individuals over the course of the first year. Laboratory tasks have shed light on the nature of this familiarity-to-novelty shift, but it is not clear what motivates the infant to change her exploratory style. We probed this by letting a Dynamic Neural Field (DNF model of visual exploration develop itself via accumulating experience in a virtual world. We then situated it in a canonical laboratory task. Much like infants, the model exhibited a familiarity-to-novelty shift. When we manipulated the initial conditions of the model, the model’s performance was developmentally delayed much like preterm infants. This delay was overcome by enhancing the model’s experience during development. We also found that the model’s performance was stable at the level of the individual. Our simulations indicate that novelty seeking emerges with no explicit motivational source via the accumulation of visual experience within a complex, dynamical exploratory system.

  5. Cognitive and psychological science insights to improve climate change data visualization

    Science.gov (United States)

    Harold, Jordan; Lorenzoni, Irene; Shipley, Thomas F.; Coventry, Kenny R.

    2016-12-01

    Visualization of climate data plays an integral role in the communication of climate change findings to both expert and non-expert audiences. The cognitive and psychological sciences can provide valuable insights into how to improve visualization of climate data based on knowledge of how the human brain processes visual and linguistic information. We review four key research areas to demonstrate their potential to make data more accessible to diverse audiences: directing visual attention, visual complexity, making inferences from visuals, and the mapping between visuals and language. We present evidence-informed guidelines to help climate scientists increase the accessibility of graphics to non-experts, and illustrate how the guidelines can work in practice in the context of Intergovernmental Panel on Climate Change graphics.

  6. Changes of the Prefrontal EEG (Electroencephalogram) Activities According to the Repetition of Audio-Visual Learning.

    Science.gov (United States)

    Kim, Yong-Jin; Chang, Nam-Kee

    2001-01-01

    Investigates the changes of neuronal response according to a four time repetition of audio-visual learning. Obtains EEG data from the prefrontal (Fp1, Fp2) lobe from 20 subjects at the 8th grade level. Concludes that the habituation of neuronal response shows up in repetitive audio-visual learning and brain hemisphericity can be changed by…

  7. Functional visual fields: a cross-sectional UK study to determine which visual field paradigms best reflect difficulty with mobility function.

    Science.gov (United States)

    Subhi, Hikmat; Latham, Keziah; Myint, Joy; Crossland, Michael

    2017-11-20

    To develop an appropriate method of assessing visual field (VF) loss which reflects its functional consequences, this study aims to determine which method(s) of assessing VF best reflect mobility difficulty. This cross-sectional observational study took place within a single primary care setting. Participants attended a single session at a University Eye Clinic, Cambridge, UK, with data collected by a single researcher (HS), a qualified optometrist. 50 adult participants with peripheral field impairment were recruited for this study. Individuals with conditions not primarily affecting peripheral visual function, such as macular degeneration, were excluded from the study. Participants undertook three custom and one standard binocular VF tests assessing VF to 60°, and also integrated monocular threshold 24-2 visual fields (IVF). Primary VF outcomes were average mean threshold, percentage of stimuli seen and VF area. VF outcomes were compared with self-reported mobility function assessed with the Independent Mobility Questionnaire, and time taken and patient acceptability were also considered. Receiver operating characteristic (ROC) curves determined which tests best predicted difficulty with mobility tasks. Greater VF loss was associated with greater self-reported mobility difficulty with all field paradigms (R 2 0.38-0.48, all Pmobility tasks in ROC analysis. Mean duration of the tests ranged from 1 min 26 s (±9 s) for kinetic assessment to 9 min 23 s (±24 s) for IVF. The binocular VF tests extending to 60° eccentricity all relate similarly to self-reported mobility function, and slightly better than integrated monocular VFs. A kinetic assessment of VF area is quicker than and as effective at predicting mobility function as static threshold assessment. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  8. Facing climate change in forests and fields

    Science.gov (United States)

    Amy Daniels; Nancy Shaw; Dave Peterson; Keith Nislow; Monica Tomosy; Mary Rowland

    2014-01-01

    As a growing body of science shows, climate change impacts on wildlife are already profound - from shifting species' ranges and altering the synchronicity of food sources to changing the availability of water. Such impacts are only expected to increase in the coming decades. As climate change shapes complex, interwoven ecological processes, novel conditions and...

  9. Response bias reveals enhanced attention to inferior visual field in signers of American Sign Language.

    Science.gov (United States)

    Dye, Matthew W G; Seymour, Jenessa L; Hauser, Peter C

    2016-04-01

    Deafness results in cross-modal plasticity, whereby visual functions are altered as a consequence of a lack of hearing. Here, we present a reanalysis of data originally reported by Dye et al. (PLoS One 4(5):e5640, 2009) with the aim of testing additional hypotheses concerning the spatial redistribution of visual attention due to deafness and the use of a visuogestural language (American Sign Language). By looking at the spatial distribution of errors made by deaf and hearing participants performing a visuospatial selective attention task, we sought to determine whether there was evidence for (1) a shift in the hemispheric lateralization of visual selective function as a result of deafness, and (2) a shift toward attending to the inferior visual field in users of a signed language. While no evidence was found for or against a shift in lateralization of visual selective attention as a result of deafness, a shift in the allocation of attention from the superior toward the inferior visual field was inferred in native signers of American Sign Language, possibly reflecting an adaptation to the perceptual demands imposed by a visuogestural language.

  10. Emotion separation is completed early and it depends on visual field presentation.

    Directory of Open Access Journals (Sweden)

    Lichan Liu

    Full Text Available It is now apparent that the visual system reacts to stimuli very fast, with many brain areas activated within 100 ms. It is, however, unclear how much detail is extracted about stimulus properties in the early stages of visual processing. Here, using magnetoencephalography we show that the visual system separates different facial expressions of emotion well within 100 ms after image onset, and that this separation is processed differently depending on where in the visual field the stimulus is presented. Seven right-handed males participated in a face affect recognition experiment in which they viewed happy, fearful and neutral faces. Blocks of images were shown either at the center or in one of the four quadrants of the visual field. For centrally presented faces, the emotions were separated fast, first in the right superior temporal sulcus (STS; 35-48 ms, followed by the right amygdala (57-64 ms and medial pre-frontal cortex (83-96 ms. For faces presented in the periphery, the emotions were separated first in the ipsilateral amygdala and contralateral STS. We conclude that amygdala and STS likely play a different role in early visual processing, recruiting distinct neural networks for action: the amygdala alerts sub-cortical centers for appropriate autonomic system response for fight or flight decisions, while the STS facilitates more cognitive appraisal of situations and links appropriate cortical sites together. It is then likely that different problems may arise when either network fails to initiate or function properly.

  11. The role of awake craniotomy in reducing intraoperative visual field deficits during tumor surgery

    Science.gov (United States)

    Wolfson, Racheal; Soni, Neil; Shah, Ashish H.; Hosein, Khadil; Sastry, Ananth; Bregy, Amade; Komotar, Ricardo J.

    2015-01-01

    Objective: Homonymous hemianopia due to damage to the optic radiations or visual cortex is a possible consequence of tumor resection involving the temporal or occipital lobes. The purpose of this review is to present and analyze a series of studies regarding the use of awake craniotomy (AC) to decrease visual field deficits following neurosurgery. Materials and Methods: A literature search was performed using the Medline and PubMed databases from 1970 and 2014 that compared various uses of AC other than intraoperative motor/somatosensory/language mapping with a focus on visual field mapping. Results: For the 17 patients analyzed in this study, 14 surgeries resulted in quadrantanopia, 1 in hemianopia, and 2 without visual deficits. Overall, patient satisfaction with AC was high, and AC was a means to reduce surgery-related complications and cost related with the procedure. Conclusion AC is a safe and tolerable procedure that can be used effectively to map optic radiations and the visual cortices in order to preserve visual function during resection of tumors infiltrating the temporal and occipital lobes. In the majority of cases, a homonymous hemianopia was prevented and patients were left with a quadrantanopia that did not interfere with daily function. PMID:26396597

  12. Visual Field Defects and Retinal Ganglion Cell Losses in Human Glaucoma Patients

    Science.gov (United States)

    Harwerth, Ronald S.; Quigley, Harry A.

    2007-01-01

    Objective The depth of visual field defects are correlated with retinal ganglion cell densities in experimental glaucoma. This study was to determine whether a similar structure-function relationship holds for human glaucoma. Methods The study was based on retinal ganglion cell densities and visual thresholds of patients with documented glaucoma (Kerrigan-Baumrind, et al.) The data were analyzed by a model that predicted ganglion cell densities from standard clinical perimetry, which were then compared to histologic cell counts. Results The model, without free parameters, produced accurate and relatively precise quantification of ganglion cell densities associated with visual field defects. For 437 sets of data, the unity correlation for predicted vs. measured cell densities had a coefficient of determination of 0.39. The mean absolute deviation of the predicted vs. measured values was 2.59 dB, the mean and SD of the distribution of residual errors of prediction was -0.26 ± 3.22 dB. Conclusions Visual field defects by standard clinical perimetry are proportional to neural losses caused by glaucoma. Clinical Relevance The evidence for quantitative structure-function relationships provides a scientific basis of interpreting glaucomatous neuropathy from visual thresholds and supports the application of standard perimetry to establish the stage of the disease. PMID:16769839

  13. The magnetic source imaging of pattern reversal stimuli of various visual fields

    International Nuclear Information System (INIS)

    Zhang Shuqian; Ye Yufang; Sun Jilin; Wu Jie; Jia Xiuchuan; Li Sumin; Wu Jing; Zhao Huadong; Liu Lianxiang; Wu Yujin

    2006-01-01

    Objective: To have acknowledgement of characteristics of normal volunteers visual evoked fields about full field, vertical half field and quadrant field and their dipole location by magnetoencephalography. Methods: The visual evoked fields of full field, vertical half field and quadrant field were detected with 13 subjects. The latency, dipole strength and dipoles' location on x, y and z axis were analyzed. The exact locations of the dipoles were detected by overlapping on MR images. Results: The isocontour map of M100 of full field stimulation demonstrated two separate sources. The two M100 dipoles had same peak latency and different strength. And for vertical half field and quadrant field stimulation, evoked magnetic fields of M100 distributed contralateral to the stimulated side. The M100 dipoles on the z-axis to the lower quadrant field stimulation were located significantly higher than those to the upper quadrant field stimulation. The Z value median of left upper quadrant was 49.6 (35.1-72.8) mm. The Z value median of left lower quadrant was 53.5 (44.8-76.3) mm. The different of two left quadrant medians, 3.9 mm, was significant (P<0.05). The Z value median of right upper quadrant was 40.0 (34.8-44.6) mm. The Z value median of right lower quadrant was 53.8 (40.6-61.3) mm. The different of two right quadrant medians, 13.8 mm, was also significant (P<0.05). Although each of the visual evoked fields waveforms and dipole locations demonstrated large intra- and inter-individual variations, the dipole of M100 was mainly located at area Brodmann 17, which includes superior lingual gyrus, posterior cuneus-lingual gyrus and inferior cuneus gyms. Conclusion: The M100 of visual evoked fields of pattern reversal stimulation is mainly generated by the neurons of striate cortex of contralateral to the stimulated side, which is at the lateral bottom of the calcarine fissure. (authors)

  14. Clinical evaluation of a novel population-based regression analysis for detecting glaucomatous visual field progression.

    Science.gov (United States)

    Kovalska, M P; Bürki, E; Schoetzau, A; Orguel, S F; Orguel, S; Grieshaber, M C

    2011-04-01

    The distinction of real progression from test variability in visual field (VF) series may be based on clinical judgment, on trend analysis based on follow-up of test parameters over time, or on identification of a significant change related to the mean of baseline exams (event analysis). The aim of this study was to compare a new population-based method (Octopus field analysis, OFA) with classic regression analyses and clinical judgment for detecting glaucomatous VF changes. 240 VF series of 240 patients with at least 9 consecutive examinations available were included into this study. They were independently classified by two experienced investigators. The results of such a classification served as a reference for comparison for the following statistical tests: (a) t-test global, (b) r-test global, (c) regression analysis of 10 VF clusters and (d) point-wise linear regression analysis. 32.5 % of the VF series were classified as progressive by the investigators. The sensitivity and specificity were 89.7 % and 92.0 % for r-test, and 73.1 % and 93.8 % for the t-test, respectively. In the point-wise linear regression analysis, the specificity was comparable (89.5 % versus 92 %), but the sensitivity was clearly lower than in the r-test (22.4 % versus 89.7 %) at a significance level of p = 0.01. A regression analysis for the 10 VF clusters showed a markedly higher sensitivity for the r-test (37.7 %) than the t-test (14.1 %) at a similar specificity (88.3 % versus 93.8 %) for a significant trend (p = 0.005). In regard to the cluster distribution, the paracentral clusters and the superior nasal hemifield progressed most frequently. The population-based regression analysis seems to be superior to the trend analysis in detecting VF progression in glaucoma, and may eliminate the drawbacks of the event analysis. Further, it may assist the clinician in the evaluation of VF series and may allow better visualization of the correlation between function and structure owing to VF

  15. Seeing without the Occipito-Parietal Cortex: Simultagnosia as a Shrinkage of the Attentional Visual Field

    Directory of Open Access Journals (Sweden)

    François Michel

    2004-01-01

    Full Text Available Following bi-parietal lesions patient AT showed a severe inability to relocate her attention within a visual field which perimetry proved to be near-normal. An experimental approach with tasks testing visuo-spatial attention demonstrated a shrinkage of A.T.’s attentional visual field. With her visual attention narrowed to a kind of functional tunnel vision, the patient exhibited simultanagnosia (Wolpert, 1924, a symptom previously described in 1909 by Balint under the label of Psychic paralysis of “Gaze”. In striking contrast AT showed an efficient and effortless perception of complex natural scenes, which, according to recent work in normal subjects, necessitate few if any attentional resources.

  16. Who Should Be Served? A Dilemma in the Field of Blindness and Visual Impairment

    Science.gov (United States)

    Pogrund, Rona L.

    2017-01-01

    As much as the field of visual impairment has advanced over the last half century and as growing populations of children and adults continue to be served by its practitioners, the issue of personnel shortages to meet the diverse needs of students and consumers seems to continue. More vision professionals are being trained than ever, but it seems…

  17. Visual field defect as a presenting sign for hemorrhagic stroke caused by sildenafil

    Directory of Open Access Journals (Sweden)

    Mehdizadeh Morteza

    2008-01-01

    Full Text Available Herein, we describe the presenting symptoms, history, ophthalmic examination, visual fields and brain magnetic resonance imaging of a patient who developed left homonymous hemianopia due to right occipital lobe hemorrhage after ingestion of sildenafil citrate (Novagra Forte. To the best of our knowledge, association of homonymous hemianopia with sildenafil usage has not been reported before.

  18. Difficulties in daily life reported by patients with homonymous visual field defects

    NARCIS (Netherlands)

    Heutink, Jochem; de Haan, Gera; Melis-Dankers, Bart; Brouwer, Wiebo; Tucha, Oliver

    2015-01-01

    Background: Homonymous visual field defects (HVFDs) are a common consequence of posterior brain injury and may have a substantial influence on ADL and participation in society. In this study we analysed self-reported visionrelated difficulties in daily life in a group of patients with HVFDs.

  19. The effect of internal and external fields of view on visually induced motion sickness

    NARCIS (Netherlands)

    Bos, J.E.; Vries, S.C. de; Emmerik, M.L. van; Groen, E.L.

    2010-01-01

    Field of view (FOV) is said to affect visually induced motion sickness. FOV, however, is characterized by an internal setting used by the graphics generator (iFOV) and an external factor determined by screen size and viewing distance (eFOV). We hypothesized that especially the incongruence between

  20. Swivel arm perimeter for visual field testing in different body positions.

    Science.gov (United States)

    Flammer, J; Hendrickson, P; Lietz, A; Stümpfig, D

    1993-01-01

    To investigate the influence of body position on visual field results, a 'swivel arm perimeter' was built, based on a modified Octopus 1-2-3. Here, the measuring unit was detected from the control unit and mounted on a swivel arm, allowing its movement in all directions. The first results obtained with this device have indicated that its development was worthwhile.

  1. Testing a Conceptual Change Model Framework for Visual Data

    Science.gov (United States)

    Finson, Kevin D.; Pedersen, Jon E.

    2015-01-01

    An emergent data analysis technique was employed to test the veracity of a conceptual framework constructed around visual data use and instruction in science classrooms. The framework incorporated all five key components Vosniadou (2007a, 2007b) described as existing in a learner's schema: framework theory, presuppositions, conceptual domains,…

  2. Changing Perspective: Zooming in and out during Visual Search

    Science.gov (United States)

    Solman, Grayden J. F.; Cheyne, J. Allan; Smilek, Daniel

    2013-01-01

    Laboratory studies of visual search are generally conducted in contexts with a static observer vantage point, constrained by a fixation cross or a headrest. In contrast, in many naturalistic search settings, observers freely adjust their vantage point by physically moving through space. In two experiments, we evaluate behavior during free vantage…

  3. Changes in brain morphology in albinism reflect reduced visual acuity.

    Science.gov (United States)

    Bridge, Holly; von dem Hagen, Elisabeth A H; Davies, George; Chambers, Claire; Gouws, Andre; Hoffmann, Michael; Morland, Antony B

    2014-07-01

    Albinism, in humans and many animal species, has a major impact on the visual system, leading to reduced acuity, lack of binocular function and nystagmus. In addition to the lack of a foveal pit, there is a disruption to the routing of the nerve fibers crossing at the optic chiasm, resulting in excessive crossing of fibers to the contralateral hemisphere. However, very little is known about the effect of this misrouting on the structure of the post-chiasmatic visual pathway, and the occipital lobes in particular. Whole-brain analyses of cortical thickness in a large cohort of subjects with albinism showed an increase in cortical thickness, relative to control subjects, particularly in posterior V1, corresponding to the foveal representation. Furthermore, mean cortical thickness across entire V1 was significantly greater in these subjects compared to controls and negatively correlated with visual acuity in albinism. Additionally, the group with albinism showed decreased gyrification in the left ventral occipital lobe. While the increase in cortical thickness in V1, also found in congenitally blind subjects, has been interpreted to reflect a lack of pruning, the decreased gyrification in the ventral extrastriate cortex may reflect the reduced input to the foveal regions of the ventral visual stream. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Real-time visualization and analysis of airflow field by use of digital holography

    Science.gov (United States)

    Di, Jianglei; Wu, Bingjing; Chen, Xin; Liu, Junjiang; Wang, Jun; Zhao, Jianlin

    2013-04-01

    The measurement and analysis of airflow field is very important in fluid dynamics. For airflow, smoke particles can be added to visually observe the turbulence phenomena by particle tracking technology, but the effect of smoke particles to follow the high speed airflow will reduce the measurement accuracy. In recent years, with the advantage of non-contact, nondestructive, fast and full-field measurement, digital holography has been widely applied in many fields, such as deformation and vibration analysis, particle characterization, refractive index measurement, and so on. In this paper, we present a method to measure the airflow field by use of digital holography. A small wind tunnel model made of acrylic glass is built to control the velocity and direction of airflow. Different shapes of samples such as aircraft wing and cylinder are placed in the wind tunnel model to produce different forms of flow field. With a Mach-Zehnder interferometer setup, a series of digital holograms carrying the information of airflow filed distributions in different states are recorded by CCD camera and corresponding holographic images are numerically reconstructed from the holograms by computer. Then we can conveniently obtain the velocity or pressure information of the airflow deduced from the quantitative phase information of holographic images and visually display the airflow filed and its evolution in the form of a movie. The theory and experiment results show that digital holography is a robust and feasible approach for real-time visualization and analysis of airflow field.

  5. Visually Evoked Visual-Auditory Changes Associated with Auditory Performance in Children with Cochlear Implants

    Directory of Open Access Journals (Sweden)

    Maojin Liang

    2017-10-01

    Full Text Available Activation of the auditory cortex by visual stimuli has been reported in deaf children. In cochlear implant (CI patients, a residual, more intense cortical activation in the frontotemporal areas in response to photo stimuli was found to be positively associated with poor auditory performance. Our study aimed to investigate the mechanism by which visual processing in CI users activates the auditory-associated cortex during the period after cochlear implantation as well as its relation to CI outcomes. Twenty prelingually deaf children with CI were recruited. Ten children were good CI performers (GCP and ten were poor (PCP. Ten age- and sex- matched normal-hearing children were recruited as controls, and visual evoked potentials (VEPs were recorded. The characteristics of the right frontotemporal N1 component were analyzed. In the prelingually deaf children, higher N1 amplitude was observed compared to normal controls. While the GCP group showed significant decreases in N1 amplitude, and source analysis showed the most significant decrease in brain activity was observed in the primary visual cortex (PVC, with a downward trend in the primary auditory cortex (PAC activity, but these did not occur in the PCP group. Meanwhile, higher PVC activation (comparing to controls before CI use (0M and a significant decrease in source energy after CI use were found to be related to good CI outcomes. In the GCP group, source energy decreased in the visual-auditory cortex with CI use. However, no significant cerebral hemispheric dominance was found. We supposed that intra- or cross-modal reorganization and higher PVC activation in prelingually deaf children may reflect a stronger potential ability of cortical plasticity. Brain activity evolution appears to be related to CI auditory outcomes.

  6. Visually Evoked Visual-Auditory Changes Associated with Auditory Performance in Children with Cochlear Implants.

    Science.gov (United States)

    Liang, Maojin; Zhang, Junpeng; Liu, Jiahao; Chen, Yuebo; Cai, Yuexin; Wang, Xianjun; Wang, Junbo; Zhang, Xueyuan; Chen, Suijun; Li, Xianghui; Chen, Ling; Zheng, Yiqing

    2017-01-01

    Activation of the auditory cortex by visual stimuli has been reported in deaf children. In cochlear implant (CI) patients, a residual, more intense cortical activation in the frontotemporal areas in response to photo stimuli was found to be positively associated with poor auditory performance. Our study aimed to investigate the mechanism by which visual processing in CI users activates the auditory-associated cortex during the period after cochlear implantation as well as its relation to CI outcomes. Twenty prelingually deaf children with CI were recruited. Ten children were good CI performers (GCP) and ten were poor (PCP). Ten age- and sex- matched normal-hearing children were recruited as controls, and visual evoked potentials (VEPs) were recorded. The characteristics of the right frontotemporal N1 component were analyzed. In the prelingually deaf children, higher N1 amplitude was observed compared to normal controls. While the GCP group showed significant decreases in N1 amplitude, and source analysis showed the most significant decrease in brain activity was observed in the primary visual cortex (PVC), with a downward trend in the primary auditory cortex (PAC) activity, but these did not occur in the PCP group. Meanwhile, higher PVC activation (comparing to controls) before CI use (0M) and a significant decrease in source energy after CI use were found to be related to good CI outcomes. In the GCP group, source energy decreased in the visual-auditory cortex with CI use. However, no significant cerebral hemispheric dominance was found. We supposed that intra- or cross-modal reorganization and higher PVC activation in prelingually deaf children may reflect a stronger potential ability of cortical plasticity. Brain activity evolution appears to be related to CI auditory outcomes.

  7. Population receptive field (pRF) measurements of chromatic responses in human visual cortex using fMRI.

    Science.gov (United States)

    Welbourne, Lauren E; Morland, Antony B; Wade, Alex R

    2018-02-15

    The spatial sensitivity of the human visual system depends on stimulus color: achromatic gratings can be resolved at relatively high spatial frequencies while sensitivity to isoluminant color contrast tends to be more low-pass. Models of early spatial vision often assume that the receptive field size of pattern-sensitive neurons is correlated with their spatial frequency sensitivity - larger receptive fields are typically associated with lower optimal spatial frequency. A strong prediction of this model is that neurons coding isoluminant chromatic patterns should have, on average, a larger receptive field size than neurons sensitive to achromatic patterns. Here, we test this assumption using functional magnetic resonance imaging (fMRI). We show that while spatial frequency sensitivity depends on chromaticity in the manner predicted by behavioral measurements, population receptive field (pRF) size measurements show no such dependency. At any given eccentricity, the mean pRF size for neuronal populations driven by luminance, opponent red/green and S-cone isolating contrast, are identical. Changes in pRF size (for example, an increase with eccentricity and visual area hierarchy) are also identical across the three chromatic conditions. These results suggest that fMRI measurements of receptive field size and spatial resolution can be decoupled under some circumstances - potentially reflecting a fundamental dissociation between these parameters at the level of neuronal populations. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  8. End-to-End Flow Control for Visual-Haptic Communication under Bandwidth Change

    Science.gov (United States)

    Yashiro, Daisuke; Tian, Dapeng; Yakoh, Takahiro

    This paper proposes an end-to-end flow controller for visual-haptic communication. A visual-haptic communication system transmits non-real-time packets, which contain large-size visual data, and real-time packets, which contain small-size haptic data. When the transmission rate of visual data exceeds the communication bandwidth, the visual-haptic communication system becomes unstable owing to buffer overflow. To solve this problem, an end-to-end flow controller is proposed. This controller determines the optimal transmission rate of visual data on the basis of the traffic conditions, which are estimated by the packets for haptic communication. Experimental results confirm that in the proposed method, a short packet-sending interval and a short delay are achieved under bandwidth change, and thus, high-precision visual-haptic communication is realized.

  9. Collision avoidance in persons with homonymous visual field defects under virtual reality conditions.

    Science.gov (United States)

    Papageorgiou, Eleni; Hardiess, Gregor; Ackermann, Hermann; Wiethoelter, Horst; Dietz, Klaus; Mallot, Hanspeter A; Schiefer, Ulrich

    2012-01-01

    The aim of the present study was to examine the effect of homonymous visual field defects (HVFDs) on collision avoidance of dynamic obstacles at an intersection under virtual reality (VR) conditions. Overall performance was quantitatively assessed as the number of collisions at a virtual intersection at two difficulty levels. HVFDs were assessed by binocular semi-automated kinetic perimetry within the 90° visual field, stimulus III4e and the area of sparing within the affected hemifield (A-SPAR in deg(2)) was calculated. The effect of A-SPAR, age, gender, side of brain lesion, time since brain lesion and presence of macular sparing on the number of collisions, as well as performance over time were investigated. Thirty patients (10 female, 20 male, age range: 19-71 years) with HVFDs due to unilateral vascular brain lesions and 30 group-age-matched subjects with normal visual fields were examined. The mean number of collisions was higher for patients and in the more difficult level they experienced more collisions with vehicles approaching from the blind side than the seeing side. Lower A-SPAR and increasing age were associated with decreasing performance. However, in agreement with previous studies, wide variability in performance among patients with identical visual field defects was observed and performance of some patients was similar to that of normal subjects. Both patients and healthy subjects displayed equal improvement of performance over time in the more difficult level. In conclusion, our results suggest that visual-field related parameters per se are inadequate in predicting successful collision avoidance. Individualized approaches which also consider compensatory strategies by means of eye and head movements should be introduced. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Relationship among visual field, blood flow, and neural structure measurements in glaucoma.

    Science.gov (United States)

    Hwang, John C; Konduru, Ranjith; Zhang, Xinbo; Tan, Ou; Francis, Brian A; Varma, Rohit; Sehi, Mitra; Greenfield, David S; Sadda, Srinivas R; Huang, David

    2012-05-17

    To determine the relationship among visual field, neural structural, and blood flow measurements in glaucoma. Case-control study. Forty-seven eyes of 42 patients with perimetric glaucoma were age-matched with 27 normal eyes of 27 patients. All patients underwent Doppler Fourier-domain optical coherence tomography to measure retinal blood flow and standard glaucoma evaluation with visual field testing and quantitative structural imaging. Linear regression analysis was performed to analyze the relationship among visual field, blood flow, and structure, after all variables were converted to logarithmic decibel scale. Retinal blood flow was reduced in glaucoma eyes compared to normal eyes (P flow and structural loss of rim area and retinal nerve fiber layer (RNFL). There was no correlation or paradoxical correlation between blood flow and structure. Multivariate regression analysis revealed that reduced blood flow and structural loss are independent predictors of visual field loss. Each dB decrease in blood flow was associated with at least 1.62 dB loss in mean deviation (P ≤ 0.001), whereas each dB decrease in rim area and RNFL was associated with 1.15 dB and 2.56 dB loss in mean deviation, respectively (P ≤ 0.03). There is a close link between reduced retinal blood flow and visual field loss in glaucoma that is largely independent of structural loss. Further studies are needed to elucidate the causes of the vascular dysfunction and potential avenues for therapeutic intervention. Blood flow measurement may be useful as an independent assessment of glaucoma severity.

  11. Evaluation of Visual Field and Imaging Outcomes for Glaucoma Clinical Trials (An American Ophthalomological Society Thesis).

    Science.gov (United States)

    Garway-Heath, David F; Quartilho, Ana; Prah, Philip; Crabb, David P; Cheng, Qian; Zhu, Haogang

    2017-08-01

    To evaluate the ability of various visual field (VF) analysis methods to discriminate treatment groups in glaucoma clinical trials and establish the value of time-domain optical coherence tomography (TD OCT) imaging as an additional outcome. VFs and retinal nerve fibre layer thickness (RNFLT) measurements (acquired by TD OCT) from 373 glaucoma patients in the UK Glaucoma Treatment Study (UKGTS) at up to 11 scheduled visits over a 2 year interval formed the cohort to assess the sensitivity of progression analysis methods. Specificity was assessed in 78 glaucoma patients with up to 11 repeated VF and OCT RNFLT measurements over a 3 month interval. Growth curve models assessed the difference in VF and RNFLT rate of change between treatment groups. Incident progression was identified by 3 VF-based methods: Guided Progression Analysis (GPA), 'ANSWERS' and 'PoPLR', and one based on VFs and RNFLT: 'sANSWERS'. Sensitivity, specificity and discrimination between treatment groups were evaluated. The rate of VF change was significantly faster in the placebo, compared to active treatment, group (-0.29 vs +0.03 dB/year, P <.001); the rate of RNFLT change was not different (-1.7 vs -1.1 dB/year, P =.14). After 18 months and at 95% specificity, the sensitivity of ANSWERS and PoPLR was similar (35%); sANSWERS achieved a sensitivity of 70%. GPA, ANSWERS and PoPLR discriminated treatment groups with similar statistical significance; sANSWERS did not discriminate treatment groups. Although the VF progression-detection method including VF and RNFLT measurements is more sensitive, it does not improve discrimination between treatment arms.

  12. Improvement of visual field defects after focal resection for occipital lobe epilepsy: case report.

    Science.gov (United States)

    Yamamoto, Takahiro; Hamasaki, Tadashi; Nakamura, Hideo; Yamada, Kazumichi

    2018-03-01

    Improvement of visual field defects after surgical treatment for occipital lobe epilepsy is rare. Here, the authors report on a 24-year-old man with a 15-year history of refractory epilepsy that developed after he had undergone an occipital craniotomy to remove a cerebellar astrocytoma at the age of 4. His seizures started with an elementary visual aura, followed by secondary generalized tonic-clonic convulsion. Perimetry revealed left-sided incomplete hemianopia, and MRI showed an old contusion in the right occipital lobe. After evaluation with ictal video-electroencephalography, electrocorticography, and mapping of the visual cortex with subdural electrodes, the patient underwent resection of the scarred tissue, including the epileptic focus at the occipital lobe. After surgery, he became seizure free and his visual field defect improved gradually. In addition, postoperative 123 I-iomazenil (IMZ) SPECT showed partly normalized IMZ uptake in the visual cortex. This case is a practical example suggesting that neurological deficits attributable to the functional deficit zone can be remedied by successful focal resection.

  13. ABRUPT LONGITUDINAL MAGNETIC FIELD CHANGES IN FLARING ACTIVE REGIONS

    International Nuclear Information System (INIS)

    Petrie, G. J. D.; Sudol, J. J.

    2010-01-01

    We characterize the changes in the longitudinal photospheric magnetic field during 38 X-class and 39 M-class flares within 65 0 of disk center using 1 minute GONG magnetograms. In all 77 cases, we identify at least one site in the flaring active region where clear, permanent, stepwise field changes occurred. The median duration of the field changes was about 15 minutes and was approximately equal for X-class and for M-class flares. The absolute values of the field changes ranged from the detection limit of ∼10 G to as high as ∼450 G in two exceptional cases. The median value was 69 G. Field changes were significantly stronger for X-class than for M-class flares and for limb flares than for disk-center flares. Longitudinal field changes less than 100 G tended to decrease longitudinal field strengths, both close to disk center and close to the limb, while field changes greater than 100 G showed no such pattern. Likewise, longitudinal flux strengths tended to decrease during flares. Flux changes, particularly net flux changes near disk center, correlated better than local field changes with GOES peak X-ray flux. The strongest longitudinal field and flux changes occurred in flares observed close to the limb. We estimate the change of Lorentz force associated with each flare and find that this is large enough in some cases to power seismic waves. We find that longitudinal field decreases would likely outnumber increases at all parts of the solar disk within 65 0 of disk center, as in our observations, if photospheric field tilts increase during flares as predicted by Hudson et al.

  14. Temporal Changes of the Photospheric Velocity Fields

    Czech Academy of Sciences Publication Activity Database

    Klvaňa, Miroslav; Švanda, Michal; Bumba, Václav

    2005-01-01

    Roč. 29, č. 1 (2005), s. 89-98 ISSN 0351-2657. [Hvar astrophysical colloquium /7./: Solar activity cycle and global phenomena. Hvar, 20.09.2004-24.09.2004] R&D Projects: GA ČR GA205/04/2129 Institutional research plan: CEZ:AV0Z10030501 Keywords : Solar photosphere * velocity fields * tidal waves Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  15. Visualization of Morse connection graphs for topologically rich 2D vector fields.

    Science.gov (United States)

    Szymczak, Andrzej; Sipeki, Levente

    2013-12-01

    Recent advances in vector field topologymake it possible to compute its multi-scale graph representations for autonomous 2D vector fields in a robust and efficient manner. One of these representations is a Morse Connection Graph (MCG), a directed graph whose nodes correspond to Morse sets, generalizing stationary points and periodic trajectories, and arcs - to trajectories connecting them. While being useful for simple vector fields, the MCG can be hard to comprehend for topologically rich vector fields, containing a large number of features. This paper describes a visual representation of the MCG, inspired by previous work on graph visualization. Our approach aims to preserve the spatial relationships between the MCG arcs and nodes and highlight the coherent behavior of connecting trajectories. Using simulations of ocean flow, we show that it can provide useful information on the flow structure. This paper focuses specifically on MCGs computed for piecewise constant (PC) vector fields. In particular, we describe extensions of the PC framework that make it more flexible and better suited for analysis of data on complex shaped domains with a boundary. We also describe a topology simplification scheme that makes our MCG visualizations less ambiguous. Despite the focus on the PC framework, our approach could also be applied to graph representations or topological skeletons computed using different methods.

  16. The retest distribution of the visual field summary index mean deviation is close to normal.

    Science.gov (United States)

    Anderson, Andrew J; Cheng, Allan C Y; Lau, Samantha; Le-Pham, Anne; Liu, Victor; Rahman, Farahnaz

    2016-09-01

    When modelling optimum strategies for how best to determine visual field progression in glaucoma, it is commonly assumed that the summary index mean deviation (MD) is normally distributed on repeated testing. Here we tested whether this assumption is correct. We obtained 42 reliable 24-2 Humphrey Field Analyzer SITA standard visual fields from one eye of each of five healthy young observers, with the first two fields excluded from analysis. Previous work has shown that although MD variability is higher in glaucoma, the shape of the MD distribution is similar to that found in normal visual fields. A Shapiro-Wilks test determined any deviation from normality. Kurtosis values for the distributions were also calculated. Data from each observer passed the Shapiro-Wilks normality test. Bootstrapped 95% confidence intervals for kurtosis encompassed the value for a normal distribution in four of five observers. When examined with quantile-quantile plots, distributions were close to normal and showed no consistent deviations across observers. The retest distribution of MD is not significantly different from normal in healthy observers, and so is likely also normally distributed - or nearly so - in those with glaucoma. Our results increase our confidence in the results of influential modelling studies where a normal distribution for MD was assumed. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

  17. ANLIZE: a molecular mechanics force field visualization tool and its application to 18-crown-6.

    Science.gov (United States)

    Stolworthy, L D; Shirts, R B

    1997-03-01

    We describe a software tool that allows one to visualize and analyze the importance of each individual steric interaction in a molecular mechanics force field. ANLIZE is presently implemented for the Dreiding force field for use with the Cerius2 software package, but could be implemented in any molecular mechanics package with a graphical user interface. ANLIZE calculates individual interactions in the force field, sorts them by size, and displays them in several ways from a menu of choices. This allows the user to scan through selected interactions to visualize which interactions are the primary determinants of preferred conformations. The features of ANLIZE are illustrated using 18-crown-6 as an example, and the factors governing conformational preference in 18-crown-6 are demonstrated. Users of molecular mechanics packages are encouraged to demand this functionality from commercial software producers.

  18. Changes in otoacoustic emissions during selective auditory and visual attention.

    Science.gov (United States)

    Walsh, Kyle P; Pasanen, Edward G; McFadden, Dennis

    2015-05-01

    Previous studies have demonstrated that the otoacoustic emissions (OAEs) measured during behavioral tasks can have different magnitudes when subjects are attending selectively or not attending. The implication is that the cognitive and perceptual demands of a task can affect the first neural stage of auditory processing-the sensory receptors themselves. However, the directions of the reported attentional effects have been inconsistent, the magnitudes of the observed differences typically have been small, and comparisons across studies have been made difficult by significant procedural differences. In this study, a nonlinear version of the stimulus-frequency OAE (SFOAE), called the nSFOAE, was used to measure cochlear responses from human subjects while they simultaneously performed behavioral tasks requiring selective auditory attention (dichotic or diotic listening), selective visual attention, or relative inattention. Within subjects, the differences in nSFOAE magnitude between inattention and attention conditions were about 2-3 dB for both auditory and visual modalities, and the effect sizes for the differences typically were large for both nSFOAE magnitude and phase. These results reveal that the cochlear efferent reflex is differentially active during selective attention and inattention, for both auditory and visual tasks, although they do not reveal how attention is improved when efferent activity is greater.

  19. Changes in otoacoustic emissions during selective auditory and visual attention

    Science.gov (United States)

    Walsh, Kyle P.; Pasanen, Edward G.; McFadden, Dennis

    2015-01-01

    Previous studies have demonstrated that the otoacoustic emissions (OAEs) measured during behavioral tasks can have different magnitudes when subjects are attending selectively or not attending. The implication is that the cognitive and perceptual demands of a task can affect the first neural stage of auditory processing—the sensory receptors themselves. However, the directions of the reported attentional effects have been inconsistent, the magnitudes of the observed differences typically have been small, and comparisons across studies have been made difficult by significant procedural differences. In this study, a nonlinear version of the stimulus-frequency OAE (SFOAE), called the nSFOAE, was used to measure cochlear responses from human subjects while they simultaneously performed behavioral tasks requiring selective auditory attention (dichotic or diotic listening), selective visual attention, or relative inattention. Within subjects, the differences in nSFOAE magnitude between inattention and attention conditions were about 2–3 dB for both auditory and visual modalities, and the effect sizes for the differences typically were large for both nSFOAE magnitude and phase. These results reveal that the cochlear efferent reflex is differentially active during selective attention and inattention, for both auditory and visual tasks, although they do not reveal how attention is improved when efferent activity is greater. PMID:25994703

  20. Decoding facial blends of emotion: visual field, attentional and hemispheric biases.

    Science.gov (United States)

    Ross, Elliott D; Shayya, Luay; Champlain, Amanda; Monnot, Marilee; Prodan, Calin I

    2013-12-01

    Most clinical research assumes that modulation of facial expressions is lateralized predominantly across the right-left hemiface. However, social psychological research suggests that facial expressions are organized predominantly across the upper-lower face. Because humans learn to cognitively control facial expression for social purposes, the lower face may display a false emotion, typically a smile, to enable approach behavior. In contrast, the upper face may leak a person's true feeling state by producing a brief facial blend of emotion, i.e. a different emotion on the upper versus lower face. Previous studies from our laboratory have shown that upper facial emotions are processed preferentially by the right hemisphere under conditions of directed attention if facial blends of emotion are presented tachistoscopically to the mid left and right visual fields. This paper explores how facial blends are processed within the four visual quadrants. The results, combined with our previous research, demonstrate that lower more so than upper facial emotions are perceived best when presented to the viewer's left and right visual fields just above the horizontal axis. Upper facial emotions are perceived best when presented to the viewer's left visual field just above the horizontal axis under conditions of directed attention. Thus, by gazing at a person's left ear, which also avoids the social stigma of eye-to-eye contact, one's ability to decode facial expressions should be enhanced. Published by Elsevier Inc.

  1. Visual search for features and conjunctions following declines in the useful field of view.

    Science.gov (United States)

    Cosman, Joshua D; Lees, Monica N; Lee, John D; Rizzo, Matthew; Vecera, Shaun P

    2012-01-01

    BACKGROUND/STUDY CONTEXT: Typical measures for assessing the useful field (UFOV) of view involve many components of attention. The objective of the current experiment was to examine differences in visual search efficiency for older individuals with and without UFOV impairment. The authors used a computerized screening instrument to assess the useful field of view and to characterize participants as having an impaired or normal UFOV. Participants also performed two visual search tasks, a feature search (e.g., search for a green target among red distractors) or a conjunction search (e.g., a green target with a gap on its left or right side among red distractors with gaps on the left or right and green distractors with gaps on the top or bottom). Visual search performance did not differ between UFOV impaired and unimpaired individuals when searching for a basic feature. However, search efficiency was lower for impaired individuals than unimpaired individuals when searching for a conjunction of features. The results suggest that UFOV decline in normal aging is associated with conjunction search. This finding suggests that the underlying cause of UFOV decline may arise from an overall decline in attentional efficiency. Because the useful field of view is a reliable predictor of driving safety, the results suggest that decline in the everyday visual behavior of older adults might arise from attentional declines.

  2. Visualization of velocity field and phase distribution in gas-liquid two-phase flow by NMR imaging

    International Nuclear Information System (INIS)

    Matsui, G.; Monji, H.; Obata, J.

    2004-01-01

    NMR imaging has been applied in the field of fluid mechanics, mainly single phase flow, to visualize the instantaneous flow velocity field. In the present study, NMR imaging was used to visualize simultaneously both the instantaneous phase structure and velocity field of gas-liquid two-phase flow. Two methods of NMR imaging were applied. One is useful to visualize both the one component of liquid velocity and the phase distribution. This method was applied to horizontal two-phase flow and a bubble rising in stagnant oil. It was successful in obtaining some pictures of velocity field and phase distribution on the cross section of the pipe. The other is used to visualize a two-dimensional velocity field. This method was applied to a bubble rising in a stagnant water. The velocity field was visualized after and before the passage of a bubble at the measuring cross section. Furthermore, the distribution of liquid velocity was obtained. (author)

  3. Comparison of visual receptive fields in the dorsolateral prefrontal cortex and ventral intraparietal area in macaques.

    Science.gov (United States)

    Viswanathan, Pooja; Nieder, Andreas

    2017-12-01

    The concept of receptive field (RF) describes the responsiveness of neurons to sensory space. Neurons in the primate association cortices have long been known to be spatially selective but a detailed characterisation and direct comparison of RFs between frontal and parietal association cortices are missing. We sampled the RFs of a large number of neurons from two interconnected areas of the frontal and parietal lobes, the dorsolateral prefrontal cortex (dlPFC) and ventral intraparietal area (VIP), of rhesus monkeys by systematically presenting a moving bar during passive fixation. We found that more than half of neurons in both areas showed spatial selectivity. Single neurons in both areas could be assigned to five classes according to the spatial response patterns: few non-uniform RFs with multiple discrete response maxima could be dissociated from the vast majority of uniform RFs showing a single maximum; the latter were further classified into full-field and confined foveal, contralateral and ipsilateral RFs. Neurons in dlPFC showed a preference for the contralateral visual space and collectively encoded the contralateral visual hemi-field. In contrast, VIP neurons preferred central locations, predominantly covering the foveal visual space. Putative pyramidal cells with broad-spiking waveforms in PFC had smaller RFs than putative interneurons showing narrow-spiking waveforms, but distributed similarly across the visual field. In VIP, however, both putative pyramidal cells and interneurons had similar RFs at similar eccentricities. We provide a first, thorough characterisation of visual RFs in two reciprocally connected areas of a fronto-parietal cortical network. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  4. Real time visualization of dynamic magnetic fields with a nanomagnetic ferrolens

    Science.gov (United States)

    Markoulakis, Emmanouil; Rigakis, Iraklis; Chatzakis, John; Konstantaras, Antonios; Antonidakis, Emmanuel

    2018-04-01

    Due to advancements in nanomagnetism and latest nanomagnetic materials and devices, a new potential field has been opened up for research and applications which was not possible before. We herein propose a new research field and application for nanomagnetism for the visualization of dynamic magnetic fields in real-time. In short, Nano Magnetic Vision. A new methodology, technique and apparatus were invented and prototyped in order to demonstrate and test this new application. As an application example the visualization of the dynamic magnetic field on a transmitting antenna was chosen. Never seen before high-resolution, photos and real-time color video revealing the actual dynamic magnetic field inside a transmitting radio antenna rod has been captured for the first time. The antenna rod is fed with six hundred volts, orthogonal pulses. This unipolar signal is in the very low frequency (i.e. VLF) range. The signal combined with an extremely short electrical length of the rod, ensures the generation of a relatively strong fluctuating magnetic field, analogue to the signal transmitted, along and inside the antenna. This field is induced into a ferrolens and becomes visible in real-time within the normal human eyes frequency spectrum. The name we have given to the new observation apparatus is, SPIONs Superparamagnetic Ferrolens Microscope (SSFM), a powerful passive scientific observation tool with many other potential applications in the near future.

  5. Reliability of kinetic visual field testing in children with mutation-proven retinal dystrophies: Implications for therapeutic clinical trials.

    Science.gov (United States)

    Dedania, Vaidehi S; Liu, Jerry Y; Schlegel, Dana; Andrews, Chris A; Branham, Kari; Khan, Naheed W; Musch, David C; Heckenlively, John R; Jayasundera, K Thiran

    2018-01-01

    Kinetic visual field testing is used to monitor disease course in retinal dystrophy clinical care and treatment response in treatment trials, which are increasingly recruiting children. This study investigates Goldmann visual field (GVF) changes in young children with mutation-proven retinal dystrophies as they age and with progression of the retinal degeneration. Retrospective review of children ≤ 17 years old with a mutation-proven retinal dystrophy. Objective clinical disease activity was assessed by a retinal degeneration specialist masked to GVF results. Digital quantification of GVF area was performed. Twenty-nine children (58 eyes), ages 5-16, were identified. GVF area increased with age despite progression in 20 children and clinical stability in nine children. Mean ± standard error increase in GVF area/year was 333 ± 130 mm 2 (I4e, p = 0.012), 720 ± 155 mm 2 (III4e, p children with mutation-proven retinal dystrophies, there is a significant increase in GVF area with age, particularly those children with retinal dystrophies can be an unreliable measure of response to treatment and on which to base appropriate counseling about visual impairment.

  6. Morphological and cytochemical changes in the symmetric areas of the visual cortex during irradiation of one hemisphere in rabbits

    International Nuclear Information System (INIS)

    Gelashvili, N.A.; Kumsiashvili, L.B.; Gikoshvili, T.I.; Amashukeli, I.S.

    1980-01-01

    Made is an attempt of layer analysis of DNA content in the cells of brain hemisphere in connection with morphological changes of the nervous tissue after irradiation of animals. Investigations of the 17-th and 18-th fields of the brain visual cortex of rabbits have been subjected to morphologic and hystologic analysis. The left hemisphere of animals has received a single dose of irradiation while the other part of the head and body has been shielded till the formation of pronounced signs of depression of the brain bioelectric activity at the side of irradiation. It is established, that by the moment of depression of bioelectric activity of brain on the side of irradiation are characterized by similar radiosensitivity according to changes of the general amount of cells, nuclear DNA content, nucleus-cytoplasm ratio, the increase in the number of picnotic and degenerated nuclei of cells of the 17-th and 18-th fields of different layers of the visual cortex of rabbit's brain. Pyramid neurons of different layers of the visual cortex, reveal similar radiosensitivity. The difference between irradiated and shielded visual cortex to the moment of brain bioelectric activity depression in the content of nuclear DNA in nervous and macroglial cells is statistically authentic

  7. Situational Awareness Applied to Geology Field Mapping using Integration of Semantic Data and Visualization Techniques

    Science.gov (United States)

    Houser, P. I. Q.

    2017-12-01

    21st century earth science is data-intensive, characterized by heterogeneous, sometimes voluminous collections representing phenomena at different scales collected for different purposes and managed in disparate ways. However, much of the earth's surface still requires boots-on-the-ground, in-person fieldwork in order to detect the subtle variations from which humans can infer complex structures and patterns. Nevertheless, field experiences can and should be enabled and enhanced by a variety of emerging technologies. The goal of the proposed research project is to pilot test emerging data integration, semantic and visualization technologies for evaluation of their potential usefulness in the field sciences, particularly in the context of field geology. The proposed project will investigate new techniques for data management and integration enabled by semantic web technologies, along with new techniques for augmented reality that can operate on such integrated data to enable in situ visualization in the field. The research objectives include: Develop new technical infrastructure that applies target technologies to field geology; Test, evaluate, and assess the technical infrastructure in a pilot field site; Evaluate the capabilities of the systems for supporting and augmenting field science; and Assess the generality of the system for implementation in new and different types of field sites. Our hypothesis is that these technologies will enable what we call "field science situational awareness" - a cognitive state formerly attained only through long experience in the field - that is highly desirable but difficult to achieve in time- and resource-limited settings. Expected outcomes include elucidation of how, and in what ways, these technologies are beneficial in the field; enumeration of the steps and requirements to implement these systems; and cost/benefit analyses that evaluate under what conditions the investments of time and resources are advisable to construct

  8. Visualizing code and coverage changes for code review

    NARCIS (Netherlands)

    Oosterwaal, Sebastiaan; van Deursen, A.; De Souza Coelho, R.; Sawant, A.A.; Bacchelli, A.

    2016-01-01

    One of the tasks of reviewers is to verify that code modifications are well tested. However, current tools offer little support in understanding precisely how changes to the code relate to changes to the tests. In particular, it is hard to see whether (modified) test code covers the changed code.

  9. How 3D immersive visualization is changing medical diagnostics

    Science.gov (United States)

    Koning, Anton H. J.

    2011-03-01

    Originally the only way to look inside the human body without opening it up was by means of two dimensional (2D) images obtained using X-ray equipment. The fact that human anatomy is inherently three dimensional leads to ambiguities in interpretation and problems of occlusion. Three dimensional (3D) imaging modalities such as CT, MRI and 3D ultrasound remove these drawbacks and are now part of routine medical care. While most hospitals 'have gone digital', meaning that the images are no longer printed on film, they are still being viewed on 2D screens. However, this way valuable depth information is lost, and some interactions become unnecessarily complex or even unfeasible. Using a virtual reality (VR) system to present volumetric data means that depth information is presented to the viewer and 3D interaction is made possible. At the Erasmus MC we have developed V-Scope, an immersive volume visualization system for visualizing a variety of (bio-)medical volumetric datasets, ranging from 3D ultrasound, via CT and MRI, to confocal microscopy, OPT and 3D electron-microscopy data. In this talk we will address the advantages of such a system for both medical diagnostics as well as for (bio)medical research.

  10. A study on the natural history of scanning behaviour in patients with visual field defects after stroke.

    Science.gov (United States)

    Loetscher, Tobias; Chen, Celia; Wignall, Sophie; Bulling, Andreas; Hoppe, Sabrina; Churches, Owen; Thomas, Nicole A; Nicholls, Michael E R; Lee, Andrew

    2015-04-24

    A visual field defect (VFD) is a common consequence of stroke with a detrimental effect upon the survivors' functional ability and quality of life. The identification of effective treatments for VFD is a key priority relating to life post-stroke. Understanding the natural evolution of scanning compensation over time may have important ramifications for the development of efficacious therapies. The study aims to unravel the natural history of visual scanning behaviour in patients with VFD. The assessment of scanning patterns in the acute to chronic stages of stroke will reveal who does and does not learn to compensate for vision loss. Eye-tracking glasses are used to delineate eye movements in a cohort of 100 stroke patients immediately after stroke, and additionally at 6 and 12 months post-stroke. The longitudinal study will assess eye movements in static (sitting) and dynamic (walking) conditions. The primary outcome constitutes the change of lateral eye movements from the acute to chronic stages of stroke. Secondary outcomes include changes of lateral eye movements over time as a function of subgroup characteristics, such as side of VFD, stroke location, stroke severity and cognitive functioning. The longitudinal comparison of patients who do and do not learn compensatory scanning techniques may reveal important prognostic markers of natural recovery. Importantly, it may also help to determine the most effective treatment window for visual rehabilitation.

  11. Corporate rebranding: effects of corporate visual identity changes on employees and consumers

    NARCIS (Netherlands)

    Bolhuis, W.; de Jong, Menno D.T.; van den Bosch, A.L.M.

    2018-01-01

    Many organizations invest periodically in a new corporate visual identity (CVI). This study investigates the main effects of CVI changes in four organizations, taking into account three independent variables: stakeholder type (employees vs. consumers), the specific organization, and communication

  12. Improvement in Visual Search with Practice : Mapping Learning-Related Changes in Neurocognitive Stages of Processing

    NARCIS (Netherlands)

    Clark, Kait; Appelbaum, L. Gregory; van den Berg, Berry; Mitroff, Stephen R.; Woldorff, Marty G.

    2015-01-01

    Practice can improve performance on visual search tasks; the neural mechanisms underlying such improvements, however, are not clear. Response time typically shortens with practice, but which components of the stimulus-response processing chain facilitate this behavioral change? Improved search

  13. Augmented asymmetrical visual field dependence in asymptomatic diabetics: evidence of subclinical asymmetrical bilateral vestibular dysfunction.

    Science.gov (United States)

    Razzak, Rima Abdul; Bagust, Jeffery; Docherty, Sharon; Hussein, Wiam; Al-Otaibi, Abdullah

    2015-01-01

    Diabetes negatively affects the vestibular system in many ways, with vestibular dysfunction (VD), a co-morbidity with a high prevalence in diabetics. The ability to perceive subjective visual vertical (SVV), as a sign of vestibular dysfunction, and visual field dependence was measured using a computerized rod and frame test (CRAF). Alignment errors recorded from 47 asymptomatic Type II diabetics (no vertigo or falls, without peripheral neuropathy or retinopathy) were compared to 29 healthy age matched (46-69years) controls. Visual field dependence was significantly larger and more asymmetrical in the diabetics than controls. In the absence of any visual references, or when a vertical reference frame was provided, SVV perception was accurate in both groups, with no significant difference between the controls and diabetics. During tilted frame presentations, the proportion of subjects with either SVV deviations, or an asymmetry index, larger than an upper limit derived from the control data was significantly greater in diabetics than controls. These results suggest that the decreased ability to resolve visuo-vestibular conflict in asymptomatic diabetic patients (free of retinopathy and peripheral neuropathy) compared to controls may be related to diabetic complications affecting vestibular structures and thus causing a decompensation of subclinical vestibular asymmetries. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Bright-field Nanoscopy: Visualizing Nano-structures with Localized Optical Contrast Using a Conventional Microscope.

    Science.gov (United States)

    Suran, Swathi; Bharadwaj, Krishna; Raghavan, Srinivasan; Varma, Manoj M

    2016-04-26

    Most methods for optical visualization beyond the diffraction limit rely on fluorescence emission by molecular tags. Here, we report a method for visualization of nanostructures down to a few nanometers using a conventional bright-field microscope without requiring additional molecular tags such as fluorophores. The technique, Bright-field Nanoscopy, is based on the strong thickness dependent color of ultra-thin germanium on an optically thick gold film. We demonstrate the visualization of grain boundaries in chemical vapour deposited single layer graphene and the detection of single 40 nm Ag nanoparticles. We estimate a size detection limit of about 2 nm using this technique. In addition to visualizing nano-structures, this technique can be used to probe fluid phenomena at the nanoscale, such as transport through 2D membranes. We estimated the water transport rate through a 1 nm thick polymer film using this technique, as an illustration. Further, the technique can also be extended to study the transport of specific ions in the solution. It is anticipated that this technique will find use in applications ranging from single-nanoparticles resolved sensing to studying nanoscale fluid-solid interface phenomena.

  15. The feasibility of an infrared system for real-time visualization and mapping of ultrasound fields

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, Adam; Nunn, John, E-mail: adam.shaw@npl.co.u [National Physical Laboratory, Teddington, Middlesex, TW11 0LW (United Kingdom)

    2010-06-07

    In treatment planning for ultrasound therapy, it is desirable to know the 3D structure of the ultrasound field. However, mapping an ultrasound field in 3D is very slow, with even a single planar raster scan taking typically several hours. Additionally, hydrophones that are used for field mapping are expensive and can be damaged in some therapy fields. So there is value in rapid methods which enable visualization and mapping of the ultrasound field in about 1 min. In this note we explore the feasibility of mapping the intensity distribution by measuring the temperature distribution produced in a thin sheet of absorbing material. A 0.2 mm thick acetate sheet forms a window in the wall of a water tank containing the transducer. The window is oriented at 45{sup 0} to the beam axis, and the distance from the transducer to the window can be varied. The temperature distribution is measured with an infrared camera; thermal images of the inclined plane could be viewed in real time or images could be captured for later analysis and 3D field reconstruction. We conclude that infrared thermography can be used to gain qualitative information about ultrasound fields. Thermal images are easily visualized with good spatial and thermal resolutions (0.044 mm and 0.05 {sup 0}C in our system). The focus and field structure such as side lobes can be identified in real time from the direct video output. 3D maps and image planes at arbitrary orientations to the beam axis can be obtained and reconstructed within a few minutes. In this note we are primarily interested in the technique for characterization of high intensity focused ultrasound (HIFU) fields, but other applications such as physiotherapy fields are also possible. (note)

  16. The feasibility of an infrared system for real-time visualization and mapping of ultrasound fields

    International Nuclear Information System (INIS)

    Shaw, Adam; Nunn, John

    2010-01-01

    In treatment planning for ultrasound therapy, it is desirable to know the 3D structure of the ultrasound field. However, mapping an ultrasound field in 3D is very slow, with even a single planar raster scan taking typically several hours. Additionally, hydrophones that are used for field mapping are expensive and can be damaged in some therapy fields. So there is value in rapid methods which enable visualization and mapping of the ultrasound field in about 1 min. In this note we explore the feasibility of mapping the intensity distribution by measuring the temperature distribution produced in a thin sheet of absorbing material. A 0.2 mm thick acetate sheet forms a window in the wall of a water tank containing the transducer. The window is oriented at 45 0 to the beam axis, and the distance from the transducer to the window can be varied. The temperature distribution is measured with an infrared camera; thermal images of the inclined plane could be viewed in real time or images could be captured for later analysis and 3D field reconstruction. We conclude that infrared thermography can be used to gain qualitative information about ultrasound fields. Thermal images are easily visualized with good spatial and thermal resolutions (0.044 mm and 0.05 0 C in our system). The focus and field structure such as side lobes can be identified in real time from the direct video output. 3D maps and image planes at arbitrary orientations to the beam axis can be obtained and reconstructed within a few minutes. In this note we are primarily interested in the technique for characterization of high intensity focused ultrasound (HIFU) fields, but other applications such as physiotherapy fields are also possible. (note)

  17. VISUAL ARTS AS THE FIELD OF KNOWLEDGE IN ARTE NA ESCOLA - DAC / UFSC PROJECT

    Directory of Open Access Journals (Sweden)

    Richard Perassi Luiz de Sousa

    2011-07-01

    Full Text Available This paper presents and justifies the content worked in the extension course "The Visual Arts as a field of knowledge," which was sponsored by the Departamento Artístico Cultural – DAC/ UFSC, within the project "Arte na Escola". The course was directed at teachers of Art and also received other stakeholders in the study of Visual Arts, focusing on contemporary art. Art is justified as a field of knowledge in that, throughout its history, many have been developed knowledge, technologies and expertise applied to the development of artistic activities. In addition, each work of art represents a unique and innovative testimony of their time and offers a new set of knowledge, which broadens the cultural heritage of humanity. Finally, knowledge and artistic products are also applied in developing other areas of knowledge.

  18. Whole-field visual motion drives swimming in larval zebrafish via a stochastic process.

    Science.gov (United States)

    Portugues, Ruben; Haesemeyer, Martin; Blum, Mirella L; Engert, Florian

    2015-05-01

    Caudo-rostral whole-field visual motion elicits forward locomotion in many organisms, including larval zebrafish. Here, we investigate the dependence on the latency to initiate this forward swimming as a function of the speed of the visual motion. We show that latency is highly dependent on speed for slow speeds (1.5 s, which is much longer than neuronal transduction processes. What mechanisms underlie these long latencies? We propose two alternative, biologically inspired models that could account for this latency to initiate swimming: an integrate and fire model, which is history dependent, and a stochastic Poisson model, which has no history dependence. We use these models to predict the behavior of larvae when presented with whole-field motion of varying speed and find that the stochastic process shows better agreement with the experimental data. Finally, we discuss possible neuronal implementations of these models. © 2015. Published by The Company of Biologists Ltd.

  19. Effects of spatial attention on motion discrimination are greater in the left than right visual field.

    Science.gov (United States)

    Bosworth, Rain G; Petrich, Jennifer A F; Dobkins, Karen R

    2012-01-01

    In order to investigate differences in the effects of spatial attention between the left visual field (LVF) and the right visual field (RVF), we employed a full/poor attention paradigm using stimuli presented in the LVF vs. RVF. In addition, to investigate differences in the effects of spatial attention between the dorsal and ventral processing streams, we obtained motion thresholds (motion coherence thresholds and fine direction discrimination thresholds) and orientation thresholds, respectively. The results of this study showed negligible effects of attention on the orientation task, in either the LVF or RVF. In contrast, for both motion tasks, there was a significant effect of attention in the LVF, but not in the RVF. These data provide psychophysical evidence for greater effects of spatial attention in the LVF/right hemisphere, specifically, for motion processing in the dorsal stream. Published by Elsevier Ltd.

  20. Propulsion Physics Under the Changing Density Field Model

    Science.gov (United States)

    Robertson, Glen A.

    2011-01-01

    To grow as a space faring race, future spaceflight systems will requires new propulsion physics. Specifically a propulsion physics model that does not require mass ejection without limiting the high thrust necessary to accelerate within or beyond our solar system and return within a normal work period or lifetime. In 2004 Khoury and Weltman produced a density dependent cosmology theory they called Chameleon Cosmology, as at its nature, it is hidden within known physics. This theory represents a scalar field within and about an object, even in the vacuum. Whereby, these scalar fields can be viewed as vacuum energy fields with definable densities that permeate all matter; having implications to dark matter/energy with universe acceleration properties; implying a new force mechanism for propulsion physics. Using Chameleon Cosmology, the author has developed a new propulsion physics model, called the Changing Density Field (CDF) Model. This model relates to density changes in these density fields, where the density field density changes are related to the acceleration of matter within an object. These density changes in turn change how an object couples to the surrounding density fields. Whereby, thrust is achieved by causing a differential in the coupling to these density fields about an object. Since the model indicates that the density of the density field in an object can be changed by internal mass acceleration, even without exhausting mass, the CDF model implies a new propellant-less propulsion physics model

  1. Age-Related Change in Visual Working Memory: A study of 55,753 Participants Aged 8 to 75

    Directory of Open Access Journals (Sweden)

    James R. Brockmole

    2013-01-01

    Full Text Available Visual working memory abilities of 55,753 individuals between the ages of 8 and 75 were assessed to provide the most fine-grain analysis of age-related change in visual working memory to date. Results showed that visual working memory changes throughout the lifespan, peaking at age 20. A sharp linear decline follows that is so severe that by age 55, adults possess poorer immediate visual memory than 8 and 9 year olds. These developmental changes were largely explained by changing visual working memory capacity coupled with small short-term visual feature binding difficulties among children and older adults.

  2. Field: a new meta-authoring platform for data-intensive scientific visualization

    Science.gov (United States)

    Downie, M.; Ameres, E.; Fox, P. A.; Goebel, J.; Graves, A.; Hendler, J.

    2012-12-01

    This presentation will demonstrate a new platform for data-intensive scientific visualization, called Field, that rethinks the problem of visual data exploration. Several new opportunities for scientific visualization present themselves here at this moment in time. We believe that when taken together they may catalyze a transformation of the practice of science and to begin to seed a technical culture within science that fuses data analysis, programming and myriad visual strategies. It is at integrative levels that the principle challenges exist, for many fundamental technical components of our field are now well understood and widely available. File formats from CSV through HDF all have broad library support; low-level high-performance graphics APIs (OpenGL) are in a period of stable growth; and a dizzying ecosystem of analysis and machine learning libraries abound. The hardware of computer graphics offers unprecedented computing power within commodity components; programming languages and platforms are coalescing around a core set of umbrella runtimes. Each of these trends are each set to continue — computer graphics hardware is developing at a super-Moore-law rate, and trends in publication and dissemination point only towards an increasing amount of access to code and data. The critical opportunity here for scientific visualization is, we maintain, not a in developing a new statistical library, nor a new tool centered on a particular technique, but rather new visual, "live" programming environment that is promiscuous in its scope. We can identify the necessarily methodological practice and traditions required here not in science or engineering but in the "live-coding" practices prevalent in the fields of digital art and design. We can define this practice as an approach to programming that is live, iterative, integrative, speculative and exploratory. "Live" because it is exclusively practiced in real-time (often during performance); "iterative", because

  3. Optical visualization of electric and magnetic field perturbations in tokamak discharges by hydrogen pellet injection

    International Nuclear Information System (INIS)

    Drawin, H.W.; Dubois, M.A.

    1992-04-01

    Two-dimensional intensity distribution mappings of photographs of pellet ablation cloud trajectories in the TFR and TS tokamaks reveal irregular shapes of the luminous striations. The observed features are not well understood, but can be described and interpreted as the first direct visual observation of pre-existing electric and/or magnetic field perturbations in the hot core of tokamak plasmas. It is suggested to use pellet injection as a diagnostic tool for the study of plasma structures and transport phenomena

  4. Visualizing flow fields using acoustic Doppler current profilers and the Velocity Mapping Toolbox

    Science.gov (United States)

    Jackson, P. Ryan

    2013-01-01

    The purpose of this fact sheet is to provide examples of how the U.S. Geological Survey is using acoustic Doppler current profilers for much more than routine discharge measurements. These instruments are capable of mapping complex three-dimensional flow fields within rivers, lakes, and estuaries. Using the Velocity Mapping Toolbox to process the ADCP data allows detailed visualization of the data, providing valuable information for a range of studies and applications.

  5. Effect of visual field locus and oscillation frequencies on posture control in an ecological environment.

    Science.gov (United States)

    Piponnier, Jean-Claude; Hanssens, Jean-Marie; Faubert, Jocelyn

    2009-01-14

    To examine the respective roles of central and peripheral vision in the control of posture, body sway amplitude (BSA) and postural perturbations (given by velocity root mean square or vRMS) were calculated in a group of 19 healthy young adults. The stimulus was a 3D tunnel, either static or moving sinusoidally in the anterior-posterior direction. There were nine visual field conditions: four central conditions (4, 7, 15, and 30 degrees); four peripheral conditions (central occlusions of 4, 7, 15, and 30 degrees); and a full visual field condition (FF). The virtual tunnel respected all the aspects of a real physical tunnel (i.e., stereoscopy and size increase with proximity). The results show that, under static conditions, central and peripheral visual fields appear to have equal importance for the control of stance. In the presence of an optic flow, peripheral vision plays a crucial role in the control of stance, since it is responsible for a compensatory sway, whereas central vision has an accessory role that seems to be related to spatial orientation.

  6. Visualization of landscape changes and threatening environmental processes using a digital landscape model

    International Nuclear Information System (INIS)

    Svatonova, H; Rybansky, M

    2014-01-01

    Visualizations supported by new geoinformation technologies prove to be appropriate tools for presenting and sharing the research results by professional and general public. The object of the research was to evaluate the benefits of visualizations for the nonexpert users. The subject of evaluation was: the success rate of interpreting the information; forming of a realistic idea of the unknown landscape; and the preference of the users during selection of the appropriate visualization for the purpose of solving the task. The tasks concerned: assessing the current situation and changes of the landscape; assessing the erosion in the landscape; and the ways of their visualizing. To prepare and process the landscape visualizations, it was necessary to select areas that allow tracking of land use changes and representative environmental processes. Then the digital landscape model was created and a number of visualizations were generated. The results of visualization testing show that the users prefer maps to orthophotos, they are able to formulate correct statements concerning the landscape with the help of visualizations, and that the simulated fly throughs represent a very suitable tool supporting formation of a realistic ideas about the landscape

  7. Visualization of mole fraction distribution of slow jet forming stably stratified field

    International Nuclear Information System (INIS)

    Fumizawa, Motoo; Hishida, Makoto

    1990-01-01

    An experimental study has been performed to investigate the behavior of flow and mass transfer in gaseous slow jet in which buoyancy force opposed the flow forming stably stratified field. The study has been performed to understand the basic features of air ingress phenomena at pipe rupture accident of the high temperature gas-cooled reactor. A displacement fringe technique was adopted in Mach-Zehnder interferometer to visualize the mole fraction distribution. As the result, the followings were obtained: (1) The stably stratified fields were formed in the vicinity of the outlet of the slow jet. The penetration distance of the stably stratified fields increased with Froude number. (2) Mass fraction distributions in the stably stratified fields were well correlated with the present model using the ramp mole velocity profile. (author)

  8. Visualizing special relativity: the field of an electric dipole moving at relativistic speed

    International Nuclear Information System (INIS)

    Smith, Glenn S

    2011-01-01

    The electromagnetic field is determined for a time-varying electric dipole moving with a constant velocity that is parallel to its moment. Graphics are used to visualize this field in the rest frame of the dipole and in the laboratory frame when the dipole is moving at relativistic speed. Various phenomena from special relativity are clearly illustrated by these graphics and explained with simple calculations; these include the constancy of the speed of light in inertial frames, the Doppler effect, the headlight effect, and the concentration of field lines. In addition, the energy and linear momentum of the radiated field are determined and shown to satisfy the transformation and invariance required by special relativity.

  9. RGB-NDVI colour composites for visualizing forest change dynamics

    Science.gov (United States)

    Sader, S. A.; Winne, J. C.

    1992-01-01

    The study presents a simple and logical technique to display and quantify forest change using three dates of satellite imagery. The normalized difference vegetation index (NDVI) was computed for each date of imagery to define high and low vegetation biomass. Color composites were generated by combining each date of NDVI with either the red, green, or blue (RGB) image planes in an image display monitor. Harvest and regeneration areas were quantified by applying a modified parallelepiped classification creating an RGB-NDVI image with 27 classes that were grouped into nine major forest change categories. Aerial photographs and stand history maps are compared with the forest changes indicated by the RGB-NDVI image. The utility of the RGB-NDVI technique for supporting forest inventories and updating forest resource information systems are presented and discussed.

  10. Visual perception and appraisal of persons with impairments: a randomised controlled field experiment using photo elicitation.

    Science.gov (United States)

    Reinhardt, Jan Dietrich; Ballert, Carolina Saskia; Fellinghauer, Bernd; Lötscher, Alexander; Gradinger, Felix; Hilfiker, Roger; Graf, Sibylle; Stucki, Gerold

    2011-01-01

    Visual cues from persons with impairments may trigger stereotypical generalisations that lead to prejudice and discrimination. The main objective of this pilot study is to examine whether visual stimuli of impairment activate latent prejudice against disability and whether this connection can be counteracted with priming strategies. In a field experiment, participants were asked to rate photographs showing models with mental impairments, wheelchair users with paraplegia, and persons without any visible impairment. Participants should appraise the models with regard to several features (e.g. communicativeness, intelligence). One hundred participants rated 12 photo models yielding a total of 1183 observations. One group of participants was primed with a cover story introducing visual perception of impairment as the study's gist, while controls received neutral information. Photo models with mental impairments were rated lowest and models without visible impairment highest. In participants who did not have prior contacts with persons with impairments, priming led to a levelling of scores of models with and without impairment. Prior contacts with persons with impairments created similar effects as the priming. Unexpectedly, a pattern of converse double discrimination to the disadvantage of men with mental impairments was revealed. Signs of stereotypical processing of visual cues of impairment have been found in participants of the Swiss general population. Personal contact with persons with impairments as well as priming participants seems to reduce stereotyping.

  11. The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration.The AGIS Investigators.

    Science.gov (United States)

    2000-10-01

    To investigate the association between control of intraocular pressure after surgical intervention for glaucoma and visual field deterioration. In the Advanced Glaucoma Intervention Study, eyes were randomly assigned to one of two sequences of glaucoma surgery, one beginning with argon laser trabeculoplasty and the other trabeculectomy. In the present article we examine the relationship between intraocular pressure and progression of visual field damage over 6 or more years of follow-up. In the first analysis, designated Predictive Analysis, we categorize 738 eyes into three groups based on intraocular pressure determinations over the first three 6-month follow-up visits. In the second analysis, designated Associative Analysis, we categorize 586 eyes into four groups based on the percent of 6-month visits over the first 6 follow-up years in which eyes presented with intraocular pressure less than 18 mm Hg. The outcome measure in both analyses is change from baseline in follow-up visual field defect score (range, 0 to 20 units). In the Predictive Analysis, eyes with early average intraocular pressure greater than 17.5 mm Hg had an estimated worsening during subsequent follow-up that was 1 unit of visual field defect score greater than eyes with average intraocular pressure less than 14 mm Hg (P =.002). This amount of worsening was greater at 7 years (1.89 units; P <.001) than at 2 years (0.64 units; P =.071). In the Associative Analysis, eyes with 100% of visits with intraocular pressure less than 18 mm Hg over 6 years had mean changes from baseline in visual field defect score close to zero during follow-up, whereas eyes with less than 50% of visits with intraocular pressure less than 18 mm Hg had an estimated worsening over follow-up of 0.63 units of visual field defect score (P =.083). This amount of worsening was greater at 7 years (1.93 units; P <.001) than at 2 years (0.25 units; P =.572). In both analyses low intraocular pressure is associated with reduced

  12. Altered Balance of Receptive Field Excitation and Suppression in Visual Cortex of Amblyopic Macaque Monkeys.

    Science.gov (United States)

    Hallum, Luke E; Shooner, Christopher; Kumbhani, Romesh D; Kelly, Jenna G; García-Marín, Virginia; Majaj, Najib J; Movshon, J Anthony; Kiorpes, Lynne

    2017-08-23

    In amblyopia, a visual disorder caused by abnormal visual experience during development, the amblyopic eye (AE) loses visual sensitivity whereas the fellow eye (FE) is largely unaffected. Binocular vision in amblyopes is often disrupted by interocular suppression. We used 96-electrode arrays to record neurons and neuronal groups in areas V1 and V2 of six female macaque monkeys ( Macaca nemestrina ) made amblyopic by artificial strabismus or anisometropia in early life, as well as two visually normal female controls. To measure suppressive binocular interactions directly, we recorded neuronal responses to dichoptic stimulation. We stimulated both eyes simultaneously with large sinusoidal gratings, controlling their contrast independently with raised-cosine modulators of different orientations and spatial frequencies. We modeled each eye's receptive field at each cortical site using a difference of Gaussian envelopes and derived estimates of the strength of central excitation and surround suppression. We used these estimates to calculate ocular dominance separately for excitation and suppression. Excitatory drive from the FE dominated amblyopic visual cortex, especially in more severe amblyopes, but suppression from both the FE and AEs was prevalent in all animals. This imbalance created strong interocular suppression in deep amblyopes: increasing contrast in the AE decreased responses at binocular cortical sites. These response patterns reveal mechanisms that likely contribute to the interocular suppression that disrupts vision in amblyopes. SIGNIFICANCE STATEMENT Amblyopia is a developmental visual disorder that alters both monocular vision and binocular interaction. Using microelectrode arrays, we examined binocular interaction in primary visual cortex and V2 of six amblyopic macaque monkeys ( Macaca nemestrina ) and two visually normal controls. By stimulating the eyes dichoptically, we showed that, in amblyopic cortex, the binocular combination of signals is

  13. Gender differences in pre-attentive change detection for visual but not auditory stimuli.

    Science.gov (United States)

    Yang, Xiuxian; Yu, Yunmiao; Chen, Lu; Sun, Hailian; Qiao, Zhengxue; Qiu, Xiaohui; Zhang, Congpei; Wang, Lin; Zhu, Xiongzhao; He, Jincai; Zhao, Lun; Yang, Yanjie

    2016-01-01

    Despite ongoing debate about gender differences in pre-attention processes, little is known about gender effects on change detection for auditory and visual stimuli. We explored gender differences in change detection while processing duration information in auditory and visual modalities. We investigated pre-attentive processing of duration information using a deviant-standard reverse oddball paradigm (50 ms/150 ms) for auditory and visual mismatch negativity (aMMN and vMMN) in males and females (n=21/group). In the auditory modality, decrement and increment aMMN were observed at 150-250 ms after the stimulus onset, and there was no significant gender effect on MMN amplitudes in temporal or fronto-central areas. In contrast, in the visual modality, only increment vMMN was observed at 180-260 ms after the onset of stimulus, and it was higher in males than in females. No gender effect was found in change detection for auditory stimuli, but change detection was facilitated for visual stimuli in males. Gender effects should be considered in clinical studies of pre-attention for visual stimuli. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  14. The frontal eye fields limit the capacity of visual short-term memory in rhesus monkeys.

    Science.gov (United States)

    Lee, Kyoung-Min; Ahn, Kyung-Ha

    2013-01-01

    The frontal eye fields (FEF) in rhesus monkeys have been implicated in visual short-term memory (VSTM) as well as control of visual attention. Here we examined the importance of the area in the VSTM capacity and the relationship between VSTM and attention, using the chemical inactivation technique and multi-target saccade tasks with or without the need of target-location memory. During FEF inactivation, serial saccades to targets defined by color contrast were unaffected, but saccades relying on short-term memory were impaired when the target count was at the capacity limit of VSTM. The memory impairment was specific to the FEF-coded retinotopic locations, and subject to competition among targets distributed across visual fields. These results together suggest that the FEF plays a crucial role during the entry of information into VSTM, by enabling attention deployment on targets to be remembered. In this view, the memory capacity results from the limited availability of attentional resources provided by FEF: The FEF can concurrently maintain only a limited number of activations to register the targets into memory. When lesions render part of the area unavailable for activation, the number would decrease, further reducing the capacity of VSTM.

  15. The frontal eye fields limit the capacity of visual short-term memory in rhesus monkeys.

    Directory of Open Access Journals (Sweden)

    Kyoung-Min Lee

    Full Text Available The frontal eye fields (FEF in rhesus monkeys have been implicated in visual short-term memory (VSTM as well as control of visual attention. Here we examined the importance of the area in the VSTM capacity and the relationship between VSTM and attention, using the chemical inactivation technique and multi-target saccade tasks with or without the need of target-location memory. During FEF inactivation, serial saccades to targets defined by color contrast were unaffected, but saccades relying on short-term memory were impaired when the target count was at the capacity limit of VSTM. The memory impairment was specific to the FEF-coded retinotopic locations, and subject to competition among targets distributed across visual fields. These results together suggest that the FEF plays a crucial role during the entry of information into VSTM, by enabling attention deployment on targets to be remembered. In this view, the memory capacity results from the limited availability of attentional resources provided by FEF: The FEF can concurrently maintain only a limited number of activations to register the targets into memory. When lesions render part of the area unavailable for activation, the number would decrease, further reducing the capacity of VSTM.

  16. Affective priming of emotional pictures in parafoveal vision: left visual field advantage.

    Science.gov (United States)

    Calvo, Manuel G; Avero, Pedro

    2008-03-01

    This study investigated whether stimulus affective content can be extracted from visual scenes when these appear in parafoveal locations of the visual field and are foveally masked, and whether there is lateralization involved. Parafoveal prime pleasant or unpleasant scenes were presented for 150 msec 2.5 degrees away from fixation and were followed by a foveal probe scene that was either congruent or incongruent in emotional valence with the prime. Participants responded whether the probe was emotionally positive or negative. Affective priming was demonstrated by shorter response latencies for congruent than for incongruent prime-probe pairs. This effect occurred when the prime was presented in the left visual field at a 300-msec prime-probe stimulus onset asynchrony, even when the prime and the probe were different in physical appearance and semantic category. This result reveals that the affective significance of emotional stimuli can be assessed early through covert attention mechanisms, in the absence of overt eye fixations on the stimuli, and suggests that right-hemisphere dominance is involved.

  17. Glaucoma Severity and Participation in Diverse Social Roles: Does Visual Field Loss Matter?

    Science.gov (United States)

    Yang, Yelin; Trope, Graham E; Buys, Yvonne M; Badley, Elizabeth M; Gignac, Monique A M; Shen, Carl; Jin, Ya-Ping

    2016-07-01

    To assess the association between glaucoma severity and participation in diverse social roles. Cross-sectional survey. Individuals with glaucoma, 50+, with visual acuity in the better eye >20/50 were enrolled. They were classified into 3 groups based on visual field loss in the better eye: mild [mean deviation (MD)>-6 dB], moderate (MD, -6 to -12 dB), and severe (MDSocial Role Participation Questionnaire assessed respondents' perceptions of the importance, difficulty, and satisfaction with participation in 11 social role domains (eg, community events, travel). Differences between groups were examined using multivariate linear regression analyses. A total of 118 participants (52% female) were included: 60 mild, 29 moderate, and 29 severe. All social role domains were rated as important by all participants except for education and employment. Women (Psocial activities. Compared with those with mild glaucoma, individuals with severe glaucoma reported significantly more difficulty participating in community/religious/cultural events (Psocial events (P=0.04). Participation in diverse social roles is valued by individuals with glaucoma. Severe visual field loss impedes involvement in and satisfaction with activities in community/religious/cultural events, travelling, and relationships with family members. Appropriate community and targeted interventions are needed to allow people with severe glaucoma to maintain active social participation-a key component to successful aging.

  18. Correlation between Macular Thickness and Visual Field in Early Open Angle Glaucoma: A Cross-Sectional Study.

    Science.gov (United States)

    Fallahi Motlagh, Behzad; Sadeghi, Ali

    2017-01-01

    The aim of this study was to correlate macular thickness and visual field parameters in early glaucoma. A total of 104 eyes affected with early glaucoma were examined in a cross-sectional, prospective study. Visual field testing using both standard automated perimetry (SAP) and shortwave automated perimetry (SWAP) was performed. Global visual field parameters, including mean deviation (MD) and pattern standard deviation (PSD), were recorded and correlated with spectral domain optical coherence tomography (SD-OCT)-measured macular thickness and asymmetry. Average macular thickness correlated significantly with all measures of visual field including MD-SWAP (r = 0.42), MD-SAP (r = 0.41), PSD-SWAP (r = -0.23), and PSD-SAP (r = -0.21), with P-values field parameters in early glaucoma. The results of this study should make macular thickness measurements even more meaningful to glaucoma specialists.

  19. Comparison between visual field defect in pigmentary glaucoma and primary open-angle glaucoma.

    Science.gov (United States)

    Nilforushan, Naveed; Yadgari, Maryam; Jazayeri, Anisalsadat

    2016-10-01

    To compare visual field defect patterns between pigmentary glaucoma and primary open-angle glaucoma. Retrospective, comparative study. Patients with diagnosis of primary open-angle glaucoma (POAG) and pigmentary glaucoma (PG) in mild to moderate stages were enrolled in this study. Each of the 52 point locations in total and pattern deviation plot (excluding 2 points adjacent to blind spot) of 24-2 Humphrey visual field as well as six predetermined sectors were compared using SPSS software version 20. Comparisons between 2 groups were performed with the Student t test for continuous variables and the Chi-square test for categorical variables. Thirty-eight eyes of 24 patients with a mean age of 66.26 ± 11 years (range 48-81 years) in the POAG group and 36 eyes of 22 patients with a mean age of 50.52 ± 11 years (range 36-69 years) in the PG group were studied. (P = 0.00). More deviation was detected in points 1, 3, 4, and 32 in total deviation (P = 0.03, P = 0.015, P = 0.018, P = 0.023) and in points 3, 4, and 32 in pattern deviation (P = 0.015, P = 0.049, P = 0.030) in the POAG group, which are the temporal parts of the field. It seems that the temporal area of the visual field in primary open-angle glaucoma is more susceptible to damage in comparison with pigmentary glaucoma.

  20. Efficient Incorporation of Markov Random Fields in Change Detection

    DEFF Research Database (Denmark)

    Aanæs, Henrik; Nielsen, Allan Aasbjerg; Carstensen, Jens Michael

    2009-01-01

    of noise, implying that the pixel-wise classifier is also noisy. There is thus a need for incorporating local homogeneity constraints into such a change detection framework. For this modelling task Markov Random Fields are suitable. Markov Random Fields have, however, previously been plagued by lack...

  1. Changing struggles for relevance in eight fields of natural science

    NARCIS (Netherlands)

    Hessels, L.K.; Lente, H. van; Smits, R.E.H.M.; Grin, J.

    2011-01-01

    This paper investigates the consequences of institutional changes on academic research practices in eight fields of natural science in the Netherlands. The authors analyse the similarities and differences among the dynamics of these different fields and reflect on possible explanations for the

  2. The calculation and visualization of the fluid field in the canned pump

    International Nuclear Information System (INIS)

    Cheng De; Xue Yabo; Shen Hong; Yao Zhenqiang; Lu Xiangping; Li Cangxue

    2013-01-01

    A kind of canned pump is composed of the motor and the pump section. The canned motor is lubricated and cooled by high pressure water. The rotor in the motor is big and the rotor's velocity is high. The water channel inside the motor is complicated. In this article, the software Fluent is used to calculate the fluid field of the key parts in the motor. Then post-processing software Ensight is used to visualize the result of the FEM analysis. The velocity and pressure of the fluid fields in the motor's key parts can be studied thoroughly. A video and pictures are created to illustrate the function of the middle impeller and the gratitude of the fluid fields. (authors)

  3. Near-field visualization of plasmonic lenses: an overall analysis of characterization errors

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2015-10-01

    Full Text Available Many factors influence the near-field visualization of plasmonic structures that are based on perforated elliptical slits. Here, characterization errors are experimentally analyzed in detail from both fabrication and measurement points of view. Some issues such as geometrical parameter, probe–sample surface interaction, misalignment, stigmation, and internal stress, have influence on the final near-field probing results. In comparison to the theoretical ideal case of near-field probing of the structures, numerical calculation is carried out on the basis of a finite-difference and time-domain (FDTD algorithm so as to support the error analyses. The analyses performed on the basis of both theoretical calculation and experimental probing can provide a helpful reference for the researchers probing their plasmonic structures and nanophotonic devices.

  4. Does age matter? Age and rehabilitation of visual field disorders after brain injury.

    Science.gov (United States)

    Schuett, Susanne; Zihl, Josef

    2013-04-01

    Homonymous visual field disorders (HVFD) are frequent and disabling consequences of acquired brain injury, particularly in older age. Their rehabilitation is therefore of great importance. Compensatory oculomotor therapy has been found to be effective in improving the associated functional impairments in reading and visual exploration. But older age is commonly considered to adversely affect practice-dependent functional plasticity and, thus, functional and rehabilitation outcome after acquired brain injury. The effect of age in the compensatory treatment of HVFD, however, has never been investigated hitherto. It remains unknown whether age determines not only patients' functional impairments but also the rehabilitation outcome and the required amount of treatment. We therefore present the first study to determine the effect of age in 38 patients with HVFD receiving compensatory oculomotor treatment for their reading and visual exploration impairments. We investigated whether older patients with HVFD (1) show more pronounced impairments and less spontaneous adaptation, (2) show lesser compensatory treatment-related improvement in reading and visual exploration, and (3) require a higher amount of treatment than younger patients. Our main finding is that older patients achieve the same treatment-induced improvements in reading and visual exploration with the same amount of treatment as younger patients; severity of functional impairment also did not differ between older and younger patients, at least in reading. Age does not seem to be a critical factor determining the functional and rehabilitation outcome in the compensatory treatment of HVFD. Older age per se is not necessarily associated with a decline in practice-dependent functional plasticity and adaptation. To the contrary, the effectiveness of compensatory treatment to reduce the functional impairments to a similar extent in younger and older patients with HVFD adds to the growing evidence for a life

  5. Involvement of the visual change detection process in facilitating perceptual alternation in the bistable image.

    Science.gov (United States)

    Urakawa, Tomokazu; Bunya, Mao; Araki, Osamu

    2017-08-01

    A bistable image induces one of two perceptual alternatives. When the bistable visual image is continuously viewed, the percept of the image alternates from one possible percept to the other. Perceptual alternation was previously reported to be induced by an exogenous perturbation in the bistable image, and this perturbation was theoretically interpreted to cause neural noise, prompting a transition between two stable perceptual states. However, little is known experimentally about the visual processing of exogenously driven perceptual alternation. Based on the findings of a previous behavioral study (Urakawa et al. in Perception 45:474-482, 2016), the present study hypothesized that the automatic visual change detection process, which is relevant to the detection of a visual change in a sequence of visual events, has an enhancing effect on the induction of perceptual alternation, similar to neural noise. In order to clarify this issue, we developed a novel experimental paradigm in which visual mismatch negativity (vMMN), an electroencephalographic brain response that reflects visual change detection, was evoked while participants continuously viewed the bistable image. In terms of inter-individual differences in neural and behavioral data, we found that enhancements in the peak amplitude of vMMN1, early vMMN at a latency of approximately 150 ms, correlated with increases in the proportion of perceptual alternation across participants. Our results indicate the involvement of automatic visual change detection in the induction of perceptual alternation, similar to neural noise, thereby providing a deeper insight into the neural mechanisms underlying exogenously driven perceptual alternation in the bistable image.

  6. Equating spatial summation in visual field testing reveals greater loss in optic nerve disease.

    Science.gov (United States)

    Kalloniatis, Michael; Khuu, Sieu K

    2016-07-01

    To test the hypothesis that visual field assessment in ocular disease measured with target stimuli within or close to complete spatial summation results in larger threshold elevation compared to when measured with the standard Goldmann III target size. The hypothesis predicts a greater loss will be identified in ocular disease. Additionally, we sought to develop a theoretical framework that would allow comparisons of thresholds with disease progression when using different Goldmann targets. The Humphrey Field Analyser (HFA) 30-2 grid was used in 13 patients with early/established optic nerve disease using the current Goldmann III target size or a combination of the three smallest stimuli (target size I, II and III). We used data from control subjects at each of the visual field locations for the different target sizes to establish the number of failed points (events) for the patients with optic nerve disease, as well as global indices for mean deviation (MD) and pattern standard deviation (PSD). The 30-2 visual field testing using alternate target size stimuli showed that all 13 patients displayed more defects (events) compared to the standard Goldmann III target size. The median increase for events was seven additional failed points: (range 1-26). The global indices also increased when the new testing approach was used (MD -3.47 to -6.25 dB and PSD 4.32 to 6.63 dB). Spatial summation mapping showed an increase in critical area (Ac) in disease and overall increase in thresholds when smaller target stimuli were used. When compared to the current Goldmann III paradigm, the use of alternate sized targets within the 30-2 testing protocol revealed a greater loss in patients with optic nerve disease for both event analysis and global indices (MD and PSD). We therefore provide evidence in a clinical setting that target size is important in visual field testing. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

  7. Acetylcholinesterase in motion : Visualizing conformational changes in crystal structures by a morphing procedure

    NARCIS (Netherlands)

    Zeev-Ben-Mordehai, T; Silman, I.; Sussman, J.L.

    In order to visualize and appreciate conformational changes between homologous three-dimensional (3D) protein structures or protein/inhibitor complexes, we have developed a user-friendly morphing procedure. It enabled us to detect coordinated conformational changes not easily discernible by analytic

  8. Rapid change of field line connectivity and reconnection in stochastic magnetic fields

    International Nuclear Information System (INIS)

    Huang, Yi-Min; Bhattacharjee, A.; Boozer, Allen H.

    2014-01-01

    Magnetic fields without a direction of continuous symmetry have the generic feature that neighboring field lines exponentiate away from each other and become stochastic, and hence the ideal constraint of preserving magnetic field line connectivity becomes exponentially sensitive to small deviations from ideal Ohm's law. The idea of breaking field line connectivity by stochasticity as a mechanism for fast reconnection is tested with numerical simulations based on reduced magnetohydrodynamics equations with a strong guide field line-tied to two perfectly conducting end plates. Starting from an ideally stable force-free equilibrium, the system is allowed to undergo resistive relaxation. Two distinct phases are found in the process of resistive relaxation. During the quasi-static phase, rapid change of field line connectivity and strong induced flow are found in regions of high field line exponentiation. However, although the field line connectivity of individual field lines can change rapidly, the overall pattern of field line mapping appears to deform gradually. From this perspective, field line exponentiation appears to cause enhanced diffusion rather than reconnection. In some cases, resistive quasi-static evolution can cause the ideally stable initial equilibrium to cross a stability threshold, leading to formation of intense current filaments and rapid change of field line mapping into a qualitatively different pattern. It is in this onset phase that the change of field line connectivity is more appropriately designated as magnetic reconnection. Our results show that rapid change of field line connectivity appears to be a necessary, but not a sufficient condition for fast reconnection.

  9. Review Article. Electrophysiological Methods for Study of Changes in Visual Analyzer in Patients with Diabetes Mellitus

    Directory of Open Access Journals (Sweden)

    Elena Mermeklieva

    2017-03-01

    Full Text Available The electrophysiological (EF methods are objective methods for studying the visual analyzer function. These include electroretinography (ERG, electrooculography (EOG and visual evoked potentials (VEPs. ERG and EOG are used for diagnosis and monitoring of a number of diseases of the retina. VEPs depend on the functional integrity of the entire optical path from the retina through the optic nerve, optic tract, the optical radiation to the visual cortex. The electrophysiological methods are widely used in studying the function of the visual analyzer in the ophthalmic and neurological practice, for objectively measuring the visual acuity and the visual field in non-cooperative patients, small children and in simulation. Diabetes mellitus (DM is a group of metabolic diseases characterized by hyperglycemia. One of the late complications of DM is diabetic retinopathy (DR. It is one of the most serious complications of diabetes, often leading to blindness. Nowadays, DR includes retinal neurodegeneration and microvascular complications. By EF studies can evaluate the function of the retina in diabetic patients in an objective manner using ERG, that reflects the EF activity of the neurons in the retina and VEPs, which indicate the electrical conductivity across the optic tract to the visual cortex.

  10. Genre Differences on Visual Perception of Color Range and Depth of Field

    Directory of Open Access Journals (Sweden)

    Luisa Ballesteros

    2003-07-01

    Full Text Available Visual perception is the result of the integration of various related factors of the observed object and its environment. In this study we evaluated the impact of tridimensional form on color perception and the angle from the horizontal plane of a set of similar objets on the depth of field perception between young men and women. A panel half magenta and half white placed at the end of a black box, folded either concaved or convexed to alter the chromatic effect perceived were used to determine tridimensional form on color perception. Four sets of identical sticks where the angle from the horizontal plane varied for each, were used to determine the effect of spatial distribution of depth of field perception. The parameters taking into account were age, genre, associated visual defects for each individual evaluated. Our results show that the tridimensional form alters color perception but the range of color perceived was larger for women whereas depending on the angle from the horizontal plane we found genre differences on the depth of field perception.

  11. Changes in neurophysiologic markers of visual processing following beneficial anti-VEGF treatment in macular degeneration

    Directory of Open Access Journals (Sweden)

    Vottonen P

    2013-02-01

    Full Text Available Pasi Vottonen,1 Kai Kaarniranta,1,2 Ari Pääkkönen,3 Ina M Tarkka41Department of Ophthalmology, Kuopio University Hospital, Kuopio, Finland; 2Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland; 3Department of Clinical Neurophysiology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland; 4Department of Health Sciences, University of Jyväskylä, Jyväskylä, FinlandPurpose: Antivascular endothelial growth factor (VEGF agents have been shown to improve visual acuity and prevent vision loss in exudative age-related macular degeneration. As the vision improves relatively quickly in response to intravitreal injections, we wanted to know whether this improvement is reflected in electrophysiological markers of visual cortical processing.Patients and methods: Our interventional case series included six elderly patients who underwent injection treatment to the affected eye. Their visual acuity, tomographic images of retinal thickness, and visual evoked potentials (VEP were assessed before treatment and six weeks after the last injection.Results: All patients showed improved visual acuity and reduced retinal fluid after the treatment. All but one patient showed increased VEP P100 component amplitudes and/or shortened latencies in the treated eye. These VEP changes were consistent with improved vision while the untreated eyes showed no changes.Conclusions: Our results indicate that antivascular endothelial growth factor injections improved visual function of the treated eyes both in the level of the retina and in the level of visual cortical processing.Keywords: age-related eye diseases, exudative age-related macular degeneration, visual evoked potentials, scalp-recorded EEG, visual acuity

  12. Evaluation of Visual Field Progression in Glaucoma: Quasar Regression Program and Event Analysis.

    Science.gov (United States)

    Díaz-Alemán, Valentín T; González-Hernández, Marta; Perera-Sanz, Daniel; Armas-Domínguez, Karintia

    2016-01-01

    To determine the sensitivity, specificity and agreement between the Quasar program, glaucoma progression analysis (GPA II) event analysis and expert opinion in the detection of glaucomatous progression. The Quasar program is based on linear regression analysis of both mean defect (MD) and pattern standard deviation (PSD). Each series of visual fields was evaluated by three methods; Quasar, GPA II and four experts. The sensitivity, specificity and agreement (kappa) for each method was calculated, using expert opinion as the reference standard. The study included 439 SITA Standard visual fields of 56 eyes of 42 patients, with a mean of 7.8 ± 0.8 visual fields per eye. When suspected cases of progression were considered stable, sensitivity and specificity of Quasar, GPA II and the experts were 86.6% and 70.7%, 26.6% and 95.1%, and 86.6% and 92.6% respectively. When suspected cases of progression were considered as progressing, sensitivity and specificity of Quasar, GPA II and the experts were 79.1% and 81.2%, 45.8% and 90.6%, and 85.4% and 90.6% respectively. The agreement between Quasar and GPA II when suspected cases were considered stable or progressing was 0.03 and 0.28 respectively. The degree of agreement between Quasar and the experts when suspected cases were considered stable or progressing was 0.472 and 0.507. The degree of agreement between GPA II and the experts when suspected cases were considered stable or progressing was 0.262 and 0.342. The combination of MD and PSD regression analysis in the Quasar program showed better agreement with the experts and higher sensitivity than GPA II.

  13. A contemporary decennial global sample of changing agricultural field sizes

    Science.gov (United States)

    White, E.; Roy, D. P.

    2011-12-01

    In the last several hundred years agriculture has caused significant human induced Land Cover Land Use Change (LCLUC) with dramatic cropland expansion and a marked increase in agricultural productivity. The size of agricultural fields is a fundamental description of rural landscapes and provides an insight into the drivers of rural LCLUC. Increasing field sizes cause a subsequent decrease in the number of fields and therefore decreased landscape spatial complexity with impacts on biodiversity, habitat, soil erosion, plant-pollinator interactions, diffusion of disease pathogens and pests, and loss or degradation in buffers to nutrient, herbicide and pesticide flows. In this study, globally distributed locations with significant contemporary field size change were selected guided by a global map of agricultural yield and literature review and were selected to be representative of different driving forces of field size change (associated with technological innovation, socio-economic conditions, government policy, historic patterns of land cover land use, and environmental setting). Seasonal Landsat data acquired on a decadal basis (for 1980, 1990, 2000 and 2010) were used to extract field boundaries and the temporal changes in field size quantified and their causes discussed.

  14. Is Seeing Believing? The Process of Change During Cognitive-behavioural Therapy for Distressing Visual Hallucinations.

    Science.gov (United States)

    Wilson, Rea; Collerton, Daniel; Freeston, Mark; Christodoulides, Thomas; Dudley, Robert

    2016-07-01

    People with psychosis often report distressing visual hallucinations (VH). In contrast to auditory hallucinations, there is little empirical evidence on effective interventions. The effectiveness of a novel-focused cognitive-behavioural therapy (CBT) intervention for VH was explored using a multiple baseline single case design with four participants. Change to individual appraisals, emotional and behavioural responses to VH were measured with daily diaries kept throughout the baseline and intervention phase lasting up to 16 sessions. Maintenance of change was tracked during a follow-up period of one month. Changes in appraisals, distress and response in accordance with the theory was evident in two out of four of the cases. However, change occurred within the baseline phase that limited the conclusions that change could be attributed to CBT alone. There was some evidence of clinically significant change and reliable change for two out of four of the cases at follow-up on one of the standardized psychiatric assessments. The research reported here has theoretical and clinical implications for refinement of the model and interventions for distressing VH. Copyright © 2015 John Wiley & Sons, Ltd. Distressing visual hallucinations (VH) are a relatively common symptom of psychosis. Visual hallucinations seem to be associated with greater impairment and disability. We have no specific treatment for VH. The appraisal of the visual experience and the behavioural response is important in maintaining the distress. Cognitive-behavioural therapy for VH at present has limited value. Copyright © 2015 John Wiley & Sons, Ltd.

  15. Scotoma analysis of 10-2 visual field testing with a white target in screening for hydroxychloroquine retinopathy

    Directory of Open Access Journals (Sweden)

    Browning DJ

    2015-05-01

    Full Text Available David J Browning, Chong Lee Department of Ophthalmology, Charlotte Eye, Ear, Nose and Throat Associates, Charlotte, NC, USA Objective: To quantify the variability of scotomas detected by 10-2 visual field (VF testing in patients taking hydroxychloroquine without and with retinopathy.Design: Retrospective review of clinical charts and visual fields.Subjects: Twenty-one patients taking hydroxychloroquine without retinopathy, and nine patients taking hydroxychloroquine and one patient taking chloroquine with retinopathy.Methods: Retinopathy was defined by annular scotomas on 10-2 VF testing with corroborative spectral domain optical coherence tomographic outer retinal changes and multifocal electroretinographic changes leading to cessation of hydroxychloroquine or chloroquine. Location and depth of scotoma points on 10-2 VF testing were recorded and their fates followed in serial, reliable 10-2 VFs performed with a white target over time.Main outcome measures: Number of scotoma points and locations, percentage of persistent scotoma points, size of scotomas, location of scotomas, and percentage of scotomas deepening.Results: A median of five, interquartile range (IQR 3–8 scotoma points per VF occurred in patients without retinopathy. A median of 86%, IQR 63%–100% of these points resolve on the subsequent field. For patients with retinopathy, a median of 22%, IQR 10%–59% resolve. The median percentage of scotoma points in the zone 2–8 degrees from fixation in eyes with retinopathy was 79%, IQR 68%–85% compared to 60%, IQR 54%–75% in eyes without retinopathy (P=0.0094. Single-point scotomas were more common in eyes without than with retinopathy. Scotomas consisting of more than four contiguous scotoma points were generally indicative of retinopathy.Conclusion: Point scotomas are common and variable in 10-2 VF testing with a white target for hydroxychloroquine retinopathy in subjects without retinopathy. The annular zone 2 to 8

  16. Feature Optimization for Long-Range Visual Homing in Changing Environments

    Directory of Open Access Journals (Sweden)

    Qidan Zhu

    2014-02-01

    Full Text Available This paper introduces a feature optimization method for robot long-range feature-based visual homing in changing environments. To cope with the changing environmental appearance, the optimization procedure is introduced to distinguish the most relevant features for feature-based visual homing, including the spatial distribution, selection and updating. In the previous research on feature-based visual homing, less effort has been spent on the way to improve the feature distribution to get uniformly distributed features, which are closely related to homing performance. This paper presents a modified feature extraction algorithm to decrease the influence of anisotropic feature distribution. In addition, the feature selection and updating mechanisms, which have hardly drawn any attention in the domain of feature-based visual homing, are crucial in improving homing accuracy and in maintaining the representation of changing environments. To verify the feasibility of the proposal, several comprehensive evaluations are conducted. The results indicate that the feature optimization method can find optimal feature sets for feature-based visual homing, and adapt the appearance representation to the changing environments as well.

  17. RankExplorer: Visualization of Ranking Changes in Large Time Series Data.

    Science.gov (United States)

    Shi, Conglei; Cui, Weiwei; Liu, Shixia; Xu, Panpan; Chen, Wei; Qu, Huamin

    2012-12-01

    For many applications involving time series data, people are often interested in the changes of item values over time as well as their ranking changes. For example, people search many words via search engines like Google and Bing every day. Analysts are interested in both the absolute searching number for each word as well as their relative rankings. Both sets of statistics may change over time. For very large time series data with thousands of items, how to visually present ranking changes is an interesting challenge. In this paper, we propose RankExplorer, a novel visualization method based on ThemeRiver to reveal the ranking changes. Our method consists of four major components: 1) a segmentation method which partitions a large set of time series curves into a manageable number of ranking categories; 2) an extended ThemeRiver view with embedded color bars and changing glyphs to show the evolution of aggregation values related to each ranking category over time as well as the content changes in each ranking category; 3) a trend curve to show the degree of ranking changes over time; 4) rich user interactions to support interactive exploration of ranking changes. We have applied our method to some real time series data and the case studies demonstrate that our method can reveal the underlying patterns related to ranking changes which might otherwise be obscured in traditional visualizations.

  18. Explicit behavioral detection of visual changes develops without their implicit neurophysiological detectability

    Directory of Open Access Journals (Sweden)

    Pessi eLyyra

    2012-03-01

    Full Text Available Change blindness is a failure of explicitly detecting changes between consecutively presented images when separated, e.g., by a brief blank screen. There is a growing body of evidence of implicit detection of even explicitly undetectable changes, pointing to the possibility of the implicit change detection as a prerequisite for its explicit counterpart. We recorded event-related potentials (ERPs of the electroencephalography in adults during an oddball-variant of change blindness flicker paradigm. In this variant, rare pictures with a change were interspersed with frequent pictures with no change. In separate stimulus blocks, the blank screen between the change and no-change picture was either of 100 ms or 500 ms in duration. In both stimulus conditions the participants eventually explicitly detect the changed pictures, the blank screen of the longer duration only requiring in average 10 % longer exposure to the picture series until the ability emerged. However, during the change blindness, ERPs were displaced towards negative polarity at 200–260 ms after the stimulus onset (visual mismatch negativity only with the blank screens of the shorter ISI. Our finding of ‘implicit change blindness’ for pictorial material that, nevertheless, successfully prepares the visual system for explicit change detection suggests that implicit change detection may not be a necessary condition for explicit change detection and that they may recruit at least partially distinct memory mechanisms.

  19. Mapping and correcting respiration-induced field changes in the brain using fluorine field probes

    DEFF Research Database (Denmark)

    Andersen, Mads; Madsen, Kristoffer; Hanson, Lars G.

    2014-01-01

    strength values from signal phase by linear fitting. Ahead of imaging, the field probe positions were determined for each subject, by applying known gradients in all three dimensions while measuring with the field probes. Experiments: Measurements were performed in 4 male subjects instructed to hold...... software was updated with f0 and first order shim values, before the acquisition of every volume. Evaluation: To assess whether the dynamic field changes were captured by the field probe data, the field probe fitted fields were subtracted from the scanner B0 maps to model shimming. We then assessed whether......Purpose. Breathing induced dynamic B0 field perturbations in the head can lead to artefacts in ultra-high field MR by causing line broadening in spectroscopy and signal dropout, ghosting, displacement artifacts and blurring in imaging. It has recently been proposed to continuously stabilize...

  20. Visual illusions on the Internet: 15 years of change in technology and user behavior.

    Science.gov (United States)

    Bach, Michael

    2014-01-01

    Abstract. Looking back over 15 years of demonstrating visual phenomena and optical illusions on the Internet, I will discuss two major topics. The first concerns the methodology used to present interactive visual experiments on the web, with respect to (a) wide accessibility, ie independent of browser and platform, (b) capable and elegant graphic user interface, (c) sufficient computational power, (d) ease of development and, finally, (e) future-proofing in an ever-changing online environment. The second major topic addresses some aspects of user behaviour, mainly temporal patterns (eg changes over weeks. years, long-term), which reveal that there are more visitors during office hours.

  1. Visual half-field presentations of incongruent color words: effects of gender and handedness.

    Science.gov (United States)

    Franzon, M; Hugdahl, K

    1986-09-01

    Right-handed (dextral) and left-handed (sinistral) males and females (N = 15) were compared for language lateralization in a visual half-field (VHF) incongruent color-words paradigm. The paradigm consists of repeated brief (less than 200 msec) presentations of color-words written in an incongruent color. Presentations are either to the right or to the left of center fixation. The task of the subject is to report the color the word is written in on each trial, ignoring the color-word. Color-bars and congruent color-words were used as control stimuli. Vocal reaction time (VRT) and error frequency were used as dependent measures. The logic behind the paradigm is that incongruent color-words should lead to a greater cognitive conflict when presented in the half-field contralateral to the dominant hemisphere. The results showed significantly longer VRTs in the right half-field for the dextral subjects. Furthermore, significantly more errors were observed in the male dextral group when the incongruent stimuli were presented in the right half-field. There was a similar trend in the data for the sinistral males. No differences between half-fields were observed for the female groups. It is concluded that the present results strengthen previous findings from our laboratory (Hugdahl and Franzon, 1985) that the incongruent color-words paradigm is a useful non-invasive technique for the study of lateralization in the intact brain.

  2. Exploring BOLD changes during spatial attention in non-stimulated visual cortex.

    Directory of Open Access Journals (Sweden)

    Linda Heinemann

    Full Text Available Blood oxygen level-dependent (BOLD responses were measured in parts of primary visual cortex that represented unstimulated visual field regions at different distances from a stimulated central target location. The composition of the visual scene varied by the presence or absence of additional peripheral distracter stimuli. Bottom-up effects were assessed by comparing peripheral activity during central stimulation vs. no stimulation. Top-down effects were assessed by comparing active vs. passive conditions. In passive conditions subjects simply watched the central letter stimuli and in active conditions they had to report occurrence of pre-defined targets in a rapid serial letter stream. Onset of the central letter stream enhanced activity in V1 representations of the stimulated region. Within representations of the periphery activation decreased and finally turned into deactivation with increasing distance from the stimulated location. This pattern was most pronounced in the active conditions and during the presence of peripheral stimuli. Active search for a target did not lead to additional enhancement at areas representing the attentional focus but to a stronger deactivation in the vicinity. Suppressed neuronal activity was also found in the non distracter condition suggesting a top-down attention driven effect. Our observations suggest that BOLD signal decreases in primary visual cortex are modulated by bottom-up sensory-driven factors such as the presence of distracters in the visual field as well as by top-down attentional processes.

  3. Comparative Visualization of Vector Field Ensembles Based on Longest Common Subsequence

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Richen; Guo, Hanqi; Zhang, Jiang; Yuan, Xiaoru

    2016-04-19

    We propose a longest common subsequence (LCS) based approach to compute the distance among vector field ensembles. By measuring how many common blocks the ensemble pathlines passing through, the LCS distance defines the similarity among vector field ensembles by counting the number of sharing domain data blocks. Compared to the traditional methods (e.g. point-wise Euclidean distance or dynamic time warping distance), the proposed approach is robust to outlier, data missing, and sampling rate of pathline timestep. Taking the advantages of smaller and reusable intermediate output, visualization based on the proposed LCS approach revealing temporal trends in the data at low storage cost, and avoiding tracing pathlines repeatedly. Finally, we evaluate our method on both synthetic data and simulation data, which demonstrate the robustness of the proposed approach.

  4. Design and implementation of visualization methods for the CHANGES Spatial Decision Support System

    Science.gov (United States)

    Cristal, Irina; van Westen, Cees; Bakker, Wim; Greiving, Stefan

    2014-05-01

    The CHANGES Spatial Decision Support System (SDSS) is a web-based system aimed for risk assessment and the evaluation of optimal risk reduction alternatives at local level as a decision support tool in long-term natural risk management. The SDSS use multidimensional information, integrating thematic, spatial, temporal and documentary data. The role of visualization in this context becomes of vital importance for efficiently representing each dimension. This multidimensional aspect of the required for the system risk information, combined with the diversity of the end-users imposes the use of sophisticated visualization methods and tools. The key goal of the present work is to exploit efficiently the large amount of data in relation to the needs of the end-user, utilizing proper visualization techniques. Three main tasks have been accomplished for this purpose: categorization of the end-users, the definition of system's modules and the data definition. The graphical representation of the data and the visualization tools were designed to be relevant to the data type and the purpose of the analysis. Depending on the end-users category, each user should have access to different modules of the system and thus, to the proper visualization environment. The technologies used for the development of the visualization component combine the latest and most innovative open source JavaScript frameworks, such as OpenLayers 2.13.1, ExtJS 4 and GeoExt 2. Moreover, the model-view-controller (MVC) pattern is used in order to ensure flexibility of the system at the implementation level. Using the above technologies, the visualization techniques implemented so far offer interactive map navigation, querying and comparison tools. The map comparison tools are of great importance within the SDSS and include the following: swiping tool for comparison of different data of the same location; raster subtraction for comparison of the same phenomena varying in time; linked views for comparison

  5. [Clinico-statistical study on availability of Esterman disability score for assessment of mobility difficulty in patients with visual field loss].

    Science.gov (United States)

    Yamagata, Yoshitaka; Terada, Yuko; Suzuki, Atsushi; Mimura, Osamu

    2010-01-01

    The visual efficiency scale currently adopted to determine the legal grade of visual disability associated with visual field loss in Japan is not appropriate for the evaluation of disability regarding daily living activities. We investigated whether Esterman disability score (EDS) is suitable for the assessment of mobility difficulty in patients with visual field loss. The correlation between the EDS calculated from Goldmann's kinetic visual field and the degree of subjective mobility difficulty determined by a questionnaire was investigated in 164 patients with visual field loss. The correlation between the EDS determined using a program built into the Humphrey field analyzer and that calculated from Goldmann's kinetic visual field was also investigated. The EDS based on the kinetic visual field was correlated well with the degree of subjective mobility difficulty, and the EDS measured using the Humphrey field analyzer could be estimated from the kinetic visual field-based EDS. Instead of the currently adopted visual efficiency scale, EDS should be employed for the assessment of mobility difficulty in patients with visual field loss, also to establish new judgment criteria concerning the visual field.

  6. Structural and functional brain changes beyond visual system in patients with advanced glaucoma.

    Directory of Open Access Journals (Sweden)

    Paolo Frezzotti

    Full Text Available In order to test the hypothesis that in primary open angle glaucoma (POAG, an important cause of irreversible blindness, a spreading of neurodegeneration occurs through the brain, we performed multimodal MRI and subsequent whole-brain explorative voxelwise analyses in 13 advanced POAG patients and 12 age-matched normal controls (NC. Altered integrity (decreased fractional anisotropy or increased diffusivities of white matter (WM tracts was found not only along the visual pathway of POAG but also in nonvisual WM tracts (superior longitudinal fascicle, anterior thalamic radiation, corticospinal tract, middle cerebellar peduncle. POAG patients also showed brain atrophy in both visual cortex and other distant grey matter (GM regions (frontoparietal cortex, hippocampi and cerebellar cortex, decreased functional connectivity (FC in visual, working memory and dorsal attention networks and increased FC in visual and executive networks. In POAG, abnormalities in structure and FC within and outside visual system correlated with visual field parameters in the poorer performing eyes, thus emphasizing their clinical relevance. Altogether, this represents evidence that a vision disorder such as POAG can be considered a widespread neurodegenerative condition.

  7. Visual attention measures predict pedestrian detection in central field loss: a pilot study.

    Science.gov (United States)

    Alberti, Concetta F; Horowitz, Todd; Bronstad, P Matthew; Bowers, Alex R

    2014-01-01

    The ability of visually impaired people to deploy attention effectively to maximize use of their residual vision in dynamic situations is fundamental to safe mobility. We conducted a pilot study to evaluate whether tests of dynamic attention (multiple object tracking; MOT) and static attention (Useful Field of View; UFOV) were predictive of the ability of people with central field loss (CFL) to detect pedestrian hazards in simulated driving. 11 people with bilateral CFL (visual acuity 20/30-20/200) and 11 age-similar normally-sighted drivers participated. Dynamic and static attention were evaluated with brief, computer-based MOT and UFOV tasks, respectively. Dependent variables were the log speed threshold for 60% correct identification of targets (MOT) and the increase in the presentation duration for 75% correct identification of a central target when a concurrent peripheral task was added (UFOV divided and selective attention subtests). Participants drove in a simulator and pressed the horn whenever they detected pedestrians that walked or ran toward the road. The dependent variable was the proportion of timely reactions (could have stopped in time to avoid a collision). UFOV and MOT performance of CFL participants was poorer than that of controls, and the proportion of timely reactions was also lower (worse) (84% and 97%, respectively; p = 0.001). For CFL participants, higher proportions of timely reactions correlated significantly with higher (better) MOT speed thresholds (r = 0.73, p = 0.01), with better performance on the UFOV divided and selective attention subtests (r = -0.66 and -0.62, respectively, pattention may provide useful measures of functional visual ability of individuals with CFL relevant to more complex mobility tasks.

  8. Central and Divided Visual Field Presentation of Emotional Images to Measure Hemispheric Differences in Motivated Attention.

    Science.gov (United States)

    O'Hare, Aminda J; Atchley, Ruth Ann; Young, Keith M

    2017-11-16

    Two dominant theories on lateralized processing of emotional information exist in the literature. One theory posits that unpleasant emotions are processed by right frontal regions, while pleasant emotions are processed by left frontal regions. The other theory posits that the right hemisphere is more specialized for the processing of emotional information overall, particularly in posterior regions. Assessing the different roles of the cerebral hemispheres in processing emotional information can be difficult without the use of neuroimaging methodologies, which are not accessible or affordable to all scientists. Divided visual field presentation of stimuli can allow for the investigation of lateralized processing of information without the use of neuroimaging technology. This study compared central versus divided visual field presentations of emotional images to assess differences in motivated attention between the two hemispheres. The late positive potential (LPP) was recorded using electroencephalography (EEG) and event-related potentials (ERPs) methodologies to assess motivated attention. Future work will pair this paradigm with a more active behavioral task to explore the behavioral impacts on the attentional differences found.

  9. Visualization of Flow Field of Weis-Fogh Type Water Turbine Using the PIV

    Energy Technology Data Exchange (ETDEWEB)

    Ro, Ki Deok [Gyeongsang Nat’l Univ., Jinju (Korea, Republic of)

    2017-03-15

    In this study, the visualization of the unsteady flow field of a Weis-Fogh-type water turbine was investigated using particle-image velocimetry. The visualization experiments were performed in a parameter range that provided relatively high-efficiency wing conditions, that is, at a wing opening angle α= 40 .deg. and at a velocity ratio of the uniform flow to the moving wing U/V = 1.5~2.5. The flow fields at the opening, translational, and closing stages were investigated for each experimental parameter. In the opening stage, the fluid was drawn in between the wing and wall at a velocity that increased with an increase in the opening angle and velocity ratio. In the translational stage, the fluid on the pressure face of the wing moved in the direction of the wing motion, and the boundary layer at the back face of the wing was the thinnest and had a velocity ratio of 2.0. In the closing stage, the fluid between the wing and wall was jetted at a velocity that increased as the opening angle decreased; however, the velocity was independent of the velocity ratio.

  10. Low-cost, smartphone based frequency doubling technology visual field testing using virtual reality (Conference Presentation)

    Science.gov (United States)

    Alawa, Karam A.; Sayed, Mohamed; Arboleda, Alejandro; Durkee, Heather A.; Aguilar, Mariela C.; Lee, Richard K.

    2017-02-01

    Glaucoma is the leading cause of irreversible blindness worldwide. Due to its wide prevalence, effective screening tools are necessary. The purpose of this project is to design and evaluate a system that enables portable, cost effective, smartphone based visual field screening based on frequency doubling technology. The system is comprised of an Android smartphone to display frequency doubling stimuli and handle processing, a Bluetooth remote for user input, and a virtual reality headset to simulate the exam. The LG Nexus 5 smartphone and BoboVR Z3 virtual reality headset were used for their screen size and lens configuration, respectively. The system is capable of running the C-20, N-30, 24-2, and 30-2 testing patterns. Unlike the existing system, the smartphone FDT tests both eyes concurrently by showing the same background to both eyes but only displaying the stimulus to one eye at a time. Both the Humphrey Zeiss FDT and the smartphone FDT were tested on five subjects without a history of ocular disease with the C-20 testing pattern. The smartphone FDT successfully produced frequency doubling stimuli at the correct spatial and temporal frequency. Subjects could not tell which eye was being tested. All five subjects preferred the smartphone FDT to the Humphrey Zeiss FDT due to comfort and ease of use. The smartphone FDT is a low-cost, portable visual field screening device that can be used as a screening tool for glaucoma.

  11. Magnetohydrodynamic pressure drop in a quickly changing magnetic field

    International Nuclear Information System (INIS)

    Xu, Z.Y.; Chen, J.M.; Qian, J.P.; Jiang, W.H.; Pan, C.J.; Li, W.Z.

    1995-01-01

    The magnetohydrodynamic (MHD) pressure drop of 22 Na 78 K flow in a circular duct was measured under a quickly changing magnetic field. The MHD pressure drop reduced with time as the magnetic field strength decreased. However, the dimensionless pressure drop gradient varied with the interaction parameter and had a higher value in the middle of the range of values of the interaction parameter. Therefore, a quickly changing magnetic field is harmful to the structural material in a liquid metal self-cooled blanket of a fusion reactor, since the greater pressure drop gradient may cause a larger stress in the blanket. This is even more harmful if the magnetic field strength decreases very quickly or its distribution in space is greatly non-uniform. (orig.)

  12. Primary Generators of Visually Evoked Field Potentials Recorded in the Macaque Auditory Cortex

    Science.gov (United States)

    Smiley, John F.; Schroeder, Charles E.

    2017-01-01

    Prior studies have reported “local” field potential (LFP) responses to faces in the macaque auditory cortex and have suggested that such face-LFPs may be substrates of audiovisual integration. However, although field potentials (FPs) may reflect the synaptic currents of neurons near the recording electrode, due to the use of a distant reference electrode, they often reflect those of synaptic activity occurring in distant sites as well. Thus, FP recordings within a given brain region (e.g., auditory cortex) may be “contaminated” by activity generated elsewhere in the brain. To determine whether face responses are indeed generated within macaque auditory cortex, we recorded FPs and concomitant multiunit activity with linear array multielectrodes across auditory cortex in three macaques (one female), and applied current source density (CSD) analysis to the laminar FP profile. CSD analysis revealed no appreciable local generator contribution to the visual FP in auditory cortex, although we did note an increase in the amplitude of visual FP with cortical depth, suggesting that their generators are located below auditory cortex. In the underlying inferotemporal cortex, we found polarity inversions of the main visual FP components accompanied by robust CSD responses and large-amplitude multiunit activity. These results indicate that face-evoked FP responses in auditory cortex are not generated locally but are volume-conducted from other face-responsive regions. In broader terms, our results underscore the caution that, unless far-field contamination is removed, LFPs in general may reflect such “far-field” activity, in addition to, or in absence of, local synaptic responses. SIGNIFICANCE STATEMENT Field potentials (FPs) can index neuronal population activity that is not evident in action potentials. However, due to volume conduction, FPs may reflect activity in distant neurons superimposed upon that of neurons close to the recording electrode. This is

  13. Detecting changes in real-world objects: The relationship between visual long-term memory and change blindness.

    Science.gov (United States)

    Brady, Timothy F; Konkle, Talia; Oliva, Aude; Alvarez, George A

    2009-01-01

    A large body of literature has shown that observers often fail to notice significant changes in visual scenes, even when these changes happen right in front of their eyes. For instance, people often fail to notice if their conversation partner is switched to another person, or if large background objects suddenly disappear.1,2 These 'change blindness' studies have led to the inference that the amount of information we remember about each item in a visual scene may be quite low.1 However, in recent work we have demonstrated that long-term memory is capable of storing a massive number of visual objects with significant detail about each item.3 In the present paper we attempt to reconcile these findings by demonstrating that observers do not experience 'change blindness' with the real world objects used in our previous experiment if they are given sufficient time to encode each item. The results reported here suggest that one of the major causes of change blindness for real-world objects is a lack of encoding time or attention to each object (see also refs. 4 and 5).

  14. Interactive 3D visualization of structural changes in the brain of a person with corticobasal syndrome

    Directory of Open Access Journals (Sweden)

    Claudia eHänel

    2014-05-01

    Full Text Available The visualization of the progression of brain tissue loss, which occurs in neurodegenerative diseases like corticobasal syndrome (CBS, is an important prerequisite to understand the course and the causes of this neurodegenerative disorder. Common workflows for visual analysis are often based on single 2D sections since in 3D visualizations more internally situated structures may be occluded by structures near the surface. The reduction of dimensions from 3D to 2D allows for an holistic view onto internal and external structures, but results in a loss of spatial information. Here, we present an application with two 3D visualization designs to resolve these challenges. First, in addition to the volume changes, the semi-transparent anatomy is displayed with an anatomical section and cortical areas for spatial orientation. Second, the principle of importance-driven volume rendering is adapted to give an unrestricted line-of-sight to relevant structures by means of a frustum-like cutout. To strengthen the benefits of the 3D visualization, we decided to provide the application next to standard desktop environments in immersive virtual environments with stereoscopic viewing as well. This improves the depth perception in general and in particular for the second design. Thus, the application presented in this work allows for aneasily comprehensible visual analysis of the extent of brain degeneration and the corresponding affected regions.

  15. Visual attention measures predict pedestrian detection in central field loss: a pilot study.

    Directory of Open Access Journals (Sweden)

    Concetta F Alberti

    Full Text Available The ability of visually impaired people to deploy attention effectively to maximize use of their residual vision in dynamic situations is fundamental to safe mobility. We conducted a pilot study to evaluate whether tests of dynamic attention (multiple object tracking; MOT and static attention (Useful Field of View; UFOV were predictive of the ability of people with central field loss (CFL to detect pedestrian hazards in simulated driving.11 people with bilateral CFL (visual acuity 20/30-20/200 and 11 age-similar normally-sighted drivers participated. Dynamic and static attention were evaluated with brief, computer-based MOT and UFOV tasks, respectively. Dependent variables were the log speed threshold for 60% correct identification of targets (MOT and the increase in the presentation duration for 75% correct identification of a central target when a concurrent peripheral task was added (UFOV divided and selective attention subtests. Participants drove in a simulator and pressed the horn whenever they detected pedestrians that walked or ran toward the road. The dependent variable was the proportion of timely reactions (could have stopped in time to avoid a collision.UFOV and MOT performance of CFL participants was poorer than that of controls, and the proportion of timely reactions was also lower (worse (84% and 97%, respectively; p = 0.001. For CFL participants, higher proportions of timely reactions correlated significantly with higher (better MOT speed thresholds (r = 0.73, p = 0.01, with better performance on the UFOV divided and selective attention subtests (r = -0.66 and -0.62, respectively, p<0.04, with better contrast sensitivity scores (r = 0.54, p = 0.08 and smaller scotomas (r = -0.60, p = 0.05.Our results suggest that brief laboratory-based tests of visual attention may provide useful measures of functional visual ability of individuals with CFL relevant to more complex mobility tasks.

  16. Interplanetary magnetic field associated changes in cosmic ray intensity and geomagnetic field during 1973-75

    International Nuclear Information System (INIS)

    Singh, R.L.; Shukla, J.P.; Shukla, A.K.; Sharma, S.M.; Agrawal, S.P.

    1979-01-01

    The effects of interplanetary magnetic field (IMF) B and its Bsub(z) component on cosmic ray intensity and geomagnetic field variations have been examined for the period 1973-75. It is observed that: (1) B >= 10γ (magnetic blobs) is pre-requisite in producing cosmic ray intensity and geomagnetic field variations of varying magnitudes, (2) the longer existence of magnetic blobs on successive days produces larger decreases in cosmic ray intensity and geomagnetic field and (3) the southward component (Bsub(z)) of IMF generally gives rise to large Asub(p) changes, though it is not effective in producing cosmic ray intensity decreases. (auth.)

  17. Visual working memory and threat monitoring: Spider fearfuls show disorder-specific change detection

    NARCIS (Netherlands)

    Reinecke, A.; Becker, E.S.; Rinck, M.

    2010-01-01

    Previous studies of biased information processing in anxiety addressed biases of attention and memory, but little is known about the processes taking place between them: visual working memory (VWM) and monitoring of threat. We investigated these processes with a change detection paradigm. In

  18. “We grew as we grew”: visual methods, social change and collective ...

    African Journals Online (AJOL)

    ... participants about what impact the work has had on their lives. Each has travelled a different journey and been faced with different constraints that have implications for the effectiveness of such work. Where are they now, and as adults, what do they have to say about the visual methodologies, memory, and social change?

  19. Visualizing Nanocatalysts in Action from Color Change Reaction to Magnetic Recycling and Reuse

    Science.gov (United States)

    Hudson, Reuben; Bishop, Alexandra; Glaisher, Samuel; Katz, Jeffrey L.

    2015-01-01

    A demonstration to highlight the utility and ease of handling environmentally benign magnetically recoverable nanoparticle catalysts is described. The demonstration offers two powerful visuals. The first is a color change oxidation of tetramethylbenzidine by hydrogen peroxide catalyzed by Fe[subscript 3]O[subscript 4] nanoparticles. The second,…

  20. Scanning laser polarimetry, but not optical coherence tomography predicts permanent visual field loss in acute nonarteritic anterior ischemic optic neuropathy.

    Science.gov (United States)

    Kupersmith, Mark J; Anderson, Susan; Durbin, Mary; Kardon, Randy

    2013-08-15

    Scanning laser polarimetry (SLP) reveals abnormal retardance of birefringence in locations of the edematous peripapillary retinal nerve fiber layer (RNFL), which appear thickened by optical coherence tomography (OCT), in nonarteritic anterior ischemic optic neuropathy (NAION). We hypothesize initial sector SLP RNFL abnormalities will correlate with long-term regional visual field loss due to ischemic injury. We prospectively performed automated perimetry, SLP, and high definition OCT (HD-OCT) of the RNFL in 25 eyes with acute NAION. We grouped visual field threshold and RNFL values into Garway-Heath inferior/superior disc sectors and corresponding superior/inferior field regions. We compared sector SLP RNFL thickness with corresponding visual field values at presentation and at >3 months. At presentation, 12 eyes had superior sector SLP reduction, 11 of which had inferior field loss. Six eyes, all with superior field loss, had inferior sector SLP reduction. No eyes had reduced OCT-derived RNFL acutely. Eyes with abnormal field regions had corresponding SLP sectors thinner (P = 0.003) than for sectors with normal field regions. During the acute phase, the SLP-derived sector correlated with presentation (r = 0.59, P = 0.02) and with >3-month after presentation (r = 0.44, P = 0.02) corresponding superior and inferior field thresholds. Abnormal RNFL birefringence occurs in sectors corresponding to regional visual field loss during acute NAION when OCT-derived RNFL shows thickening. Since the visual field deficits show no significant recovery, SLP can be an early marker for axonal injury, which may be used to assess recovery potential at RNFL locations with respect to new treatments for acute NAION.

  1. Predictive Factors for Visual Field Conversion: Comparison of Scanning Laser Polarimetry and Optical Coherence Tomography.

    Science.gov (United States)

    Diekmann, Theresa; Schrems-Hoesl, Laura M; Mardin, Christian Y; Laemmer, Robert; Horn, Folkert K; Kruse, Friedrich E; Schrems, Wolfgang A

    2018-02-01

    The purpose of this study was to compare the ability of scanning laser polarimetry (SLP) and spectral-domain optical coherence tomography (SD-OCT) to predict future visual field conversion of subjects with ocular hypertension and early glaucoma. All patients were recruited from the Erlangen glaucoma registry and examined using standard automated perimetry, 24-hour intraocular pressure profile, and optic disc photography. Peripapillary retinal nerve fiber layer thickness (RNFL) measurements were obtained by SLP (GDx-VCC) and SD-OCT (Spectralis OCT). Positive and negative predictive values (PPV, NPV) were calculated for morphologic parameters of SLP and SD-OCT. Kaplan-Meier survival curves were plotted and log-rank tests were performed to compare the survival distributions. Contingency tables and Venn-diagrams were calculated to compare the predictive ability. The study included 207 patients-75 with ocular hypertension, 85 with early glaucoma, and 47 controls. Median follow-up was 4.5 years. A total of 29 patients (14.0%) developed visual field conversion during follow-up. SLP temporal-inferior RNFL [0.667; 95% confidence interval (CI), 0.281-0.935] and SD-OCT temporal-inferior RNFL (0.571; 95% CI, 0.317-0.802) achieved the highest PPV; nerve fiber indicator (0.923; 95% CI, 0.876-0.957) and SD-OCT mean (0.898; 95% CI, 0.847-0.937) achieved the highest NPV of all investigated parameters. The Kaplan-Meier curves confirmed significantly higher survival for subjects within normal limits of measurements of both devices (P<0.001). Venn diagrams tested with McNemar test statistics showed no significant difference for PPV (P=0.219) or NPV (P=0.678). Both GDx-VCC and SD-OCT demonstrate comparable results in predicting future visual field conversion if taking typical scans for GDx-VCC. In addition, the likelihood ratios suggest that GDx-VCC's nerve fiber indicator<30 may be the most useful parameter to confirm future nonconversion. (http://www.ClinicalTrials.gov number, NTC

  2. Preschool Teaching Staff’s Opinions on the Importance of Preschool Curricular Fields of Activities, Art Genres and Visual Arts Fields

    OpenAIRE

    Tomaž Zupančič; Branka Čagran; Matjaž Mulej

    2015-01-01

    This article presents preschool teachers’ and assistant teachers’ opinions on the importance of selected fields of educational work in kindergartens. The article first highlights the importance of activities expressing artistic creativity within modern curriculums. Then, it presents an empirical study that examines the preschool teachers’ and assistant teachers’ opinions on the importance of the educational fields, art genres, and visual arts fields. In research hypotheses, we presumed that p...

  3. Period Changes of 23 Field RR Lyrae Stars

    Directory of Open Access Journals (Sweden)

    Soo-Chang Rey

    1994-12-01

    Full Text Available The secular period behavior of 23 field RR Lyrae stars is studied in order to determine if the observed period changes could be attributed, at least in the mean, to stellar evolution. The sample of stars is subdivided into two Oosterhoff groups based on the metallicity and period-shift. Despite the small sample size, we found a distinct bias toward positive period changes in the group variables. The period changes of the group variables in globular clusters. This provides yet another support for the Lee, Demarque, and Zinn(1990 evolutionary models of RR Lyrae stars and their explanation of the Sandage period-shift effect.

  4. Visualization maps for the evolution of research hotspots in the field of regional health information networks.

    Science.gov (United States)

    Wang, Yanjun; Zheng, Jianzhong; Zhang, Ailian; Zhou, Wei; Dong, Haiyuan

    2018-03-01

    The aim of this study was to reveal research hotspots in the field of regional health information networks (RHINs) and use visualization techniques to explore their evolution over time and differences between countries. We conducted a literature review for a 50-year period and compared the prevalence of certain index terms during the periods 1963-1993 and 1994-2014 and in six countries. We applied keyword frequency analysis, keyword co-occurrence analysis, multidimensional scaling analysis, and network visualization technology. The total number of keywords was found to increase with time. From 1994 to 2014, the research priorities shifted from hospital planning to community health planning. The number of keywords reflecting information-based research increased. The density of the knowledge network increased significantly, and partial keywords condensed into knowledge groups. All six countries focus on keywords including Information Systems; Telemedicine; Information Service; Medical Records Systems, Computerized; Internet; etc.; however, the level of development and some research priorities are different. RHIN research has generally increased in popularity over the past 50 years. The research hotspots are evolving and are at different levels of development in different countries. Knowledge network mapping and perceptual maps provide useful information for scholars, managers, and policy-makers.

  5. Validation of SplitVectors Encoding for Quantitative Visualization of Large-Magnitude-Range Vector Fields.

    Science.gov (United States)

    Henan Zhao; Bryant, Garnett W; Griffin, Wesley; Terrill, Judith E; Jian Chen

    2017-06-01

    We designed and evaluated SplitVectors, a new vector field display approach to help scientists perform new discrimination tasks on large-magnitude-range scientific data shown in three-dimensional (3D) visualization environments. SplitVectors uses scientific notation to display vector magnitude, thus improving legibility. We present an empirical study comparing the SplitVectors approach with three other approaches - direct linear representation, logarithmic, and text display commonly used in scientific visualizations. Twenty participants performed three domain analysis tasks: reading numerical values (a discrimination task), finding the ratio between values (a discrimination task), and finding the larger of two vectors (a pattern detection task). Participants used both mono and stereo conditions. Our results suggest the following: (1) SplitVectors improve accuracy by about 10 times compared to linear mapping and by four times to logarithmic in discrimination tasks; (2) SplitVectors have no significant differences from the textual display approach, but reduce cluttering in the scene; (3) SplitVectors and textual display are less sensitive to data scale than linear and logarithmic approaches; (4) using logarithmic can be problematic as participants' confidence was as high as directly reading from the textual display, but their accuracy was poor; and (5) Stereoscopy improved performance, especially in more challenging discrimination tasks.

  6. Communicating Climate Change through ICT-Based Visualization: Towards an Analytical Framework

    Directory of Open Access Journals (Sweden)

    Björn-Ola Linnér

    2013-11-01

    Full Text Available The difficulties in communicating climate change science to the general public are often highlighted as one of the hurdles for support of enhanced climate action. The advances of interactive visualization using information and communication technology (ICT are claimed to be a game-changer in our ability to communicate complex issues. However, new analytical frameworks are warranted to analyse the role of such technologies. This paper develops a novel framework for analyzing the content, form, context and relevance of ICT-based visualization of climate change, based on insights from literature on climate change communication. Thereafter, we exemplify the analytical framework by applying it to a pilot case of ICT-based climate visualization in a GeoDome. Possibilities to use affordable advanced ICT-based visualization devices in science and policy communication are rapidly expanding. We thus see wider implications and applications of the analytical framework not only for other ICT environments but also other issue areas in sustainability communication.

  7. Losses in superconducting multifilament composites under alternating changing fields

    International Nuclear Information System (INIS)

    Turck, B.

    1979-03-01

    The first part of this report presents a brief review of the losses in superconducting composites in a changing external field. The losses are expressed for a single triangular shaped pulse and for a field varying exponentially with time. The losses are calculated as a function of two important time constants. The first is due to the coupling currents between the filaments, the second is due to the eddy currents induced in the matrix. In the second part of the report, the case of an oscillating sinusoidal field is considered. In particular, in a rapidly varying field, several layers of filaments can be saturated by returning currents. Complete expressions of the losses are provided together with simplified expressions which enable one to calculate the losses in most cases. In the third part, a comparison between several kinds of conductors shows that in some cases the losses are reduced by increasing the twist pitch of the conductor

  8. Velocity Vector Field Visualization of Flow in Liquid Acquisition Device Channel

    Science.gov (United States)

    McQuillen, John B.; Chao, David F.; Hall, Nancy R.; Zhang, Nengli

    2012-01-01

    A capillary flow liquid acquisition device (LAD) for cryogenic propellants has been developed and tested in NASA Glenn Research Center to meet the requirements of transferring cryogenic liquid propellants from storage tanks to an engine in reduced gravity environments. The prototypical mesh screen channel LAD was fabricated with a mesh screen, covering a rectangular flow channel with a cylindrical outlet tube, and was tested with liquid oxygen (LOX). In order to better understand the performance in various gravity environments and orientations at different liquid submersion depths of the screen channel LAD, a series of computational fluid dynamics (CFD) simulations of LOX flow through the LAD screen channel was undertaken. The resulting velocity vector field visualization for the flow in the channel has been used to reveal the gravity effects on the flow in the screen channel.

  9. Masking with faces in central visual field under a variety of temporal schedules.

    Science.gov (United States)

    Daar, Marwan; Wilson, Hugh R

    2015-11-01

    With a few exceptions, previous studies have explored masking using either a backward mask or a common onset trailing mask, but not both. In a series of experiments, we demonstrate the use of faces in central visual field as a viable method to study the relationship between these two types of mask schedule. We tested observers in a two alternative forced choice face identification task, where both target and mask comprised synthetic faces, and show that a simple model can successfully predict masking across a variety of masking schedules ranging from a backward mask to a common onset trailing mask and a number of intermediate variations. Our data are well accounted for by a window of sensitivity to mask interference that is centered at around 100 ms. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. The effect of internal and external fields of view on visually induced motion sickness.

    Science.gov (United States)

    Bos, Jelte E; de Vries, Sjoerd C; van Emmerik, Martijn L; Groen, Eric L

    2010-07-01

    Field of view (FOV) is said to affect visually induced motion sickness. FOV, however, is characterized by an internal setting used by the graphics generator (iFOV) and an external factor determined by screen size and viewing distance (eFOV). We hypothesized that especially the incongruence between iFOV and eFOV would lead to sickness. To that end we used a computer game environment with different iFOV and eFOV settings, and found the opposite effect. We speculate that the relative large differences between iFOV and eFOV used in this experiment caused the discrepancy, as may be explained by assuming an observer model controlling body motion. Copyright 2009 Elsevier Ltd. All rights reserved.

  11. Direct Visualization of Valence Electron Motion Using Strong-Field Photoelectron Holography

    Science.gov (United States)

    He, Mingrui; Li, Yang; Zhou, Yueming; Li, Min; Cao, Wei; Lu, Peixiang

    2018-03-01

    Watching the valence electron move in molecules on its intrinsic timescale has been one of the central goals of attosecond science and it requires measurements with subatomic spatial and attosecond temporal resolutions. The time-resolved photoelectron holography in strong-field tunneling ionization holds the promise to access this realm. However, it remains to be a challenging task hitherto. Here we reveal how the information of valence electron motion is encoded in the hologram of the photoelectron momentum distribution (PEMD) and develop a novel approach of retrieval. As a demonstration, applying it to the PEMDs obtained by solving the time-dependent Schrödinger equation for the prototypical molecule H2+ , the attosecond charge migration is directly visualized with picometer spatial and attosecond temporal resolutions. Our method represents a general approach for monitoring attosecond charge migration in more complex polyatomic and biological molecules, which is one of the central tasks in the newly emerging attosecond chemistry.

  12. Polar cap geomagnetic field responses to solar sector changes

    International Nuclear Information System (INIS)

    Campbell, W.H.

    1976-01-01

    I made a computerized analysis of digitized magnetograms from Alert, Thule, Resolute Bay, Mould Bay, and Godhavn for 1965 and from Thule and Vostok for 1967 to determine the characteristic features of the day-to-day geomagnetic field variations related to the interplanetary solar sector field direction. Higher invariant latitude stations showed the sector effects most clearly. A sector-related phase shift in the characteristic diurnal variation of the field occurred principally for the dayside vertical geomagnetic component. The amplitude of this diurnal variation was related to Ap and could not be used to identify the sector direction. The quiet nighttime level of field Z component rose and fell on days when the interplanetary magnetic field was directed toward or away from the sun, respectively. When a station's base level field was determined from quiet magnetospheric conditions by using days with low values of Dst and AE indices, the mean field level of the Z component for the whole day increased or decreased (often over 100 γ) from this level as the solar sector direction was toward or away, respectively. With respect to the earth's main field direction the souther polar station field level changes were opposite those at the northern stations. This level shift corresponded with the two solar field directions during the summer months at polar stations for about 70% of the days in 1965 and 88% of the days in 1967. In 1967 the standoff locations of the magnetopause and magnetoshock boundaries were abotu 1 R/sub E/ more distant from the earth for the average toward sector days than for the away sector days

  13. New techniques for the scientific visualization of three-dimensional multi-variate and vector fields

    Energy Technology Data Exchange (ETDEWEB)

    Crawfis, Roger A. [Univ. of California, Davis, CA (United States)

    1995-10-01

    Volume rendering allows us to represent a density cloud with ideal properties (single scattering, no self-shadowing, etc.). Scientific visualization utilizes this technique by mapping an abstract variable or property in a computer simulation to a synthetic density cloud. This thesis extends volume rendering from its limitation of isotropic density clouds to anisotropic and/or noisy density clouds. Design aspects of these techniques are discussed that aid in the comprehension of scientific information. Anisotropic volume rendering is used to represent vector based quantities in scientific visualization. Velocity and vorticity in a fluid flow, electric and magnetic waves in an electromagnetic simulation, and blood flow within the body are examples of vector based information within a computer simulation or gathered from instrumentation. Understand these fields can be crucial to understanding the overall physics or physiology. Three techniques for representing three-dimensional vector fields are presented: Line Bundles, Textured Splats and Hair Splats. These techniques are aimed at providing a high-level (qualitative) overview of the flows, offering the user a substantial amount of information with a single image or animation. Non-homogenous volume rendering is used to represent multiple variables. Computer simulations can typically have over thirty variables, which describe properties whose understanding are useful to the scientist. Trying to understand each of these separately can be time consuming. Trying to understand any cause and effect relationships between different variables can be impossible. NoiseSplats is introduced to represent two or more properties in a single volume rendering of the data. This technique is also aimed at providing a qualitative overview of the flows.

  14. Numbers and functional lateralization: A visual half-field and dichotic listening study in proficient bilinguals.

    Science.gov (United States)

    Klichowski, Michal; Króliczak, Gregory

    2017-06-01

    Potential links between language and numbers and the laterality of symbolic number representations in the brain are still debated. Furthermore, reports on bilingual individuals indicate that the language-number interrelationships might be quite complex. Therefore, we carried out a visual half-field (VHF) and dichotic listening (DL) study with action words and different forms of symbolic numbers used as stimuli to test the laterality of word and number processing in single-, dual-language and mixed -task and language- contexts. Experiment 1 (VHF) showed a significant right visual field/left hemispheric advantage in response accuracy for action word, as compared to any form of symbolic number processing. Experiment 2 (DL) revealed a substantially reversed effect - a significant right ear/left hemisphere advantage for arithmetic operations as compared to action word processing, and in response times in single- and dual-language contexts for number vs. action words. All these effects were language independent. Notably, for within-task response accuracy compared across modalities significant differences were found in all studied contexts. Thus, our results go counter to findings showing that action-relevant concepts and words, as well as number words are represented/processed primarily in the left hemisphere. Instead, we found that in the auditory context, following substantial engagement of working memory (here: by arithmetic operations), there is a subsequent functional reorganization of processing single stimuli, whether verbs or numbers. This reorganization - their weakened laterality - at least for response accuracy is not exclusive to processing of numbers, but the number of items to be processed. For response times, except for unpredictable tasks in mixed contexts, the "number problem" is more apparent. These outcomes are highly relevant to difficulties that simultaneous translators encounter when dealing with lengthy auditory material in which single items such

  15. Prevention of postoperative visual field defect after the occipital transtentorial approach: anatomical study.

    Science.gov (United States)

    Matsuo, Satoshi; Baydin, Serhat; Güngör, Abuzer; Middlebrooks, Erik H; Komune, Noritaka; Iihara, Koji; Rhoton, Albert L

    2017-10-20

    OBJECTIVE A postoperative visual field defect resulting from damage to the occipital lobe during surgery is a unique complication of the occipital transtentorial approach. Though the association between patient position and this complication is well investigated, preventing the complication remains a challenge. To define the area of the occipital lobe in which retraction is least harmful, the surface anatomy of the brain, course of the optic radiations, and microsurgical anatomy of the occipital transtentorial approach were examined. METHODS Twelve formalin-fixed cadaveric adult heads were examined with the aid of a surgical microscope and 0° and 45° endoscopes. The optic radiations were examined by fiber dissection and MR tractography techniques. RESULTS The arterial and venous relationships of the lateral, medial, and inferior surfaces of the occipital lobe were defined anatomically. The full course of the optic radiations was displayed via both fiber dissection and MR tractography. Although the stems of the optic radiations as exposed by both techniques are similar, the terminations of the fibers are slightly different. The occipital transtentorial approach provides access for the removal of lesions involving the splenium, pineal gland, collicular plate, cerebellomesencephalic fissure, and anterosuperior part of the cerebellum. An angled endoscope can aid in exposing the superior medullary velum and superior cerebellar peduncles. CONCLUSIONS Anatomical findings suggest that retracting the inferior surface of the occipital lobe may avoid direct damage and perfusion deficiency around the calcarine cortex and optic radiations near their termination. An accurate understanding of the course of the optic radiations and vascular relationships around the occipital lobe and careful retraction of the inferior surface of the occipital lobe may reduce the incidence of postoperative visual field defect.

  16. Negative body image associated with changes in the visual body appearance increases pain perception.

    Directory of Open Access Journals (Sweden)

    Michihiro Osumi

    Full Text Available Changing the visual body appearance by use of as virtual reality system, funny mirror, or binocular glasses has been reported to be helpful in rehabilitation of pain. However, there are interindividual differences in the analgesic effect of changing the visual body image. We hypothesized that a negative body image associated with changing the visual body appearance causes interindividual differences in the analgesic effect although the relationship between the visual body appearance and analgesic effect has not been clarified. We investigated whether a negative body image associated with changes in the visual body appearance increased pain. Twenty-five healthy individuals participated in this study. To evoke a negative body image, we applied the method of rubber hand illusion. We created an "injured rubber hand" to evoke unpleasantness associated with pain, a "hairy rubber hand" to evoke unpleasantness associated with embarrassment, and a "twisted rubber hand" to evoke unpleasantness associated with deviation from the concept of normality. We also created a "normal rubber hand" as a control. The pain threshold was measured while the participant observed the rubber hand using a device that measured pain caused by thermal stimuli. Body ownership experiences were elicited by observation of the injured rubber hand and hairy rubber hand as well as the normal rubber hand. Participants felt more unpleasantness by observing the injured rubber hand and hairy rubber hand than the normal rubber hand and twisted rubber hand (p<0.001. The pain threshold was lower under the injured rubber hand condition than with the other conditions (p<0.001. We conclude that a negative body appearance associated with pain can increase pain sensitivity.

  17. Preschool Teaching Staff’s Opinions on the Importance of Preschool Curricular Fields of Activities, Art Genres and Visual Arts Fields

    Directory of Open Access Journals (Sweden)

    Tomaž Zupančič

    2015-12-01

    Full Text Available This article presents preschool teachers’ and assistant teachers’ opinions on the importance of selected fields of educational work in kindergartens. The article first highlights the importance of activities expressing artistic creativity within modern curriculums. Then, it presents an empirical study that examines the preschool teachers’ and assistant teachers’ opinions on the importance of the educational fields, art genres, and visual arts fields. In research hypotheses, we presumed that preschool teachers find individual educational fields, individual art genres, and individual visual arts activities to be of different importance; consequently, education in kindergarten does not achieve the requisite holism. The study is based on the descriptive and causal-non-experimental method. We have determined that the greatest importance is attributed to movement and language, followed by nature, society, art and mathematics. Within art genres, the greatest importance is attributed to visual arts and music and the least to audio-visual activities. Within visual arts, drawing and painting are considered to be the most important and sculpting the least. These findings can support future studies and deliberation on the possible effects on practice in terms of requisitely holistically planned preschool education.

  18. The riddle of style changes in the visual arts after interference with the right brain

    Directory of Open Access Journals (Sweden)

    Olaf eBlanke

    2012-01-01

    Full Text Available What is visual art? What are paintings? What are films? Although innumerous answers have been proposed to these questions, we here analyze the paintings and films of several visual artists, who suffered from a well-defined neuropsychological deficit, visuo-spatial hemineglect, following vascular stroke to the right brain. We focus our analysis in particular on the oeuvre of Lovis Corinth and Luchino Visconti and point out aspects of their post-stroke paintings and films (that differ from their pre-stroke work and argue that these changes may be associated with visuo-spatial hemineglect. We discuss how the neuropsychological investigation of visual artists may allow us to investigate the relationship between brain and art.

  19. Visual long-term memory and change blindness: Different effects of pre- and post-change information on one-shot change detection using meaningless geometric objects.

    Science.gov (United States)

    Nishiyama, Megumi; Kawaguchi, Jun

    2014-11-01

    To clarify the relationship between visual long-term memory (VLTM) and online visual processing, we investigated whether and how VLTM involuntarily affects the performance of a one-shot change detection task using images consisting of six meaningless geometric objects. In the study phase, participants observed pre-change (Experiment 1), post-change (Experiment 2), or both pre- and post-change (Experiment 3) images appearing in the subsequent change detection phase. In the change detection phase, one object always changed between pre- and post-change images and participants reported which object was changed. Results showed that VLTM of pre-change images enhanced the performance of change detection, while that of post-change images decreased accuracy. Prior exposure to both pre- and post-change images did not influence performance. These results indicate that pre-change information plays an important role in change detection, and that information in VLTM related to the current task does not always have a positive effect on performance. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. The Advanced Glaucoma Intervention Study (AGIS): 14. Distinguishing progression of glaucoma from visual field fluctuations.

    Science.gov (United States)

    Kim, Jonghyeon; Dally, Leonard G; Ederer, Fred; Gaasterland, Douglas E; VanVeldhuisen, Paul C; Blackwell, Beth; Sullivan, E Kenneth; Prum, Bruce; Shafranov, George; Beck, Allen; Spaeth, George L

    2004-11-01

    To determine the least worsening of a visual field (VF) and the least number of confirming tests needed to identify progression of glaucomatous VF defects. Cohort study of participants in a clinical trial. Seven hundred fifty-two eyes of 565 patients with advanced glaucoma. Visual field tests were quantified with the Advanced Glaucoma Intervention Study (AGIS) VF defect score and the Humphrey Field Analyzer mean deviation (MD). Follow-up was 8 to 13 years. Two measures based on the AGIS VF defect score: (1) sustained decrease of VF (SDVF), a worsening from baseline by 2 (alternatively, 3 or 4) or more units and sustained for 2 (alternatively, 3) consecutive 6-month visits and (2) after the occurrence of SDVF, the average percent of eyes with worsening by 2 (alternatively, 3 or 4) or more units from baseline. Two similar measures based on MD. Based on the original AGIS criteria for SDVF (a worsening of 4 units in the AGIS score sustained during 3 consecutive 6-month visits), 31% of eyes had an SDVF. The percent of eyes with a sustained event increases by approximately 10% when either the minimum number of units of field loss or the minimum number of 6-month visits during which the loss is sustained decreases by 1. During 3 years of follow-up after a sustained event, a worsening of at least 2 units was found in 72% of eyes that had a 2-visit sustained event. The same worsening was found in 84% of eyes that had a 3-visit sustained event. Through the next 10 years after a sustained event, based on worsening of 2, 3, or 4 units at 2 or 3 consecutive tests, the loss reoccurred, on average, in >/=75% of study eyes. Results for MD are similar. In patients with advanced glaucoma, a single confirmatory test 6 months after a VF worsening indicates with at least 72% probability a persistent defect when the worsening is defined by at least 2 units of AGIS score or by at least 2 decibels of MD. When the number of confirmatory tests is increased from 1 to 2, the percentage of

  1. Simultaneous density-field visualization and PIV of a shock-accelerated gas curtain

    Energy Technology Data Exchange (ETDEWEB)

    Prestridge, K.; Rightley, P.M.; Vorobieff, P. [Los Alamos Nat. Lab., NM (United States). Dynamic Exp. Div.; Benjamin, R.F.; Kurnit, N.A.

    2000-10-01

    We describe a highly-detailed experimental characterization of the Richtmyer-Meshkov instability (the impulsively driven Rayleigh-Taylor instability) (Meshkov 1969; Richtmyer 1960). In our experiment, a vertical curtain of heavy gas (SF{sub 6}) flows into the test section of an air-filled, horizontal shock tube. The instability evolves after a Mach 1.2 shock passes through the curtain. For visualization, we pre-mix the SF{sub 6} with a small ({proportional_to}10{sup -5}) volume fraction of sub-micron-sized glycol/water droplets. A horizontal section of the flow is illuminated by a light sheet produced by a combination of a customized, burst-mode Nd:YAG laser and a commercial pulsed laser. Three CCD cameras are employed in visualization. The ''dynamic imaging camera'' images the entire test section, but does not detect the individual droplets. It produces a sequence of instantaneous images of local droplet concentration, which in the post-shock flow is proportional to density. The gas curtain is convected out of the test section about 1 ms after the shock passes through the curtain. A second camera images the initial conditions with high resolution, since the initial conditions vary from test to test. The third camera, ''PIV camera,'' has a spatial resolution sufficient to detect the individual droplets in the light sheet. Images from this camera are interrogated using particle image velocimetry (PIV) to recover instantaneous snapshots of the velocity field in a small (19 x 14 mm) field of view. The fidelity of the flow-seeding technique for density-field acquisition and the reliability of the PIV technique are both quantified in this paper. In combination with wide-field density data, PIV measurements give us additional physical insight into the evolution of the Richtmyer-Meshkov instability in a problem which serves as an excellent test case for general transition-to-turbulence studies. (orig.)

  2. Is visual activation associated with changes in cerebral high-energy phosphate levels?

    Science.gov (United States)

    van de Bank, Bart L; Maas, Marnix C; Bains, Lauren J; Heerschap, Arend; Scheenen, Tom W J

    2018-03-23

    Phosphorus magnetic resonance spectroscopy ( 31 P MRS) has been employed before to assess phosphocreatine (PCr) and other high-energy phosphates in the visual cortex during visual stimulation with inconsistent results. We performed functional 31 P MRS imaging in the visual cortex and control regions during a visual stimulation paradigm at an unprecedented sensitivity, exploiting a dedicated RF coil design at a 7 T MR system. Visual stimulation in a 3 min 24 s on-off paradigm in eight young healthy adults generated a clear BOLD effect with traditional 1 H functional MRI in the visual cortex (average z score 9.9 ± 0.2). However, no significant event-related changes in any of the 31 P metabolite concentrations, linewidths (7.9 ± 1.8 vs 7.8 ± 1.9 Hz) or tissue pH (7.07 ± 0.13 vs 7.06 ± 0.07) were detectable. Overall, our study of 31 P MRSI in 15 cm 3 voxels had a detection threshold for changes in PCr, Pi and γ-ATP between stimulation and rest of 5, 17 and 10%, respectively. In individual subjects, the mean coefficients of variance for PCr and Pi levels of control voxels were 6 ± 3 and 19 ± 8% (three time point average of 3 min 24 s). Altogether this indicates that energy supply for neuronal activation at this temporal resolution does not drain global PCr resources.

  3. Performance of an iPad Application to Detect Moderate and Advanced Visual Field Loss in Nepal.

    Science.gov (United States)

    Johnson, Chris A; Thapa, Suman; George Kong, Yu Xiang; Robin, Alan L

    2017-10-01

    To evaluate the accuracy and efficiency of Visual Fields Easy (VFE), a free iPad app, for performing suprathreshold perimetric screening. Prospective, cross-sectional validation study. We performed screening visual fields using a calibrated iPad 2 with the VFE application on 206 subjects (411 eyes): 210 normal (NL), 183 glaucoma (GL), and 18 diabetic retinopathy (DR) at Tilganga Institute of Ophthalmology, Kathmandu, Nepal. We correlated the results with a Humphrey Field Analyzer using 24-2 SITA Standard tests on 373 of these eyes (198 NL, 160 GL, 15 DR). The number of missed locations on the VFE correlated with mean deviation (MD, r = 0.79), pattern standard deviation (PSD, r = 0.60), and number of locations that were worse than the 95% confidence limits for total deviation (r = 0.51) and pattern deviation (r = 0.68) using SITA Standard. iPad suprathreshold perimetry was able to detect most visual field deficits with moderate (MD of -6 to -12 dB) and advanced (MD worse than -12 dB) loss, but had greater difficulty in detecting early (MD better than -6 dB) loss, primarily owing to an elevated false-positive response rate. The average time to perform the Visual Fields Easy test was 3 minutes, 18 seconds (standard deviation = 16.88 seconds). The Visual Fields Easy test procedure is a portable, fast, effective procedure for detecting moderate and advanced visual field loss. Improvements are currently underway to monitor eye and head tracking during testing, reduce testing time, improve performance, and eliminate the need to touch the video screen surface. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Analysis on Longitudinal Dose according to Change of Field Width

    International Nuclear Information System (INIS)

    Jung, Won Seok; Shin, Ryung Mi; Oh, Byung Cheon; Jo, Jun Young; Kim, Gi Chul; Choi, Tae Gu; Back, Jong Geal

    2011-01-01

    To analyze the accuracy of tumor volume dose following field width change, to check the difference of dose change by using self-made moving car, and to evaluate practical delivery tumor dose when tomotherapy in the treatment of organ influenced by breathing. By using self-made moving car, the difference of longitudinal movement (0.0 cm, 1.0 cm, 1.5 cm, 2.0 cm) was applied and compared calculated dose with measured dose according to change of field width (1.05 cm, 2.50 cm, 5.02 cm) and apprehended margin of error. Then done comparative analysis in degree of photosensitivity of DQA film measured by using Gafchromic EBT film. Dose profile and Gamma histogram were used to measure degree of photosensitivity of DQA film. When field width were 1.05 cm, 2.50 cm, 5.02 cm, margin of error of dose delivery coefficient was -2.00%, -0.39%, -2.55%. In dose profile of Gafchromic EBT film's analysis, the movement of moving car had greater motion toward longitudinal direction and as field width was narrower, big error increased considerably at high dose part compared to calculated dose. The more field width was narrowed, gamma index had a large considerable influence of moving at gamma histogram. We could check the difference of longitudinal dose of moving organ. In order to small field width and minimize organ moving due to breathing, it is thought to be needed to develop breathing control unit and fixation tool.

  5. The Effect of Extremely Low Frequency Electromagnetic Fields on Visual Learning & Memory and Anatomical Structures of the Brain in Male Rhesus Monkeys

    Directory of Open Access Journals (Sweden)

    Elahe Tekieh

    2018-04-01

    Full Text Available Background: Humans in modern societies expose to substantially elevated levels of electromagnetic field (EMF emissions with different frequencies.The neurobiological effects of EMF have been the subject of debate and intensive research over the past few decades. Therefore, we evaluated the effects of EMF on visual learning and anatomical dimensions of the hippocampus and the prefrontal area (PFA in male Rhesus monkeys. Materials and Methods:In this study, four rhesus monkeys were irradiated by 0.7 microtesla ELF-EMF either at 5 or 30 Hz, 4 h a day, for 30 days. Alterations in visual learning and memory were assessed before and after irradiation phase by using a box designed that cchallenging animals for gaining rewards Also, the monkeys’ brains were scanned by using MRI technique one week before and one week after irradiation. The monkeys were anesthetized by intramuscular injection of ketamine hydrochloride (10–20 mg/kg and xylazine (0.2–0.4 mg/kg, and scanned with a 3-Tesla Magnetom, in axial, sagittal, and coronal planes using T2 weight­ed protocol with a slice thickness of 3 mm. The anatomical changes of hippocampus and the prefrontal area (PFA was measured by volumetric study. Results: Electromagnetic field exposure at a frequency of 30 Hz reduced the number of correct responses in the learning process and delayed memory formation in the two tested monkeys. While, ELF-EMF at 5 Hz had no effect on the visual learning and memory changes. No anatomical changes were found in the prefrontal area and the hippocampus at both frequencies. Conclusion: ELF-EMF irradiation at 30 Hz adversely affected visual learning and memory, pprobably through these changes apply through effects on other factors except changes in brain structure and anatomy.

  6. Effect of Visual Angle on the Head Movement Caused by Changing Binocular Disparity

    Directory of Open Access Journals (Sweden)

    Toru Maekawa

    2011-10-01

    Full Text Available It has been shown that vertical binocular disparity has no or little effect on the perception of visual direction (Banks et al., 2002. On the other hand, our previous study has reported that a continuous change of vertical disparity causes an involuntary sway of the head (Maekawa et al., 2009. We predict that the difference between those results attributes to the dissociation between the processes for perception and action in the brain. The aim of this study is to investigate in more details the condition that influences the process of disparity information. The present experiment particularly varied the visual angle of stimulus presentation and measured the head movement and body sway caused by changing vertical disparity. Results showed that the head movement was greater as the visual angle of the stimulus was smaller. It has been reported that stimulus of only small visual angle affect depth perception (Erklens et al., 1995. Thus, our result suggests that perception and action produced by vertical disparity are consistent as far as the effect of the stimulus size is concerned.

  7. Informing Hospital Change Processes through Visualization and Simulation: A Case Study at a Children's Emergency Clinic.

    Science.gov (United States)

    Persson, Johanna; Dalholm, Elisabeth Hornyánszky; Johansson, Gerd

    2014-01-01

    To demonstrate the use of visualization and simulation tools in order to involve stakeholders and inform the process in hospital change processes, illustrated by an empirical study from a children's emergency clinic. Reorganization and redevelopment of a hospital is a complex activity that involves many stakeholders and demands. Visualization and simulation tools have proven useful for involving practitioners and eliciting relevant knowledge. More knowledge is desired about how these tools can be implemented in practice for hospital planning processes. A participatory planning process including practitioners and researchers was executed over a 3-year period to evaluate a combination of visualization and simulation tools to involve stakeholders in the planning process and to elicit knowledge about needs and requirements. The initial clinic proposal from the architect was discarded as a result of the empirical study. Much general knowledge about the needs of the organization was extracted by means of the adopted tools. Some of the tools proved to be more accessible than others for the practitioners participating in the study. The combination of tools added value to the process by presenting information in alternative ways and eliciting questions from different angles. Visualization and simulation tools inform a planning process (or other types of change processes) by providing the means to see beyond present demands and current work structures. Long-term involvement in combination with accessible tools is central for creating a participatory setting where the practitioners' knowledge guides the process. © 2014 Vendome Group, LLC.

  8. [Transient elevation of intraocular pressure in primary open-angle glaucoma patients after automated visual field examination in the winter].

    Science.gov (United States)

    Nishino, Kazuaki; Yoshida, Fujiko; Nitta, Akari; Saito, Mieko; Saito, Kazuuchi

    2013-12-01

    To evaluate retrospectively seasonal fluctuations of transient intraocular pressure (IOP) elevation after automated visual field examination in patients with primary open-angle glaucoma (POAG). We reviewed 53 consecutive patients with POAG who visited Kaimeido Ophthalmic and Dental Clinic from January 2011 to March 2013, 21 men and 32 women aged 67.7 +/- 11.2 years. The patients were divided into 4 groups, spring, summer, autumn, and winter according to the month of automated visual field examination and both eyes of each patient were enrolled. IOP was measured immediately after automated visual field examination (vf IOP) and compared with the average IOP from the previous 3 months (pre IOP) and with the average IOP from the following 3 months (post IOP) in each season. IOP elevation rate was defined as (vf IOP- pre IOP)/pre IOP x 100% and calculated for each season (paired t test). Additionally, the correlation between mean deviation (MD) and IOP elevation rate was evaluated (single regression analysis). Exclusion criteria were patients who received cataract surgery during this study or had a history of any previous glaucoma surgery. The automated visual field test was performed with a Humphrey field analyzer and the Central 30-2 FASTPAC threshold program. The average vf IOP was 14.5 +/- 2.5 mmHg, higher than pre IOP 13.8 +/- 2.4 mmHg (p field examination, especially in the winter but not in the summer.

  9. ANOMALOUS CHANGES OF THE GEOMAGNETIC FIELD VERTICAL COMPONENT IN KAMCHATKA

    Directory of Open Access Journals (Sweden)

    Y. F. Moroz

    2016-11-01

    Full Text Available Secular changes of the lithospheric electric conductivity were analyzed based on the monitoring data of the Earth’s electric field over the period from 2001 to 2014. Those measures were carried out in Verchniya Paratunka, Tundroviy, and Shipunskiy that are located alongside the coastline of the Avacha Bay of Kamchatka and where the catastrophic earthquake is to be expected according the long-term forecast. It is noticed that the changes in behavior of the secular movements of the lithospheric electric conductivity sannual average values represented with changes at along and transverse directions of the seismic focal zone extension. A great many of such changes were detected on the Shipunskiy peninsula.

  10. THE TOPOLOGICAL CHANGES OF SOLAR CORONAL MAGNETIC FIELDS. II. THE RECLOSING OF AN OPENED FIELD

    International Nuclear Information System (INIS)

    Low, B. C.; Janse, A. M.

    2009-01-01

    This is a study of the spontaneous formation of current sheets responding to the closing of an opened magnetic field by resistive reconnection in an electrically, highly conducting atmosphere outside a unit sphere. Pairs of initial-final equilibrium states are calculated explicitly, taking the field to be composed of three systems of untwisted flux in both states. In the initial state, two of the three flux systems are closed potential fields whereas the third system contains an equilibrium current sheet that keeps the potential fields on its two sides globally open. The final state is an everywhere potential field, with all three flux systems closed, produced by the resistive dissipation of the current sheet in the initial state. The unit sphere is taken to be a rigid, perfectly conducting wall during reconnection, so that the normal flux distribution is unchanged on the unit sphere. Field solutions subject to this unchanging boundary condition are obtained with and without the assumption of axisymmetry. The mathematical model has been designed to show that the topological changes produced by the current-sheet dissipation are simple under axisymmetry but radically different in the absence of axisymmetry, a fundamental point established in the first paper of this series. In the general case, the topological changes imply that other current sheets must have formed. Some of these current sheets form on the separatrix flux surfaces of the multipolar field. Others form throughout the closed-flux systems induced by volumetric changes. The opening and reclosing of magnetic fields during a solar coronal mass ejection may produce a multitude of current sheets not previously anticipated in the current understanding of this phenomenon. Basic to this study is a general topological property of magnetic flux tubes treated separately in the Appendix.

  11. Radial Peripapillary Capillary Network Visualized Using Wide-Field Montage Optical Coherence Tomography Angiography.

    Science.gov (United States)

    Mase, Tomoko; Ishibazawa, Akihiro; Nagaoka, Taiji; Yokota, Harumasa; Yoshida, Akitoshi

    2016-07-01

    We quantitatively analyzed the features of a radial peripapillary capillary (RPC) network visualized using wide-field montage optical coherence tomography (OCT) angiography in healthy human eyes. Twenty eyes of 20 healthy subjects were recruited. En face 3 × 3-mm OCT angiograms of multiple locations in the posterior pole were acquired using the RTVue XR Avanti, and wide-field montage images of the RPC were created. To evaluate the RPC density, the montage images were binarized and skeletonized. The correlation between the RPC density and the retinal nerve fiber layer (RNFL) thickness measured by an OCT circle scan was investigated. The RPC at the temporal retina was detected as far as 7.6 ± 0.7 mm from the edge of the optic disc but not around the perifoveal area within 0.9 ± 0.1 mm of the fovea. Capillary-free zones beside the first branches of the arterioles were significantly (P optic disc edge were 13.6 ± 0.8, 11.9 ± 0.9, and 10.4 ± 0.9 mm-1. The RPC density also was correlated significantly (r = 0.64, P network. The RPC is present in the superficial peripapillary retina in proportion to the RNFL thickness, supporting the idea that the RPC may be the vascular network primarily responsible for RNFL nourishment.

  12. Visual representation of knowledge in the field of Library and Information Science of IRAN

    Directory of Open Access Journals (Sweden)

    Afsoon Sabetpour

    2015-05-01

    Full Text Available Purpose: The present research has been done to visual representation of knowledge and determination vacuum and density points of scientific trends of faculty members of state universities of IRAN in Library & Information Science field. Method: Curriculum Vitae of each faculty member with census method were collected and its content analyzed. Then using a checklist, the rate scientific tendencies were extracted. NodeXL software was deployed to map out the levels. Results: The results showed that the trends are concentrated in Scientometrics, Research method in Library & Information Science, information organization, information resources, psychology, Education, Management, the Web, Knowledge management, Academic Libraries, Information services, Information Theories and collection management. Apparently, the Library & Information Science community of experts pays little or no attention to the Library & Information Science applications in the fields of chemistry, Cartography, museum, law, art, school libraries as well as to independent subject clusters such as minorities in library, information architecture, mentoring in library science, library automation, preservation, oral history, cybernetics, copyright, information marketing and information economy. Lack of efforts on these areas is remarkable.

  13. The Visualization of the flow field Using Lidar's Range Detection and Digital Image Correlation

    International Nuclear Information System (INIS)

    Park, Nak-Gyu; Baik, Seung-Hoon; Park, Seung-Kyu; Kim, Dong-lyul; Ahn, Yong-Jin

    2015-01-01

    In this paper however we focused on flow velocity, visualization measurement. Using cameras one is able to collect large amount of spatial flow structure data in a very short time. Image data is further processed to determine velocity fields and other flow properties. Therefore, we tried to find a way to measure change of image and to apply it to the lidar technique, which is a powerful technique in the field of climate study and we have an interest in the digital image correlation (DIC). Among the DIC algorithms, the sum of squared differences (SSD) method is a way to track the sub-set image in different images. We used this algorithm for tracking the same point in different moving smoke images. For the lidar system, we used an injection seeded pulsed Nd:YAG laser as the transmitter and an photon multiplier tube (PMT) as the laser light sensor to measure the distance to the target clouds. We used the DIC system to track the smoke image and calculate the actual displacement per unit time. The configured lidar system acquired the lidar signal of smoke at a distance of about 150m. The developed fast correlation algorithm of the DIC, which is used to track the fast moving smoke relatively, was efficient to measure the smoke velocity in real time

  14. Contextual remapping in visual search after predictable target-location changes.

    Science.gov (United States)

    Conci, Markus; Sun, Luning; Müller, Hermann J

    2011-07-01

    Invariant spatial context can facilitate visual search. For instance, detection of a target is faster if it is presented within a repeatedly encountered, as compared to a novel, layout of nontargets, demonstrating a role of contextual learning for attentional guidance ('contextual cueing'). Here, we investigated how context-based learning adapts to target location (and identity) changes. Three experiments were performed in which, in an initial learning phase, observers learned to associate a given context with a given target location. A subsequent test phase then introduced identity and/or location changes to the target. The results showed that contextual cueing could not compensate for target changes that were not 'predictable' (i.e. learnable). However, for predictable changes, contextual cueing remained effective even immediately after the change. These findings demonstrate that contextual cueing is adaptive to predictable target location changes. Under these conditions, learned contextual associations can be effectively 'remapped' to accommodate new task requirements.

  15. Visual search for changes in scenes creates long-term, incidental memory traces.

    Science.gov (United States)

    Utochkin, Igor S; Wolfe, Jeremy M

    2018-05-01

    Humans are very good at remembering large numbers of scenes over substantial periods of time. But how good are they at remembering changes to scenes? In this study, we tested scene memory and change detection two weeks after initial scene learning. In Experiments 1-3, scenes were learned incidentally during visual search for change. In Experiment 4, observers explicitly memorized scenes. At test, after two weeks observers were asked to discriminate old from new scenes, to recall a change that they had detected in the study phase, or to detect a newly introduced change in the memorization experiment. Next, they performed a change detection task, usually looking for the same change as in the study period. Scene recognition memory was found to be similar in all experiments, regardless of the study task. In Experiment 1, more difficult change detection produced better scene memory. Experiments 2 and 3 supported a "depth-of-processing" account for the effects of initial search and change detection on incidental memory for scenes. Of most interest, change detection was faster during the test phase than during the study phase, even when the observer had no explicit memory of having found that change previously. This result was replicated in two of our three change detection experiments. We conclude that scenes can be encoded incidentally as well as explicitly and that changes in those scenes can leave measurable traces even if they are not explicitly recalled.

  16. Sudden flux change studies in high field superconducting accelerator magnets

    International Nuclear Information System (INIS)

    Feher, S.; Bordini, B.; Carcagno, R.; Makulski, A.; Orris, D.F.; Pischalnikov, Y.M.; Sylvester, C.; Tartaglia, M.; Tompkins, J.C.; Zlobin, A.V.

    2004-01-01

    As part of the High Field Magnet Program at Fermilab many magnets have been tested which utilize multi strand Rutherford type cable made of state-of-the art Nb 3 Sn strands. During these magnet tests we observed sudden flux changes by monitoring coil voltages and the magnetic field close to the magnets. These flux changes might be linked to magnet instabilities. The voltage spike signals were correlated with quench antenna signals, a strong indication that these are magnet phenomena. With a new high resolution voltage spike detection system, we were able to observe the detailed structure of the spikes. Two fundamentally different signal shapes were distinguished, most likely generated by different mechanisms

  17. Visualization of 2-D and 3-D fields from its value in a finite number of points

    International Nuclear Information System (INIS)

    Dari, E.A.; Venere, M.J.

    1990-01-01

    This work describes a method for the visualization of two- and three-dimensional fields, given its value in a finite number of points. These data can be originated in experimental measurements, numerical results, or any other source. For the field interpolation, the space is divided into simplices (triangles or tetrahedrons), using the Watson algorithm to obtain the Delaunay triangulation. Inside each simplex, linear interpolation is assumed. The visualization is accomplished by means of Finite Elements post-processors, capable of handling unstructured meshes, which were also developed by the authors. (Author) [es

  18. Level conceptual change pre-service elementary teachers on electric current conceptions through visual multimedia supported conceptual change

    Science.gov (United States)

    Hermita, N.; Suhandi, A.; Syaodih, E.; Samsudin, A.; Marhadi, H.; Sapriadil, S.; Zaenudin, Z.; Rochman, C.; Mansur, M.; Wibowo, F. C.

    2018-05-01

    Now a day, conceptual change is the most valuable issues in the science education perspective, especially in the elementary education. Researchers have already dialed with the aim of the research to increase level conceptual change process on the electric conceptions through Visual Multimedia Supported Conceptual Change Text (VMMSCCText). We have ever utilized research and development method namely 3D-1I stands for Define, Design, Development, and Implementation. The 27 pre-service elementary teachers were involved in the research. The battery function in circuit electric conception is the futuristic concept which should have been learned by the students. Moreover, the data which was collected reports that static about 0%, disorientation about 0%, reconstruction about 55.6%, and construction about 25.9%. It can be concluded that the implementation of VMMSCCText to pre-service elementary teachers are increased to level conceptual change categories.

  19. A toolbox to visually explore cerebellar shape changes in cerebellar disease and dysfunction

    Science.gov (United States)

    Abulnaga, S. Mazdak; Yang, Zhen; Carass, Aaron; Kansal, Kalyani; Jedynak, Bruno M.; Onyike, Chiadi U.; Ying, Sarah H.; Prince, Jerry L.

    2016-03-01

    The cerebellum plays an important role in motor control and is also involved in cognitive processes. Cerebellar function is specialized by location, although the exact topographic functional relationship is not fully understood. The spinocerebellar ataxias are a group of neurodegenerative diseases that cause regional atrophy in the cerebellum, yielding distinct motor and cognitive problems. The ability to study the region-specific atrophy patterns can provide insight into the problem of relating cerebellar function to location. In an effort to study these structural change patterns, we developed a toolbox in MATLAB to provide researchers a unique way to visually explore the correlation between cerebellar lobule shape changes and function loss, with a rich set of visualization and analysis modules. In this paper, we outline the functions and highlight the utility of the toolbox. The toolbox takes as input landmark shape representations of subjects' cerebellar substructures. A principal component analysis is used for dimension reduction. Following this, a linear discriminant analysis and a regression analysis can be performed to find the discriminant direction associated with a specific disease type, or the regression line of a specific functional measure can be generated. The characteristic structural change pattern of a disease type or of a functional score is visualized by sampling points on the discriminant or regression line. The sampled points are used to reconstruct synthetic cerebellar lobule shapes. We showed a few case studies highlighting the utility of the toolbox and we compare the analysis results with the literature.

  20. A toolbox to visually explore cerebellar shape changes in cerebellar disease and dysfunction.

    Science.gov (United States)

    Abulnaga, S Mazdak; Yang, Zhen; Carass, Aaron; Kansal, Kalyani; Jedynak, Bruno M; Onyike, Chiadi U; Ying, Sarah H; Prince, Jerry L

    2016-02-27

    The cerebellum plays an important role in motor control and is also involved in cognitive processes. Cerebellar function is specialized by location, although the exact topographic functional relationship is not fully understood. The spinocerebellar ataxias are a group of neurodegenerative diseases that cause regional atrophy in the cerebellum, yielding distinct motor and cognitive problems. The ability to study the region-specific atrophy patterns can provide insight into the problem of relating cerebellar function to location. In an effort to study these structural change patterns, we developed a toolbox in MATLAB to provide researchers a unique way to visually explore the correlation between cerebellar lobule shape changes and function loss, with a rich set of visualization and analysis modules. In this paper, we outline the functions and highlight the utility of the toolbox. The toolbox takes as input landmark shape representations of subjects' cerebellar substructures. A principal component analysis is used for dimension reduction. Following this, a linear discriminant analysis and a regression analysis can be performed to find the discriminant direction associated with a specific disease type, or the regression line of a specific functional measure can be generated. The characteristic structural change pattern of a disease type or of a functional score is visualized by sampling points on the discriminant or regression line. The sampled points are used to reconstruct synthetic cerebellar lobule shapes. We showed a few case studies highlighting the utility of the toolbox and we compare the analysis results with the literature.

  1. How do field of view and resolution affect the information content of panoramic scenes for visual navigation? A computational investigation.

    Science.gov (United States)

    Wystrach, Antoine; Dewar, Alex; Philippides, Andrew; Graham, Paul

    2016-02-01

    The visual systems of animals have to provide information to guide behaviour and the informational requirements of an animal's behavioural repertoire are often reflected in its sensory system. For insects, this is often evident in the optical array of the compound eye. One behaviour that insects share with many animals is the use of learnt visual information for navigation. As ants are expert visual navigators it may be that their vision is optimised for navigation. Here we take a computational approach in asking how the details of the optical array influence the informational content of scenes used in simple view matching strategies for orientation. We find that robust orientation is best achieved with low-resolution visual information and a large field of view, similar to the optical properties seen for many ant species. A lower resolution allows for a trade-off between specificity and generalisation for stored views. Additionally, our simulations show that orientation performance increases if different portions of the visual field are considered as discrete visual sensors, each giving an independent directional estimate. This suggests that ants might benefit by processing information from their two eyes independently.

  2. The effect of concentric constriction of the visual field to 10 and 15 degrees on simulated motor vehicle accidents

    Science.gov (United States)

    Udagawa, Sachiko; Iwase, Aiko; Susuki, Yuto; Kunimatsu-Sanuki, Shiho; Fukuchi, Takeo; Matsumoto, Chota; Ohno, Yuko; Ono, Hiroshi; Sugiyama, Kazuhisa; Araie, Makoto

    2018-01-01

    Purpose Traffic accidents are associated with the visual function of drivers, as well as many other factors. Driving simulator systems have the advantage of controlling for traffic- and automobile-related conditions, and using pinhole glasses can control the degree of concentric concentration of the visual field. We evaluated the effect of concentric constriction of the visual field on automobile driving, using driving simulator tests. Methods Subjects meeting criteria for normal eyesight were included in the study. Pinhole glasses with variable aperture sizes were adjusted to mimic the conditions of concentric visual field constrictions of 10° and 15°, using a CLOCK CHART®. The test contained 8 scenarios (2 oncoming right-turning cars and 6 jump-out events from the side). Results Eighty-eight subjects were included in the study; 37 (mean age = 52.9±15.8 years) subjects were assigned to the 15° group, and 51 (mean = 48.6±15.5 years) were assigned to the 10° group. For all 8 scenarios, the number of accidents was significantly higher among pinhole wearing subjects. The average number of all types of accidents per person was significantly higher in the pinhole 10° group (4.59±1.81) than the pinhole 15° group (3.68±1.49) (P = 0.032). The number of accidents associated with jump-out scenarios, in which a vehicle approaches from the side on a straight road with a good view, was significantly higher in the pinhole 10° group than in the pinhole 15° group. Conclusions Concentric constriction of the visual field was associated with increased number of traffic accidents. The simulation findings indicated that a visual field of 10° to 15° may be important for avoiding collisions in places where there is a straight road with a good view. PMID:29538425

  3. [DSM-5: important changes in the field of addictive diseases].

    Science.gov (United States)

    Heinz, A; Friedel, E

    2014-05-01

    There are two major changes in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) concerning the field of addiction. Firstly, the previous distinction between abuse and dependence has been abolished and both disorders are now subsumed under the category addiction and related disorders. Secondly, pathological gambling has now been included in the section of addiction with slight changes in diagnostic criteria. Both changes have major implications for the definition and conceptualization of what we call a psychiatric "disease" or "disorder", which have also been addressed in the introductory statement of DSM-5. Concerning the category of abuse that is now part of substance use disorders, there is a concern that a well-defined disorder ("dependence") is now mixed with a less well-defined syndrome ("abuse"). The inclusion of non-substance, behavioral addictions poses the danger of pathologizing a wide range of human behavior in future revisions of the classification. Both concerns are further addressed in this article.

  4. Direction of Auditory Pitch-Change Influences Visual Search for Slope From Graphs.

    Science.gov (United States)

    Parrott, Stacey; Guzman-Martinez, Emmanuel; Orte, Laura; Grabowecky, Marcia; Huntington, Mark D; Suzuki, Satoru

    2015-01-01

    Linear trend (slope) is important information conveyed by graphs. We investigated how sounds influenced slope detection in a visual search paradigm. Four bar graphs or scatter plots were presented on each trial. Participants looked for a positive-slope or a negative-slope target (in blocked trials), and responded to targets in a go or no-go fashion. For example, in a positive-slope-target block, the target graph displayed a positive slope while other graphs displayed negative slopes (a go trial), or all graphs displayed negative slopes (a no-go trial). When an ascending or descending sound was presented concurrently, ascending sounds slowed detection of negative-slope targets whereas descending sounds slowed detection of positive-slope targets. The sounds had no effect when they immediately preceded the visual search displays, suggesting that the results were due to crossmodal interaction rather than priming. The sounds also had no effect when targets were words describing slopes, such as "positive," "negative," "increasing," or "decreasing," suggesting that the results were unlikely due to semantic-level interactions. Manipulations of spatiotemporal similarity between sounds and graphs had little effect. These results suggest that ascending and descending sounds influence visual search for slope based on a general association between the direction of auditory pitch-change and visual linear trend.

  5. Will musculoskeletal and visual stress change when Visual Display Unit (VDU) operators move from small offices to an ergonomically optimized office landscape?

    Science.gov (United States)

    Helland, Magne; Horgen, Gunnar; Kvikstad, Tor Martin; Garthus, Tore; Aarås, Arne

    2011-11-01

    This study investigated the effect of moving from small offices to a landscape environment for 19 Visual Display Unit (VDU) operators at Alcatel Denmark AS. The operators reported significantly improved lighting condition and glare situation. Further, visual discomfort was also significantly reduced on a Visual Analogue Scale (VAS). There was no significant correlation between lighting condition and visual discomfort neither in the small offices nor in the office landscape. However, visual discomfort correlated significantly with glare in small offices i.e. more glare is related to more visual discomfort. This correlation disappeared after the lighting system in the office landscape had been improved. There was also a significant correlation between glare and itching of the eyes as well as blurred vision in the small offices, i.e. more glare more visual symptoms. Experience of pain was found to reduce the subjective assessment of work capacity during VDU tasks. There was a significant correlation between visual discomfort and reduced work capacity in small offices and in the office landscape. When moving from the small offices to the office landscape, there was a significant reduction in headache as well as back pain. No significant changes in pain intensity in the neck, shoulder, forearm, and wrist/hand were observed. The pain levels in different body areas were significantly correlated with subjective assessment of reduced work capacity in small offices and in the office landscape. By careful design and construction of an office landscape with regard to lighting and visual conditions, transfer from small offices may be acceptable from a visual-ergonomic point of view. Copyright © 2011 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  6. A normalization model suggests that attention changes the weighting of inputs between visual areas.

    Science.gov (United States)

    Ruff, Douglas A; Cohen, Marlene R

    2017-05-16

    Models of divisive normalization can explain the trial-averaged responses of neurons in sensory, association, and motor areas under a wide range of conditions, including how visual attention changes the gains of neurons in visual cortex. Attention, like other modulatory processes, is also associated with changes in the extent to which pairs of neurons share trial-to-trial variability. We showed recently that in addition to decreasing correlations between similarly tuned neurons within the same visual area, attention increases correlations between neurons in primary visual cortex (V1) and the middle temporal area (MT) and that an extension of a classic normalization model can account for this correlation increase. One of the benefits of having a descriptive model that can account for many physiological observations is that it can be used to probe the mechanisms underlying processes such as attention. Here, we use electrical microstimulation in V1 paired with recording in MT to provide causal evidence that the relationship between V1 and MT activity is nonlinear and is well described by divisive normalization. We then use the normalization model and recording and microstimulation experiments to show that the attention dependence of V1-MT correlations is better explained by a mechanism in which attention changes the weights of connections between V1 and MT than by a mechanism that modulates responses in either area. Our study shows that normalization can explain interactions between neurons in different areas and provides a framework for using multiarea recording and stimulation to probe the neural mechanisms underlying neuronal computations.

  7. Recording visual evoked potentials and auditory evoked P300 at 9.4T static magnetic field.

    Science.gov (United States)

    Arrubla, Jorge; Neuner, Irene; Hahn, David; Boers, Frank; Shah, N Jon

    2013-01-01

    Simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has shown a number of advantages that make this multimodal technique superior to fMRI alone. The feasibility of recording EEG at ultra-high static magnetic field up to 9.4 T was recently demonstrated and promises to be implemented soon in fMRI studies at ultra high magnetic fields. Recording visual evoked potentials are expected to be amongst the most simple for simultaneous EEG/fMRI at ultra-high magnetic field due to the easy assessment of the visual cortex. Auditory evoked P300 measurements are of interest since it is believed that they represent the earliest stage of cognitive processing. In this study, we investigate the feasibility of recording visual evoked potentials and auditory evoked P300 in a 9.4 T static magnetic field. For this purpose, EEG data were recorded from 26 healthy volunteers inside a 9.4 T MR scanner using a 32-channel MR compatible EEG system. Visual stimulation and auditory oddball paradigm were presented in order to elicit evoked related potentials (ERP). Recordings made outside the scanner were performed using the same stimuli and EEG system for comparison purposes. We were able to retrieve visual P100 and auditory P300 evoked potentials at 9.4 T static magnetic field after correction of the ballistocardiogram artefact using independent component analysis. The latencies of the ERPs recorded at 9.4 T were not different from those recorded at 0 T. The amplitudes of ERPs were higher at 9.4 T when compared to recordings at 0 T. Nevertheless, it seems that the increased amplitudes of the ERPs are due to the effect of the ultra-high field on the EEG recording system rather than alteration in the intrinsic processes that generate the electrophysiological responses.

  8. Simulation of the Chang'E-5 mission contribution in lunar long wavelength gravity field improvement

    Science.gov (United States)

    Yan, Jianguo; Yang, Xuan; Ping, Jinsong; Ye, Mao; Liu, Shanhong; Jin, Weitong; Li, Fei; Barriot, Jean-Pierre

    2018-06-01

    The precision of lunar gravity field estimation has improved by means of three to five orders of magnitude since the successful GRAIL lunar mission. There are still discrepancies however, in the low degree coefficients and long wavelength components of the solutions developed by two space research centers (JPL and GSFC). These discrepancies hint at the possibilities for improving the accuracy in the long wavelength part of the lunar gravity field. In the near future, China will launch the Chang'E-5 lunar mission. In this sample-return mission, there will be a chance to do KBRR measurements between an ascending module and an orbiting module. These two modules will fly around lunar at an inclination of ˜49 degrees, with an orbital height of 100 km and an inter-satellite distance of 200 km. In our research, we simulated the contribution of the KBRR tracking mode for different GRAIL orbital geometries. This analysis indicated possible deficiencies in the low degree coefficient solutions for the polar satellite-to-satellite tracking mode at various orbital heights. We also investigated the potential contributions of the KBRR to the Chang'E-5 mission goal of lunar gravity field recovery, especially in the long wavelength component. Potential improvements were assessed using various power spectrums of the lunar gravity field models. In addition, we also investigated possible improvements in solving lunar tidal Love number K2. These results may assist the implementation of the Chang'E-5 mission.

  9. Visualization of particle trajectories in time-varying electromagnetic fields by CAVE-type virtual reality system

    International Nuclear Information System (INIS)

    Ohno, Nobuaki; Ohtani, Hiroaki; Horiuchi, Ritoku; Matsuoka, Daisuke

    2012-01-01

    The particle kinetic effects play an important role in breaking the frozen-in condition and exciting collisionless magnetic reconnection in high temperature plasmas. Because this effect is originating from a complex thermal motion near reconnection point, it is very important to examine particle trajectories using scientific visualization technique, especially in the presence of plasma instability. We developed interactive visualization environment for the particle trajectories in time-varying electromagnetic fields in the CAVE-type virtual reality system based on VFIVE, which is interactive visualization software for the CAVE system. From the analysis of ion trajectories using the particle simulation data, it was found that time-varying electromagnetic fields around the reconnection region accelerate ions toward the downstream region. (author)

  10. Human rather than ape-like orbital morphology allows much greater lateral visual field expansion with eye abduction

    Science.gov (United States)

    Denion, Eric; Hitier, Martin; Levieil, Eric; Mouriaux, Frédéric

    2015-01-01

    While convergent, the human orbit differs from that of non-human apes in that its lateral orbital margin is significantly more rearward. This rearward position does not obstruct the additional visual field gained through eye motion. This additional visual field is therefore considered to be wider in humans than in non-human apes. A mathematical model was designed to quantify this difference. The mathematical model is based on published computed tomography data in the human neuro-ocular plane (NOP) and on additional anatomical data from 100 human skulls and 120 non-human ape skulls (30 gibbons; 30 chimpanzees / bonobos; 30 orangutans; 30 gorillas). It is used to calculate temporal visual field eccentricity values in the NOP first in the primary position of gaze then for any eyeball rotation value in abduction up to 45° and any lateral orbital margin position between 85° and 115° relative to the sagittal plane. By varying the lateral orbital margin position, the human orbit can be made “non-human ape-like”. In the Pan-like orbit, the orbital margin position (98.7°) was closest to the human orbit (107.1°). This modest 8.4° difference resulted in a large 21.1° difference in maximum lateral visual field eccentricity with eyeball abduction (Pan-like: 115°; human: 136.1°). PMID:26190625

  11. Effects of visual fields, stimulus degradation, and level of practice on event-related potentials of the brain

    NARCIS (Netherlands)

    Kok, A.; van de Vijver, F.R.; Rooijakkers, J.A.

    1985-01-01

    12 male undergraduates were instructed to indicate whether letter pairs that were randomly presented in the center and peripheral (left and right) visual fields were semantically same or different. Letter pairs could be either intact or perceptually degraded, and all Ss participated in 3 consecutive

  12. Risk Factors for Visual Field Progression in the Groningen Longitudinal Glaucoma Study : A Comparison of Different Statistical Approaches

    NARCIS (Netherlands)

    Wesselink, Christiaan; Marcus, Michael W.; Jansonius, Nomdo M.

    2012-01-01

    Purpose: To identify risk factors for visual field progression in glaucoma and to compare different statistical approaches with this risk factor analysis. Patients and Methods: We included 221 eyes of 221 patients. Progression was analyzed using Nonparametric Progression Analysis applied to Humphrey

  13. The Effects of Visual Cues and Learners' Field Dependence in Multiple External Representations Environment for Novice Program Comprehension

    Science.gov (United States)

    Wei, Liew Tze; Sazilah, Salam

    2012-01-01

    This study investigated the effects of visual cues in multiple external representations (MER) environment on the learning performance of novices' program comprehension. Program codes and flowchart diagrams were used as dual representations in multimedia environment to deliver lessons on C-Programming. 17 field independent participants and 16 field…

  14. Effects of electromagnetic fields induced from the visual display terminal on the micronucleus frequencies in tradescantia

    International Nuclear Information System (INIS)

    Shin, Hae Shik; Kim, Jin Kyu; Lee, Jin Hong

    2002-01-01

    Humans are exposed daily to electromagnetic fields (EMFs) originating from a variety of devices and VDT (Visual Display Terminal) workstations. This research was designed to examine the biological effects of electromagnetic fields from VDT using the Tradescantia- micronuclesus (Trad-MCN) bioassay. Tradescantia BNL 4430 clone was used to evaluate the influence of EMFs radiated from the VDT workstation. Trad-MCN assay is a cytogenetic test based on the formation of micronuclei that result from chromosome breakage in the meiotic pollen mother cells. No study has established unequivocally a causal relationship between EMFs and animals or plants. Fresh cuttings bearing young flower buds were exposed for 24hours in front of the VDT workstation. The cuttings were placed at 30, 50, 70, and 90cm distances from the workstations. The micronucleus were scored under a light microscope (400 x magnification). Three hundreds of tetrads were scored from each of the slides in every the experimental group. The frequencies expressed in terms of MCN / 100 tetrads. Trad-MCN frequencies were 8.93 ± 0.32, 11.2 ± 0.50, 7.67 ± 0.61, and 6.22 ± 1.78/ 100 tetrads at 30, 50, 70, and 90cm, respectively. In conclusion, EMFs from VDT give rise to damage the chromosome this plant. In addition, The results of the study indicate that Trad-MCN assay can detect chromosome damage due to EMFs from the electrical device workstation. In conclusion, the Trad-MCN assay is sensitive, reproducible, easy to perform, well standardized, inexpensive and undemanding in equipment

  15. Target locations in visual field and character recognition by students of Chinese.

    Science.gov (United States)

    Chen, Yuan-Ho; Hsu, Sheng-Hsiung

    2003-02-01

    The potential influence of target location in a visual field on search should be considered in layouts of control panels and advertisements. This investigation was done to verify the assumption that the upper-left portion of a page or its equivalent naturally attracts the attention of the viewer. Exp. 1 used a tachistoscope to test which of eight Chinese characters first attracted the attention of viewers. The eight Chinese characters are arranged in a square and a circular configuration. In the square layout, a large square (18 cm x 18 cm) was first conceptually subdivided into nine equal parts (6 cm x 6 cm). Then, the eight Chinese characters were put in the center of each part, leaving the central part blank. In the circular layout, the same Chinese characters were symmetrically placed on the conceptual circumference (r = 6 cm) of a circle within a large square. Exp. 2 was a paper-and-pencil test. An embedded-fault-character-search was used to examine the location of the first faulty character discovered by the subjects. 60 college students and 36 schoolchildren were selected as subjects for the tachistoscopic experiment and paper-and-pencil test. Finally, five graduate students participated in Exp. 3 in which an eye camera registered subjects' eye movements to measured distribution of durations of looking over eight locations. The measurements indicated a slight predominance of the upper-left portion for college students and graduate students, and a slight predominance of the upper-right portion for schoolchildren.

  16. Visualization of nano risk research field to clarify domains year by year

    International Nuclear Information System (INIS)

    Matsui, Yasuto; Hayashi, Takeshi; Miyaoi, Kenichi; Yamaguchi, Yukio; Tomobe, Hironori; Kajikawa, Yuya; Matsushima, Katsumori

    2009-01-01

    With rising interest of nano technology R and D, nano risk researches have been greatly studied recently. They attract much attention since influence of nano products in the society is not well-known. Now the current state of nano risk research field is not fully investigated, and the object is overviewing this structure until 2008 and predicting the direction of next-coming studies. Nano risk 1611 papers were searched out with certain query and further refinement. And these papers were clustered by bibliometric method. The selected papers were clustered to seven parts and visually seen as aggregated blocks. Each cluster was labeled with proper name by analyzing in detail and the content of each cluster was classified with three terms, i.e. 'Material', 'Hazard' and 'Kinetics'. The biggest cluster was cluster no. 0 'atmospheric nanoparticles', and secondly cluster no. 1 'nanoparticles used in imaging', thirdly cluster no. 2 'toxicity of manufactured nano materials'. Furthermore, historical trend of the number of papers of each cluster was studied year by year. From the all results, short-term future predicting was performed by examining titles of papers or transition of the number of papers in each cluster and by watching the cluster position and gaps between clusters.

  17. Hemispheric asymmetry of emotion words in a non-native mind: a divided visual field study.

    Science.gov (United States)

    Jończyk, Rafał

    2015-05-01

    This study investigates hemispheric specialization for emotional words among proficient non-native speakers of English by means of the divided visual field paradigm. The motivation behind the study is to extend the monolingual hemifield research to the non-native context and see how emotion words are processed in a non-native mind. Sixty eight females participated in the study, all highly proficient in English. The stimuli comprised 12 positive nouns, 12 negative nouns, 12 non-emotional nouns and 36 pseudo-words. To examine the lateralization of emotion, stimuli were presented unilaterally in a random fashion for 180 ms in a go/no-go lexical decision task. The perceptual data showed a right hemispheric advantage for processing speed of negative words and a complementary role of the two hemispheres in the recognition accuracy of experimental stimuli. The data indicate that processing of emotion words in non-native language may require greater interhemispheric communication, but at the same time demonstrates a specific role of the right hemisphere in the processing of negative relative to positive valence. The results of the study are discussed in light of the methodological inconsistencies in the hemifield research as well as the non-native context in which the study was conducted.

  18. Multifocal electroretinogram and central visual field testing in central areolar choroidal dystrophy.

    Science.gov (United States)

    Gundogan, Fatih Cakir; Dinç, Umut Asli; Erdem, Uzeyir; Ozge, Gokhan; Sobaci, Gungor

    2010-01-01

    To study multifocal electroretinogram (mfERG) and its relation to retinal sensitivity assessed by Humphrey visual field (HVF) analysis in central areolar choroidal dystrophy (CACD). Seven eyes of 4 patients with CACD and 15 normal control subjects were examined. mfERG and central 30/2 HVF were tested for each participant. Ring analysis in mfERG was evaluated. HVF results were evaluated in 5 concentric rings in order to compare the results to concentric ring analysis in mfERG. The differences between control subjects and patients were evaluated by Mann-Whitney U test and the correlations were assessed by Spearman test. Mean Snellen acuity was 0.49+/-0.10 in patients. HVF revealed central scotoma in 6 of 7 eyes (85.7%), whereas a paracentral scotoma extending to fixation point was detected in 1 eye. The retinal sensitivities in 5 concentric rings in HVF were significantly lower (p<0.001 for ring 1 to ring 4, and p=0.017 in ring 5) in CACD patients. Similarly, CACD patients had lower P1/N1 amplitudes (p<0.05) and delayed P1/N1 implicit times (p<0.05). In CACD, in the areas of scotoma detected by HVF, mfERG values were depressed. However, both mfERG and HVF abnormalities were found outside the areas of ophthalmoscopically normal retinal areas.

  19. Comparison of Glaucoma Progression Detection by Optical Coherence Tomography and Visual Field.

    Science.gov (United States)

    Zhang, Xinbo; Dastiridou, Anna; Francis, Brian A; Tan, Ou; Varma, Rohit; Greenfield, David S; Schuman, Joel S; Huang, David

    2017-12-01

    To compare longitudinal glaucoma progression detection using optical coherence tomography (OCT) and visual field (VF). Validity assessment. We analyzed subjects with more than 4 semi-annual follow-up visits (every 6 months) in the multicenter Advanced Imaging for Glaucoma Study. Fourier-domain optical coherence tomography (OCT) was used to map the thickness of the peripapillary retinal nerve fiber layer (NFL) and ganglion cell complex (GCC). OCT-based progression detection was defined as a significant negative trend for either NFL or GCC. VF progression was reached if either the event or trend analysis reached significance. The analysis included 356 glaucoma suspect/preperimetric glaucoma (GS/PPG) eyes and 153 perimetric glaucoma (PG) eyes. Follow-up length was 54.1 ± 16.2 months for GS/PPG eyes and 56.7 ± 16.0 for PG eyes. Progression was detected in 62.1% of PG eyes and 59.8% of GS/PPG eyes by OCT, significantly (P glaucoma. While the utility of NFL declines in advanced glaucoma, GCC remains a sensitive progression detector from early to advanced stages. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Regional vascular density-visual field sensitivity relationship in glaucoma according to disease severity.

    Science.gov (United States)

    Shin, Joong Won; Lee, Jiyun; Kwon, Junki; Choi, Jaewan; Kook, Michael S

    2017-12-01

    To study whether there are global and regional relationships between peripapillary vascular density (pVD) assessed by optical coherence tomography angiography (OCT-A) and visual field (VF) mean sensitivity at different glaucoma stages. Microvascular images and peripapillary retinal nerve fibre layer (pRNFL) thicknesses were obtained using a Cirrus OCT-A device in 91 glaucoma subjects. The pVD was measured at various spatial locations according to the Garway-Heath map, using a MATLAB software (The MathWorks, Natick, Massachusetts). VF mean sensitivity (VFMS) was recorded in the 1/L scale. Global and regional vasculature-function (pVD vs VFMS) relationships were assessed in separate patient groups at mild and moderate-to-advanced stages of glaucoma. The pVDs at superotemporal and inferotemporal regions were significantly associated with corresponding VFMS in mild glaucoma (pglaucoma, there were significant associations between pVD and VFMS, regardless of location. The association between global pVD and VFMS was significantly stronger than that between global pRNFL thickness and VFMS in moderate-to-advanced stage glaucoma (p glaucoma. OCT-A may be useful in monitoring glaucoma at various stages. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  1. The Effect of Patient Characteristics and Sleep Quality on Visual Field Performance Reliability

    Directory of Open Access Journals (Sweden)

    Swarup S. Swaminathan

    2018-01-01

    Full Text Available Purpose. To investigate the association of automated visual field (VF reliability indices (false positive [FP], false negative [FN], and fixation loss [FL] and sleep quality, VF experience, and age. Methods. Prospective, cross-sectional study. Adult patients (age ≥ 18 years completing automated VF testing were invited to participate. Baseline participant characteristics were obtained, and all participants were asked to complete the Pittsburgh Sleep Quality Index (PSQI questionnaire. Nonparametric Spearman correlations and logistical regression models were performed. Results. 63 patients were enrolled. Lower PSQI score was correlated with higher percentage (% FL in the right eye (p=0.03. Fewer prior VF was significantly correlated with higher %FP in the right eye (p=0.008. Older age was significantly correlated with higher %FN in the left eye (p=0.01. Greater mean deviation (MD and pattern standard deviation (PSD were strongly correlated with higher %FN in the right (p=0.02 and 0.002, resp. and left eyes (p=0.01 and 0.02, resp.. Conclusion. In this prospective, cross-sectional study, worse MD and PSD are strongly correlated with increased FN in both eyes. Increased FN in the left eye associated with older age might be attributable to test fatigue. Worse sleep quality is associated with decreased FL in the right eye.

  2. Simultaneous density-field visualization and PIV of the Richtmyer-Meshkov instability

    Science.gov (United States)

    Prestridge, Katherine; Rightley, Paul; Benjamin, Robert; Kurnit, Norman; Boxx, Isaac; Vorobieff, Peter

    1999-11-01

    We describe a highly-detailed experimental characterization of the Richtmyer-Meshkov instability. A vertical curtain of heavy gas (SF_6) flows into the test section of an air-filled, horizontal shock tube, and the instability evolves after the passage of a Mach 1.2 shock past the curtain. The evolution of the curtain is visualized by seeding the SF6 with small (d ≈ 0.5 μm) glycol/water droplets using a modified theatrical fog generator. Because the event lasts only 1 ms and the initial conditions vary from test to test, rapid and high-resolution (both spatial and temporal) data acquisition is required in order to characterize the initial and dynamic conditions for each experimental event. A customized, frequency-doubled, burst mode Nd:YAG laser and a commercial single-pulse laser are used for the implementation of simultaneous density-field imaging and PIV diagnostics. We have provided data about flow scaling and mixing through image analysis, and PIV data gives us further quantitative physical insight into the evolution of the Richtmyer-Meshkov instability.

  3. Addressing the difficulty of changing fields in geophysics

    Science.gov (United States)

    Civilini, F.; Savage, M. K.

    2014-12-01

    Geophysics is a wonderfully diverse field of study, encompassing a variety of disciplines greatly different from one other. Even within the same discipline, various branches of study can have drastically different vocabulary and methodologies. The difficulty of breaking this "jargon" barrier is also an important reminder for scientists of how critical it is to clearly and concisely convey information. This presentation will focus on strategies that students can focus on to ease a transition between fields in geophysics. I believe that a student changing disciplines should proceed in the following steps: [1] Do a cursory literature review to find a review paper of the desired topic and work backwards through the details until a level of understanding or recognition is reached, [2] Obtain a clear physical understanding of the data and methods of the proposed study, and [3] Establish a support network through the research group or elsewhere which will recognize the areas in which the student is behind and offer remedies in a supportive and productive manner. These strategies are based on my own personal experience changing from music to geophysics in my undergrad and working on projects spanning various subdisciplines of geophysics during my Masters and PhD. It is worthwhile for research groups to spend the time to mentor students switching from other disciplines because those students will in time be able to observe the research in a different way than their peers, and easily adapt to changes of direction within the research.

  4. Architecture of a spatial data service system for statistical analysis and visualization of regional climate changes

    Science.gov (United States)

    Titov, A. G.; Okladnikov, I. G.; Gordov, E. P.

    2017-11-01

    The use of large geospatial datasets in climate change studies requires the development of a set of Spatial Data Infrastructure (SDI) elements, including geoprocessing and cartographical visualization web services. This paper presents the architecture of a geospatial OGC web service system as an integral part of a virtual research environment (VRE) general architecture for statistical processing and visualization of meteorological and climatic data. The architecture is a set of interconnected standalone SDI nodes with corresponding data storage systems. Each node runs a specialized software, such as a geoportal, cartographical web services (WMS/WFS), a metadata catalog, and a MySQL database of technical metadata describing geospatial datasets available for the node. It also contains geospatial data processing services (WPS) based on a modular computing backend realizing statistical processing functionality and, thus, providing analysis of large datasets with the results of visualization and export into files of standard formats (XML, binary, etc.). Some cartographical web services have been developed in a system’s prototype to provide capabilities to work with raster and vector geospatial data based on OGC web services. The distributed architecture presented allows easy addition of new nodes, computing and data storage systems, and provides a solid computational infrastructure for regional climate change studies based on modern Web and GIS technologies.

  5. Visual Learning Induces Changes in Resting-State fMRI Multivariate Pattern of Information.

    Science.gov (United States)

    Guidotti, Roberto; Del Gratta, Cosimo; Baldassarre, Antonello; Romani, Gian Luca; Corbetta, Maurizio

    2015-07-08

    When measured with functional magnetic resonance imaging (fMRI) in the resting state (R-fMRI), spontaneous activity is correlated between brain regions that are anatomically and functionally related. Learning and/or task performance can induce modulation of the resting synchronization between brain regions. Moreover, at the neuronal level spontaneous brain activity can replay patterns evoked by a previously presented stimulus. Here we test whether visual learning/task performance can induce a change in the patterns of coded information in R-fMRI signals consistent with a role of spontaneous activity in representing task-relevant information. Human subjects underwent R-fMRI before and after perceptual learning on a novel visual shape orientation discrimination task. Task-evoked fMRI patterns to trained versus novel stimuli were recorded after learning was completed, and before the second R-fMRI session. Using multivariate pattern analysis on task-evoked signals, we found patterns in several cortical regions, as follows: visual cortex, V3/V3A/V7; within the default mode network, precuneus, and inferior parietal lobule; and, within the dorsal attention network, intraparietal sulcus, which discriminated between trained and novel visual stimuli. The accuracy of classification was strongly correlated with behavioral performance. Next, we measured multivariate patterns in R-fMRI signals before and after learning. The frequency and similarity of resting states representing the task/visual stimuli states increased post-learning in the same cortical regions recruited by the task. These findings support a representational role of spontaneous brain activity. Copyright © 2015 the authors 0270-6474/15/359786-13$15.00/0.

  6. The riddle of style changes in the visual arts after interference with the right brain.

    Science.gov (United States)

    Blanke, Olaf; Pasqualini, Isabella

    2011-01-01

    We here analyze the paintings and films of several visual artists, who suffered from a well-defined neuropsychological deficit, visuo-spatial hemineglect, following vascular stroke to the right brain. In our analysis we focus in particular on the oeuvre of Lovis Corinth and Luchino Visconti as both major artists continued to be highly productive over many years after their right brain damage. We analyzed their post-stroke paintings and films, indicate several aspects that differ from their pre-stroke work (omissions, use of color, perseveration, deformation), and propose-although both artists come from different times, countries, genres, and styles-that their post-stroke oeuvre reveals important similarities in style. We argue that these changes may be associated with visuo-spatial hemineglect and the right brain. We discuss future avenues of how the neuropsychological investigation of visual artists with and without neglect may allow us to investigate the relationship between brain and art.

  7. Visual Scanning Patterns during the Dimensional Change Card Sorting Task in Children with Autism Spectrum Disorder

    Directory of Open Access Journals (Sweden)

    Li Yi

    2012-01-01

    Full Text Available Impaired cognitive flexibility in children with autism spectrum disorder (ASD has been reported in previous literature. The present study explored ASD children’s visual scanning patterns during the Dimensional Change Card Sorting (DCCS task using eye-tracking technique. ASD and typical developing (TD children completed the standardized DCCS procedure on the computer while their eye movements were tracked. Behavioral results confirmed previous findings on ASD children’s deficits in executive function. ASD children’s visual scanning patterns also showed some specific underlying processes in the DCCS task compared to TD children. For example, ASD children looked shorter at the correct card in the postswitch phase and spent longer time at blank areas than TD children did. ASD children did not show a bias to the color dimension as TD children did. The correlations between the behavioral performance and eye moments were also discussed.

  8. Visualizing an Iterative, Dynamic Model for Improving Leadership-Employee Communication in the Organizational Change process

    DEFF Research Database (Denmark)

    Broillet, Alexandra; Barchilon, Marian; Kampf, Constance Elizabeth

    2012-01-01

    Change Management Literature addresses successful and unsuccessful change factors, but there is a conceptual gap that overlooks ways in which Leadership-Employee Communication can be operationalized. To deal with this concern, we address themes emerging from interviews focused on employees....../user metaphor from the technical communication field. These perspectives broaden Change Management to include production and reception of messages about change through a link to 1) sensemaking, 2) Change Management ethos and 3) cultural resources for action available in the organization. We use a series...

  9. Progressive Decrease of Peripapillary Angioflow Vessel Density During Structural and Visual Field Progression in Early Primary Open-angle Glaucoma.

    Science.gov (United States)

    Holló, Gábor

    2017-07-01

    To present a case of early primary open-angle glaucoma in which retinal nerve fiber layer thickness (RNFLT), ganglion cell complex (GCC), and visual field progression were accompanied with significant progression of peripapillary angioflow vessel density (PAFD) measured with optical coherence tomographic angiography. A 68-year-old female patient who was under topical intraocular pressure (IOP) lowering medication for 20 years for ocular hypertension of the right and preperimetric primary open-angle glaucoma of the left eye (with reproducible inferotemporal and superotemporal neuroretinal rim and RNFL loss) was prospectively imaged with the AngioVue OCT for RNFLT, GCC thickness, and PAFD, and investigated with the Octopus Normal G2 visual field test on the same days at 6-month intervals for 18 months, while the IOP of the left eye escaped from control. IOP of the left eye fluctuated between 14 and 30 mm Hg in the study period. RNFLT, GCC thickness, and peripapillary PAFD all decreased significantly (linear regression analysis, P=0.030, 0.040, and 0.020, respectively), and a significant 2.1 dB/y progression was seen for a superior visual field cluster. The RNFLT, peripapillary PAFD, and visual field of the right eye remained normal and unchanged. In our case IOP elevation, glaucomatous visual field conversion, and structural progression were accompanied with significant progressive decrease of peripapillary PAFD. The simultaneous thinning of RNFLT and GCC and decrease of peripapillary PAFD suggest that PAFD may potentially be an additional indicator of early progression in primary open-angle glaucoma.

  10. A comparison of the sensitivity of EQ-5D, SF-6D and TTO utility values to changes in vision and perceived visual function in patients with primary open-angle glaucoma

    Directory of Open Access Journals (Sweden)

    Bozzani Fiammetta Maria

    2012-08-01

    Full Text Available Abstract Background Economic viability of treatments for primary open-angle glaucoma (POAG should be assessed objectively to prioritise health care interventions. This study aims to identify the methods for eliciting utility values (UVs most sensitive to differences in visual field and visual functioning in patients with POAG. As a secondary objective, the dimensions of generic health-related and vision-related quality of life most affected by progressive vision loss will be identified. Methods A total of 132 POAG patients were recruited. Three sets of utility values (EuroQoL EQ-5D, Short Form SF-6D, Time Trade Off and a measure of perceived visual functioning from the National Eye Institute Visual Function Questionnaire (VFQ-25 were elicited during face-to-face interviews. The sensitivity of UVs to differences in the binocular visual field, visual acuity and visual functioning measures was analysed using non-parametric statistical methods. Results Median utilities were similar across Integrated Visual Field score quartiles for EQ-5D (P = 0.08 whereas SF-6D and Time-Trade-Off UVs significantly decreased (p = 0.01 and p = 0.001, respectively. The VFQ-25 score varied across Integrated Visual Field and binocular visual acuity groups and was associated with all three UVs (P ≤ 0.001; most of its vision-specific sub-scales were associated with the vision markers. The most affected dimension was driving. A relationship with vision markers was found for the physical component of SF-36 and not for any dimension of EQ-5D. Conclusions The Time-Trade-Off was more sensitive than EQ-5D and SF-6D to changes in vision and visual functioning associated with glaucoma progression but could not measure quality of life changes in the mildest disease stages.

  11. 3-D visualization of ensemble weather forecasts - Part 2: Forecasting warm conveyor belt situations for aircraft-based field campaigns

    Science.gov (United States)

    Rautenhaus, M.; Grams, C. M.; Schäfler, A.; Westermann, R.

    2015-02-01

    We present the application of interactive 3-D visualization of ensemble weather predictions to forecasting warm conveyor belt situations during aircraft-based atmospheric research campaigns. Motivated by forecast requirements of the T-NAWDEX-Falcon 2012 campaign, a method to predict 3-D probabilities of the spatial occurrence of warm conveyor belts has been developed. Probabilities are derived from Lagrangian particle trajectories computed on the forecast wind fields of the ECMWF ensemble prediction system. Integration of the method into the 3-D ensemble visualization tool Met.3D, introduced in the first part of this study, facilitates interactive visualization of WCB features and derived probabilities in the context of the ECMWF ensemble forecast. We investigate the sensitivity of the method with respect to trajectory seeding and forecast wind field resolution. Furthermore, we propose a visual analysis method to quantitatively analyse the contribution of ensemble members to a probability region and, thus, to assist the forecaster in interpreting the obtained probabilities. A case study, revisiting a forecast case from T-NAWDEX-Falcon, illustrates the practical application of Met.3D and demonstrates the use of 3-D and uncertainty visualization for weather forecasting and for planning flight routes in the medium forecast range (three to seven days before take-off).

  12. Steady-state multifocal visual evoked potential (ssmfVEP) using dartboard stimulation as a possible tool for objective visual field assessment.

    Science.gov (United States)

    Horn, Folkert K; Selle, Franziska; Hohberger, Bettina; Kremers, Jan

    2016-02-01

    To investigate whether a conventional, monitor-based multifocal visual evoked potential (mfVEP) system can be used to record steady-state mfVEP (ssmfVEP) in healthy subjects and to study the effects of temporal frequency, electrode configuration and alpha waves. Multifocal pattern reversal VEP measurements were performed at 58 dartboard fields using VEP recording equipment. The responses were measured using m-sequences with four pattern reversals per m-step. Temporal frequencies were varied between 6 and 15 Hz. Recordings were obtained from nine normal subjects with a cross-shaped, four-electrode device (two additional channels were derived). Spectral analyses were performed on the responses at all locations. The signal to noise ratio (SNR) was computed for each response using the signal amplitude at the reversal frequency and the noise at the neighbouring frequencies. Most responses in the ssmfVEP were significantly above noise. The SNR was largest for an 8.6-Hz reversal frequency. The individual alpha electroencephalogram (EEG) did not strongly influence the results. The percentage of the records in which each of the 6 channels had the largest SNR was between 10.0 and 25.2 %. Our results in normal subjects indicate that reliable mfVEP responses can be achieved by steady-state stimulation using a conventional dartboard stimulator and multi-channel electrode device. The ssmfVEP may be useful for objective visual field assessment as spectrum analysis can be used for automated evaluation of responses. The optimal reversal frequency is 8.6 Hz. Alpha waves have only a minor influence on the analysis. Future studies must include comparisons with conventional mfVEP and psychophysical visual field tests.

  13. An optimized content-aware image retargeting method: toward expanding the perceived visual field of the high-density retinal prosthesis recipients

    Science.gov (United States)

    Li, Heng; Zeng, Yajie; Lu, Zhuofan; Cao, Xiaofei; Su, Xiaofan; Sui, Xiaohong; Wang, Jing; Chai, Xinyu

    2018-04-01

    Objective. Retinal prosthesis devices have shown great value in restoring some sight for individuals with profoundly impaired vision, but the visual acuity and visual field provided by prostheses greatly limit recipients’ visual experience. In this paper, we employ computer vision approaches to seek to expand the perceptible visual field in patients implanted potentially with a high-density retinal prosthesis while maintaining visual acuity as much as possible. Approach. We propose an optimized content-aware image retargeting method, by introducing salient object detection based on color and intensity-difference contrast, aiming to remap important information of a scene into a small visual field and preserve their original scale as much as possible. It may improve prosthetic recipients’ perceived visual field and aid in performing some visual tasks (e.g. object detection and object recognition). To verify our method, psychophysical experiments, detecting object number and recognizing objects, are conducted under simulated prosthetic vision. As control, we use three other image retargeting techniques, including Cropping, Scaling, and seam-assisted shrinkability. Main results. Results show that our method outperforms in preserving more key features and has significantly higher recognition accuracy in comparison with other three image retargeting methods under the condition of small visual field and low-resolution. Significance. The proposed method is beneficial to expand the perceived visual field of prosthesis recipients and improve their object detection and recognition performance. It suggests that our method may provide an effective option for image processing module in future high-density retinal implants.

  14. Geographic divergence and colour change in response to visual backgrounds and illumination intensity in bearded dragons.

    Science.gov (United States)

    Cadena, Viviana; Smith, Kathleen R; Endler, John A; Stuart-Fox, Devi

    2017-03-15

    Animals may improve camouflage by both dynamic colour change and local evolutionary adaptation of colour but we have little understanding of their relative importance in colour-changing species. We tested for differences in colour change in response to background colour and light intensity in two populations of central bearded dragon lizards ( Pogona vitticeps ) representing the extremes in body coloration and geographical range. We found that bearded dragons change colour in response to various backgrounds and that colour change is affected by illumination intensity. Within-individual colour change was similar in magnitude in the two populations but varied between backgrounds. However, at the endpoints of colour change, each population showed greater similarity to backgrounds that were representative of the local habitat compared with the other population, indicating local adaptation to visual backgrounds. Our results suggest that even in species that change colour, both phenotypic plasticity and geographic divergence of coloration may contribute to improved camouflage. © 2017. Published by The Company of Biologists Ltd.

  15. Milking liquid nano-droplets by an IR laser: a new modality for the visualization of electric field lines

    International Nuclear Information System (INIS)

    Vespini, Veronica; Coppola, Sara; Grilli, Simonetta; Paturzo, Melania; Ferraro, Pietro

    2013-01-01

    Liquid handling at micron- and nano-scale is of paramount importance in many fields of application such as biotechnology and biochemistry. In fact, the microfluidics technologies play an important role in lab-on-a-chip devices and, in particular, the dispensing of liquid droplets is a required functionality. Different approaches have been developed for manipulating, dispensing and controlling nano-droplets under a wide variety of configurations. Here we demonstrate that nano-droplets can be drawn from liquid drop or film reservoirs through a sort of milking effect achieved by the absorption of IR laser radiation into a pyroelectric crystal. The generation of the pyroelectric field induced by the IR laser is calculated numerically and a specific experiment has been designed to visualize the electric field stream lines that are responsible for the liquid milking effect. The experiments performed are expected to open a new route for the visualization, measure and characterization procedures in the case of electrohydrodynamic applications. (paper)

  16. The Effective Dynamic Ranges for Glaucomatous Visual Field Progression With Standard Automated Perimetry and Stimulus Sizes III and V.

    Science.gov (United States)

    Wall, Michael; Zamba, Gideon K D; Artes, Paul H

    2018-01-01

    It has been shown that threshold estimates below approximately 20 dB have little effect on the ability to detect visual field progression in glaucoma. We aimed to compare stimulus size V to stimulus size III, in areas of visual damage, to confirm these findings by using (1) a different dataset, (2) different techniques of progression analysis, and (3) an analysis to evaluate the effect of censoring on mean deviation (MD). In the Iowa Variability in Perimetry Study, 120 glaucoma subjects were tested every 6 months for 4 years with size III SITA Standard and size V Full Threshold. Progression was determined with three complementary techniques: pointwise linear regression (PLR), permutation of PLR, and linear regression of the MD index. All analyses were repeated on "censored'' datasets in which threshold estimates below a given criterion value were set to equal the criterion value. Our analyses confirmed previous observations that threshold estimates below 20 dB contribute much less to visual field progression than estimates above this range. These findings were broadly similar with stimulus sizes III and V. Censoring of threshold values < 20 dB has relatively little impact on the rates of visual field progression in patients with mild to moderate glaucoma. Size V, which has lower retest variability, performs at least as well as size III for longitudinal glaucoma progression analysis and appears to have a larger useful dynamic range owing to the upper sensitivity limit being higher.

  17. Visualization of Longitudinal and Transverse Components of Strongly Focused Optical Field by means of Photo-Reactive Azopolymers

    Directory of Open Access Journals (Sweden)

    Kharitonov A.V.

    2015-01-01

    Full Text Available Most important problems in modern photonics are fabrication, visualization and characterization of nanomaterials at optical frequencies. A number of optical techniques uses tightly focused laser beams to access longitudinal electromagnetic fields, which are directed towards the wave vector. In this Letter, the distribution of transverse and longitudinal optical fields in tightly focused laser beams, polarized in a new fashion, is investigated. Polarization dependent fingerprints of transverse and longitudinal optical fields are experimentally captured by means of photoinduced surface deformations in azobenzene polymer thin films.

  18. A technique for visualization and mapping of local cartilage thickness changes in MR images of osteoarthritic knee

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Quanxu, E-mail: gequanxu@yahoo.com.cn [Department of Radiology, Weihai Municipal Hospital, Weihai City, Shandong Province, 164200 (China); Cheng, Yuanzhi, E-mail: yzcheng@hitwh.edu.cn [School of Computer Science and Technology, Harbin Institute of Technology, Harbin, 150001 (China); Bi, Kesen, E-mail: whbks@yahoo.com.cn [Department of Radiology, Weihai Municipal Hospital, Weihai City, Shandong Province, 164200 (China); Guo, Changyong, E-mail: hit_gcy@163.com [School of Computer Science and Technology, Harbin Institute of Technology, Harbin, 150001 (China); Bai, Jing, E-mail: deabj@tsinghua.edu.cn [Department of Biomedical Engineering, School of Medicine, Tsinghua University, China B209, Medical School Building, Tsinghua University, Beijing, 100084 (China); Tamura, Shinichi, E-mail: tamuras@nblmt.jp [Center for Advanced Medical Engineering and Informatics, Osaka University, D11, 2-2, Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2012-11-15

    Purpose: The aim of this paper is to describe a technique for the visualization and mapping of focal, local cartilage thickness changes over time in magnetic resonance images of osteoarthritic knee. Methods: Magnetic resonance imaging was performed in 25 fresh frozen pig knee joints and 15 knees of patients with borderline to mild osteoarthritis (51.2 {+-} 6.3 years). Cartilage and corresponding bone structures were extracted by semi-automatic segmentation. Each point in the bone surface which was part of the bone-cartilage interface was assigned a cartilage thickness value. Cartilage thicknesses were computed for each point in the bone-cartilage interfaces and transferred to the bone surfaces. Moreover, we developed a three dimensional registration method for the identification of anatomically corresponding points of the bone surface to quantify local cartilage thickness changes. One of the main advantages of our method compared to other studies in the field of registration is a global optimization algorithm that does not require any initialization. Results and conclusion: The registration accuracy was 0.93 {+-} 0.05 mm (less than a voxel of magnetic resonance data). Local cartilage thickness changes were seen as having follow-up clinical study for detecting local changes in cartilage thickness. Experiment results suggest that our method was sufficiently accurate and effective for monitoring knee joint diseases.

  19. Directed coupling in local field potentials of macaque V4 during visual short-term memory revealed by multivariate autoregressive models

    Directory of Open Access Journals (Sweden)

    Gregor M Hoerzer

    2010-05-01

    Full Text Available Processing and storage of sensory information is based on the interaction between different neural populations rather than the isolated activity of single neurons. In order to characterize the dynamic interaction and transient cooperation of sub-circuits within a neural network, multivariate autoregressive (MVAR models have proven to be an important analysis tool. In this study, we apply directed functional coupling based on MVAR models and describe the temporal and spatial changes of functional coupling between simultaneously recorded local field potentials (LFP in extrastriate area V4 during visual memory. Specifically, we compare the strength and directional relations of coupling based on Generalized Partial Directed Coherence (GDPC measures while two rhesus monkeys perform a visual short-term memory task. In both monkeys we find increases in theta power during the memory period that are accompanied by changes in directed coupling. These interactions are most prominent in the low frequency range encompassing the theta band (3-12~Hz and, more importantly, are asymmetric between pairs of recording sites. Furthermore, we find that the degree of interaction decreases as a function of distance between electrode positions, suggesting that these interactions are a predominantly local phenomenon. Taken together, our results show that directed coupling measures based on MVAR models are able to provide important insights into the spatial and temporal formation of local functionally coupled ensembles during visual memory in V4. Moreover, our findings suggest that visual memory is accompanied not only by a temporary increase of oscillatory activity in the theta band, but by a direction-dependent change in theta coupling, which ultimately represents a change in functional connectivity within the neural circuit.

  20. Within- and cross-modal distance information disambiguate visual size-change perception.

    Directory of Open Access Journals (Sweden)

    Peter W Battaglia

    2010-03-01

    Full Text Available Perception is fundamentally underconstrained because different combinations of object properties can generate the same sensory information. To disambiguate sensory information into estimates of scene properties, our brains incorporate prior knowledge and additional "auxiliary" (i.e., not directly relevant to desired scene property sensory information to constrain perceptual interpretations. For example, knowing the distance to an object helps in perceiving its size. The literature contains few demonstrations of the use of prior knowledge and auxiliary information in combined visual and haptic disambiguation and almost no examination of haptic disambiguation of vision beyond "bistable" stimuli. Previous studies have reported humans integrate multiple unambiguous sensations to perceive single, continuous object properties, like size or position. Here we test whether humans use visual and haptic information, individually and jointly, to disambiguate size from distance. We presented participants with a ball moving in depth with a changing diameter. Because no unambiguous distance information is available under monocular viewing, participants rely on prior assumptions about the ball's distance to disambiguate their -size percept. Presenting auxiliary binocular and/or haptic distance information augments participants' prior distance assumptions and improves their size judgment accuracy-though binocular cues were trusted more than haptic. Our results suggest both visual and haptic distance information disambiguate size perception, and we interpret these results in the context of probabilistic perceptual reasoning.

  1. Transcranial magnetic stimulation changes response selectivity of neurons in the visual cortex

    Science.gov (United States)

    Kim, Taekjun; Allen, Elena A.; Pasley, Brian N.; Freeman, Ralph D.

    2015-01-01

    Background Transcranial magnetic stimulation (TMS) is used to selectively alter neuronal activity of specific regions in the cerebral cortex. TMS is reported to induce either transient disruption or enhancement of different neural functions. However, its effects on tuning properties of sensory neurons have not been studied quantitatively. Objective/Hypothesis Here, we use specific TMS application parameters to determine how they may alter tuning characteristics (orientation, spatial frequency, and contrast sensitivity) of single neurons in the cat’s visual cortex. Methods Single unit spikes were recorded with tungsten microelectrodes from the visual cortex of anesthetized and paralyzed cats (12 males). Repetitive TMS (4Hz, 4sec) was delivered with a 70mm figure-8 coil. We quantified basic tuning parameters of individual neurons for each pre- and post-TMS condition. The statistical significance of changes for each tuning parameter between the two conditions was evaluated with a Wilcoxon signed-rank test. Results We generally find long-lasting suppression which persists well beyond the stimulation period. Pre- and post-TMS orientation tuning curves show constant peak values. However, strong suppression at non-preferred orientations tends to narrow the widths of tuning curves. Spatial frequency tuning exhibits an asymmetric change in overall shape, which results in an emphasis on higher frequencies. Contrast tuning curves show nonlinear changes consistent with a gain control mechanism. Conclusions These findings suggest that TMS causes extended interruption of the balance between sub-cortical and intra-cortical inputs. PMID:25862599

  2. Images of climate change in the news: Visual framing of a global environmental issue

    Science.gov (United States)

    Rebich Hespanha, S.; Rice, R. E.; Montello, D. R.; Retzloff, S.; Tien, S.

    2012-12-01

    News media play a powerful role in disseminating and framing information and shaping public opinion on environmental issues. Choices of text and images that are made by the creators and distributors of news media not only influence public perception about which issues are important, but also surreptitiously lead consumers of these media to perceive certain aspects or perspectives on an issue while neglecting to consider others. Our research was motivated by a desire to obtain comprehensive quantitative and qualitative understanding of the types of information - both textual and visual -- that have been provided to the U.S. public over the past several decades through news reports about climate change. As part of this project, we documented and examined 118 themes in 19 categories presented in 350 randomly-selected visual images from U.S. news coverage of global climate change between 1969 and late 2009. This study examines how the use of imagery in print news positions climate change within public and private arenas and how it emphasizes particular geographic, political, scientific, technological, sociological, and ideological aspects of the issue.

  3. Enhancement of Visual Field Predictions with Pointwise Exponential Regression (PER) and Pointwise Linear Regression (PLR).

    Science.gov (United States)

    Morales, Esteban; de Leon, John Mark S; Abdollahi, Niloufar; Yu, Fei; Nouri-Mahdavi, Kouros; Caprioli, Joseph

    2016-03-01

    The study was conducted to evaluate threshold smoothing algorithms to enhance prediction of the rates of visual field (VF) worsening in glaucoma. We studied 798 patients with primary open-angle glaucoma and 6 or more years of follow-up who underwent 8 or more VF examinations. Thresholds at each VF location for the first 4 years or first half of the follow-up time (whichever was greater) were smoothed with clusters defined by the nearest neighbor (NN), Garway-Heath, Glaucoma Hemifield Test (GHT), and weighting by the correlation of rates at all other VF locations. Thresholds were regressed with a pointwise exponential regression (PER) model and a pointwise linear regression (PLR) model. Smaller root mean square error (RMSE) values of the differences between the observed and the predicted thresholds at last two follow-ups indicated better model predictions. The mean (SD) follow-up times for the smoothing and prediction phase were 5.3 (1.5) and 10.5 (3.9) years. The mean RMSE values for the PER and PLR models were unsmoothed data, 6.09 and 6.55; NN, 3.40 and 3.42; Garway-Heath, 3.47 and 3.48; GHT, 3.57 and 3.74; and correlation of rates, 3.59 and 3.64. Smoothed VF data predicted better than unsmoothed data. Nearest neighbor provided the best predictions; PER also predicted consistently more accurately than PLR. Smoothing algorithms should be used when forecasting VF results with PER or PLR. The application of smoothing algorithms on VF data can improve forecasting in VF points to assist in treatment decisions.

  4. Clinical Correlates of Computationally Derived Visual Field Defect Archetypes in Patients from a Glaucoma Clinic.

    Science.gov (United States)

    Cai, Sophie; Elze, Tobias; Bex, Peter J; Wiggs, Janey L; Pasquale, Louis R; Shen, Lucy Q

    2017-04-01

    To assess the clinical validity of visual field (VF) archetypal analysis, a previously developed machine learning method for decomposing any Humphrey VF (24-2) into a weighted sum of clinically recognizable VF loss patterns. For each of 16 previously identified VF loss patterns ("archetypes," denoted AT1 through AT16), we screened 30,995 reliable VFs to select 10-20 representative patients whose VFs had the highest decomposition coefficients for each archetype. VF global indices and patient ocular and demographic features were extracted retrospectively. Based on resemblances between VF archetypes and clinically observed VF patterns, hypotheses were generated for associations between certain VF archetypes and clinical features, such as an association between AT6 (central island, representing severe VF loss) and large cup-to-disk ratio (CDR). Distributions of the selected clinical features were compared between representative eyes of certain archetypes and all other eyes using the two-tailed t-test or Fisher exact test. 243 eyes from 243 patients were included, representative of AT1 through AT16. CDR was more often ≥ 0.7 among eyes representative of AT6 (central island; p = 0.002), AT10 (inferior arcuate defect; p = 0.048), AT14 (superior paracentral defect; p = 0.016), and AT16 (inferior paracentral defect; p = 0.016) than other eyes. CDR was more often 6D (p = 0.069). Shared clinical features between computationally derived VF archetypes and clinically observed VF patterns support the clinical validity of VF archetypal analysis.

  5. Perceived changes in ordinary autobiographical events' affect and visual imagery colorfulness.

    Science.gov (United States)

    Ritchie, Timothy D; Batteson, Tamzin J

    2013-06-01

    We examined the extent to which the perceived changes in visual imagery colorfulness impact on the affect intensity associated with ordinary autobiographical events across time. We garnered support for the hypothesis that recent events become memorial phenomena via an emotion regulation process such that positive events retained their affective pleasantness longer than negative events retained affective unpleasantness because, in part, across 2 weeks the former retained their imagery colorfulness longer than the latter events did. A similar but distinct model was unsupported. We discuss the significance of imagery colorfulness and affect intensity in the context of memory for everyday autobiographical events. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Change detection algorithms for surveillance in visual iot: a comparative study

    International Nuclear Information System (INIS)

    Akram, B.A.; Zafar, A.; Akbar, A.H.; Chaudhry, A.

    2018-01-01

    The VIoT (Visual Internet of Things) connects virtual information world with real world objects using sensors and pervasive computing. For video surveillance in VIoT, ChD (Change Detection) is a critical component. ChD algorithms identify regions of change in multiple images of the same scene recorded at different time intervals for video surveillance. This paper presents performance comparison of histogram thresholding and classification ChD algorithms using quantitative measures for video surveillance in VIoT based on salient features of datasets. The thresholding algorithms Otsu, Kapur, Rosin and classification methods k-means, EM (Expectation Maximization) were simulated in MATLAB using diverse datasets. For performance evaluation, the quantitative measures used include OSR (Overall Success Rate), YC (Yule’s Coefficient) and JC (Jaccard’s Coefficient), execution time and memory consumption. Experimental results showed that Kapur’s algorithm performed better for both indoor and outdoor environments with illumination changes, shadowing and medium to fast moving objects. However, it reflected degraded performance for small object size with minor changes. Otsu algorithm showed better results for indoor environments with slow to medium changes and nomadic object mobility. k-means showed good results in indoor environment with small object size producing slow change, no shadowing and scarce illumination changes. (author)

  7. Change Detection Algorithms for Surveillance in Visual IoT: A Comparative Study

    Science.gov (United States)

    Akram, Beenish Ayesha; Zafar, Amna; Akbar, Ali Hammad; Wajid, Bilal; Chaudhry, Shafique Ahmad

    2018-01-01

    The VIoT (Visual Internet of Things) connects virtual information world with real world objects using sensors and pervasive computing. For video surveillance in VIoT, ChD (Change Detection) is a critical component. ChD algorithms identify regions of change in multiple images of the same scene recorded at different time intervals for video surveillance. This paper presents performance comparison of histogram thresholding and classification ChD algorithms using quantitative measures for video surveillance in VIoT based on salient features of datasets. The thresholding algorithms Otsu, Kapur, Rosin and classification methods k-means, EM (Expectation Maximization) were simulated in MATLAB using diverse datasets. For performance evaluation, the quantitative measures used include OSR (Overall Success Rate), YC (Yule's Coefficient) and JC (Jaccard's Coefficient), execution time and memory consumption. Experimental results showed that Kapur's algorithm performed better for both indoor and outdoor environments with illumination changes, shadowing and medium to fast moving objects. However, it reflected degraded performance for small object size with minor changes. Otsu algorithm showed better results for indoor environments with slow to medium changes and nomadic object mobility. k-means showed good results in indoor environment with small object size producing slow change, no shadowing and scarce illumination changes.

  8. Myocardial infarction increases progressive visual field defects in well treated early primary open angle glaucoma--a prospective case control study.

    Science.gov (United States)

    Mondal, Lakshmikanta; Baidya, Krishnapada; Choudhury, Himadri; Roy, Rupam

    2013-06-01

    The purpose of the study was to evaluate the progression of glaucomatous field damage in patients with stable primary open angle glaucoma after an attack of myocardial infarction. In this case control study, 62 open angle glaucoma patients were selected and regularly followed up. Among 62 patients, 9 had an attack of myocardial infarction. The intra-ocular pressure and visual field progression of both the groups (myocardial infarction versus no myocardial infarction) were analysed. Three (33.3%) out of 9 patients who had suffered from myocardial infarction showed progressive visual field loss whereas only 9 (16.9%) out of 53 patients who did not suffer from myocardial infarction, showed progressive field changes. Both the groups had stable target intra-ocular pressure between 14 and 16 mm Hg. Myocardial infarction may adversely influence the progression of primary open angle glaucoma which is suspected to result from ischaemia induced neuronal loss and only control of intraocular pressure is not the only solution. We have to look for other drugs that prevents ischaemia induced neuronal damage.

  9. Relationship between visual field progression and baseline refraction in primary open-angle glaucoma.

    Science.gov (United States)

    Naito, Tomoko; Yoshikawa, Keiji; Mizoue, Shiro; Nanno, Mami; Kimura, Tairo; Suzumura, Hirotaka; Umeda, Yuzo; Shiraga, Fumio

    2016-01-01

    To analyze the relationship between visual field (VF) progression and baseline refraction in Japanese patients with primary open-angle glaucoma (POAG) including normal-tension glaucoma. In this retrospective study, the subjects were patients with POAG who had undergone VF tests at least ten times with a Humphrey Field Analyzer (Swedish interactive thresholding algorithm standard, Central 30-2 program). VF progression was defined as a significantly negative value of mean deviation (MD) slope at the final VF test. Multivariate logistic regression models were applied to detect an association between MD slope deterioration and baseline refraction. A total of 156 eyes of 156 patients were included in this analysis. Significant deterioration of MD slope was observed in 70 eyes of 70 patients (44.9%), whereas no significant deterioration was evident in 86 eyes of 86 patients (55.1%). The eyes with VF progression had significantly higher baseline refraction compared to those without apparent VF progression (-1.9±3.8 diopter [D] vs -3.5±3.4 D, P=0.0048) (mean ± standard deviation). When subject eyes were classified into four groups by the level of baseline refraction applying spherical equivalent (SE): no myopia (SE > -1D), mild myopia (-1D ≥ SE > -3D), moderate myopia (-3D ≥ SE > -6D), and severe myopia (-6D ≥ SE), the Cochran-Armitage trend analysis showed a decreasing trend in the proportion of MD slope deterioration with increasing severity of myopia (P=0.0002). The multivariate analysis revealed that baseline refraction (P=0.0108, odds ratio [OR]: 1.13, 95% confidence interval [CI]: 1.03-1.25) and intraocular pressure reduction rate (P=0.0150, OR: 0.97, 95% CI: 0.94-0.99) had a significant association with MD slope deterioration. In the current analysis of Japanese patients with POAG, baseline refraction was a factor significantly associated with MD slope deterioration as well as intraocular pressure reduction rate. When baseline refraction was classified into

  10. Using Interactive Data Visualizations for Exploratory Analysis in Undergraduate Genomics Coursework: Field Study Findings and Guidelines

    Science.gov (United States)

    Kumar, Anuj; Nong, Paige; Su, Gang; Meng, Fan

    2016-01-01

    Life scientists increasingly use visual analytics to explore large data sets and generate hypotheses. Undergraduate biology majors should be learning these same methods. Yet visual analytics is one of the most underdeveloped areas of undergraduate biology education. This study sought to determine the feasibility of undergraduate biology majors conducting exploratory analysis using the same interactive data visualizations as practicing scientists. We examined 22 upper level undergraduates in a genomics course as they engaged in a case-based inquiry with an interactive heat map. We qualitatively and quantitatively analyzed students’ visual analytic behaviors, reasoning and outcomes to identify student performance patterns, commonly shared efficiencies and task completion. We analyzed students’ successes and difficulties in applying knowledge and skills relevant to the visual analytics case and related gaps in knowledge and skill to associated tool designs. Findings show that undergraduate engagement in visual analytics is feasible and could be further strengthened through tool usability improvements. We identify these improvements. We speculate, as well, on instructional considerations that our findings suggested may also enhance visual analytics in case-based modules. PMID:26877625

  11. Efeitos da ibopamina 2% tópica nos resultados da campimetria visual computadorizada Effects of 2% ibopamine eye drops on computerized visual field results

    Directory of Open Access Journals (Sweden)

    Mara Agi Pigini

    2009-06-01

    Full Text Available OBJETIVO: Avaliar os efeitos do uso do colírio de ibopamina a 2% nos resultados da campimetria visual computadorizada em indivíduos normais. MÉTODOS: Voluntários oriundos do CEROF-UFG, sem alterações ao exame oftalmológico que pudessem afetar o campo visual foram selecionados. Os indivíduos foram submetidos a exame de perimetria computadorizada SITA-standard 24-2 antes e após dilatação com o colírio de ibopamina a 2% ou ciclopentolato, com intervalo mínimo de 3 dias entre si e em ordem aleatória. Índices globais e número de pontos alterados foram comparados entre os grupos. RESULTADOS: Foram avaliados 30 olhos de 30 indivíduos normais. Não houve diferença estatisticamente significativa entre o "mean deviation" (MD nos pacientes não dilatados e nos mesmos após a instilação da ibopamina (MD: -1,05 ± 0,26 dB vs. -1,47 ± 0,20 dB, P=0,08, o que ocorreu após cicloplegia (MD: -3,19 ± 0,29 dB, PPURPOSE: To evaluate the influence of 2% ibopamine eye drops on the results of computerized visual field exams. METHODS: Normal volunteers from CEROF-UFG were selected, with no variance in the ophthalmologic examination that could affect the visual field test. The volunteers underwent computerized visual field test before and after dilation with 2% ibopamine eye drop or cyclopentolate, with a minimum interval of three days between them and in a random order. Global indices and number of altered points were compared between the groups. RESULTS: Thirty eyes of 30 normal individuals were selected. There was no statistically significant difference on Mean Deviation (MD before and after dilation with ibopamine (MD: -1.05 ± 0.26 dB vs. -1.47 ± 0.20 dB, P=0.08. However, after cycloplegia (MD: -3.19 ± 0.29 dB, there was a significant difference on MD (P<0.001 for both ibopamine and pre-dilation. No significant difference was detected in the Pattern Standard Deviation when comparing ibopamine with pre-dilation and cycloplegia values, but it

  12. Persistence, Spatial Distribution and Implications for Progression Detection of Blind Parts of the Visual Field in Glaucoma : A Clinical Cohort Study

    NARCIS (Netherlands)

    Montolio, Francisco G. Junoy; Wesselink, Christiaan; Jansonius, Nomdo M.

    2012-01-01

    Background: Visual field testing is an essential part of glaucoma care. It is hampered by variability related to the disease itself, response errors and fatigue. In glaucoma, blind parts of the visual field contribute to the diagnosis but - once established - not to progression detection; they only

  13. Persistence, spatial distribution and implications for progression detection of blind parts of the visual field in glaucoma: A clinical cohort study

    NARCIS (Netherlands)

    F.G. Junoy Montolio (Francisco); C. Wesselink (Christiaan); N.M. Jansonius (Nomdo)

    2012-01-01

    textabstractBackground: Visual field testing is an essential part of glaucoma care. It is hampered by variability related to the disease itself, response errors and fatigue. In glaucoma, blind parts of the visual field contribute to the diagnosis but - once established - not to progression

  14. Scenic Vistas and the Changing Policy Landscape: Visualizing and Testing the Role of Visual Resources in Ecosystem Management

    Science.gov (United States)

    Robert G. Ribe; Edward T. Armstrong; Paul H. Gobster

    2002-01-01

    The Northwest Forest Plan applies a shift in policy to national forests in the Pacific Northwest, with implications for other public landscapes. This shift offers potentially strong scenic implications for areas that have historically emphasized clearcutting with little visual impact mitigation. These areas will now emphasize biocentric concerns and harvests formed...

  15. Morphoquantitative changes in central and intermediate sections of visual analyzer after whole-body x-irradiation

    International Nuclear Information System (INIS)

    Logvinov, S.V.; Ryzhov, A.I.

    1989-01-01

    Morphoquantitative estimation of changes in 4 and 5 layers of visual cortex and outer geniculated bodies of the brain of guinea pigs subjected to whole-body X-irradiation with a median lethal doses shows that neurons from the visual analyzer sections under study are differently damaged. The morphogenesis of changes is connected with the original variations in the quantitative structure of a neuron-glial complex displaying and selective alterative and productive reaction of the perivascular glia

  16. ["Glare vision". I. Physiological principles of vision change with increased test field luminance].

    Science.gov (United States)

    Hauser, B; Ochsner, H; Zrenner, E

    1992-02-01

    Clinical tests of visual acuity are an important measure of visual function. However visual acuity is usually determined only in narrow range of luminance levels between 160 and 320 cd/m2; therefore losses of visual acuity in other ranges of light intensity can not be detected. In a distance of 80 cm from the patients eyes, Landolt rings of varying sizes were presented on a small test field whose light intensity can be varied between 0.1 and 30,000 cd/m2. Thereby an acuity-luminance-function can be obtained. We studied such functions under different conditions of exposure time both with constant and with increasing luminance of the test field. We found that persons with normal vision can increase their visual acuity with increasing test field luminance up to a range of 5000 cd/m2. The maximum values of visual acuity under optimal lightening conditions lie (varying with age) between 2.2 and 0.9. Under pathological conditions visual acuity falls at high luminances accompanied by sensations of glare. Tests of glare sensitivity as a function of exposure time showed 4 sec to be a critical time of exposure since after 4 sec normal persons just reach their maximum visual acuity at high luminances. The underlying physiological mechanisms lead us to suppose that patients with neuronal light adaptation disturbances display a greater visual loss as a result of decreased time of exposure than those with disturbances in the ocular media. Visual acuity as well as the capacity to increase the patients visual acuity under optimal conditions of lighting were both found to be strongly age-dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Constrição campimétrica causada por vigabatrin Visual field constriction caused by vigabatrin

    Directory of Open Access Journals (Sweden)

    Mário Luiz Ribeiro Monteiro

    2000-10-01

    imaging (1 patient and visual evoked potential (1 patient. Results: Visual acuity was normal; the first patient had the visual field restricted to the 20 to 30 degree central area and the second, a mild to moderate constriction. Neuroimaging examinations were normal as well as the visual evoked potential. Mild optic disc pallor (3 eyes and very slight retinal arteriolar narrowing was observed. ERG showed reduction of the b wave (case 1 and oscillatory potential responses (case 2. Conclusions: Visual alterations caused by vigabatrin are due to a retina dysfunction presumably involving the amacrine, bipolar and ganglion cells but there are no significant pathologic findings on fundoscopic examination. Patients receiving this medication should be followed closely with periodic central and peripheral visual field testing.

  18. Metacognitive monitoring and control in visual change detection: Implications for situation awareness and cognitive control

    Science.gov (United States)

    McAnally, Ken I.; Morris, Adam P.; Best, Christopher

    2017-01-01

    Metacognitive monitoring and control of situation awareness (SA) are important for a range of safety-critical roles (e.g., air traffic control, military command and control). We examined the factors affecting these processes using a visual change detection task that included representative tactical displays. SA was assessed by asking novice observers to detect changes to a tactical display. Metacognitive monitoring was assessed by asking observers to estimate the probability that they would correctly detect a change, either after study of the display and before the change (judgement of learning; JOL) or after the change and detection response (judgement of performance; JOP). In Experiment 1, observers failed to detect some changes to the display, indicating imperfect SA, but JOPs were reasonably well calibrated to objective performance. Experiment 2 examined JOLs and JOPs in two task contexts: with study-time limits imposed by the task or with self-pacing to meet specified performance targets. JOPs were well calibrated in both conditions as were JOLs for high performance targets. In summary, observers had limited SA, but good insight about their performance and learning for high performance targets and allocated study time appropriately. PMID:28915244

  19. Representing climate change futures: a critique on the use of images for visual communication

    Energy Technology Data Exchange (ETDEWEB)

    Nicholson-Cole, Sophie A. [School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, (United Kingdom)

    2005-05-15

    How people perceive their role and the responsibilities of others in determining the outcomes of climate change is of great importance for policy-making, adaptation and climate change mitigation. However, for many people, climate change is a remote problem and not one of personal concern. Meaningful visualisations depicting climate change futures could help to bridge the gap between what may seem an abstract concept and everyday experience, making clearer its local and individual relevance. Computer aided visualisation has great potential as a means to interest and engage different groups in society. However, the way in which information is represented affects an individual's interpretation and uptake, and how they see their present choices affecting their future and that of others. The empirical content of this paper summarises the results of an exploratory qualitative study, consisting of 30 semi-structured interviews investigating people's visual conceptions and feelings about climate change. The emphasis of the inquiry is focussed on eliciting people's spontaneous visualisations of climate change and their feelings of involvement with the issue. The insights gained from the described empirical work set the scene for further research, which will employ the use of a range of images and visualisations for evaluation. (Author)

  20. Active training and driving-specific feedback improve older drivers' visual search prior to lane changes

    Directory of Open Access Journals (Sweden)

    Lavallière Martin

    2012-03-01

    Full Text Available Abstract Background Driving retraining classes may offer an opportunity to attenuate some effects of aging that may alter driving skills. Unfortunately, there is evidence that classroom programs (driving refresher courses do not improve the driving performance of older drivers. The aim of the current study was to evaluate if simulator training sessions with video-based feedback can modify visual search behaviors of older drivers while changing lanes in urban driving. Methods In order to evaluate the effectiveness of the video-based feedback training, 10 older drivers who received a driving refresher course and feedback about their driving performance were tested with an on-road standardized evaluation before and after participating to a simulator training program (Feedback group. Their results were compared to a Control group (12 older drivers who received the same refresher course and in-simulator active practice as the Feedback group without receiving driving-specific feedback. Results After attending the training program, the Control group showed no increase in the frequency of the visual inspection of three regions of interests (rear view and left side mirrors, and blind spot. In contrast, for the Feedback group, combining active training and driving-specific feedbacks increased the frequency of blind spot inspection by 100% (32.3 to 64.9% of verification before changing lanes. Conclusions These results suggest that simulator training combined with driving-specific feedbacks helped older drivers to improve their visual inspection strategies, and that in-simulator training transferred positively to on-road driving. In order to be effective, it is claimed that driving programs should include active practice sessions with driving-specific feedbacks. Simulators offer a unique environment for developing such programs adapted to older drivers' needs.

  1. Active training and driving-specific feedback improve older drivers' visual search prior to lane changes.

    Science.gov (United States)

    Lavallière, Martin; Simoneau, Martin; Tremblay, Mathieu; Laurendeau, Denis; Teasdale, Normand

    2012-03-02

    Driving retraining classes may offer an opportunity to attenuate some effects of aging that may alter driving skills. Unfortunately, there is evidence that classroom programs (driving refresher courses) do not improve the driving performance of older drivers. The aim of the current study was to evaluate if simulator training sessions with video-based feedback can modify visual search behaviors of older drivers while changing lanes in urban driving. In order to evaluate the effectiveness of the video-based feedback training, 10 older drivers who received a driving refresher course and feedback about their driving performance were tested with an on-road standardized evaluation before and after participating to a simulator training program (Feedback group). Their results were compared to a Control group (12 older drivers) who received the same refresher course and in-simulator active practice as the Feedback group without receiving driving-specific feedback. After attending the training program, the Control group showed no increase in the frequency of the visual inspection of three regions of interests (rear view and left side mirrors, and blind spot). In contrast, for the Feedback group, combining active training and driving-specific feedbacks increased the frequency of blind spot inspection by 100% (32.3 to 64.9% of verification before changing lanes). These results suggest that simulator training combined with driving-specific feedbacks helped older drivers to improve their visual inspection strategies, and that in-simulator training transferred positively to on-road driving. In order to be effective, it is claimed that driving programs should include active practice sessions with driving-specific feedbacks. Simulators offer a unique environment for developing such programs adapted to older drivers' needs.

  2. Comparison of onboard low-field magnetic resonance imaging versus onboard computed tomography for anatomy visualization in radiotherapy.

    Science.gov (United States)

    Noel, Camille E; Parikh, Parag J; Spencer, Christopher R; Green, Olga L; Hu, Yanle; Mutic, Sasa; Olsen, Jeffrey R

    2015-01-01

    Onboard magnetic resonance imaging (OB-MRI) for daily localization and adaptive radiotherapy has been under development by several groups. However, no clinical studies have evaluated whether OB-MRI improves visualization of the target and organs at risk (OARs) compared to standard onboard computed tomography (OB-CT). This study compared visualization of patient anatomy on images acquired on the MRI-(60)Co ViewRay system to those acquired with OB-CT. Fourteen patients enrolled on a protocol approved by the Institutional Review Board (IRB) and undergoing image-guided radiotherapy for cancer in the thorax (n = 2), pelvis (n = 6), abdomen (n = 3) or head and neck (n = 3) were imaged with OB-MRI and OB-CT. For each of the 14 patients, the OB-MRI and OB-CT datasets were displayed side-by-side and independently reviewed by three radiation oncologists. Each physician was asked to evaluate which dataset offered better visualization of the target and OARs. A quantitative contouring study was performed on two abdominal patients to assess if OB-MRI could offer improved inter-observer segmentation agreement for adaptive planning. In total 221 OARs and 10 targets were compared for visualization on OB-MRI and OB-CT by each of the three physicians. The majority of physicians (two or more) evaluated visualization on MRI as better for 71% of structures, worse for 10% of structures, and equivalent for 14% of structures. 5% of structures were not visible on either. Physicians agreed unanimously for 74% and in majority for > 99% of structures. Targets were better visualized on MRI in 4/10 cases, and never on OB-CT. Low-field MR provides better anatomic visualization of many radiotherapy targets and most OARs as compared to OB-CT. Further studies with OB-MRI should be pursued.

  3. Contrast normalization contributes to a biologically-plausible model of receptive-field development in primary visual cortex (V1)

    Science.gov (United States)

    Willmore, Ben D.B.; Bulstrode, Harry; Tolhurst, David J.

    2012-01-01

    Neuronal populations in the primary visual cortex (V1) of mammals exhibit contrast normalization. Neurons that respond strongly to simple visual stimuli – such as sinusoidal gratings – respond less well to the same stimuli when they are presented as part of a more complex stimulus which also excites other, neighboring neurons. This phenomenon is generally attributed to generalized patterns of inhibitory connections between nearby V1 neurons. The Bienenstock, Cooper and Munro (BCM) rule is a neural network learning rule that, when trained on natural images, produces model neurons which, individually, have many tuning properties in common with real V1 neurons. However, when viewed as a population, a BCM network is very different from V1 – each member of the BCM population tends to respond to the same dominant features of visual input, producing an incomplete, highly redundant code for visual information. Here, we demonstrate that, by adding contrast normalization into the BCM rule, we arrive at a neurally-plausible Hebbian learning rule that can learn an efficient sparse, overcomplete representation that is a better model for stimulus selectivity in V1. This suggests that one role of contrast normalization in V1 is to guide the neonatal development of receptive fields, so that neurons respond to different features of visual input. PMID:22230381

  4. Pretest Calculations of Temperature Changes for Field Thermal Conductivity Tests

    International Nuclear Information System (INIS)

    N.S. Brodsky

    2002-01-01

    A large volume fraction of the potential monitored geologic repository at Yucca Mountain may reside in the Tptpll (Tertiary, Paintbrush Group, Topopah Spring Tuff, crystal poor, lower lithophysal) lithostratigraphic unit. This unit is characterized by voids, or lithophysae, which range in size from centimeters to meters. A series of thermal conductivity field tests are planned in the Enhanced Characterization of the Repository Block (ECRB) Cross Drift. The objective of the pretest calculation described in this document is to predict changes in temperatures in the surrounding rock for these tests for a given heater power and a set of thermal transport properties. The calculation can be extended, as described in this document, to obtain thermal conductivity, thermal capacitance (density x heat capacity, J · m -3 · K -1 ), and thermal diffusivity from the field data. The work has been conducted under the ''Technical Work Plan For: Testing and Monitoring'' (BSC 2001). One of the outcomes of this analysis is to determine the initial output of the heater. This heater output must be sufficiently high that it will provide results in a reasonably short period of time (within several weeks or a month) and be sufficiently high that the heat increase is detectable by the instruments employed in the test. The test will be conducted in stages and heater output will be step increased as the test progresses. If the initial temperature is set too high, the experiment will not have as many steps and thus fewer thermal conductivity data points will result

  5. Detecting gradual visual changes in colour and brightness agnosia: a double dissociation.

    Science.gov (United States)

    Nijboer, Tanja C W; te Pas, Susan F; van der Smagt, Maarten J

    2011-03-09

    Two patients, one with colour agnosia and one with brightness agnosia, performed a task that required the detection of gradual temporal changes in colour and brightness. The results for these patients, who showed anaverage or an above-average performance on several tasks designed to test low-level colour and luminance (contrast) perception in the spatial domain, yielded a double dissociation; the brightness agnosic patient was within the normal range for the coloured stimuli, but much slower to detect brightness differences, whereas the colour agnosic patient was within the normal range for the achromatic stimuli, but much slower for the coloured stimuli. These results suggest that a modality-specific impairment in the detection of gradual temporal changes might be related to, if not underlie, the phenomenon of visual agnosia.