Peripheral vision of youths with low vision: motion perception, crowding, and visual search.

PubMed

Tadin, Duje; Nyquist, Jeffrey B; Lusk, Kelly E; Corn, Anne L; Lappin, Joseph S

2012-08-24

Effects of low vision on peripheral visual function are poorly understood, especially in children whose visual skills are still developing. The aim of this study was to measure both central and peripheral visual functions in youths with typical and low vision. Of specific interest was the extent to which measures of foveal function predict performance of peripheral tasks. We assessed central and peripheral visual functions in youths with typical vision (n = 7, ages 10-17) and low vision (n = 24, ages 9-18). Experimental measures used both static and moving stimuli and included visual crowding, visual search, motion acuity, motion direction discrimination, and multitarget motion comparison. In most tasks, visual function was impaired in youths with low vision. Substantial differences, however, were found both between participant groups and, importantly, across different tasks within participant groups. Foveal visual acuity was a modest predictor of peripheral form vision and motion sensitivity in either the central or peripheral field. Despite exhibiting normal motion discriminations in fovea, motion sensitivity of youths with low vision deteriorated in the periphery. This contrasted with typically sighted participants, who showed improved motion sensitivity with increasing eccentricity. Visual search was greatly impaired in youths with low vision. Our results reveal a complex pattern of visual deficits in peripheral vision and indicate a significant role of attentional mechanisms in observed impairments. These deficits were not adequately captured by measures of foveal function, arguing for the importance of independently assessing peripheral visual function.

Biofuels E0, E15, E85 Neurophysiology Data

EPA Pesticide Factsheets

Visual, auditory, somatosensory, and peripheral nerve evoked responses.This dataset is associated with the following publication:Herr , D., D. Freeborn , L. Degn , S.A. Martin, J. Ortenzio, L. Pantlin, C. Hamm , and W. Boyes. Neurophysiological Assessment of Auditory, Peripheral Nerve, Somatosensory, and Visual System Function After Developmental Exposure to Gasoline, E15 and E85 Vapors. NEUROTOXICOLOGY AND TERATOLOGY. Elsevier Science Ltd, New York, NY, USA, 54: 78-88, (2016).

Reclaiming the Periphery: Automated Kinetic Perimetry for Measuring Peripheral Visual Fields in Patients With Glaucoma.

PubMed

Mönter, Vera M; Crabb, David P; Artes, Paul H

2017-02-01

Peripheral vision is important for mobility, balance, and guidance of attention, but standard perimetry examines only <20% of the entire visual field. We report on the relation between central and peripheral visual field damage, and on retest variability, with a simple approach for automated kinetic perimetry (AKP) of the peripheral field. Thirty patients with glaucoma (median age 68, range 59-83 years; median Mean Deviation -8.0, range -16.3-0.1 dB) performed AKP and static automated perimetry (SAP) (German Adaptive Threshold Estimation strategy, 24-2 test). Automated kinetic perimetry consisted of a fully automated measurement of a single isopter (III.1.e). Central and peripheral visual fields were measured twice on the same day. Peripheral and central visual fields were only moderately related (Spearman's ρ, 0.51). Approximately 90% of test-retest differences in mean isopter radius were < ±4 deg. Relative to the range of measurements in this sample, the retest variability of AKP was similar to that of SAP. Patients with similar central visual field loss can have strikingly different peripheral visual fields, and therefore measuring the peripheral visual field may add clinically valuable information.

Real-time, label-free, intraoperative visualization of peripheral nerves and micro-vasculatures using multimodal optical imaging techniques

PubMed Central

Cha, Jaepyeong; Broch, Aline; Mudge, Scott; Kim, Kihoon; Namgoong, Jung-Man; Oh, Eugene; Kim, Peter

2018-01-01

Accurate, real-time identification and display of critical anatomic structures, such as the nerve and vasculature structures, are critical for reducing complications and improving surgical outcomes. Human vision is frequently limited in clearly distinguishing and contrasting these structures. We present a novel imaging system, which enables noninvasive visualization of critical anatomic structures during surgical dissection. Peripheral nerves are visualized by a snapshot polarimetry that calculates the anisotropic optical properties. Vascular structures, both venous and arterial, are identified and monitored in real-time using a near-infrared laser-speckle-contrast imaging. We evaluate the system by performing in vivo animal studies with qualitative comparison by contrast-agent-aided fluorescence imaging. PMID:29541506

Visual function, driving safety, and the elderly.

PubMed

Keltner, J L; Johnson, C A

1987-09-01

The authors have conducted a survey of the Departments of Motor Vehicles in all 50 states, the District of Columbia, and Puerto Rico requesting information about the visual standards, accidents, and conviction rates for different age groups. In addition, we have reviewed the literature on visual function and traffic safety. Elderly drivers have a greater number of vision problems that affect visual acuity and/or peripheral visual fields. Although the elderly are responsible for a small percentage of the total number of traffic accidents, the types of accidents they are involved in (e.g., failure to yield the right-of-way, intersection collisions, left turns onto crossing streets) may be related to peripheral and central visual field problems. Because age-related changes in performance occur at different rates for various individuals, licensing of the elderly driver should be based on functional abilities rather than age. Based on information currently available, we can make the following recommendations: (1) periodic evaluations of visual acuity and visual fields should be performed every 1 to 2 years in the population over age 65; (2) drivers of any age with multiple accidents or moving violations should have visual acuity and visual fields evaluated; and (3) a system should be developed for physicians to report patients with potentially unsafe visual function. The authors believe that these recommendations may help to reduce the number of traffic accidents that result from peripheral visual field deficits.

Visual brain plasticity induced by central and peripheral visual field loss.

PubMed

Sanda, Nicolae; Cerliani, Leonardo; Authié, Colas N; Sabbah, Norman; Sahel, José-Alain; Habas, Christophe; Safran, Avinoam B; Thiebaut de Schotten, Michel

2018-06-23

Disorders that specifically affect central and peripheral vision constitute invaluable models to study how the human brain adapts to visual deafferentation. We explored cortical changes after the loss of central or peripheral vision. Cortical thickness (CoTks) and resting-state cortical entropy (rs-CoEn), as a surrogate for neural and synaptic complexity, were extracted in 12 Stargardt macular dystrophy, 12 retinitis pigmentosa (tunnel vision stage), and 14 normally sighted subjects. When compared to controls, both groups with visual loss exhibited decreased CoTks in dorsal area V3d. Peripheral visual field loss also showed a specific CoTks decrease in early visual cortex and ventral area V4, while central visual field loss in dorsal area V3A. Only central visual field loss exhibited increased CoEn in LO-2 area and FG1. Current results revealed biomarkers of brain plasticity within the dorsal and the ventral visual streams following central and peripheral visual field defects.

Choice of Grating Orientation for Evaluation of Peripheral Vision

PubMed Central

Venkataraman, Abinaya Priya; Winter, Simon; Rosén, Robert; Lundström, Linda

2016-01-01

ABSTRACT Purpose Peripheral resolution acuity depends on the orientation of the stimuli. However, it is uncertain if such a meridional effect also exists for peripheral detection tasks because they are affected by optical errors. Knowledge of the quantitative differences in acuity for different grating orientations is crucial for choosing the appropriate stimuli for evaluations of peripheral resolution and detection tasks. We assessed resolution and detection thresholds for different grating orientations in the peripheral visual field. Methods Resolution and detection thresholds were evaluated for gratings of four different orientations in eight different visual field meridians in the 20-deg visual field in white light. Detection measurements in monochromatic light (543 nm; bandwidth, 10 nm) were also performed to evaluate the effects of chromatic aberration on the meridional effect. A combination of trial lenses and adaptive optics system was used to correct the monochromatic lower- and higher-order aberrations. Results For both resolution and detection tasks, gratings parallel to the visual field meridian had better threshold compared with the perpendicular gratings, whereas the two oblique gratings had similar thresholds. The parallel and perpendicular grating acuity differences for resolution and detection tasks were 0.16 logMAR and 0.11 logMAD, respectively. Elimination of chromatic errors did not affect the meridional preference in detection acuity. Conclusions Similar to peripheral resolution, detection also shows a meridional effect that appears to have a neural origin. The threshold difference seen for parallel and perpendicular gratings suggests the use of two oblique gratings as stimuli in alternative forced-choice procedures for peripheral vision evaluation to reduce measurement variation. PMID:26889822

Choice of Grating Orientation for Evaluation of Peripheral Vision.

PubMed

Venkataraman, Abinaya Priya; Winter, Simon; Rosén, Robert; Lundström, Linda

2016-06-01

Peripheral resolution acuity depends on the orientation of the stimuli. However, it is uncertain if such a meridional effect also exists for peripheral detection tasks because they are affected by optical errors. Knowledge of the quantitative differences in acuity for different grating orientations is crucial for choosing the appropriate stimuli for evaluations of peripheral resolution and detection tasks. We assessed resolution and detection thresholds for different grating orientations in the peripheral visual field. Resolution and detection thresholds were evaluated for gratings of four different orientations in eight different visual field meridians in the 20-deg visual field in white light. Detection measurements in monochromatic light (543 nm; bandwidth, 10 nm) were also performed to evaluate the effects of chromatic aberration on the meridional effect. A combination of trial lenses and adaptive optics system was used to correct the monochromatic lower- and higher-order aberrations. For both resolution and detection tasks, gratings parallel to the visual field meridian had better threshold compared with the perpendicular gratings, whereas the two oblique gratings had similar thresholds. The parallel and perpendicular grating acuity differences for resolution and detection tasks were 0.16 logMAR and 0.11 logMAD, respectively. Elimination of chromatic errors did not affect the meridional preference in detection acuity. Similar to peripheral resolution, detection also shows a meridional effect that appears to have a neural origin. The threshold difference seen for parallel and perpendicular gratings suggests the use of two oblique gratings as stimuli in alternative forced-choice procedures for peripheral vision evaluation to reduce measurement variation.

Optical and neural anisotropy in peripheral vision

PubMed Central

Zheleznyak, Len; Barbot, Antoine; Ghosh, Atanu; Yoon, Geunyoung

2016-01-01

Optical blur in the peripheral retina is known to be highly anisotropic due to nonrotationally symmetric wavefront aberrations such as astigmatism and coma. At the neural level, the visual system exhibits anisotropies in orientation sensitivity across the visual field. In the fovea, the visual system shows higher sensitivity for cardinal over diagonal orientations, which is referred to as the oblique effect. However, in the peripheral retina, the neural visual system becomes more sensitive to radially-oriented signals, a phenomenon known as the meridional effect. Here, we examined the relative contributions of optics and neural processing to the meridional effect in 10 participants at 0°, 10°, and 20° in the temporal retina. Optical anisotropy was quantified by measuring the eye's habitual wavefront aberrations. Alternatively, neural anisotropy was evaluated by measuring contrast sensitivity (at 2 and 4 cyc/deg) while correcting the eye's aberrations with an adaptive optics vision simulator, thus bypassing any optical factors. As eccentricity increased, optical and neural anisotropy increased in magnitude. The average ratio of horizontal to vertical optical MTF (at 2 and 4 cyc/deg) at 0°, 10°, and 20° was 0.96 ± 0.14, 1.41 ± 0.54 and 2.15 ± 1.38, respectively. Similarly, the average ratio of horizontal to vertical contrast sensitivity with full optical correction at 0°, 10°, and 20° was 0.99 ± 0.15, 1.28 ± 0.28 and 1.75 ± 0.80, respectively. These results indicate that the neural system's orientation sensitivity coincides with habitual blur orientation. These findings support the neural origin of the meridional effect and raise important questions regarding the role of peripheral anisotropic optical quality in developing the meridional effect and emmetropization. PMID:26928220

Enhanced visualization of peripheral retinal vasculature with wavefront sensorless adaptive optics OCT angiography in diabetic patients

PubMed Central

Polans, James; Cunefare, David; Cole, Eli; Keller, Brenton; Mettu, Priyatham S.; Cousins, Scott W.; Allingham, Michael J.; Izatt, Joseph A.; Farsiu, Sina

2017-01-01

Optical coherence tomography angiography (OCTA) is a promising technique for non-invasive visualization of vessel networks in the human eye. We debut a system capable of acquiring wide field-of-view (>70°) OCT angiograms without mosaicking. Additionally, we report on enhancing the visualization of peripheral microvasculature using wavefront sensorless adaptive optics (WSAO). We employed a fast WSAO algorithm that enabled wavefront correction in <2 seconds by iterating the mirror shape at the speed of OCT B-scans rather than volumes. Also, we contrasted ~7° field-of-view OCTA angiograms acquired in the periphery with and without WSAO correction. On average, WSAO improved the sharpness of microvasculature by 65% in healthy and 38% in diseased eyes. Preliminary observations demonstrated that the location of 7° images could be identified directly from the wide field-of-view angiogram. A pilot study on a normal subject and patients with diabetic retinopathy showed the impact of utilizing WSAO for OCTA when visualizing peripheral vasculature pathologies. PMID:28059209

Facing the Limitations of Electronic Document Handling.

ERIC Educational Resources Information Center

Moralee, Dennis

1985-01-01

This essay addresses problems associated with technology used in the handling of high-resolution visual images in electronic document delivery. Highlights include visual fidelity, laser-driven optical disk storage, electronics versus micrographics for document storage, videomicrographics, and system configurations and peripherals. (EJS)

Use of the Dynamic Visual Acuity Test as a screener for community-dwelling older adults who fall.

PubMed

Honaker, Julie A; Shepard, Neil T

2011-01-01

Adequate function of the peripheral vestibular system, specifically the vestibulo-ocular reflex (VOR; a network of neural connections between the peripheral vestibular system and the extraocular muscles) is essential for maintaining stable vision during head movements. Decreased visual acuity resulting from an impaired peripheral vestibular system may impede balance and postural control and place an individual at risk of falling. Therefore, sensitive measures of the vestibular system are warranted to screen for the tendency to fall, alerting clinicians to recommend further risk of falling assessment and referral to a falling risk reduction program. Dynamic Visual Acuity (DVA) testing is a computerized VOR assessment method to evaluate the peripheral vestibular system during head movements; reduced visual acuity as documented with DVA testing may be sensitive to screen for falling risk. This study examined the sensitivity and specificity of the computerized DVA test with yaw plane head movements for identifying community-dwelling adults (58-78 years) who are prone to falling. A total of 16 older adults with a history of two or more unexplained falls in the previous twelve months and 16 age and gender matched controls without a history of falls in the previous twelve months participated. Computerized DVA with horizontal head movements at a fixed velocity of 120 deg/sec was measured and compared with the Dynamic Gait Index (DGI) a gold standard gait assessment measurement for identifying falling risk. Receiver operating characteristics (ROC) curve analysis and area under the ROC curve (AUC) were used to assess the sensitivity and specificity of the computerized DVA as a screening measure for falling risk as determined by the DGI. Results suggested a link between computerized DVA and the propensity to fall; DVA in the yaw plane was found to be a sensitive (92%) and accurate screening measure when using a cutoff logMAR value of >0.25.

Vestibular-visual interactions in flight simulators

NASA Technical Reports Server (NTRS)

Clark, B.

1977-01-01

The following research work is reported: (1) vestibular-visual interactions; (2) flight management and crew system interactions; (3) peripheral cue utilization in simulation technology; (4) control of signs and symptoms of motion sickness; (5) auditory cue utilization in flight simulators, and (6) vestibular function: Animal experiments.

Accuracy of System Step Response Roll Magnitude Estimation from Central and Peripheral Visual Displays and Simulator Cockpit Motion

NASA Technical Reports Server (NTRS)

Hosman, R. J. A. W.; Vandervaart, J. C.

1984-01-01

An experiment to investigate visual roll attitude and roll rate perception is described. The experiment was also designed to assess the improvements of perception due to cockpit motion. After the onset of the motion, subjects were to make accurate and quick estimates of the final magnitude of the roll angle step response by pressing the appropriate button of a keyboard device. The differing time-histories of roll angle, roll rate and roll acceleration caused by a step response stimulate the different perception processes related the central visual field, peripheral visual field and vestibular organs in different, yet exactly known ways. Experiments with either of the visual displays or cockpit motion and some combinations of these were run to asses the roles of the different perception processes. Results show that the differences in response time are much more pronounced than the differences in perception accuracy.

Smart unattended sensor networks with scene understanding capabilities

NASA Astrophysics Data System (ADS)

Kuvich, Gary

2006-05-01

Unattended sensor systems are new technologies that are supposed to provide enhanced situation awareness to military and law enforcement agencies. A network of such sensors cannot be very effective in field conditions only if it can transmit visual information to human operators or alert them on motion. In the real field conditions, events may happen in many nodes of a network simultaneously. But the real number of control personnel is always limited, and attention of human operators can be simply attracted to particular network nodes, while more dangerous threat may be unnoticed at the same time in the other nodes. Sensor networks would be more effective if equipped with a system that is similar to human vision in its abilities to understand visual information. Human vision uses for that a rough but wide peripheral system that tracks motions and regions of interests, narrow but precise foveal vision that analyzes and recognizes objects in the center of selected region of interest, and visual intelligence that provides scene and object contexts and resolves ambiguity and uncertainty in the visual information. Biologically-inspired Network-Symbolic models convert image information into an 'understandable' Network-Symbolic format, which is similar to relational knowledge models. The equivalent of interaction between peripheral and foveal systems in the network-symbolic system is achieved via interaction between Visual and Object Buffers and the top-level knowledge system.

High-resolution ultrasound imaging and noninvasive optoacoustic monitoring of blood variables in peripheral blood vessels

NASA Astrophysics Data System (ADS)

Petrov, Irene Y.; Petrov, Yuriy; Prough, Donald S.; Esenaliev, Rinat O.

2011-03-01

Ultrasound imaging is being widely used in clinics to obtain diagnostic information non-invasively and in real time. A high-resolution ultrasound imaging platform, Vevo (VisualSonics, Inc.) provides in vivo, real-time images with exceptional resolution (up to 30 microns) using high-frequency transducers (up to 80 MHz). Recently, we built optoacoustic systems for probing radial artery and peripheral veins that can be used for noninvasive monitoring of total hemoglobin concentration, oxyhemoglobin saturation, and concentration of important endogenous and exogenous chromophores (such as ICG). In this work we used the high-resolution ultrasound imaging system Vevo 770 for visualization of the radial artery and peripheral veins and acquired corresponding optoacoustic signals from them using the optoacoustic systems. Analysis of the optoacoustic data with a specially developed algorithm allowed for measurement of blood oxygenation in the blood vessels as well as for continuous, real-time monitoring of arterial and venous blood oxygenation. Our results indicate that: 1) the optoacoustic technique (unlike pure optical approaches and other noninvasive techniques) is capable of accurate peripheral venous oxygenation measurement; and 2) peripheral venous oxygenation is dependent on skin temperature and local hemodynamics. Moreover, we performed for the first time (to the best of our knowledge) a comparative study of optoacoustic arterial oximetry and a standard pulse oximeter in humans and demonstrated superior performance of the optoacoustic arterial oximeter, in particular at low blood flow.

Seeing number using texture: How summary statistics account for reductions in perceived numerosity in the visual periphery.

PubMed

Balas, Benjamin

2016-11-01

Peripheral visual perception is characterized by reduced information about appearance due to constraints on how image structure is represented. Visual crowding is a consequence of excessive integration in the visual periphery. Basic phenomenology of visual crowding and other tasks have been successfully accounted for by a summary-statistic model of pooling, suggesting that texture-like processing is useful for how information is reduced in peripheral vision. I attempt to extend the scope of this model by examining a property of peripheral vision: reduced perceived numerosity in the periphery. I demonstrate that a summary-statistic model of peripheral appearance accounts for reduced numerosity in peripherally viewed arrays of randomly placed dots, but does not account for observed effects of dot clustering within such arrays. The model thus offers a limited account of how numerosity is perceived in the visual periphery. I also demonstrate that the model predicts that numerosity estimation is sensitive to element shape, which represents a novel prediction regarding the phenomenology of peripheral numerosity perception. Finally, I discuss ways to extend the model to a broader range of behavior and the potential for using the model to make further predictions about how number is perceived in untested scenarios in peripheral vision.

Is lower peripheral information weighted differently as a function of step number during step climbing?

PubMed

Graci, Valentina; Rabuffetti, Marco; Frigo, Carlo; Ferrarin, Maurizio

2017-02-01

The importance of peripheral visual information during stair climbing and how peripheral visual information is weighted as a function of step number during step climbing is unclear. Previous authors postulated that the knowledge of predictable characteristics of the steps may decrease reliance on foveal vision and transfer the online visual guidance of stair climbing to peripheral vision. Hence the aim of this study was to investigate if and how the occlusion of the lower peripheral visual field influenced stair climbing and if peripheral visual information was weighted differently between steps. Ten young adult male participants ascended a 5-step staircase under 2 visual conditions: full vision (FV) and lower visual occlusion (LO). Kinematic data (100Hz) were collected. The effect of Vision and Step condition on vertical forefoot clearance was examined with a Repeated Measures 2-way ANOVA. Tukey's HSD test was used for post-hoc comparisons. A significant interaction Vision x Step and main effect of Step were found (p<=0.04): vertical forefoot clearance was greater in LO compared to FV condition only on the 1st and the 2nd steps (p<0.013) and on the last step compared to the other steps (p<0.01). These findings suggest that online peripheral visual information is more relevant when negotiating the first two steps, rather than the end of a staircase and that the steps subsequent the first few ones may require different information likely based on proprioception or working memory of the step height. Copyright © 2016 Elsevier B.V. All rights reserved.

Octopus vulgaris uses visual information to determine the location of its arm.

PubMed

Gutnick, Tamar; Byrne, Ruth A; Hochner, Binyamin; Kuba, Michael

2011-03-22

Octopuses are intelligent, soft-bodied animals with keen senses that perform reliably in a variety of visual and tactile learning tasks. However, researchers have found them disappointing in that they consistently fail in operant tasks that require them to combine central nervous system reward information with visual and peripheral knowledge of the location of their arms. Wells claimed that in order to filter and integrate an abundance of multisensory inputs that might inform the animal of the position of a single arm, octopuses would need an exceptional computing mechanism, and "There is no evidence that such a system exists in Octopus, or in any other soft bodied animal." Recent electrophysiological experiments, which found no clear somatotopic organization in the higher motor centers, support this claim. We developed a three-choice maze that required an octopus to use a single arm to reach a visually marked goal compartment. Using this operant task, we show for the first time that Octopus vulgaris is capable of guiding a single arm in a complex movement to a location. Thus, we claim that octopuses can combine peripheral arm location information with visual input to control goal-directed complex movements. Copyright © 2011 Elsevier Ltd. All rights reserved.

Deployment of spatial attention to words in central and peripheral vision.

PubMed

Ducrot, Stéphanie; Grainger, Jonathan

2007-05-01

Four perceptual identification experiments examined the influence of spatial cues on the recognition of words presented in central vision (with fixation on either the first or last letter of the target word) and in peripheral vision (displaced left or right of a central fixation point). Stimulus location had a strong effect on word identification accuracy in both central and peripheral vision, showing a strong right visual field superiority that did not depend on eccentricity. Valid spatial cues improved word identification for peripherally presented targets but were largely ineffective for centrally presented targets. Effects of spatial cuing interacted with visual field effects in Experiment 1, with valid cues reducing the right visual field superiority for peripherally located targets, but this interaction was shown to depend on the type of neutral cue. These results provide further support for the role of attentional factors in visual field asymmetries obtained with targets in peripheral vision but not with centrally presented targets.

Wide-field retinal optical coherence tomography with wavefront sensorless adaptive optics for enhanced imaging of targeted regions.

PubMed

Polans, James; Keller, Brenton; Carrasco-Zevallos, Oscar M; LaRocca, Francesco; Cole, Elijah; Whitson, Heather E; Lad, Eleonora M; Farsiu, Sina; Izatt, Joseph A

2017-01-01

The peripheral retina of the human eye offers a unique opportunity for assessment and monitoring of ocular diseases. We have developed a novel wide-field (>70°) optical coherence tomography system (WF-OCT) equipped with wavefront sensorless adaptive optics (WSAO) for enhancing the visualization of smaller (<25°) targeted regions in the peripheral retina. We iterated the WSAO algorithm at the speed of individual OCT B-scans (~20 ms) by using raw spectral interferograms to calculate the optimization metric. Our WSAO approach with a 3 mm beam diameter permitted primarily low- but also high- order peripheral wavefront correction in less than 10 seconds. In preliminary imaging studies in five normal human subjects, we quantified statistically significant changes with WSAO correction, corresponding to a 10.4% improvement in average pixel brightness (signal) and 7.0% improvement in high frequency content (resolution) when visualizing 1 mm (~3.5°) B-scans of the peripheral (>23°) retina. We demonstrated the ability of our WF-OCT system to acquire non wavefront-corrected wide-field images rapidly, which could then be used to locate regions of interest, zoom into targeted features, and visualize the same region at different time points. A pilot clinical study was conducted on seven healthy volunteers and two subjects with prodromal Alzheimer's disease which illustrated the capability to image Drusen-like pathologies as far as 32.5° from the fovea in un-averaged volume scans. This work suggests that the proposed combination of WF-OCT and WSAO may find applications in the diagnosis and treatment of ocular, and potentially neurodegenerative, diseases of the peripheral retina, including diabetes and Alzheimer's disease.

Wide-field retinal optical coherence tomography with wavefront sensorless adaptive optics for enhanced imaging of targeted regions

PubMed Central

Polans, James; Keller, Brenton; Carrasco-Zevallos, Oscar M.; LaRocca, Francesco; Cole, Elijah; Whitson, Heather E.; Lad, Eleonora M.; Farsiu, Sina; Izatt, Joseph A.

2016-01-01

The peripheral retina of the human eye offers a unique opportunity for assessment and monitoring of ocular diseases. We have developed a novel wide-field (>70°) optical coherence tomography system (WF-OCT) equipped with wavefront sensorless adaptive optics (WSAO) for enhancing the visualization of smaller (<25°) targeted regions in the peripheral retina. We iterated the WSAO algorithm at the speed of individual OCT B-scans (~20 ms) by using raw spectral interferograms to calculate the optimization metric. Our WSAO approach with a 3 mm beam diameter permitted primarily low- but also high- order peripheral wavefront correction in less than 10 seconds. In preliminary imaging studies in five normal human subjects, we quantified statistically significant changes with WSAO correction, corresponding to a 10.4% improvement in average pixel brightness (signal) and 7.0% improvement in high frequency content (resolution) when visualizing 1 mm (~3.5°) B-scans of the peripheral (>23°) retina. We demonstrated the ability of our WF-OCT system to acquire non wavefront-corrected wide-field images rapidly, which could then be used to locate regions of interest, zoom into targeted features, and visualize the same region at different time points. A pilot clinical study was conducted on seven healthy volunteers and two subjects with prodromal Alzheimer’s disease which illustrated the capability to image Drusen-like pathologies as far as 32.5° from the fovea in un-averaged volume scans. This work suggests that the proposed combination of WF-OCT and WSAO may find applications in the diagnosis and treatment of ocular, and potentially neurodegenerative, diseases of the peripheral retina, including diabetes and Alzheimer’s disease. PMID:28101398

Is Posner's "beam" the same as Treisman's "glue"?: On the relation between visual orienting and feature integration theory.

PubMed

Briand, K A; Klein, R M

1987-05-01

In the present study we investigated whether the visually allocated "beam" studied by Posner and others is the same visual attentional resource that performs the role of feature integration in Treisman's model. Subjects were cued to attend to a certain spatial location by a visual cue, and performance at expected and unexpected stimulus locations was compared. Subjects searched for a target letter (R) with distractor letters that either could give rise to illusory conjunctions (PQ) or could not (PB). Results from three separate experiments showed that orienting attention in response to central cues (endogenous orienting) showed similar effects for both conjunction and feature search. However, when attention was oriented with peripheral visual cues (exogenous orienting), conjunction search showed larger effects of attention than did feature search. It is suggested that the attentional systems that are oriented in response to central and peripheral cues may not be the same and that only the latter performs a role in feature integration. Possibilities for future research are discussed.

Early and Late Inhibitions Elicited by a Peripheral Visual Cue on Manual Response to a Visual Target: Are They Based on Cartesian Coordinates?

ERIC Educational Resources Information Center

Gawryszewski, Luiz G.; Carreiro, Luiz Renato R.; Magalhaes, Fabio V.

2005-01-01

A non-informative cue (C) elicits an inhibition of manual reaction time (MRT) to a visual target (T). We report an experiment to examine if the spatial distribution of this inhibitory effect follows Polar or Cartesian coordinate systems. C appeared at one out of 8 isoeccentric (7[degrees]) positions, the C-T angular distances (in polar…

Peripheral refraction in 7- and 14-year-old children in central China: the Anyang Childhood Eye Study.

PubMed

Li, Shi-Ming; Li, Si-Yuan; Liu, Luo-Ru; Zhou, Yue-Hua; Yang, Zhou; Kang, Meng-Tian; Li, He; Yang, Xiao-Yuan; Wang, Yi-Peng; Zhan, Si-Yan; Mitchell, Paul; Wang, Ningli; Atchison, David A

2015-05-01

To determine the distribution of peripheral refraction, including astigmatism, in 7- and 14-year-old Chinese children. 2134 7-year-old and 1780 14-year-old children were measured with cycloplegic central and horizontal peripheral refraction (15° and 30° at temporal and nasal visual fields). 7- and 14-year-old children included 9 and 594, respectively, with moderate and high myopia (≤-3.0 D), 259 and 831 with low myopia (-2.99 to -0.5 D), 1207 and 305 with emmetropia (-0.49 to +1.0 D), and 659 and 50 with hyperopia (>1.0 D), respectively. Myopic children had relative peripheral hyperopia while hyperopic and emmetropic children had relative peripheral myopia, with greater changes in relative peripheral refraction occurring in the nasal than the temporal visual field. The older group had the greater relative peripheral hyperopia and higher peripheral J180. Both age groups showed positive slopes of J45 across the visual field, with greater slopes in the older group. Myopic children in mainland China have relative peripheral hyperopia while hyperopic and emmetropic children have relative peripheral myopia. Significant differences exist between 7- and 14-year-old children, with the latter showing more relative peripheral hyperopia, greater rate of change in J45 across the visual field, and higher peripheral J180. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Perceptual training yields rapid improvements in visually impaired youth.

PubMed

Nyquist, Jeffrey B; Lappin, Joseph S; Zhang, Ruyuan; Tadin, Duje

2016-11-30

Visual function demands coordinated responses to information over a wide field of view, involving both central and peripheral vision. Visually impaired individuals often seem to underutilize peripheral vision, even in absence of obvious peripheral deficits. Motivated by perceptual training studies with typically sighted adults, we examined the effectiveness of perceptual training in improving peripheral perception of visually impaired youth. Here, we evaluated the effectiveness of three training regimens: (1) an action video game, (2) a psychophysical task that combined attentional tracking with a spatially and temporally unpredictable motion discrimination task, and (3) a control video game. Training with both the action video game and modified attentional tracking yielded improvements in visual performance. Training effects were generally larger in the far periphery and appear to be stable 12 months after training. These results indicate that peripheral perception might be under-utilized by visually impaired youth and that this underutilization can be improved with only ~8 hours of perceptual training. Moreover, the similarity of improvements following attentional tracking and action video-game training suggest that well-documented effects of action video-game training might be due to the sustained deployment of attention to multiple dynamic targets while concurrently requiring rapid attending and perception of unpredictable events.

Visual Suppression is Impaired in Spinocerebellar Ataxia Type 6 but Preserved in Benign Paroxysmal Positional Vertigo

PubMed Central

Kishi, Masahiko; Sakakibara, Ryuji; Yoshida, Tomoe; Yamamoto, Masahiko; Suzuki, Mitsuya; Kataoka, Manabu; Tsuyusaki, Yohei; Tateno, Akihiko; Tateno, Fuyuki

2012-01-01

Positional vertigo is a common neurologic emergency and mostly the etiology is peripheral. However, central diseases may mimic peripheral positional vertigo at their initial presentation. We here describe the results of a visual suppression test in six patients with spinocerebellar ataxia type 6 (SCA6), a central positional vertigo, and nine patients with benign paroxysmal positional vertigo (BPPV), the major peripheral positional vertigo. As a result, the visual suppression value of both diseases differed significantly; e.g., 22.5% in SCA6 and 64.3% in BPPV (p < 0.001). There was a positive correlation between the visual suppression value and disease duration, cerebellar atrophy, and CAG repeat length of SCA6 but they were not statistically significant. In conclusion, the present study showed for the first time that visual suppression is impaired in SCA6, a central positional vertigo, but preserved in BPPV, the major peripheral positional vertigo, by directly comparing both groups. The abnormality in the SCA6 group presumably reflects dysfunction in the central visual fixation pathway at the cerebellar flocculus and nodulus. This simple test might aid differential diagnosis of peripheral and central positional vertigo at the earlier stage of disease. PMID:26859398

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

PubMed

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.

A low-cost and versatile system for projecting wide-field visual stimuli within fMRI scanners

PubMed Central

Greco, V.; Frijia, F.; Mikellidou, K.; Montanaro, D.; Farini, A.; D’Uva, M.; Poggi, P.; Pucci, M.; Sordini, A.; Morrone, M. C.; Burr, D. C.

2016-01-01

We have constructed and tested a custom-made magnetic-imaging-compatible visual projection system designed to project on a very wide visual field (~80°). A standard projector was modified with a coupling lens, projecting images into the termination of an image fiber. The other termination of the fiber was placed in the 3-T scanner room with a projection lens, which projected the images relayed by the fiber onto a screen over the head coil, viewed by a participant wearing magnifying goggles. To validate the system, wide-field stimuli were presented in order to identify retinotopic visual areas. The results showed that this low-cost and versatile optical system may be a valuable tool to map visual areas in the brain that process peripheral receptive fields. PMID:26092392

Learning to Read Vertical Text in Peripheral Vision

PubMed Central

Subramanian, Ahalya; Legge, Gordon E.; Wagoner, Gunther Harrison; Yu, Deyue

2014-01-01

Purpose English–language text is almost always written horizontally. Text can be formatted to run vertically, but this is seldom used. Several studies have found that horizontal text can be read faster than vertical text in the central visual field. No studies have investigated the peripheral visual field. Studies have also concluded that training can improve reading speed in the peripheral visual field for horizontal text. We aimed to establish whether the horizontal vertical differences are maintained and if training can improve vertical reading in the peripheral visual field. Methods Eight normally sighted young adults participated in the first study. Rapid Serial Visual Presentation (RSVP) reading speed was measured for horizontal and vertical text in the central visual field and at 10° eccentricity in the upper or lower (horizontal text), and right or left (vertical text) visual fields. Twenty-one normally sighted young adults split equally between 2 training and 1 control group participated in the second study. Training consisted of RSVP reading either using vertical text in the left visual field or horizontal text in the inferior visual field. Subjects trained daily over 4 days. Pre and post horizontal and vertical RSVP reading speeds were carried out for all groups. For the training groups these measurements were repeated 1 week and 1 month post training. Results Prior to training, RSVP reading speeds were faster for horizontal text in the central and peripheral visual fields when compared to vertical text. Training vertical reading improved vertical reading speeds by an average factor of 2.8. There was partial transfer of training to the opposite (right) hemifield. The training effects were retained for up to a month. Conclusions RSVP training can improve RSVP vertical text reading in peripheral vision. These findings may have implications for patients with macular degeneration or hemianopic field loss. PMID:25062130

The influence of artificial scotomas on eye movements during visual search.

PubMed

Cornelissen, Frans W; Bruin, Klaas J; Kooijman, Aart C

2005-01-01

Fixation durations are normally adapted to the difficulty of the foveal analysis task. We examine to what extent artificial central and peripheral visual field defects interfere with this adaptation process. Subjects performed a visual search task while their eye movements were registered. The latter were used to drive a real-time gaze-dependent display that was used to create artificial central and peripheral visual field defects. Recorded eye movements were used to determine saccadic amplitude, number of fixations, fixation durations, return saccades, and changes in saccade direction. For central defects, although fixation duration increased with the size of the absolute central scotoma, this increase was too small to keep recognition performance optimal, evident from an associated increase in the rate of return saccades. Providing a relatively small amount of visual information in the central scotoma did substantially reduce subjects' search times but not their fixation durations. Surprisingly, reducing the size of the tunnel also prolonged fixation duration for peripheral defects. This manipulation also decreased the rate of return saccades, suggesting that the fixations were prolonged beyond the duration required by the foveal task. Although we find that adaptation of fixation duration to task difficulty clearly occurs in the presence of artificial scotomas, we also find that such field defects may render the adaptation suboptimal for the task at hand. Thus, visual field defects may not only hinder vision by limiting what the subject sees of the environment but also by limiting the visual system's ability to program efficient eye movements. We speculate this is because of how visual field defects bias the balance between saccade generation and fixation stabilization.

Fixating at far distance shortens reaction time to peripheral visual stimuli at specific locations.

PubMed

Kokubu, Masahiro; Ando, Soichi; Oda, Shingo

2018-01-18

The purpose of the present study was to examine whether the fixation distance in real three-dimensional space affects manual reaction time to peripheral visual stimuli. Light-emitting diodes were used for presenting a fixation point and four peripheral visual stimuli. The visual stimuli were located at a distance of 45cm and at 25° in the left, right, upper, and lower directions from the sagittal axis including the fixation point. Near (30cm), Middle (45cm), Far (90cm), and Very Far (300cm) fixation distance conditions were used. When one of the four visual stimuli was randomly illuminated, the participants released a button as quickly as possible. Results showed that overall peripheral reaction time decreased as the fixation distance increased. The significant interaction between fixation distance and stimulus location indicated that the effect of fixation distance on reaction time was observed at the left, right, and upper locations but not at the lower location. These results suggest that fixating at far distance would contribute to faster reaction and that the effect is specific to locations in the peripheral visual field. The present findings are discussed in terms of viewer-centered representation, the focus of attention in depth, and visual field asymmetry related to neurological and psychological aspects. Copyright © 2017 Elsevier B.V. All rights reserved.

Perceptual training yields rapid improvements in visually impaired youth

PubMed Central

Nyquist, Jeffrey B.; Lappin, Joseph S.; Zhang, Ruyuan; Tadin, Duje

2016-01-01

Visual function demands coordinated responses to information over a wide field of view, involving both central and peripheral vision. Visually impaired individuals often seem to underutilize peripheral vision, even in absence of obvious peripheral deficits. Motivated by perceptual training studies with typically sighted adults, we examined the effectiveness of perceptual training in improving peripheral perception of visually impaired youth. Here, we evaluated the effectiveness of three training regimens: (1) an action video game, (2) a psychophysical task that combined attentional tracking with a spatially and temporally unpredictable motion discrimination task, and (3) a control video game. Training with both the action video game and modified attentional tracking yielded improvements in visual performance. Training effects were generally larger in the far periphery and appear to be stable 12 months after training. These results indicate that peripheral perception might be under-utilized by visually impaired youth and that this underutilization can be improved with only ~8 hours of perceptual training. Moreover, the similarity of improvements following attentional tracking and action video-game training suggest that well-documented effects of action video-game training might be due to the sustained deployment of attention to multiple dynamic targets while concurrently requiring rapid attending and perception of unpredictable events. PMID:27901026

Foveal analysis and peripheral selection during active visual sampling

PubMed Central

Ludwig, Casimir J. H.; Davies, J. Rhys; Eckstein, Miguel P.

2014-01-01

Human vision is an active process in which information is sampled during brief periods of stable fixation in between gaze shifts. Foveal analysis serves to identify the currently fixated object and has to be coordinated with a peripheral selection process of the next fixation location. Models of visual search and scene perception typically focus on the latter, without considering foveal processing requirements. We developed a dual-task noise classification technique that enables identification of the information uptake for foveal analysis and peripheral selection within a single fixation. Human observers had to use foveal vision to extract visual feature information (orientation) from different locations for a psychophysical comparison. The selection of to-be-fixated locations was guided by a different feature (luminance contrast). We inserted noise in both visual features and identified the uptake of information by looking at correlations between the noise at different points in time and behavior. Our data show that foveal analysis and peripheral selection proceeded completely in parallel. Peripheral processing stopped some time before the onset of an eye movement, but foveal analysis continued during this period. Variations in the difficulty of foveal processing did not influence the uptake of peripheral information and the efficacy of peripheral selection, suggesting that foveal analysis and peripheral selection operated independently. These results provide important theoretical constraints on how to model target selection in conjunction with foveal object identification: in parallel and independently. PMID:24385588

Eye guidance during real-world scene search: The role color plays in central and peripheral vision.

PubMed

Nuthmann, Antje; Malcolm, George L

2016-01-01

The visual system utilizes environmental features to direct gaze efficiently when locating objects. While previous research has isolated various features' contributions to gaze guidance, these studies generally used sparse displays and did not investigate how features facilitated search as a function of their location on the visual field. The current study investigated how features across the visual field--particularly color--facilitate gaze guidance during real-world search. A gaze-contingent window followed participants' eye movements, restricting color information to specified regions. Scene images were presented in full color, with color in the periphery and gray in central vision or gray in the periphery and color in central vision, or in grayscale. Color conditions were crossed with a search cue manipulation, with the target cued either with a word label or an exact picture. Search times increased as color information in the scene decreased. A gaze-data based decomposition of search time revealed color-mediated effects on specific subprocesses of search. Color in peripheral vision facilitated target localization, whereas color in central vision facilitated target verification. Picture cues facilitated search, with the effects of cue specificity and scene color combining additively. When available, the visual system utilizes the environment's color information to facilitate different real-world visual search behaviors based on the location within the visual field.

Quantitative analysis of peripheral vasculitis, ischemia, and vascular leakage in uveitis using ultra-widefield fluorescein angiography.

PubMed

Karampelas, Michael; Sim, Dawn A; Chu, Colin; Carreno, Ester; Keane, Pearse A; Zarranz-Ventura, Javier; Westcott, Mark; Lee, Richard W J; Pavesio, Carlos E

2015-06-01

To investigate the relationships between peripheral vasculitis, ischemia, and vascular leakage in uveitis using ultra-widefield fluorescein angiography (FA). Cross-sectional, consecutive case series. Consecutive ultra-widefield FA images were collected from 82 uveitis patients (82 eyes) in a single center. The extent of peripheral vasculitis, capillary nonperfusion, and vessel leakage were quantified. Parameters included: (1) foveal avascular zone area and macular leakage, (2) peripheral diffuse capillary leakage and ischemia, (3) peripheral vasculitis, and (4) leakage from neovascularization. Central macular thickness measurements were derived with optical coherence tomography. Main outcome measures were correlations between central and peripheral fluorangiographic changes as well as associations between visual function, ultra-widefield FA-derived metrics, and central macular thickness. Although central leakage was associated with peripheral leakage (r = 0.553, P = .001), there was no association between foveal avascular zone size and peripheral ischemia (r = 0.114, P = .324), regardless of the underlying uveitic diagnosis. Peripheral ischemia was, however, correlated to neovascularization-related leakage (r = 0.462, P = .001) and focal vasculitis (r = 0.441, P = .001). Stepwise multiple regression analysis revealed that a poor visual acuity was independently associated with foveal avascular zone size and central macular thickness (R(2)-adjusted = 0.45, P = .001). We present a large cohort of patients with uveitis imaged with ultra-widefield FA and further describe novel methods for quantification of peripheral vascular pathology, in an attempt to identify visually significant parameters. Although we observed that relationships exist between peripheral vessel leakage, vasculitis, and ischemia, it was only macular ischemia and increased macular thickness that were independently associated with a reduced visual acuity. Copyright © 2015 Elsevier Inc. All rights reserved.

Retinotopic patterns of functional connectivity between V1 and large-scale brain networks during resting fixation

PubMed Central

Griffis, Joseph C.; Elkhetali, Abdurahman S.; Burge, Wesley K.; Chen, Richard H.; Bowman, Anthony D.; Szaflarski, Jerzy P.; Visscher, Kristina M.

2016-01-01

Psychophysical and neurobiological evidence suggests that central and peripheral vision are specialized for different functions. This specialization of function might be expected to lead to differences in the large-scale functional interactions of early cortical areas that represent central and peripheral visual space. Here, we characterize differences in whole-brain functional connectivity among sectors in primary visual cortex (V1) corresponding to central, near-peripheral, and far-peripheral vision during resting fixation. Importantly, our analyses reveal that eccentricity sectors in V1 have different functional connectivity with non-visual areas associated with large-scale brain networks. Regions associated with the fronto-parietal control network are most strongly connected with central sectors of V1, regions associated with the cingulo-opercular control network are most strongly connected with near-peripheral sectors of V1, and regions associated with the default mode and auditory networks are most strongly connected with far-peripheral sectors of V1. Additional analyses suggest that similar patterns are present during eyes-closed rest. These results suggest that different types of visual information may be prioritized by large-scale brain networks with distinct functional profiles, and provide insights into how the small-scale functional specialization within early visual regions such as V1 relates to the large-scale organization of functionally distinct whole-brain networks. PMID:27554527

Peripheral visual response time and visual display layout

NASA Technical Reports Server (NTRS)

Haines, R. F.

1974-01-01

Experiments were performed on a group of 42 subjects in a study of their peripheral visual response time to visual signals under positive acceleration, during prolonged bedrest, at passive 70 deg headup body lift, under exposures to high air temperatures and high luminance levels, and under normal stress-free laboratory conditions. Diagrams are plotted for mean response times to white, red, yellow, green, and blue stimuli under different conditions.

Lack of oblique astigmatism in the chicken eye.

PubMed

Maier, Felix M; Howland, Howard C; Ohlendorf, Arne; Wahl, Siegfried; Schaeffel, Frank

2015-04-01

Primate eyes display considerable oblique off-axis astigmatism which could provide information on the sign of defocus that is needed for emmetropization. The pattern of peripheral astigmatism is not known in the chicken eye, a common model of myopia. Peripheral astigmatism was mapped out over the horizontal visual field in three chickens, 43 days old, and in three near emmetropic human subjects, average age 34.7years, using infrared photoretinoscopy. There were no differences in astigmatism between humans and chickens in the central visual field (chicks -0.35D, humans -0.65D, n.s.) but large differences in the periphery (i.e. astigmatism at 40° in the temporal visual field: humans -4.21D, chicks -0.63D, p<0.001, unpaired t-test). The lack of peripheral astigmatism in chicks was not due to differences in corneal shape. Perhaps related to their superior peripheral optics, we found that chickens had excellent visual performance also in the far periphery. Using an automated optokinetic nystagmus paradigm, no difference was observed in spatial visual performance with vision restricted to either the central 67° of the visual field or to the periphery beyond 67°. Accommodation was elicited by stimuli presented far out in the visual field. Transscleral images of single infrared LEDs showed no sign of peripheral astigmatism. The chick may be the first terrestrial vertebrate described to lack oblique astigmatism. Since corneal shape cannot account for the difference in astigmatism in humans and chicks, it must trace back to the design of the crystalline lens. The lack of peripheral astigmatism in chicks also excludes a role in emmetropization. Copyright © 2015 Elsevier Ltd. All rights reserved.

Selective Attention to Visual Stimuli Using Auditory Distractors Is Altered in Alpha-9 Nicotinic Receptor Subunit Knock-Out Mice.

PubMed

Terreros, Gonzalo; Jorratt, Pascal; Aedo, Cristian; Elgoyhen, Ana Belén; Delano, Paul H

2016-07-06

During selective attention, subjects voluntarily focus their cognitive resources on a specific stimulus while ignoring others. Top-down filtering of peripheral sensory responses by higher structures of the brain has been proposed as one of the mechanisms responsible for selective attention. A prerequisite to accomplish top-down modulation of the activity of peripheral structures is the presence of corticofugal pathways. The mammalian auditory efferent system is a unique neural network that originates in the auditory cortex and projects to the cochlear receptor through the olivocochlear bundle, and it has been proposed to function as a top-down filter of peripheral auditory responses during attention to cross-modal stimuli. However, to date, there is no conclusive evidence of the involvement of olivocochlear neurons in selective attention paradigms. Here, we trained wild-type and α-9 nicotinic receptor subunit knock-out (KO) mice, which lack cholinergic transmission between medial olivocochlear neurons and outer hair cells, in a two-choice visual discrimination task and studied the behavioral consequences of adding different types of auditory distractors. In addition, we evaluated the effects of contralateral noise on auditory nerve responses as a measure of the individual strength of the olivocochlear reflex. We demonstrate that KO mice have a reduced olivocochlear reflex strength and perform poorly in a visual selective attention paradigm. These results confirm that an intact medial olivocochlear transmission aids in ignoring auditory distraction during selective attention to visual stimuli. The auditory efferent system is a neural network that originates in the auditory cortex and projects to the cochlear receptor through the olivocochlear system. It has been proposed to function as a top-down filter of peripheral auditory responses during attention to cross-modal stimuli. However, to date, there is no conclusive evidence of the involvement of olivocochlear neurons in selective attention paradigms. Here, we studied the behavioral consequences of adding different types of auditory distractors in a visual selective attention task in wild-type and α-9 nicotinic receptor knock-out (KO) mice. We demonstrate that KO mice perform poorly in the selective attention paradigm and that an intact medial olivocochlear transmission aids in ignoring auditory distractors during attention. Copyright © 2016 the authors 0270-6474/16/367198-12$15.00/0.

Neuronal Response Gain Enhancement prior to Microsaccades.

PubMed

Chen, Chih-Yang; Ignashchenkova, Alla; Thier, Peter; Hafed, Ziad M

2015-08-17

Neuronal response gain enhancement is a classic signature of the allocation of covert visual attention without eye movements. However, microsaccades continuously occur during gaze fixation. Because these tiny eye movements are preceded by motor preparatory signals well before they are triggered, it may be the case that a corollary of such signals may cause enhancement, even without attentional cueing. In six different macaque monkeys and two different brain areas previously implicated in covert visual attention (superior colliculus and frontal eye fields), we show neuronal response gain enhancement for peripheral stimuli appearing immediately before microsaccades. This enhancement occurs both during simple fixation with behaviorally irrelevant peripheral stimuli and when the stimuli are relevant for the subsequent allocation of covert visual attention. Moreover, this enhancement occurs in both purely visual neurons and visual-motor neurons, and it is replaced by suppression for stimuli appearing immediately after microsaccades. Our results suggest that there may be an obligatory link between microsaccade occurrence and peripheral selective processing, even though microsaccades can be orders of magnitude smaller than the eccentricities of peripheral stimuli. Because microsaccades occur in a repetitive manner during fixation, and because these eye movements reset neurophysiological rhythms every time they occur, our results highlight a possible mechanism through which oculomotor events may aid periodic sampling of the visual environment for the benefit of perception, even when gaze is prevented from overtly shifting. One functional consequence of such periodic sampling could be the magnification of rhythmic fluctuations of peripheral covert visual attention. Copyright © 2015 Elsevier Ltd. All rights reserved.

Endoscopic high-resolution auto fluorescence imaging and optical coherence tomography of airways in vivo (Conference Presentation)

NASA Astrophysics Data System (ADS)

Pahlevaninezhad, Hamid; Lee, Anthony; Hohert, Geoffrey; Schwartz, Carley; Shaipanich, Tawimas; Ritchie, Alexander J.; Zhang, Wei; MacAulay, Calum E.; Lam, Stephen; Lane, Pierre M.

2016-03-01

In this work, we present multimodal imaging of peripheral airways in vivo using an endoscopic imaging system capable of co-registered optical coherence tomography and autofluorescence imaging (OCT-AFI). This system employs a 0.9 mm diameter double-clad fiber optic-based catheter for endoscopic imaging of small peripheral airways. Optical coherence tomography (OCT) can visualize detailed airway morphology in the lung periphery and autofluorescence imaging (AFI) can visualize fluorescent tissue components such as collagen and elastin, improving the detection of airway lesions. Results from in vivo imaging of 40 patients indicate that OCT and AFI offer complementary information that may increase the ability to identify pulmonary nodules in the lung periphery and improve the safety of biopsy collection by identifying large blood vessels. AFI can rapidly visualize in vivo vascular networks using fast scanning parameters resulting in vascular-sensitive imaging with less breathing/cardiac motion artifacts compared to Doppler OCT imaging. By providing complementary information about structure and function of tissue, OCT-AFI may improve site selection during biopsy collection in the lung periphery.

The differential effect of trigeminal vs. peripheral pain stimulation on visual processing and memory encoding is influenced by pain-related fear.

PubMed

Schmidt, K; Forkmann, K; Sinke, C; Gratz, M; Bitz, A; Bingel, U

2016-07-01

Compared to peripheral pain, trigeminal pain elicits higher levels of fear, which is assumed to enhance the interruptive effects of pain on concomitant cognitive processes. In this fMRI study we examined the behavioral and neural effects of trigeminal (forehead) and peripheral (hand) pain on visual processing and memory encoding. Cerebral activity was measured in 23 healthy subjects performing a visual categorization task that was immediately followed by a surprise recognition task. During the categorization task subjects received concomitant noxious electrical stimulation on the forehead or hand. Our data show that fear ratings were significantly higher for trigeminal pain. Categorization and recognition performance did not differ between pictures that were presented with trigeminal and peripheral pain. However, object categorization in the presence of trigeminal pain was associated with stronger activity in task-relevant visual areas (lateral occipital complex, LOC), memory encoding areas (hippocampus and parahippocampus) and areas implicated in emotional processing (amygdala) compared to peripheral pain. Further, individual differences in neural activation between the trigeminal and the peripheral condition were positively related to differences in fear ratings between both conditions. Functional connectivity between amygdala and LOC was increased during trigeminal compared to peripheral painful stimulation. Fear-driven compensatory resource activation seems to be enhanced for trigeminal stimuli, presumably due to their exceptional biological relevance. Copyright © 2016 Elsevier Inc. All rights reserved.

Eccentricity effects in vision and attention.

PubMed

Staugaard, Camilla Funch; Petersen, Anders; Vangkilde, Signe

2016-11-01

Stimulus eccentricity affects visual processing in multiple ways. Performance on a visual task is often better when target stimuli are presented near or at the fovea compared to the retinal periphery. For instance, reaction times and error rates are often reported to increase with increasing eccentricity. Such findings have been interpreted as purely visual, reflecting neurophysiological differences in central and peripheral vision, as well as attentional, reflecting a central bias in the allocation of attentional resources. Other findings indicate that in some cases, information from the periphery is preferentially processed. Specifically, it has been suggested that visual processing speed increases with increasing stimulus eccentricity, and that this positive correlation is reduced, but not eliminated, when the amount of cortex activated by a stimulus is kept constant by magnifying peripheral stimuli (Carrasco et al., 2003). In this study, we investigated effects of eccentricity on visual attentional capacity with and without magnification, using computational modeling based on Bundesen's (1990) theory of visual attention. Our results suggest a general decrease in attentional capacity with increasing stimulus eccentricity, irrespective of magnification. We discuss these results in relation to the physiology of the visual system, the use of different paradigms for investigating visual perception across the visual field, and the use of different stimulus materials (e.g. Gabor patches vs. letters). Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Visual information without thermal energy may induce thermoregulatory-like cardiovascular responses

PubMed Central

2013-01-01

Background Human core body temperature is kept quasi-constant regardless of varying thermal environments. It is well known that physiological thermoregulatory systems are under the control of central and peripheral sensory organs that are sensitive to thermal energy. If these systems wrongly respond to non-thermal stimuli, it may disturb human homeostasis. Methods Fifteen participants viewed video images evoking hot or cold impressions in a thermally constant environment. Cardiovascular indices were recorded during the experiments. Correlations between the ‘hot-cold’ impression scores and cardiovascular indices were calculated. Results The changes of heart rate, cardiac output, and total peripheral resistance were significantly correlated with the ‘hot-cold’ impression scores, and the tendencies were similar to those in actual thermal environments corresponding to the impressions. Conclusions The present results suggest that visual information without any thermal energy can affect physiological thermoregulatory systems at least superficially. To avoid such ‘virtual’ environments disturbing human homeostasis, further study and more attention are needed. PMID:24373765

Locating the cortical bottleneck for slow reading in peripheral vision

PubMed Central

Yu, Deyue; Jiang, Yi; Legge, Gordon E.; He, Sheng

2015-01-01

Yu, Legge, Park, Gage, and Chung (2010) suggested that the neural bottleneck for slow peripheral reading is located in nonretinotopic areas. We investigated the potential rate-limiting neural site for peripheral reading using fMRI, and contrasted peripheral reading with recognition of peripherally presented line drawings of common objects. We measured the BOLD responses to both text (three-letter words/nonwords) and line-drawing objects presented either in foveal or peripheral vision (10° lower right visual field) at three presentation rates (2, 4, and 8/second). The statistically significant interaction effect of visual field × presentation rate on the BOLD response for text but not for line drawings provides evidence for distinctive processing of peripheral text. This pattern of results was obtained in all five regions of interest (ROIs). At the early retinotopic cortical areas, the BOLD signal slightly increased with increasing presentation rate for foveal text, and remained fairly constant for peripheral text. In the Occipital Word-Responsive Area (OWRA), Visual Word Form Area (VWFA), and object sensitive areas (LO and PHA), the BOLD responses to text decreased with increasing presentation rate for peripheral but not foveal presentation. In contrast, there was no rate-dependent reduction in BOLD response for line-drawing objects in all the ROIs for either foveal or peripheral presentation. Only peripherally presented text showed a distinctive rate-dependence pattern. Although it is possible that the differentiation starts to emerge at the early retinotopic cortical representation, the neural bottleneck for slower reading of peripherally presented text may be a special property of peripheral text processing in object category selective cortex. PMID:26237299

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

PubMed

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 < 0.0001), and for mobility (R 2 = 0.64; p < 0.0001). Central (0-30°) and peripheral (30-60°) visual field areas were similarly related to mobility function (R 2 = 0.61, p < 0.0001 and R 2 = 0.63, p < 0.0001 respectively), although the peripheral (30-60°) visual field was the best predictor of mobility self-reported function in multiple regression analyses. Superior and inferior visual field areas related similarly to mobility function (R 2 = 0.56, p < 0.0001 and R 2 = 0.67, p < 0.0001 respectively). The inferior field was found to be the best predictor of mobility 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.

The role of central and peripheral vision in expert decision making.

PubMed

Ryu, Donghyun; Abernethy, Bruce; Mann, David L; Poolton, Jamie M; Gorman, Adam D

2013-01-01

The purpose of this study was to investigate the role of central and peripheral vision in expert decision making. A gaze-contingent display was used to selectively present information to the central and peripheral areas of the visual field while participants performed a decision-making task. Eleven skilled and eleven less-skilled male basketball players watched video clips of basketball scenarios in three different viewing conditions: full-image control, moving window (central vision only), and moving mask (peripheral vision only). At the conclusion of each clip participants were required to decide whether it was more appropriate for the ball-carrier to pass the ball or to drive to the basket. The skilled players showed significantly higher response accuracy and faster response times compared with their lesser-skilled counterparts in all three viewing conditions, demonstrating superiority in information extraction that held irrespective of whether they were using central or peripheral vision. The gaze behaviour of the skilled players was less influenced by the gaze-contingent manipulations, suggesting they were better able to use the remaining information to sustain their normal gaze behaviour. The superior capacity of experts to interpret dynamic visual information is evident regardless of whether the visual information is presented across the whole visual field or selectively to either central or peripheral vision alone.

Numerosity estimation benefits from transsaccadic information integration

PubMed Central

Hübner, Carolin; Schütz, Alexander C.

2017-01-01

Humans achieve a stable and homogeneous representation of their visual environment, although visual processing varies across the visual field. Here we investigated the circumstances under which peripheral and foveal information is integrated for numerosity estimation across saccades. We asked our participants to judge the number of black and white dots on a screen. Information was presented either in the periphery before a saccade, in the fovea after a saccade, or in both areas consecutively to measure transsaccadic integration. In contrast to previous findings, we found an underestimation of numerosity for foveal presentation and an overestimation for peripheral presentation. We used a maximum-likelihood model to predict accuracy and reliability in the transsaccadic condition based on peripheral and foveal values. We found near-optimal integration of peripheral and foveal information, consistently with previous findings about orientation integration. In three consecutive experiments, we disrupted object continuity between the peripheral and foveal presentations to probe the limits of transsaccadic integration. Even for global changes on our numerosity stimuli, no influence of object discontinuity was observed. Overall, our results suggest that transsaccadic integration is a robust mechanism that also works for complex visual features such as numerosity and is operative despite internal or external mismatches between foveal and peripheral information. Transsaccadic integration facilitates an accurate and reliable perception of our environment. PMID:29149766

Transitions between central and peripheral vision create spatial/temporal distortions: a hypothesis concerning the perceived break of the curveball.

PubMed

Shapiro, Arthur; Lu, Zhong-Lin; Huang, Chang-Bing; Knight, Emily; Ennis, Robert

2010-10-13

The human visual system does not treat all parts of an image equally: the central segments of an image, which fall on the fovea, are processed with a higher resolution than the segments that fall in the visual periphery. Even though the differences between foveal and peripheral resolution are large, these differences do not usually disrupt our perception of seamless visual space. Here we examine a motion stimulus in which the shift from foveal to peripheral viewing creates a dramatic spatial/temporal discontinuity. The stimulus consists of a descending disk (global motion) with an internal moving grating (local motion). When observers view the disk centrally, they perceive both global and local motion (i.e., observers see the disk's vertical descent and the internal spinning). When observers view the disk peripherally, the internal portion appears stationary, and the disk appears to descend at an angle. The angle of perceived descent increases as the observer views the stimulus from further in the periphery. We examine the first- and second-order information content in the display with the use of a three-dimensional Fourier analysis and show how our results can be used to describe perceived spatial/temporal discontinuities in real-world situations. The perceived shift of the disk's direction in the periphery is consistent with a model in which foveal processing separates first- and second-order motion information while peripheral processing integrates first- and second-order motion information. We argue that the perceived distortion may influence real-world visual observations. To this end, we present a hypothesis and analysis of the perception of the curveball and rising fastball in the sport of baseball. The curveball is a physically measurable phenomenon: the imbalance of forces created by the ball's spin causes the ball to deviate from a straight line and to follow a smooth parabolic path. However, the curveball is also a perceptual puzzle because batters often report that the flight of the ball undergoes a dramatic and nearly discontinuous shift in position as the ball nears home plate. We suggest that the perception of a discontinuous shift in position results from differences between foveal and peripheral processing.

Inhibition of Return in the Visual Field

PubMed Central

Bao, Yan; Lei, Quan; Fang, Yuan; Tong, Yu; Schill, Kerstin; Pöppel, Ernst; Strasburger, Hans

2013-01-01

Inhibition of return (IOR) as an indicator of attentional control is characterized by an eccentricity effect, that is, the more peripheral visual field shows a stronger IOR magnitude relative to the perifoveal visual field. However, it could be argued that this eccentricity effect may not be an attention effect, but due to cortical magnification. To test this possibility, we examined this eccentricity effect in two conditions: the same-size condition in which identical stimuli were used at different eccentricities, and the size-scaling condition in which stimuli were scaled according to the cortical magnification factor (M-scaling), thus stimuli being larger at the more peripheral locations. The results showed that the magnitude of IOR was significantly stronger in the peripheral relative to the perifoveal visual field, and this eccentricity effect was independent of the manipulation of stimulus size (same-size or size-scaling). These results suggest a robust eccentricity effect of IOR which cannot be eliminated by M-scaling. Underlying neural mechanisms of the eccentricity effect of IOR are discussed with respect to both cortical and subcortical structures mediating attentional control in the perifoveal and peripheral visual field. PMID:23820946

Stimulus size and eccentricity in visually induced perception of horizontally translational self-motion.

PubMed

Nakamura, S; Shimojo, S

1998-10-01

The effects of the size and eccentricity of the visual stimulus upon visually induced perception of self-motion (vection) were examined with various sizes of central and peripheral visual stimulation. Analysis indicated the strength of vection increased linearly with the size of the area in which the moving pattern was presented, but there was no difference in vection strength between central and peripheral stimuli when stimulus sizes were the same. Thus, the effect of stimulus size is homogeneous across eccentricities in the visual field.

Love and fear of heights: the pathophysiology and psychology of height imbalance.

PubMed

Salassa, John R; Zapala, David A

2009-01-01

Individual psychological responses to heights vary on a continuum from acrophobia to height intolerance, height tolerance, and height enjoyment. This paper reviews the English literature and summarizes the physiologic and psychological factors that generate different responses to heights while standing still in a static or motionless environment. Perceptual cues to height arise from vision. Normal postural sway of 2 cm for peripheral objects within 3 m increases as eye-object distance increases. Postural sway >10 cm can result in a fall. A minimum of 20 minutes of peripheral retinal arc is required to detect motion. Trigonometry dictates that a 20-minute peripheral retinal arch can no longer be achieved in a standing position at an eye-object distance of >20 m. At this distance, visual cues conflict with somatosensory and vestibular inputs, resulting in variable degrees of imbalance. Co-occurring deficits in the visual, vestibular, and somatosensory systems can significantly increase height imbalance. An individual's psychological makeup, influenced by learned and genetic factors, can influence reactions to height imbalance. Enhancing peripheral vision and vestibular, proprioceptive, and haptic functions may improve height imbalance. Psychotherapy may improve the troubling subjective sensations to heights.

Interactive modeling and simulation of peripheral nerve cords in virtual environments

NASA Astrophysics Data System (ADS)

Ullrich, Sebastian; Frommen, Thorsten; Eckert, Jan; Schütz, Astrid; Liao, Wei; Deserno, Thomas M.; Ntouba, Alexandre; Rossaint, Rolf; Prescher, Andreas; Kuhlen, Torsten

2008-03-01

This paper contributes to modeling, simulation and visualization of peripheral nerve cords. Until now, only sparse datasets of nerve cords can be found. In addition, this data has not yet been used in simulators, because it is only static. To build up a more flexible anatomical structure of peripheral nerve cords, we propose a hierarchical tree data structure where each node represents a nerve branch. The shape of the nerve segments itself is approximated by spline curves. Interactive modeling allows for the creation and editing of control points which are used for branching nerve sections, calculating spline curves and editing spline representations via cross sections. Furthermore, the control points can be attached to different anatomic structures. Through this approach, nerve cords deform in accordance to the movement of the connected structures, e.g., muscles or bones. As a result, we have developed an intuitive modeling system that runs on desktop computers and in immersive environments. It allows anatomical experts to create movable peripheral nerve cords for articulated virtual humanoids. Direct feedback of changes induced by movement or deformation is achieved by visualization in real-time. The techniques and the resulting data are already used for medical simulators.

Neurophysiological assessment of auditory, peripheral nerve, somatosensory, and visual system functions after developmental exposure to ethanol vapors.

PubMed

Boyes, William K; Degn, Laura L; Martin, Sheppard A; Lyke, Danielle F; Hamm, Charles W; Herr, David W

2014-01-01

Ethanol-blended gasoline entered the market in response to demand for domestic renewable energy sources, and may result in increased inhalation of ethanol vapors in combination with other volatile gasoline constituents. It is important to understand potential risks of inhalation of ethanol vapors by themselves, and also as a baseline for evaluating the risks of ethanol combined with a complex mixture of hydrocarbon vapors. Because sensory dysfunction has been reported after developmental exposure to ethanol, we evaluated the effects of developmental exposure to ethanol vapors on neurophysiological measures of sensory function as a component of a larger project evaluating developmental ethanol toxicity. Pregnant Long-Evans rats were exposed to target concentrations 0, 5000, 10,000, or 21,000 ppm ethanol vapors for 6.5h/day over GD9-GD20. Sensory evaluations of male offspring began between PND106 and PND128. Peripheral nerve function (compound action potentials, nerve conduction velocity (NCV)), somatosensory (cortical and cerebellar evoked potentials), auditory (brainstem auditory evoked responses), and visual evoked responses were assessed. Visual function assessment included pattern elicited visual evoked potentials (VEPs), VEP contrast sensitivity, and electroretinograms recorded from dark-adapted (scotopic), light-adapted (photopic) flashes, and UV flicker and green flicker. No consistent concentration-related changes were observed for any of the physiological measures. The results show that gestational exposure to ethanol vapor did not result in detectable changes in peripheral nerve, somatosensory, auditory, or visual function when the offspring were assessed as adults. Published by Elsevier Inc.

Focal and Ambient Processing of Built Environments: Intellectual and Atmospheric Experiences of Architecture

PubMed Central

Rooney, Kevin K.; Condia, Robert J.; Loschky, Lester C.

2017-01-01

Neuroscience has well established that human vision divides into the central and peripheral fields of view. Central vision extends from the point of gaze (where we are looking) out to about 5° of visual angle (the width of one’s fist at arm’s length), while peripheral vision is the vast remainder of the visual field. These visual fields project to the parvo and magno ganglion cells, which process distinctly different types of information from the world around us and project that information to the ventral and dorsal visual streams, respectively. Building on the dorsal/ventral stream dichotomy, we can further distinguish between focal processing of central vision, and ambient processing of peripheral vision. Thus, our visual processing of and attention to objects and scenes depends on how and where these stimuli fall on the retina. The built environment is no exception to these dependencies, specifically in terms of how focal object perception and ambient spatial perception create different types of experiences we have with built environments. We argue that these foundational mechanisms of the eye and the visual stream are limiting parameters of architectural experience. We hypothesize that people experience architecture in two basic ways based on these visual limitations; by intellectually assessing architecture consciously through focal object processing and assessing architecture in terms of atmosphere through pre-conscious ambient spatial processing. Furthermore, these separate ways of processing architectural stimuli operate in parallel throughout the visual perceptual system. Thus, a more comprehensive understanding of architecture must take into account that built environments are stimuli that are treated differently by focal and ambient vision, which enable intellectual analysis of architectural experience versus the experience of architectural atmosphere, respectively. We offer this theoretical model to help advance a more precise understanding of the experience of architecture, which can be tested through future experimentation. (298 words) PMID:28360867

Focal and Ambient Processing of Built Environments: Intellectual and Atmospheric Experiences of Architecture.

PubMed

Rooney, Kevin K; Condia, Robert J; Loschky, Lester C

2017-01-01

Neuroscience has well established that human vision divides into the central and peripheral fields of view. Central vision extends from the point of gaze (where we are looking) out to about 5° of visual angle (the width of one's fist at arm's length), while peripheral vision is the vast remainder of the visual field. These visual fields project to the parvo and magno ganglion cells, which process distinctly different types of information from the world around us and project that information to the ventral and dorsal visual streams, respectively. Building on the dorsal/ventral stream dichotomy, we can further distinguish between focal processing of central vision, and ambient processing of peripheral vision. Thus, our visual processing of and attention to objects and scenes depends on how and where these stimuli fall on the retina. The built environment is no exception to these dependencies, specifically in terms of how focal object perception and ambient spatial perception create different types of experiences we have with built environments. We argue that these foundational mechanisms of the eye and the visual stream are limiting parameters of architectural experience. We hypothesize that people experience architecture in two basic ways based on these visual limitations; by intellectually assessing architecture consciously through focal object processing and assessing architecture in terms of atmosphere through pre-conscious ambient spatial processing. Furthermore, these separate ways of processing architectural stimuli operate in parallel throughout the visual perceptual system. Thus, a more comprehensive understanding of architecture must take into account that built environments are stimuli that are treated differently by focal and ambient vision, which enable intellectual analysis of architectural experience versus the experience of architectural atmosphere, respectively. We offer this theoretical model to help advance a more precise understanding of the experience of architecture, which can be tested through future experimentation. (298 words).

Agnosic vision is like peripheral vision, which is limited by crowding.

PubMed

Strappini, Francesca; Pelli, Denis G; Di Pace, Enrico; Martelli, Marialuisa

2017-04-01

Visual agnosia is a neuropsychological impairment of visual object recognition despite near-normal acuity and visual fields. A century of research has provided only a rudimentary account of the functional damage underlying this deficit. We find that the object-recognition ability of agnosic patients viewing an object directly is like that of normally-sighted observers viewing it indirectly, with peripheral vision. Thus, agnosic vision is like peripheral vision. We obtained 14 visual-object-recognition tests that are commonly used for diagnosis of visual agnosia. Our "standard" normal observer took these tests at various eccentricities in his periphery. Analyzing the published data of 32 apperceptive agnosia patients and a group of 14 posterior cortical atrophy (PCA) patients on these tests, we find that each patient's pattern of object recognition deficits is well characterized by one number, the equivalent eccentricity at which our standard observer's peripheral vision is like the central vision of the agnosic patient. In other words, each agnosic patient's equivalent eccentricity is conserved across tests. Across patients, equivalent eccentricity ranges from 4 to 40 deg, which rates severity of the visual deficit. In normal peripheral vision, the required size to perceive a simple image (e.g., an isolated letter) is limited by acuity, and that for a complex image (e.g., a face or a word) is limited by crowding. In crowding, adjacent simple objects appear unrecognizably jumbled unless their spacing exceeds the crowding distance, which grows linearly with eccentricity. Besides conservation of equivalent eccentricity across object-recognition tests, we also find conservation, from eccentricity to agnosia, of the relative susceptibility of recognition of ten visual tests. These findings show that agnosic vision is like eccentric vision. Whence crowding? Peripheral vision, strabismic amblyopia, and possibly apperceptive agnosia are all limited by crowding, making it urgent to know what drives crowding. Acuity does not (Song et al., 2014), but neural density might: neurons per deg 2 in the crowding-relevant cortical area. Copyright © 2017 Elsevier Ltd. All rights reserved.

Does a Flatter General Gradient of Visual Attention Explain Peripheral Advantages and Central Deficits in Deaf Adults?

PubMed Central

Samar, Vincent J.; Berger, Lauren

2017-01-01

Individuals deaf from early age often outperform hearing individuals in the visual periphery on attention-dependent dorsal stream tasks (e.g., spatial localization or movement detection), but sometimes show central visual attention deficits, usually on ventral stream object identification tasks. It has been proposed that early deafness adaptively redirects attentional resources from central to peripheral vision to monitor extrapersonal space in the absence of auditory cues, producing a more evenly distributed attention gradient across visual space. However, little direct evidence exists that peripheral advantages are functionally tied to central deficits, rather than determined by independent mechanisms, and previous studies using several attention tasks typically report peripheral advantages or central deficits, not both. To test the general altered attentional gradient proposal, we employed a novel divided attention paradigm that measured target localization performance along a gradient from parafoveal to peripheral locations, independent of concurrent central object identification performance in prelingually deaf and hearing groups who differed in access to auditory input. Deaf participants without cochlear implants (No-CI), with cochlear implants (CI), and hearing participants identified vehicles presented centrally, and concurrently reported the location of parafoveal (1.4°) and peripheral (13.3°) targets among distractors. No-CI participants but not CI participants showed a central identification accuracy deficit. However, all groups displayed equivalent target localization accuracy at peripheral and parafoveal locations and nearly parallel parafoveal-peripheral gradients. Furthermore, the No-CI group’s central identification deficit remained after statistically controlling peripheral performance; conversely, the parafoveal and peripheral group performance equivalencies remained after controlling central identification accuracy. These results suggest that, in the absence of auditory input, reduced central attentional capacity is not necessarily associated with enhanced peripheral attentional capacity or with flattening of a general attention gradient. Our findings converge with earlier studies suggesting that a general graded trade-off of attentional resources across the visual field does not adequately explain the complex task-dependent spatial distribution of deaf-hearing performance differences reported in the literature. Rather, growing evidence suggests that the spatial distribution of attention-mediated performance in deaf people is determined by sophisticated cross-modal plasticity mechanisms that recruit specific sensory and polymodal cortex to achieve specific compensatory processing goals. PMID:28559861

Training improves reading speed in peripheral vision: is it due to attention?

PubMed

Lee, Hye-Won; Kwon, Miyoung; Legge, Gordon E; Gefroh, Joshua J

2010-06-01

Previous research has shown that perceptual training in peripheral vision, using a letter-recognition task, increases reading speed and letter recognition (S. T. L. Chung, G. E. Legge, & S. H. Cheung, 2004). We tested the hypothesis that enhanced deployment of spatial attention to peripheral vision explains this training effect. Subjects were pre- and post-tested with 3 tasks at 10° above and below fixation-RSVP reading speed, trigram letter recognition (used to construct visual-span profiles), and deployment of spatial attention (measured as the benefit of a pre-cue for target position in a lexical-decision task). Groups of five normally sighted young adults received 4 days of trigram letter-recognition training in upper or lower visual fields, or central vision. A control group received no training. Our measure of deployment of spatial attention revealed visual-field anisotropies; better deployment of attention in the lower field than the upper, and in the lower-right quadrant compared with the other three quadrants. All subject groups exhibited slight improvement in deployment of spatial attention to peripheral vision in the post-test, but this improvement was not correlated with training-related increases in reading speed and the size of visual-span profiles. Our results indicate that improved deployment of spatial attention to peripheral vision does not account for improved reading speed and letter recognition in peripheral vision.

Simulation Evaluation of Equivalent Vision Technologies for Aerospace Operations

NASA Technical Reports Server (NTRS)

Kramer, Lynda J.; Williams, Steven P.; Wilz, Susan J.; Arthur, Jarvis J.

2009-01-01

A fixed-based simulation experiment was conducted in NASA Langley Research Center s Integration Flight Deck simulator to investigate enabling technologies for equivalent visual operations (EVO) in the emerging Next Generation Air Transportation System operating environment. EVO implies the capability to achieve or even improve on the safety of current-day Visual Flight Rules (VFR) operations, maintain the operational tempos of VFR, and perhaps even retain VFR procedures - all independent of the actual weather and visibility conditions. Twenty-four air transport-rated pilots evaluated the use of Synthetic/Enhanced Vision Systems (S/EVS) and eXternal Vision Systems (XVS) technologies as enabling technologies for future all-weather operations. The experimental objectives were to determine the feasibility of XVS/SVS/EVS to provide for all weather (visibility) landing capability without the need (or ability) for a visual approach segment and to determine the interaction of XVS/EVS and peripheral vision cues for terminal area and surface operations. Another key element of the testing investigated the pilot's awareness and reaction to non-normal events (i.e., failure conditions) that were unexpectedly introduced into the experiment. These non-normal runs served as critical determinants in the underlying safety of all-weather operations. Experimental data from this test are cast into performance-based approach and landing standards which might establish a basis for future all-weather landing operations. Glideslope tracking performance appears to have improved with the elimination of the approach visual segment. This improvement can most likely be attributed to the fact that the pilots didn't have to simultaneously perform glideslope corrections and find required visual landing references in order to continue a landing. Lateral tracking performance was excellent regardless of the display concept being evaluated or whether or not there were peripheral cues in the side window. Although workload ratings were significantly less when peripheral cues were present compared to when there were none, these differences appear to be operationally inconsequential. Larger display concepts tested in this experiment showed significant situation awareness (SA) improvements and workload reductions compared to smaller display concepts. With a fixed display size, a color display was more influential in SA and workload ratings than a collimated display.

Inhibition of return in the visual field: the eccentricity effect is independent of cortical magnification.

PubMed

Bao, Yan; Lei, Quan; Fang, Yuan; Tong, Yu; Schill, Kerstin; Pöppel, Ernst; Strasburger, Hans

2013-01-01

Inhibition of return (IOR) as an indicator of attentional control is characterized by an eccentricity effect, that is, the more peripheral visual field shows a stronger IOR magnitude relative to the perifoveal visual field. However, it could be argued that this eccentricity effect may not be an attention effect, but due to cortical magnification. To test this possibility, we examined this eccentricity effect in two conditions: the same-size condition in which identical stimuli were used at different eccentricities, and the size-scaling condition in which stimuli were scaled according to the cortical magnification factor (M-scaling), thus stimuli being larger at the more peripheral locations. The results showed that the magnitude of IOR was significantly stronger in the peripheral relative to the perifoveal visual field, and this eccentricity effect was independent of the manipulation of stimulus size (same-size or size-scaling). These results suggest a robust eccentricity effect of IOR which cannot be eliminated by M-scaling. Underlying neural mechanisms of the eccentricity effect of IOR are discussed with respect to both cortical and subcortical structures mediating attentional control in the perifoveal and peripheral visual field.

Analysis of Tumor Vessel Supply in Lewis Lung Carcinoma in Mice by Fluorescent Microsphere Distribution and Imaging with Micro- and Flat-Panel Computed Tomography

PubMed Central

Savai, Rajkumar; Wolf, Joachim C.; Greschus, Susanne; Eul, Bastian G.; Schermuly, Ralph T.; Hänze, Jörg; Voswinckel, Robert; Langheinrich, Alexander C.; Grimminger, Friedrich; Traupe, Horst; Seeger, Werner; Rose, Frank

2005-01-01

In lung carcinomas the blood supply varies depending on tumor type and stage and can develop from pulmonary or bronchial circulation, or both. To examine this in vivo, primary bronchogenic Lewis lung carcinoma cells were intratracheally instilled in C57BL/6 mice. Within 7 days, histological examinations showed progressive tumor growth at the peripheral parenchymal region. The relative contribution of tumor blood supply via the pulmonary and systemic arteries was studied in detail using fluorescent microspheres (10 μm). When compared to healthy lung parenchyma (13:1), Lewis lung carcinoma tumor tissue (52:1) showed a fourfold increase in pulmonary to systemic microspheres, indicating that the pulmonary arteries are the predominant tumor-feeding vessels. After filling the vessels with a vascular cast, the microanatomy of vessels being derived from the pulmonary artery was visualized with micro computed tomography. Flat-panel volumetric computed tomography provided longitudinal visualization of tissue bridges between the growing tumor and the pulmonary vasculature. In this model of peripheral parenchymal malignancy, new imaging techniques allowed effective visualization of lung tumor growth and vascularization in living mice, demonstrating a pulmonary blood supply for lung tumors. PMID:16192630

Peripheral detection and resolution with mid-/long-wavelength and short-wavelength sensitive cone systems.

PubMed

Zhu, Hai-Feng; Zele, Andrew J; Suheimat, Marwan; Lambert, Andrew J; Atchison, David A

2016-08-01

This study compared neural resolution and detection limits of the human mid-/long-wavelength and short-wavelength cone systems with anatomical estimates of photoreceptor and retinal ganglion cell spacings and sizes. Detection and resolution limits were measured from central fixation out to 35° eccentricity across the horizontal visual field using a modified Lotmar interferometer. The mid-/long-wavelength cone system was studied using a green (550 nm) test stimulus to which S-cones have low sensitivity. To bias resolution and detection to the short-wavelength cone system, a blue (450 nm) test stimulus was presented against a bright yellow background that desensitized the M- and L-cones. Participants were three trichromatic males with normal visual functions. With green stimuli, resolution showed a steep central-peripheral gradient that was similar between participants, whereas the detection gradient was shallower and patterns were different between participants. Detection and resolution with blue stimuli were poorer than for green stimuli. The detection of blue stimuli was superior to resolution across the horizontal visual field and the patterns were different between participants. The mid-/long-wavelength cone system's resolution is limited by midget ganglion cell spacing and its detection is limited by the size of the M- and L-cone photoreceptors, consistent with previous observations. We found that no such simple relationships occur for the short-wavelength cone system between resolution and the bistratified ganglion cell spacing, nor between detection and the S-cone photoreceptor sizes.

A novel approach to 32-channel peripheral nervous system myelin imaging in vivo, with single axon resolution.

PubMed

Grochmal, Joey; Teo, Wulin; Gambhir, Hardeep; Kumar, Ranjan; Stratton, Jo Anne; Dhaliwal, Raveena; Brideau, Craig; Biernaskie, Jeff; Stys, Peter K; Midha, Rajiv

2018-01-19

OBJECTIVE Intravital spectral imaging of the large, deeply situated nerves in the rat peripheral nervous system (PNS) has not been well described. Here, the authors have developed a highly stable platform for performing imaging of the tibial nerve in live rodents, thus allowing the capture of high-resolution, high-magnification spectral images requiring long acquisition times. By further exploiting the qualities of the topically applied myelin dye Nile red, this technique is capable of visualizing the detailed microenvironment of peripheral nerve demyelination injury and recovery, while allowing us to obtain images of exogenous Schwann cell myelination in a living animal. METHODS The authors caused doxorubicin-induced focal demyelination in the tibial nerves of 25 Thy-1 GFP rats, of which 2 subsets (n = 10 each) received either BFP-labeled SKP-SCs or SCs to the zone of injury. Prior to acquiring images of myelin recovery in these nerves, a tibial nerve window was constructed using a silicone hemitube, a fast drying silicone polymer, and a small coverslip. This construct was then affixed to a 3D-printed nerve stage, which in turn was affixed to an external fixation/microscope stage device. Myelin visualization was facilitated by the topical application of Nile red. RESULTS The authors reliably demonstrated intravital peripheral nerve myelin imaging with micron-level resolution and magnification, and minimal movement artifact. The detailed microenvironment of nerve remyelination can be vividly observed, while exogenously applied Schwann cells and skin-derived precursor Schwann cells can be seen myelinating axons. CONCLUSIONS Topically applied Nile red enables intravital study of myelin in the living rat PNS. Furthermore, the use of a tibial nerve window facilitates stable intravital peripheral nerve imaging, making possible high-definition spectral imaging with long acquisition times.

Discrepant visual speech facilitates covert selective listening in "cocktail party" conditions.

PubMed

Williams, Jason A

2012-06-01

The presence of congruent visual speech information facilitates the identification of auditory speech, while the addition of incongruent visual speech information often impairs accuracy. This latter arrangement occurs naturally when one is being directly addressed in conversation but listens to a different speaker. Under these conditions, performance may diminish since: (a) one is bereft of the facilitative effects of the corresponding lip motion and (b) one becomes subject to visual distortion by incongruent visual speech; by contrast, speech intelligibility may be improved due to (c) bimodal localization of the central unattended stimulus. Participants were exposed to centrally presented visual and auditory speech while attending to a peripheral speech stream. In some trials, the lip movements of the central visual stimulus matched the unattended speech stream; in others, the lip movements matched the attended peripheral speech. Accuracy for the peripheral stimulus was nearly one standard deviation greater with incongruent visual information, compared to the congruent condition which provided bimodal pattern recognition cues. Likely, the bimodal localization of the central stimulus further differentiated the stimuli and thus facilitated intelligibility. Results are discussed with regard to similar findings in an investigation of the ventriloquist effect, and the relative strength of localization and speech cues in covert listening.

Visual functions and disability in diabetic retinopathy patients

PubMed Central

Shrestha, Gauri Shankar; Kaiti, Raju

2013-01-01

Purpose This study was undertaken to find correlations between visual functions and visual disabilities in patients with diabetic retinopathy. Method A cross-sectional study was carried out among 38 visually impaired diabetic retinopathy subjects at the Low Vision Clinic of B.P. Koirala Lions Centre for Ophthalmic Studies, Kathmandu. The subjects underwent assessment of distance and near visual acuity, objective and subjective refraction, contrast sensitivity, color vision, and central and peripheral visual fields. The visual disabilities of each subject in their daily lives were evaluated using a standard questionnaire. Multiple regression analysis between visual functions and visual disabilities index was assessed. Result The majority of subjects (42.1%) were of the age group 60–70 years. Best corrected visual acuity was found to be 0.73 ± 0.2 in the better eye and 0.93 ± 0.27 in the worse eye, which was significantly different at p = 0.002. Visual disability scores were significantly higher for legibility of letters (1.2 ± 0.3) and sentences (1.4 ± 0.4), and least for clothing (0.7 ± 0.3). Visual disability index for legibility of letters and sentences was significantly correlated with near visual acuity and peripheral visual field. Contrast sensitivity was also significantly correlated with the visual disability index, and total scores. Conclusion Impairment of near visual acuity, contrast sensitivity, and peripheral visual field correlated significantly with different types of visual disability. Hence, these clinical tests should be an integral part of the visual assessment of diabetic eyes. PMID:24646899

Visual functions and disability in diabetic retinopathy patients.

PubMed

Shrestha, Gauri Shankar; Kaiti, Raju

2014-01-01

This study was undertaken to find correlations between visual functions and visual disabilities in patients with diabetic retinopathy. A cross-sectional study was carried out among 38 visually impaired diabetic retinopathy subjects at the Low Vision Clinic of B.P. Koirala Lions Centre for Ophthalmic Studies, Kathmandu. The subjects underwent assessment of distance and near visual acuity, objective and subjective refraction, contrast sensitivity, color vision, and central and peripheral visual fields. The visual disabilities of each subject in their daily lives were evaluated using a standard questionnaire. Multiple regression analysis between visual functions and visual disabilities index was assessed. The majority of subjects (42.1%) were of the age group 60-70 years. Best corrected visual acuity was found to be 0.73±0.2 in the better eye and 0.93±0.27 in the worse eye, which was significantly different at p=0.002. Visual disability scores were significantly higher for legibility of letters (1.2±0.3) and sentences (1.4±0.4), and least for clothing (0.7±0.3). Visual disability index for legibility of letters and sentences was significantly correlated with near visual acuity and peripheral visual field. Contrast sensitivity was also significantly correlated with the visual disability index, and total scores. Impairment of near visual acuity, contrast sensitivity, and peripheral visual field correlated significantly with different types of visual disability. Hence, these clinical tests should be an integral part of the visual assessment of diabetic eyes. Copyright © 2013 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Ultra-Widefield Fluorescein Angiography in Intermediate Uveitis.

PubMed

Laovirojjanakul, Wipada; Acharya, Nisha; Gonzales, John A

2017-10-17

To examine associations between pattern of vascular leakage on ultrawide-field fluorescein angiography (UWFFA) and visual acuity, cystoid macular edema (CME), and inflammatory activity in intermediate uveitis. Single center cross-sectional, retrospective review of medical records, spectral domain optical coherence tomography (SD-OCT) and angiographic images of intermediate uveitis patients who underwent UWFFA over a 12-month period. Forty-one eyes from 24 patients were included. Twelve eyes (29%) exhibited peripheral leakage, 26 eyes (64%) had diffuse leakage and three eyes (7%) had no leakage. Diffuse leakage was associated with 0.2 logMAR worse visual acuity than peripheral leakage (p = 0.02). There was no statistically significant difference in the odds of having CME when diffuse leakage was compared to peripheral leakage. UWFFA identifies retinal vascular pathology in intermediate uveitis not present on clinical examination. Diffuse retinal vascular leakage was associated with worse visual acuity when compared to peripheral and no leakage patterns.

Simulated visual field loss does not alter turning coordination in healthy young adults.

PubMed

Murray, Nicholas G; Ponce de Leon, Marlina; Ambati, V N Pradeep; Saucedo, Fabricio; Kennedy, Evan; Reed-Jones, Rebecca J

2014-01-01

Turning, while walking, is an important component of adaptive locomotion. Current hypotheses regarding the motor control of body segment coordination during turning suggest heavy influence of visual information. The authors aimed to examine whether visual field impairment (central loss or peripheral loss) affects body segment coordination during walking turns in healthy young adults. No significant differences in the onset time of segments or intersegment coordination were observed because of visual field occlusion. These results suggest that healthy young adults can use visual information obtained from central and peripheral visual fields interchangeably, pointing to flexibility of visuomotor control in healthy young adults. Further study in populations with chronic visual impairment and those with turning difficulties are warranted.

Raised visual detection thresholds depend on the level of complexity of cognitive foveal loading.

PubMed

Plainis, S; Murray, I J; Chauhan, K

2001-01-01

The objective of the study was to measure the interactions between visual thresholds for a simple light (the secondary task) presented peripherally and a simultaneously performed cognitive task (the primary task) presented foveally The primary task was highly visible but varied according to its cognitive complexity. Interactions between the tasks were determined by measuring detection thresholds for the peripheral task and accuracy of performance of the foveal task. Effects were measured for 5, 10, 20, and 30 deg eccentricity of the peripherally presented light and for three levels of cognitive complexity. Mesopic conditions (0.5 lx) were used. As expected, the concurrent presentation of the foveal cognitive task reduced peripheral sensitivity. Moreover, performance of the foveal task was adversely affected when conducting the peripheral task. Performance on both tasks was reduced as the level of complexity of the cognitive task increased. There were qualitative differences in task interactions between the central 10 deg and at greater eccentricities. Within 10 deg there was a disproportionate effect of eccentricity, previously interpreted as the 'tunnel-vision' model of visual field narrowing. Interactions outside 10 deg were less affected by eccentricity. These results are discussed in terms of the known neurophysiological characteristics of the primary visual pathway.

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

PubMed

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.

High-resolution fluorescence microscopy of myelin without exogenous probes.

PubMed

Christensen, Pia Crone; Brideau, Craig; Poon, Kelvin W C; Döring, Axinia; Yong, V Wee; Stys, Peter K

2014-02-15

Myelin is a critical element of the central and peripheral nervous systems of all higher vertebrates. Any disturbance in the integrity of the myelin sheath interferes with the axon's ability to conduct action potentials. Thus, the study of myelin structure and biochemistry is critically important. Accurate and even staining of myelin is often difficult because of its lipid-rich nature and multiple tight membrane wraps, hindering penetration of immunoprobes. Here we show a method of visualizing myelin that is fast, inexpensive and reliable using the cross-linking fixative glutaraldehyde that produces strong, broad-spectrum auto-fluorescence in fixed tissue. Traditionally, effort is generally aimed at eliminating this auto-fluorescence. However, we show that this intrinsic signal, which is very photostable and particularly strong in glutaraldehyde-fixed myelin, can be exploited to visualize this structure to produce very detailed images of myelin morphology. We imaged fixed rodent tissues from the central and peripheral nervous systems using spectral confocal microscopy to acquire high-resolution 3-dimensional images spanning the visual range of wavelengths (400-750 nm). Mathematical post-processing allows accurate and unequivocal separation of broadband auto-fluorescence from exogenous fluorescent probes such as DAPI and fluorescently-tagged secondary antibodies. We additionally show the feasibility of immunohistochemistry with antigen retrieval, which allows co-localization of proteins of interest together with detailed myelin morphology. The lysolecithin model of de- and remyelination is shown as an example of a practical application of this technique, which can be routinely applied when high-resolution microscopy of central or peripheral myelinated tracts is required. © 2013.

Unsold is unseen … or is it? Examining the role of peripheral vision in the consumer choice process using eye-tracking methodology.

PubMed

Wästlund, Erik; Shams, Poja; Otterbring, Tobias

2018-01-01

In visual marketing, the truism that "unseen is unsold" means that products that are not noticed will not be sold. This truism rests on the idea that the consumer choice process is heavily influenced by visual search. However, given that the majority of available products are not seen by consumers, this article examines the role of peripheral vision in guiding attention during the consumer choice process. In two eye-tracking studies, one conducted in a lab facility and the other conducted in a supermarket, the authors investigate the role and limitations of peripheral vision. The results show that peripheral vision is used to direct visual attention when discriminating between target and non-target objects in an eye-tracking laboratory. Target and non-target similarity, as well as visual saliency of non-targets, constitute the boundary conditions for this effect, which generalizes from instruction-based laboratory tasks to preference-based choice tasks in a real supermarket setting. Thus, peripheral vision helps customers to devote a larger share of attention to relevant products during the consumer choice process. Taken together, the results show how the creation of consideration set (sets of possible choice options) relies on both goal-directed attention and peripheral vision. These results could explain how visually similar packaging positively influences market leaders, while making novel brands almost invisible on supermarket shelves. The findings show that even though unsold products might be unseen, in the sense that they have not been directly observed, they might still have been evaluated and excluded by means of peripheral vision. This article is based on controlled lab experiments as well as a field study conducted in a complex retail environment. Thus, the findings are valid both under controlled and ecologically valid conditions. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Structural reorganization of the early visual cortex following Braille training in sighted adults.

PubMed

Bola, Łukasz; Siuda-Krzywicka, Katarzyna; Paplińska, Małgorzata; Sumera, Ewa; Zimmermann, Maria; Jednoróg, Katarzyna; Marchewka, Artur; Szwed, Marcin

2017-12-12

Training can induce cross-modal plasticity in the human cortex. A well-known example of this phenomenon is the recruitment of visual areas for tactile and auditory processing. It remains unclear to what extent such plasticity is associated with changes in anatomy. Here we enrolled 29 sighted adults into a nine-month tactile Braille-reading training, and used voxel-based morphometry and diffusion tensor imaging to describe the resulting anatomical changes. In addition, we collected resting-state fMRI data to relate these changes to functional connectivity between visual and somatosensory-motor cortices. Following Braille-training, we observed substantial grey and white matter reorganization in the anterior part of early visual cortex (peripheral visual field). Moreover, relative to its posterior, foveal part, the peripheral representation of early visual cortex had stronger functional connections to somatosensory and motor cortices even before the onset of training. Previous studies show that the early visual cortex can be functionally recruited for tactile discrimination, including recognition of Braille characters. Our results demonstrate that reorganization in this region induced by tactile training can also be anatomical. This change most likely reflects a strengthening of existing connectivity between the peripheral visual cortex and somatosensory cortices, which suggests a putative mechanism for cross-modal recruitment of visual areas.

High-resolution gadolinium-enhanced 3D MRA of the infrapopliteal arteries. Lessons for improving bolus-chase peripheral MRA.

PubMed

Hood, Maureen N; Ho, Vincent B; Foo, Thomas K F; Marcos, Hani B; Hess, Sandra L; Choyke, Peter L

2002-09-01

Peripheral magnetic resonance angiography (MRA) is growing in use. However, methods of performing peripheral MRA vary widely and continue to be optimized, especially for improvement in illustration of infrapopliteal arteries. The main purpose of this project was to identify imaging factors that can improve arterial visualization in the lower leg using bolus chase peripheral MRA. Eighteen healthy adults were imaged on a 1.5T MR scanner. The calf was imaged using conventional three-station bolus chase three-dimensional (3D) MRA, two dimensional (2D) time-of-flight (TOF) MRA and single-station Gadolinium (Gd)-enhanced 3D MRA. Observer comparisons of vessel visualization, signal to noise ratios (SNR), contrast to noise ratios (CNR) and spatial resolution comparisons were performed. Arterial SNR and CNR were similar for all three techniques. However, arterial visualization was dramatically improved on dedicated, arterial-phase Gd-enhanced 3D MRA compared with the multi-station bolus chase MRA and 2D TOF MRA. This improvement was related to optimization of Gd-enhanced 3D MRA parameters (fast injection rate of 2 mL/sec, high spatial resolution imaging, the use of dedicated phased array coils, elliptical centric k-space sampling and accurate arterial phase timing for image acquisition). The visualization of the infrapopliteal arteries can be substantially improved in bolus chase peripheral MRA if voxel size, contrast delivery, and central k-space data acquisition for arterial enhancement are optimized. Improvements in peripheral MRA should be directed at these parameters.

Transitions between Central and Peripheral Vision Create Spatial/Temporal Distortions: A Hypothesis Concerning the Perceived Break of the Curveball

PubMed Central

Shapiro, Arthur; Lu, Zhong-Lin; Huang, Chang-Bing; Knight, Emily; Ennis, Robert

2010-01-01

Background The human visual system does not treat all parts of an image equally: the central segments of an image, which fall on the fovea, are processed with a higher resolution than the segments that fall in the visual periphery. Even though the differences between foveal and peripheral resolution are large, these differences do not usually disrupt our perception of seamless visual space. Here we examine a motion stimulus in which the shift from foveal to peripheral viewing creates a dramatic spatial/temporal discontinuity. Methodology/Principal Findings The stimulus consists of a descending disk (global motion) with an internal moving grating (local motion). When observers view the disk centrally, they perceive both global and local motion (i.e., observers see the disk's vertical descent and the internal spinning). When observers view the disk peripherally, the internal portion appears stationary, and the disk appears to descend at an angle. The angle of perceived descent increases as the observer views the stimulus from further in the periphery. We examine the first- and second-order information content in the display with the use of a three-dimensional Fourier analysis and show how our results can be used to describe perceived spatial/temporal discontinuities in real-world situations. Conclusions/Significance The perceived shift of the disk's direction in the periphery is consistent with a model in which foveal processing separates first- and second-order motion information while peripheral processing integrates first- and second-order motion information. We argue that the perceived distortion may influence real-world visual observations. To this end, we present a hypothesis and analysis of the perception of the curveball and rising fastball in the sport of baseball. The curveball is a physically measurable phenomenon: the imbalance of forces created by the ball's spin causes the ball to deviate from a straight line and to follow a smooth parabolic path. However, the curveball is also a perceptual puzzle because batters often report that the flight of the ball undergoes a dramatic and nearly discontinuous shift in position as the ball nears home plate. We suggest that the perception of a discontinuous shift in position results from differences between foveal and peripheral processing. PMID:20967247

Scene and human face recognition in the central vision of patients with glaucoma

PubMed Central

Aptel, Florent; Attye, Arnaud; Guyader, Nathalie; Boucart, Muriel; Chiquet, Christophe; Peyrin, Carole

2018-01-01

Primary open-angle glaucoma (POAG) firstly mainly affects peripheral vision. Current behavioral studies support the idea that visual defects of patients with POAG extend into parts of the central visual field classified as normal by static automated perimetry analysis. This is particularly true for visual tasks involving processes of a higher level than mere detection. The purpose of this study was to assess visual abilities of POAG patients in central vision. Patients were assigned to two groups following a visual field examination (Humphrey 24–2 SITA-Standard test). Patients with both peripheral and central defects and patients with peripheral but no central defect, as well as age-matched controls, participated in the experiment. All participants had to perform two visual tasks where low-contrast stimuli were presented in the central 6° of the visual field. A categorization task of scene images and human face images assessed high-level visual recognition abilities. In contrast, a detection task using the same stimuli assessed low-level visual function. The difference in performance between detection and categorization revealed the cost of high-level visual processing. Compared to controls, patients with a central visual defect showed a deficit in both detection and categorization of all low-contrast images. This is consistent with the abnormal retinal sensitivity as assessed by perimetry. However, the deficit was greater for categorization than detection. Patients without a central defect showed similar performances to the controls concerning the detection and categorization of faces. However, while the detection of scene images was well-maintained, these patients showed a deficit in their categorization. This suggests that the simple loss of peripheral vision could be detrimental to scene recognition, even when the information is displayed in central vision. This study revealed subtle defects in the central visual field of POAG patients that cannot be predicted by static automated perimetry assessment using Humphrey 24–2 SITA-Standard test. PMID:29481572

The SCHEIE Visual Field Grading System

PubMed Central

Sankar, Prithvi S.; O’Keefe, Laura; Choi, Daniel; Salowe, Rebecca; Miller-Ellis, Eydie; Lehman, Amanda; Addis, Victoria; Ramakrishnan, Meera; Natesh, Vikas; Whitehead, Gideon; Khachatryan, Naira; O’Brien, Joan

2017-01-01

Objective No method of grading visual field (VF) defects has been widely accepted throughout the glaucoma community. The SCHEIE (Systematic Classification of Humphrey visual fields-Easy Interpretation and Evaluation) grading system for glaucomatous visual fields was created to convey qualitative and quantitative information regarding visual field defects in an objective, reproducible, and easily applicable manner for research purposes. Methods The SCHEIE grading system is composed of a qualitative and quantitative score. The qualitative score consists of designation in one or more of the following categories: normal, central scotoma, paracentral scotoma, paracentral crescent, temporal quadrant, nasal quadrant, peripheral arcuate defect, expansive arcuate, or altitudinal defect. The quantitative component incorporates the Humphrey visual field index (VFI), location of visual defects for superior and inferior hemifields, and blind spot involvement. Accuracy and speed at grading using the qualitative and quantitative components was calculated for non-physician graders. Results Graders had a median accuracy of 96.67% for their qualitative scores and a median accuracy of 98.75% for their quantitative scores. Graders took a mean of 56 seconds per visual field to assign a qualitative score and 20 seconds per visual field to assign a quantitative score. Conclusion The SCHEIE grading system is a reproducible tool that combines qualitative and quantitative measurements to grade glaucomatous visual field defects. The system aims to standardize clinical staging and to make specific visual field defects more easily identifiable. Specific patterns of visual field loss may also be associated with genetic variants in future genetic analysis. PMID:28932621

In vivo targeted peripheral nerve imaging with a nerve-specific nanoscale magnetic resonance probe.

PubMed

Zheng, Linfeng; Li, Kangan; Han, Yuedong; Wei, Wei; Zheng, Sujuan; Zhang, Guixiang

2014-11-01

Neuroimaging plays a pivotal role in clinical practice. Currently, computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography, and positron emission tomography (PET) are applied in the clinical setting as neuroimaging modalities. There is no optimal imaging modality for clinical peripheral nerve imaging even though fluorescence/bioluminescence imaging has been used for preclinical studies on the nervous system. Some studies have shown that molecular and cellular MRI (MCMRI) can be used to visualize and image the cellular and molecular level of the nervous system. Other studies revealed that there are different pathological/molecular changes in the proximal and distal sites after peripheral nerve injury (PNI). Therefore, we hypothesized that in vivo peripheral nerve targets can be imaged using MCMRI with specific MRI probes. Specific probes should have higher penetrability for the blood-nerve barrier (BNB) in vivo. Here, a functional nanometre MRI probe that is based on nerve-specific proteins as targets, specifically, using a molecular antibody (mAb) fragment conjugated to iron nanoparticles as an MRI probe, was constructed for further study. The MRI probe allows for imaging the peripheral nerve targets in vivo. Copyright © 2014 Elsevier Ltd. All rights reserved.

Visual field tunneling in aviators induced by memory demands.

PubMed

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.

Continuous and Noninvasive Recording of Cardiovascular Parameters with the Finapres Finger Cuff Enhances Undergraduate Student Understanding of Physiology

ERIC Educational Resources Information Center

Hodgson, Yvonne; Choate, Julia

2012-01-01

The Finapres finger cuff recording system provides continuous calculations of beat-to-beat variations in cardiac output (CO), total peripheral resistance, heart rate (HR), and blood pressure (BP). This system is unique in that it allows experimental subjects to immediately, continuously, and noninvasively visualize changes in CO at rest and during…

Influence of eye rotation on peripheral eye length measurement obtained with a partial coherence interferometry instrument.

PubMed

Verkicharla, Pavan K; Suheimat, Marwan; Mallen, Edward A H; Atchison, David A

2014-01-01

The eye rotation approach for measuring peripheral eye length leads to concern about whether the rotation influences results, such as through pressure exerted by eyelids or extra-ocular muscles. This study investigated whether this approach is valid. Peripheral eye lengths were measured with a Lenstar LS 900 biometer for eye rotation and no-eye rotation conditions (head rotation for horizontal meridian and instrument rotation for vertical meridian). Measurements were made for 23 healthy young adults along the horizontal visual field (± 30°) and, for a subset of eight participants along the vertical visual field (± 25°). To investigate the influence of the duration of eye rotation, for six participants measurements were made at 0, 60, 120, 180 and 210 s after eye rotation to ± 30° along horizontal and vertical visual fields. Peripheral eye lengths were not significantly different for the conditions along the vertical meridian (F1,7 = 0.16, p = 0.71). The peripheral eye lengths for the conditions were significantly different along the horizontal meridian (F1,22 = 4.85, p = 0.04), although not at individual positions (p ≥ 0.10) and were not important. There were no apparent differences between the emmetropic and myopic groups. There was no significant change in eye length at any position after maintaining position for 210 s. Eye rotation and no-eye rotation conditions were similar for measuring peripheral eye lengths along horizontal and vertical visual field meridians at ± 30° and ± 25°, respectively. Either condition can be used to estimate retinal shape from peripheral eye lengths. © 2013 The Authors Ophthalmic & Physiological Optics © 2013 The College of Optometrists.

Mini-review: Far peripheral vision.

PubMed

Simpson, Michael J

2017-11-01

The region of far peripheral vision, beyond 60 degrees of visual angle, is important to the evaluation of peripheral dark shadows (negative dysphotopsia) seen by some intraocular lens (IOL) patients. Theoretical calculations show that the limited diameter of an IOL affects ray paths at large angles, leading to a dimming of the main image for small pupils, and to peripheral illumination by light bypassing the IOL for larger pupils. These effects are rarely bothersome, and cataract surgery is highly successful, but there is a need to improve the characterization of far peripheral vision, for both pseudophakic and phakic eyes. Perimetry is the main quantitative test, but the purpose is to evaluate pathologies rather than characterize vision (and object and image regions are no longer uniquely related in the pseudophakic eye). The maximum visual angle is approximately 105 0 , but there is limited information about variations with age, race, or refractive error (in case there is an unexpected link with the development of myopia), or about how clear cornea, iris location, and the limiting retina are related. Also, the detection of peripheral motion is widely recognized to be important, yet rarely evaluated. Overall, people rarely complain specifically about this visual region, but with "normal" vision including an IOL for >5% of people, and increasing interest in virtual reality and augmented reality, there are new reasons to characterize peripheral vision more completely. Copyright © 2017 Elsevier Ltd. All rights reserved.

Improved Arthroscopic Visualization of Peripheral Compartment

PubMed Central

Suslak, Adam G.; Mather, Richard C.; Kelly, Bryan T.; Nho, Shane J.

2012-01-01

Femoroacetabular impingement is a recognized cause of hip pain and motion restrictions. Advancements in hip arthroscopy have allowed surgeons the ability to treat this condition more effectively. However, the learning curve is steep for osteochondroplasty of the femoral head-neck junction in the peripheral compartment. Therefore we present a reproducible technique that allows improved visualization of the peripheral compartment and treatment of the cam lesion with hip arthroscopy. Our technique uses the anterior portal as a viewing portal, a distal anterolateral accessory portal as a working portal, and the anterolateral portal for soft-tissue retraction. PMID:23766977

Neurophysiological Assessment of Auditory, Peripheral Nerve, Somatosensory, and Visual System Functions after Developmental Exposure to Ethanol Vapors

EPA Science Inventory

Ethanol-blended gasoline entered the market in response to demand for domestic renewable energy sources, and may result in increased inhalation of ethanol vapors in combination with other volatile gasoline constituents. It is important to understand potential risks of inhalation ...

Peripheral type of choline acetyltransferase: biological and evolutionary implications for novel mechanisms in cholinergic system.

PubMed

Bellier, J-P; Kimura, H

2011-12-01

The peripheral type of choline acetyltransferase (pChAT) is an isoform of the well-studied common type of choline acetyltransferase (cChAT), the synthesizing enzyme of acetylcholine. Since pChAT arises by exons skipping, its amino acid sequence is similar to that of cChAT, except the lack of a continuous peptide sequence encoded by all the four exons from 6 to 9. While cChAT expression has been observed in both the central and peripheral nervous systems, pChAT is preferentially expressed in the peripheral nervous system. pChAT appears to be a reliable marker for the visualization of peripheral cholinergic neurons and their processes, whereas other conventional markers including cChAT have not been used successfully for it. In mammals like rodents, pChAT immunoreactivity has been observed in most, if not all, physiologically identified peripheral cholinergic structures such as all parasympathetic postganglionic neurons and most neurons of the enteric nervous system. In addition, pChAT has been found in many peripheral neurons that are derived from the neural crest. These include sensory neurons of the trigeminal ganglion and the dorsal root ganglion, and sympathetic postganglionic neurons. Recent studies moreover indicate that pChAT, as well as cChAT, appears ubiquitously expressed among various species not only of vertebrate mammals but also of invertebrate mollusks. This finding implies that the alternative splicing mechanism to generate pChAT and cChAT has been preserved during evolution, probably for some functional benefits. Copyright © 2011 Elsevier B.V. All rights reserved.

Immunohistochemical Analysis in the Rat Central Nervous System and Peripheral Lymph Node Tissue Sections.

PubMed

Adzemovic, Milena Z; Zeitelhofer, Manuel; Leisser, Marianne; Köck, Ulricke; Kury, Angela; Olsson, Tomas

2016-11-14

Immunohistochemistry (IHC) provides highly specific, reliable and attractive protein visualization. Correct performance and interpretation of an IHC-based multicolor labeling is challenging, especially when utilized for assessing interrelations between target proteins in the tissue with a high fat content such as the central nervous system (CNS). Our protocol represents a refinement of the standard immunolabeling technique particularly adjusted for detection of both structural and soluble proteins in the rat CNS and peripheral lymph nodes (LN) affected by neuroinflammation. Nonetheless, with or without further modifications, our protocol could likely be used for detection of other related protein targets, even in other organs and species than here presented.

Varied Human Tolerance to the Combined Conditions of Low Contrast and Diminished Luminance: A Quasi-Meta Analysis

DTIC Science & Technology

2017-08-30

as being three-fold: 1) a measurement of the integrity of both the central and peripheral visual processing centers; 2) an indicator of detail...visual assessment task 12 integral to the Army’s Class 1 Flight Physical (Ginsburg, 1981 and 1984; Bachman & Behar, 1986). During a Class 1 flight...systems. Meta-analysis has been defined as the statistical analysis of a collection of analytical results for the purpose of integrating the findings

Irinotecan in Treating Children With Refractory Solid Tumors

ClinicalTrials.gov

2013-06-13

Childhood Central Nervous System Germ Cell Tumor; Childhood Choroid Plexus Tumor; Childhood Craniopharyngioma; Childhood Grade I Meningioma; Childhood Grade II Meningioma; Childhood Grade III Meningioma; Childhood Infratentorial Ependymoma; Childhood Oligodendroglioma; Childhood Supratentorial Ependymoma; Previously Treated Childhood Rhabdomyosarcoma; Recurrent Childhood Cerebellar Astrocytoma; Recurrent Childhood Cerebral Astrocytoma; Recurrent Childhood Ependymoma; Recurrent Childhood Medulloblastoma; Recurrent Childhood Rhabdomyosarcoma; Recurrent Childhood Visual Pathway and Hypothalamic Glioma; Recurrent Childhood Visual Pathway Glioma; Recurrent Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor; Recurrent Neuroblastoma; Recurrent Osteosarcoma; Unspecified Childhood Solid Tumor, Protocol Specific

People with diabetic peripheral neuropathy display a decreased stepping accuracy during walking: potential implications for risk of tripping.

PubMed

Handsaker, J C; Brown, S J; Bowling, F L; Marple-Horvat, D E; Boulton, A J M; Reeves, N D

2016-05-01

To examine the stepping accuracy of people with diabetes and diabetic peripheral neuropathy. Fourteen patients with diabetic peripheral neuropathy (DPN), 12 patients with diabetes but no neuropathy (D) and 10 healthy non-diabetic control participants (C). Accuracy of stepping was measured whilst the participants walked along a walkway consisting of 18 stepping targets. Preliminary data on visual gaze characteristics were also captured in a subset of participants (diabetic peripheral neuropathy group: n = 4; diabetes-alone group: n = 4; and control group: n = 4) during the same task. Patients in the diabetic peripheral neuropathy group, and patients in the diabetes-alone group were significantly less accurate at stepping on targets than were control subjects (P < 0.05). Preliminary visual gaze analysis identified that patients diabetic peripheral neuropathy were slower to look between targets, resulting in less time being spent looking at a target before foot-target contact. Impaired motor control is theorized to be a major factor underlying the changes in stepping accuracy, and potentially altered visual gaze behaviour may also play a role. Reduced stepping accuracy may indicate a decreased ability to control the placement of the lower limbs, leading to patients with neuropathy potentially being less able to avoid observed obstacles during walking. © 2015 Diabetes UK.

Macular degeneration affects eye movement behavior during visual search.

PubMed

Van der Stigchel, Stefan; Bethlehem, Richard A I; Klein, Barrie P; Berendschot, Tos T J M; Nijboer, Tanja C W; Dumoulin, Serge O

2013-01-01

Patients with a scotoma in their central vision (e.g., due to macular degeneration, MD) commonly adopt a strategy to direct the eyes such that the image falls onto a peripheral location on the retina. This location is referred to as the preferred retinal locus (PRL). Although previous research has investigated the characteristics of this PRL, it is unclear whether eye movement metrics are modulated by peripheral viewing with a PRL as measured during a visual search paradigm. To this end, we tested four MD patients in a visual search paradigm and contrasted their performance with a healthy control group and a healthy control group performing the same experiment with a simulated scotoma. The experiment contained two conditions. In the first condition the target was an unfilled circle hidden among c-shaped distractors (serial condition) and in the second condition the target was a filled circle (pop-out condition). Saccadic search latencies for the MD group were significantly longer in both conditions compared to both control groups. Results of a subsequent experiment indicated that this difference between the MD and the control groups could not be explained by a difference in target selection sensitivity. Furthermore, search behavior of MD patients was associated with saccades with smaller amplitudes toward the scotoma, an increased intersaccadic interval and an increased number of eye movements necessary to locate the target. Some of these characteristics, such as the increased intersaccadic interval, were also observed in the simulation group, which indicate that these characteristics are related to the peripheral viewing itself. We suggest that the combination of the central scotoma and peripheral viewing can explain the altered search behavior and no behavioral evidence was found for a possible reorganization of the visual system associated with the use of a PRL. Thus the switch from a fovea-based to a PRL-based reference frame impairs search efficiency.

COMPARING PERIPHERAL VITRECTOMY UNDER AIR AND FLUID INFUSION FOR PRIMARY RHEGMATOGENOUS RETINAL DETACHMENT.

PubMed

Erdogan, Gurkan; Unlu, Cihan; Karasu, Bugra; Kardes, Esra; Ergin, Ahmet

2016-07-01

To evaluate the efficacy and safety of peripheral vitrectomy under air infusion in comparison with fluid infusion in patients undergoing 23-gauge pars plana vitrectomy for primary rhegmatogenous retinal detachment. A total of 80 eyes of 80 patients with primary rhegmatogenous retinal detachment were enrolled into the study. Forty cases underwent peripheral vitrectomy under air infusion (air group), and a control group of equal number underwent peripheral vitrectomy under fluid infusion (fluid group). Peripheral iatrogenic retinal breaks during peripheral vitrectomy, postoperative visual acuities, and retinal redetachment rates were compared. The number of eyes with peripheral iatrogenic retinal breaks in air group during peripheral vitrectomy was statistically comparable with that in fluid group (1/40 and 4/40, 2.5% and 10%, respectively; P = 0.16). Scleral depression was necessitated in 7 of 40 cases (17.5%) during the operation in the air group. There were no statistically significant differences between the groups in means of postoperative visual acuity and retinal redetachment (P = 0.18 and P = 1.0, respectively). Peripheral vitrectomy under air infusion for primary rhegmatogenous retinal detachment revealed comparable results with fluid infusion in terms of intraoperative and postoperative complications and surgical outcomes.

Neural Responses to Central and Peripheral Objects in the Lateral Occipital Cortex

PubMed Central

Wang, Bin; Guo, Jiayue; Yan, Tianyi; Ohno, Seiichiro; Kanazawa, Susumu; Huang, Qiang; Wu, Jinglong

2016-01-01

Human object recognition and classification depend on the retinal location where the object is presented and decrease as eccentricity increases. The lateral occipital complex (LOC) is thought to be preferentially involved in the processing of objects, and its neural responses exhibit category biases to objects presented in the central visual field. However, the nature of LOC neural responses to central and peripheral objects remains largely unclear. In the present study, we used functional magnetic resonance imaging (fMRI) and a wide-view presentation system to investigate neural responses to four categories of objects (faces, houses, animals, and cars) in the primary visual cortex (V1) and the lateral visual cortex, including the LOC and the retinotopic areas LO-1 and LO-2. In these regions, the neural responses to objects decreased as the distance between the location of presentation and center fixation increased, which is consistent with the diminished perceptual ability that was found for peripherally presented images. The LOC and LO-2 exhibited significantly positive neural responses to all eccentricities (0–55°), but LO-1 exhibited significantly positive responses only to central eccentricities (0–22°). By measuring the ratio relative to V1 (RRV1), we further demonstrated that eccentricity, category and the interaction between them significantly affected neural processing in these regions. LOC, LO-1, and LO-2 exhibited larger RRV1s when stimuli were presented at an eccentricity of 0° compared to when they were presented at the greater eccentricities. In LOC and LO-2, the RRV1s for images of faces, animals and cars showed an increasing trend when the images were presented at eccentricities of 11 to 33°. However, the RRV1s for houses showed a decreasing trend in LO-1 and no difference in the LOC and LO-2. We hypothesize, that when houses and the images in the other categories were presented in the peripheral visual field, they were processed via different strategies in the lateral visual cortex. PMID:26924972

Device 2F112 (F-14A WST (Weapon System Trainers)) Instructor Console Review.

DTIC Science & Technology

1983-12-01

Cockpit Section-Trainee Station, b. Instructor Operator Station (OS), c. Computer System, d. Wide-Angle Visual System (WAVS), e. Auxiliary Systems. The...relationship of the three stations can be seen in Figure 1. The stations will be reviewed in greater detail in following sections. Fhe computer system...d) Printer 2) TRAINEE AREA 3) HYDRAULIC POWFR ROOM 4) ELEC. POWER/AIR COMPRESSORS 5) COMPUTER /PERIPHERAL AREA Figure 1. Device 2FI12 general layout

Detection of Visual Field Loss in Pituitary Disease: Peripheral Kinetic Versus Central Static

PubMed Central

Rowe, Fiona J.; Cheyne, Christopher P.; García-Fiñana, Marta; Noonan, Carmel P.; Howard, Claire; Smith, Jayne; Adeoye, Joanne

2015-01-01

Abstract Visual field assessment is an important clinical evaluation for eye disease and neurological injury. We evaluated Octopus semi-automated kinetic peripheral perimetry (SKP) and Humphrey static automated central perimetry for detection of neurological visual field loss in patients with pituitary disease. We carried out a prospective cross-sectional diagnostic accuracy study comparing Humphrey central 30-2 SITA threshold programme with a screening protocol for SKP on Octopus perimetry. Humphrey 24-2 data were extracted from 30-2 results. Results were independently graded for presence/absence of field defect plus severity of defect. Fifty patients (100 eyes) were recruited (25 males and 25 females), with mean age of 52.4 years (SD = 15.7). Order of perimeter assessment (Humphrey/Octopus first) and order of eye tested (right/left first) were randomised. The 30-2 programme detected visual field loss in 85%, the 24-2 programme in 80%, and the Octopus combined kinetic/static strategy in 100% of eyes. Peripheral visual field loss was missed by central threshold assessment. Qualitative comparison of type of visual field defect demonstrated a match between Humphrey and Octopus results in 58%, with a match for severity of defect in 50%. Tests duration was 9.34 minutes (SD = 2.02) for Humphrey 30-2 versus 10.79 minutes (SD = 4.06) for Octopus perimetry. Octopus semi-automated kinetic perimetry was found to be superior to central static testing for detection of pituitary disease-related visual field loss. Where reliant on Humphrey central static perimetry, the 30-2 programme is recommended over the 24-2 programme. Where kinetic perimetry is available, this is preferable to central static programmes for increased detection of peripheral visual field loss. PMID:27928344

Effects of Peripheral Visual Field Loss on Eye Movements During Visual Search

PubMed Central

Wiecek, Emily; Pasquale, Louis R.; Fiser, Jozsef; Dakin, Steven; Bex, Peter J.

2012-01-01

Natural vision involves sequential eye movements that bring the fovea to locations selected by peripheral vision. How peripheral visual field loss (PVFL) affects this process is not well understood. We examine how the location and extent of PVFL affects eye movement behavior in a naturalistic visual search task. Ten patients with PVFL and 13 normally sighted subjects with full visual fields (FVF) completed 30 visual searches monocularly. Subjects located a 4° × 4° target, pseudo-randomly selected within a 26° × 11° natural image. Eye positions were recorded at 50 Hz. Search duration, fixation duration, saccade size, and number of saccades per trial were not significantly different between PVFL and FVF groups (p > 0.1). A χ2 test showed that the distributions of saccade directions for PVFL and FVL subjects were significantly different in 8 out of 10 cases (p < 0.01). Humphrey Visual Field pattern deviations for each subject were compared with the spatial distribution of eye movement directions. There were no significant correlations between saccade directional bias and visual field sensitivity across the 10 patients. Visual search performance was not significantly affected by PVFL. An analysis of eye movement directions revealed patients with PVFL show a biased directional distribution that was not directly related to the locus of vision loss, challenging feed-forward models of eye movement control. Consequently, many patients do not optimally compensate for visual field loss during visual search. PMID:23162511

Assessment of the vision-specific quality of life using clustered visual field in glaucoma patients.

PubMed

Sawada, Hideko; Yoshino, Takaiko; Fukuchi, Takeo; Abe, Haruki

2014-02-01

To investigate the significance of vision-specific quality of life (QOL) in glaucoma patients based on the location of visual field defects. We examined 336 eyes of 168 patients. The 25-item National Eye Institute Visual Function Questionnaire was used to evaluate patients' QOL. Visual field testing was performed using the Humphrey Field Analyzer; the visual field was divided into 10 clusters. We defined the eye with better mean deviation as the better eye and the fellow eye as the worse eye. A single linear regression analysis was applied to assess the significance of the relationship between QOL and the clustered visual field. The strongest correlation was observed in the lower paracentral visual field in the better eye. The lower peripheral visual field in the better eye also showed a good correlation. Correlation coefficients in the better eye were generally higher than those in the worse eye. For driving, the upper temporal visual field in the better eye was the most strongly correlated (r=0.509). For role limitation and peripheral vision, the lower peripheral visual field in the better eye had the highest correlation coefficients at 0.459 and 0.425, respectively. Overall, clusters in the lower hemifield in the better eye were more strongly correlated with QOL than those in the worse eye. In particular, the lower paracentral visual field in the better eye was correlated most strongly of all. Driving, however, strongly correlated with the upper hemifield in the better eye.

Use of nontraditional flight displays for the reduction of central visual overload in the cockpit

NASA Technical Reports Server (NTRS)

Weinstein, Lisa F.; Wickens, Christopher D.

1992-01-01

The use of nontraditional flight displays to reduce visual overload in the cockpit was investigated in a dual-task paradigm. Three flight displays (central, peripheral, and ecological) were used between subjects for the primary tasks, and the type of secondary task (object identification or motion judgment) and the presentation of the location of the task in the visual field (central or peripheral) were manipulated with groups. The two visual-spatial tasks were time-shared to study the possibility of a compatibility mapping between task type and task location. The ecological display was found to allow for the most efficient time-sharing.

Why are there eccentricity effects in visual search? Visual and attentional hypotheses.

PubMed

Wolfe, J M; O'Neill, P; Bennett, S C

1998-01-01

In standard visual search experiments, observers search for a target item among distracting items. The locations of target items are generally random within the display and ignored as a factor in data analysis. Previous work has shown that targets presented near fixation are, in fact, found more efficiently than are targets presented at more peripheral locations. This paper proposes that the primary cause of this "eccentricity effect" (Carrasco, Evert, Chang, & Katz, 1995) is an attentional bias that allocates attention preferentially to central items. The first four experiments dealt with the possibility that visual, and not attentional, factors underlie the eccentricity effect. They showed that the eccentricity effect cannot be accounted for by the peripheral reduction in visual sensitivity, peripheral crowding, or cortical magnification. Experiment 5 tested the attention allocation model and also showed that RT x set size effects can be independent of eccentricity effects. Experiment 6 showed that the effective set size in a search task depends, in part, on the eccentricity of the target because observers search from fixation outward.

Recovery from retinal lesions: molecular plasticity mechanisms in visual cortex far beyond the deprived zone.

PubMed

Hu, Tjing-Tjing; Van den Bergh, Gert; Thorrez, Lieven; Heylen, Kevin; Eysel, Ulf T; Arckens, Lutgarde

2011-12-01

In cats with central retinal lesions, deprivation of the lesion projection zone (LPZ) in primary visual cortex (area 17) induces remapping of the cortical topography. Recovery of visually driven cortical activity in the LPZ involves distinct changes in protein expression. Recent observations, about molecular activity changes throughout area 17, challenge the view that its remote nondeprived parts would not be involved in this recovery process. We here investigated the dynamics of the protein expression pattern of remote nondeprived area 17 triggered by central retinal lesions to explore to what extent far peripheral area 17 would contribute to the topographic map reorganization inside the visual cortex. Using functional proteomics, we identified 40 proteins specifically differentially expressed between far peripheral area 17 of control and experimental animals 14 days to 8 months postlesion. Our results demonstrate that far peripheral area 17 is implicated in the functional adaptation to the visual deprivation, involving a meshwork of interacting proteins, operating in diverse pathways. In particular, endocytosis/exocytosis processes appeared to be essential via their intimate correlation with long-term potentiation and neurite outgrowth mechanisms.

Classic Peripheral Signs of Subacute Bacterial Endocarditis

PubMed Central

Chong, Yooyoung; Han, Sung Joon; Rhee, Youn Ju; Kang, Shin Kwang; Yu, Jae Hyeon; Na, Myung Hoon

2016-01-01

A 50-year-old female patient with visual disturbances was referred for further evaluation of a heart murmur. Fundoscopy revealed a Roth spot in both eyes. A physical examination showed peripheral signs of infective endocarditis, including Osler nodes, Janeway lesions, and splinter hemorrhages. Our preoperative diagnosis was subacute bacterial endocarditis with severe aortic regurgitation. The patient underwent aortic valve replacement and was treated with intravenous antibiotics for 6 weeks postoperatively. The patient made a remarkable recovery and was discharged without complications. We report this case of subacute endocarditis with all 4 classic peripheral signs in a patient who presented with visual disturbance. PMID:27734006

Axonal ensheathment and septate junction formation in the peripheral nervous system of Drosophila.

PubMed

Banerjee, Swati; Pillai, Anilkumar M; Paik, Raehum; Li, Jingjun; Bhat, Manzoor A

2006-03-22

Axonal insulation is critical for efficient action potential propagation and normal functioning of the nervous system. In Drosophila, the underlying basis of nerve ensheathment is the axonal insulation by glial cells and the establishment of septate junctions (SJs) between glial cell membranes. However, the details of the cellular and molecular mechanisms underlying axonal insulation and SJ formation are still obscure. Here, we report the characterization of axonal insulation in the Drosophila peripheral nervous system (PNS). Targeted expression of tau-green fluorescent protein in the glial cells and ultrastructural analysis of the peripheral nerves allowed us to visualize the glial ensheathment of axons. We show that individual or a group of axons are ensheathed by inner glial processes, which in turn are ensheathed by the outer perineurial glial cells. SJs are formed between the inner and outer glial membranes. We also show that Neurexin IV, Contactin, and Neuroglian are coexpressed in the peripheral glial membranes and that these proteins exist as a complex in the Drosophila nervous system. Mutations in neurexin IV, contactin, and neuroglian result in the disruption of blood-nerve barrier function in the PNS, and ultrastructural analyses of the mutant embryonic peripheral nerves show loss of glial SJs. Interestingly, the murine homologs of Neurexin IV, Contactin, and Neuroglian are expressed at the paranodal SJs and play a key role in axon-glial interactions of myelinated axons. Together, our data suggest that the molecular machinery underlying axonal insulation and axon-glial interactions may be conserved across species.

Neurophysiological Assessment of Auditory, Peripheral Nerve, Somatosensory, and Visual System Function After Developmental Exposure to Gasoline, E15 and E85 Vapors

EPA Science Inventory

The use of gasolines blended with a range of ethanol concentrations may result in inhalation of vapors containing a variable combination of ethanol with other volatile gasoline constituents. The possibility of exposure and potential interactions between vapor constituents suggest...

Competitive interactions of attentional resources in early visual cortex during sustained visuospatial attention within or between visual hemifields: evidence for the different-hemifield advantage.

PubMed

Walter, Sabrina; Quigley, Cliodhna; Mueller, Matthias M

2014-05-01

Performing a task across the left and right visual hemifields results in better performance than in a within-hemifield version of the task, termed the different-hemifield advantage. Although recent studies used transient stimuli that were presented with long ISIs, here we used a continuous objective electrophysiological (EEG) measure of competitive interactions for attentional processing resources in early visual cortex, the steady-state visual evoked potential (SSVEP). We frequency-tagged locations in each visual quadrant and at central fixation by flickering light-emitting diodes (LEDs) at different frequencies to elicit distinguishable SSVEPs. Stimuli were presented for several seconds, and participants were cued to attend to two LEDs either in one (Within) or distributed across left and right visual hemifields (Across). In addition, we introduced two reference measures: one for suppressive interactions between the peripheral LEDs by using a task at fixation where attention was withdrawn from the periphery and another estimating the upper bound of SSVEP amplitude by cueing participants to attend to only one of the peripheral LEDs. We found significantly greater SSVEP amplitude modulations in Across compared with Within hemifield conditions. No differences were found between SSVEP amplitudes elicited by the peripheral LEDs when participants attended to the centrally located LEDs compared with when peripheral LEDs had to be ignored in Across and Within trials. Attending to only one LED elicited the same SSVEP amplitude as Across conditions. Although behavioral data displayed a more complex pattern, SSVEP amplitudes were well in line with the predictions of the different-hemifield advantage account during sustained visuospatial attention.

Peripheral neuropathy may not be the only fundamental reason explaining increased sway in diabetic individuals.

PubMed

Bonnet, Cédrick T; Ray, Christopher

2011-08-01

Individuals with diabetic neuropathy sway more than control individuals while standing. This review specifically evaluated whether peripheral sensory neuropathy can be the only fundamental reason accounting for significant increased sway within this population. Twenty-six experimental articles were selected using MEDLINE and reference lists of relevant articles. The articles chosen investigated kinematic data of postural behaviour in controls and individuals with diabetic neuropathy during stance. Results of literature were compared with four expectations related to the peripheral sensory neuropathy fundamental hypothesis. Consistent with the peripheral sensory neuropathy hypothesis, the literature showed that individuals with diabetic neuropathy sway more than controls in quiet stance and even more so if their visual or vestibular systems were perturbed. Inconsistent with the hypothesis, individuals with diabetic neuropathy are more destabilised than controls in conditions altering sensation of the feet and legs (standing on a sway-referenced surface). The review showed that the peripheral sensory neuropathy hypothesis may not be the only fundamental cause accounting for significant increased postural sway in individuals with diabetic neuropathy. Visual impairments and changes in postural coordination may explain the divergence between expectations and results. In order to develop interventions aimed at improving postural control in individuals with diabetic neuropathy, scientific exploration of these new expectations should be detailed. Also at the practical level, the review discussed which additional sensory information - at the level of the hands and feet - may be more beneficial in individuals with diabetic neuropathy to reduce their postural sway. Copyright © 2011 Elsevier Ltd. All rights reserved.

The effect of acute sleep deprivation on visual evoked potentials in professional drivers.

PubMed

Jackson, Melinda L; Croft, Rodney J; Owens, Katherine; Pierce, Robert J; Kennedy, Gerard A; Crewther, David; Howard, Mark E

2008-09-01

Previous studies have demonstrated that as little as 18 hours of sleep deprivation can cause deleterious effects on performance. It has also been suggested that sleep deprivation can cause a "tunnel-vision" effect, in which attention is restricted to the center of the visual field. The current study aimed to replicate these behavioral effects and to examine the electrophysiological underpinnings of these changes. Repeated-measures experimental study. University laboratory. Nineteen professional drivers (1 woman; mean age = 45.3 +/- 9.1 years). Two experimental sessions were performed; one following 27 hours of sleep deprivation and the other following a normal night of sleep, with control for circadian effects. A tunnel-vision task (central versus peripheral visual discrimination) and a standard checkerboard-viewing task were performed while 32-channel EEG was recorded. For the tunnel-vision task, sleep deprivation resulted in an overall slowing of reaction times and increased errors of omission for both peripheral and foveal stimuli (P < 0.05). These changes were related to reduced P300 amplitude (indexing cognitive processing) but not measures of early visual processing. No evidence was found for an interaction effect between sleep deprivation and visual-field position, either in terms of behavior or electrophysiological responses. Slower processing of the sustained parvocellular visual pathway was demonstrated. These findings suggest that performance deficits on visual tasks during sleep deprivation are due to higher cognitive processes rather than early visual processing. Sleep deprivation may differentially impair processing of more-detailed visual information. Features of the study design (eg, visual angle, duration of sleep deprivation) may influence whether peripheral visual-field neglect occurs.

Evaluation of peripheral binocular visual field in patients with glaucoma: a pilot study

PubMed Central

Ana, Banc; Cristina, Stan; Dorin, Chiselita

2016-01-01

Objective: The objective of this study was to evaluate the peripheral binocular visual field (PBVF) in patients with glaucoma using the threshold strategy of Humphrey Field Analyzer. Methods: We conducted a case-control pilot study in which we enrolled 59 patients with glaucoma and 20 controls. All participants were evaluated using a custom PBVF test and central 24° monocular visual field tests for each eye using the threshold strategy. The central binocular visual field (CBVF) was predicted from the monocular tests using the most sensitive point at each field location. The glaucoma patients were grouped according to Hodapp classification and age. The PBVF was compared to controls and the relationship between the PBVF and CBVF was tested. Results: The areas of frame-induced artefacts were determined (over 50° in each temporal field, 24° superiorly and 45° inferiorly) and excluded from interpretation. The patients presented a statistically significant generalized decrease of the peripheral retinal sensitivity compared to controls for Hodapp initial stage - groups aged 50-59 (t = 11.93 > 2.06; p < 0.05) and 60-69 (t = 7.55 > 2.06; p < 0.05). For the initial Hodapp stage there was no significant relationship between PBVF and CBVF (r = 0.39). For the moderate and advanced Hodapp stages, the interpretation of data was done separately for each patient. Conclusions: This pilot study suggests that glaucoma patients present a decrease of PBVF compared to controls and CBVF cannot predict the PBVF in glaucoma. Abbreviations: CBVF = central binocular visual field, PBVF = peripheral binocular visual field, MD = mean deviation PMID:27220228

Towards an assistive peripheral visual prosthesis for long-term treatment of retinitis pigmentosa: evaluating mobility performance in immersive simulations

NASA Astrophysics Data System (ADS)

Zapf, Marc Patrick H.; Boon, Mei-Ying; Matteucci, Paul B.; Lovell, Nigel H.; Suaning, Gregg J.

2015-06-01

Objective. The prospective efficacy of a future peripheral retinal prosthesis complementing residual vision to raise mobility performance in non-end stage retinitis pigmentosa (RP) was evaluated using simulated prosthetic vision (SPV). Approach. Normally sighted volunteers were fitted with a wide-angle head-mounted display and carried out mobility tasks in photorealistic virtual pedestrian scenarios. Circumvention of low-lying obstacles, path following, and navigating around static and moving pedestrians were performed either with central simulated residual vision of 10° alone or enhanced by assistive SPV in the lower and lateral peripheral visual field (VF). Three layouts of assistive vision corresponding to hypothetical electrode array layouts were compared, emphasizing higher visual acuity, a wider visual angle, or eccentricity-dependent acuity across an intermediate angle. Movement speed, task time, distance walked and collisions with the environment were analysed as performance measures. Main results. Circumvention of low-lying obstacles was improved with all tested configurations of assistive SPV. Higher-acuity assistive vision allowed for greatest improvement in walking speeds—14% above that of plain residual vision, while only wide-angle and eccentricity-dependent vision significantly reduced the number of collisions—both by 21%. Navigating around pedestrians, there were significant reductions in collisions with static pedestrians by 33% and task time by 7.7% with the higher-acuity layout. Following a path, higher-acuity assistive vision increased walking speed by 9%, and decreased collisions with stationary cars by 18%. Significance. The ability of assistive peripheral prosthetic vision to improve mobility performance in persons with constricted VFs has been demonstrated. In a prospective peripheral visual prosthesis, electrode array designs need to be carefully tailored to the scope of tasks in which a device aims to assist. We posit that maximum benefit might come from application alongside existing visual aids, to further raise life quality of persons living through the prolonged early stages of RP.

Novel Immunohistochemical Techniques Using Discrete Signal Amplification Systems for Human Cutaneous Peripheral Nerve Fiber Imaging

PubMed Central

Wang, Ningshan; Gibbons, Christopher H.; Freeman, Roy

2011-01-01

Confocal imaging uses immunohistochemical binding of specific antibodies to visualize tissues, but technical obstacles limit more widespread use of this technique in the imaging of peripheral nerve tissue. These obstacles include same-species antibody cross-reactivity and weak fluorescent signals of individual and co-localized antigens. The aims of this study were to develop new immunohistochemical techniques for imaging of peripheral nerve fibers. Three-millimeter punch skin biopsies of healthy individuals were fixed, frozen, and cut into 50-µm sections. Tissues were stained with a variety of antibody combinations with two signal amplification systems, streptavidin-biotin-fluorochrome (sABC) and tyramide-horseradish peroxidase-fluorochrome (TSA), used simultaneously to augment immunohistochemical signals. The combination of the TSA and sABC amplification systems provided the first successful co-localization of sympathetic adrenergic and sympathetic cholinergic nerve fibers in cutaneous human sweat glands and vasomotor and pilomotor systems. Primary antibodies from the same species were amplified individually without cross-reactivity or elevated background interference. The confocal fluorescent signal-to-noise ratio increased, and image clarity improved. These modifications to signal amplification systems have the potential for widespread use in the study of human neural tissues. PMID:21411809

Assessment of hydroxychloroquine maculopathy after cessation of treatment: an optical coherence tomography and multifocal electroretinography study

PubMed Central

Moschos, Marilita M; Nitoda, Eirini; Chatziralli, Irini P; Gatzioufas, Zisis; Koutsandrea, Chryssanthi; Kitsos, George

2015-01-01

Objective This study was conducted to evaluate the macular status of patients treated with hydroxychloroquine before and after cessation of treatment. Methods Forty-two patients with systemic lupus erythematosus underwent ocular examination based on visual acuity evaluation, optical coherence tomography retinal thickness measurements, and multifocal electroretinography (mfERG) records at first visit. The tests were repeated 6 months after treatment withdrawal and compared to the findings at their first visit. Results Mean visual acuity (measured in log minimum angle of resolution) of both eyes was statistically increased after hydroxychloroquine discontinuation (difference in means: 0.06 [P<0.0001] and 0.01 [P=0.003] for the right and left eyes, respectively). Retinal response amplitudes of central and peripheral areas were significantly improved for both eyes. The following values were observed for central responses: the difference in means was −19.9 (P<0.0001) and −13.6 (P<0.0001) for the right eye and the left eye, respectively; for peripheral responses, difference in means was −10.3 (P<0.0001) and −9.5 (P<0.0001) for right eye and left eye, respectively, after the 6-month examination. There were no statistically significant differences in the retinal thickness of patients after cessation of treatment. The visual acuity of the patients was correlated to central and peripheral mfERG responses (r=−0.53 [P<0.0001] and r=−0.53 [P<0.0001], for the right eye and the left eye, respectively). Conclusion The visual acuity of patients receiving hydroxychloroquine improves along with the amplitudes of the mfERG responses 6 months after discontinuation of the drug, but no difference in retinal thickness is identified. PMID:26089648

Assessment of hydroxychloroquine maculopathy after cessation of treatment: an optical coherence tomography and multifocal electroretinography study.

PubMed

Moschos, Marilita M; Nitoda, Eirini; Chatziralli, Irini P; Gatzioufas, Zisis; Koutsandrea, Chryssanthi; Kitsos, George

2015-01-01

This study was conducted to evaluate the macular status of patients treated with hydroxychloroquine before and after cessation of treatment. Forty-two patients with systemic lupus erythematosus underwent ocular examination based on visual acuity evaluation, optical coherence tomography retinal thickness measurements, and multifocal electroretinography (mfERG) records at first visit. The tests were repeated 6 months after treatment withdrawal and compared to the findings at their first visit. Mean visual acuity (measured in log minimum angle of resolution) of both eyes was statistically increased after hydroxychloroquine discontinuation (difference in means: 0.06 [P<0.0001] and 0.01 [P=0.003] for the right and left eyes, respectively). Retinal response amplitudes of central and peripheral areas were significantly improved for both eyes. The following values were observed for central responses: the difference in means was -19.9 (P<0.0001) and -13.6 (P<0.0001) for the right eye and the left eye, respectively; for peripheral responses, difference in means was -10.3 (P<0.0001) and -9.5 (P<0.0001) for right eye and left eye, respectively, after the 6-month examination. There were no statistically significant differences in the retinal thickness of patients after cessation of treatment. The visual acuity of the patients was correlated to central and peripheral mfERG responses (r=-0.53 [P<0.0001] and r=-0.53 [P<0.0001], for the right eye and the left eye, respectively). The visual acuity of patients receiving hydroxychloroquine improves along with the amplitudes of the mfERG responses 6 months after discontinuation of the drug, but no difference in retinal thickness is identified.

Peripheral resolution and contrast sensitivity: Effects of stimulus drift.

PubMed

Venkataraman, Abinaya Priya; Lewis, Peter; Unsbo, Peter; Lundström, Linda

2017-04-01

Optimal temporal modulation of the stimulus can improve foveal contrast sensitivity. This study evaluates the characteristics of the peripheral spatiotemporal contrast sensitivity function in normal-sighted subjects. The purpose is to identify a temporal modulation that can potentially improve the remaining peripheral visual function in subjects with central visual field loss. High contrast resolution cut-off for grating stimuli with four temporal frequencies (0, 5, 10 and 15Hz drift) was first evaluated in the 10° nasal visual field. Resolution contrast sensitivity for all temporal frequencies was then measured at four spatial frequencies between 0.5 cycles per degree (cpd) and the measured stationary cut-off. All measurements were performed with eccentric optical correction. Similar to foveal vision, peripheral contrast sensitivity is highest for a combination of low spatial frequency and 5-10Hz drift. At higher spatial frequencies, there was a decrease in contrast sensitivity with 15Hz drift. Despite this decrease, the resolution cut-off did not vary largely between the different temporal frequencies tested. Additional measurements of contrast sensitivity at 0.5 cpd and resolution cut-off for stationary (0Hz) and 7.5Hz stimuli performed at 10, 15, 20 and 25° in the nasal visual field also showed the same characteristics across eccentricities. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Eye Movements of Patients with Tunnel Vision while Walking

PubMed Central

Vargas-Martín, Fernando; Peli, Eli

2006-01-01

Purpose To determine how severe peripheral field loss (PFL) affects the dispersion of eye movements relative to the head, while walking in real environments. This information should help to better define the visual field and clearance requirements for head-mounted mobility visual aids. Methods Eye positions relative to the head were recorded in five retinitis pigmentosa patients with less than 15° of visual field and three normally-sighted people, each walking in varied environments for more than 30 minutes. The eye position recorder was made portable by modifying a head-mounted ISCAN system. Custom data processing was implemented to reject unreliable data. Sample standard deviations of eye position (dispersion) were compared across subject groups and environments. Results PFL patients exhibited narrower horizontal eye position dispersions than normally-sighted subjects (9.4° vs. 14.2°, p < 0.0001) and PFL patients’ vertical dispersions were smaller when walking indoors than outdoors (8.2° vs. 10.3°, p = 0.048). Conclusions When walking, the PFL patients did not increase their scanning eye movements to compensate for missing peripheral vision information. Their horizontal scanning was actually reduced, possibly because saccadic amplitude is limited by a lack of peripheral stimulation. The results suggest that a field-of-view as wide as 40° may be needed for closed (immersive) head-mounted mobility aids, while a much narrower display, perhaps as narrow as 20°, might be sufficient with an open design. PMID:17122116

Eye movements of patients with tunnel vision while walking.

PubMed

Vargas-Martín, Fernando; Peli, Eli

2006-12-01

To determine how severe peripheral field loss (PFL) affects the dispersion of eye movements relative to the head in patients walking in real environments. This information should help to define the visual field and clearance requirements for head-mounted mobility visual aids. Eye positions relative to the head were recorded in five patients with retinitis pigmentosa who had less than 15 degrees of visual field and in three normally sighted people, each walking in varied environments for more than 30 minutes. The eye-position recorder was made portable by modifying a head-mounted system (ISCAN, Burlington, MA). Custom data processing was implemented, to reject unreliable data. Sample standard deviations of eye position (dispersion) were compared across subject groups and environments. The patients with PFL exhibited narrower horizontal eye-position dispersions than did the normally sighted subjects (9.4 degrees vs. 14.2 degrees , P < 0.0001), and the vertical dispersions of patients with PFL were smaller when they were walking indoors than when walking outdoors (8.2 degrees vs. 10.3 degrees ; P = 0.048). When walking, the patients with PFL did not increase their scanning eye movements to compensate for missing peripheral vision information. Their horizontal scanning was actually reduced, possibly because of lack of peripheral stimulation. The results suggest that a field of view as wide as 40 degrees may be needed for closed (immersive) head-mounted mobility aids, whereas a much narrower display, perhaps as narrow as 20 degrees , may be sufficient with an open design.

Perception of linear horizontal self-motion induced by peripheral vision /linearvection/ - Basic characteristics and visual-vestibular interactions

NASA Technical Reports Server (NTRS)

Berthoz, A.; Pavard, B.; Young, L. R.

1975-01-01

The basic characteristics of the sensation of linear horizontal motion have been studied. Objective linear motion was induced by means of a moving cart. Visually induced linear motion perception (linearvection) was obtained by projection of moving images at the periphery of the visual field. Image velocity and luminance thresholds for the appearance of linearvection have been measured and are in the range of those for image motion detection (without sensation of self motion) by the visual system. Latencies of onset are around 1 sec and short term adaptation has been shown. The dynamic range of the visual analyzer as judged by frequency analysis is lower than the vestibular analyzer. Conflicting situations in which visual cues contradict vestibular and other proprioceptive cues show, in the case of linearvection a dominance of vision which supports the idea of an essential although not independent role of vision in self motion perception.

Evaluation of central and peripheral neuropathy in patients with chronic obstructive pulmonary disease.

PubMed

Aras, Yeşim Güzey; Aydemir, Yusuf; Güngen, Belma Doğan; Güngen, Adil Can

2018-01-01

The aim of the study was to investigate the frequency and characteristics of peripheral nervous system (PNS) and central nervous system (CNS) involvement in COPD. The study included 41 COPD patients and 41 healthy volunteers. Electrophysiological studies were carried out: electromyography (EMG) and visual evoked potentials (VEPs). The median nerve, ulnar nerve, common peroneal nerve, and tibial nerve were evaluated for latency, amplitude, and conduction velocity. The mean age of patients with COPD was 61.8 years and disease duration 10.3 years. There was no difference between patient and control groups in terms of age, BMI, smoking status, or biochemical parameters. Upon VEP examination, latencies were significantly prolonged and amplitudes shortened in the patient group compared to the control group. In EMG measurements, conduction velocity and amplitudes in all nerves were low in the patient group. Similarly, latencies in all nerves were higher in patients with COPD. Central and peripheral nervous system involvement could develop in patients with moderate-severe COPD, and these patients should be monitored for neuropathic changes in combination with neurological examination.

Rotary acceleration of a subject inhibits choice reaction time to motion in peripheral vision

NASA Technical Reports Server (NTRS)

Borkenhagen, J. M.

1974-01-01

Twelve pilots were tested in a rotation device with visual simulation, alone and in combination with rotary stimulation, in experiments with variable levels of acceleration and variable viewing angles, in a study of the effect of S's rotary acceleration on the choice reaction time for an accelerating target in peripheral vision. The pilots responded to the direction of the visual motion by moving a hand controller to the right or left. Visual-plus-rotary stimulation required a longer choice reaction time, which was inversely related to the level of acceleration and directly proportional to the viewing angle.

Neurophysiological assessment of auditory, peripheral nerve, somatosensory, and visual system function after developmental exposure to gasoline, E15, and E85 vapors.

PubMed

Herr, David W; Freeborn, Danielle L; Degn, Laura; Martin, Sheppard A; Ortenzio, Jayna; Pantlin, Lara; Hamm, Charles W; Boyes, William K

2016-01-01

The use of gasolines blended with a range of ethanol concentrations may result in inhalation of vapors containing a variable combination of ethanol with other volatile gasoline constituents. The possibility of exposure and potential interactions between vapor constituents suggests the need to evaluate the possible risks of this complex mixture. Previously we evaluated the effects of developmental exposure to ethanol vapors on neurophysiological measures of sensory function as a component of a larger project evaluating developmental ethanol toxicity. Here we report an evaluation using the same battery of sensory function testing in offspring of pregnant dams exposed during gestation to condensed vapors of gasoline (E0), gasoline blended with 15% ethanol (E15) or gasoline blended with 85% ethanol (E85). Pregnant Long-Evans rats were exposed to target concentrations 0, 3000, 6000, or 9000 ppm total hydrocarbon vapors for 6.5h/day over GD9 - GD20. Sensory evaluations of male offspring began as adults. The electrophysiological testing battery included tests of: peripheral nerve (compound action potentials, nerve conduction velocity [NCV]), somatosensory (cortical and cerebellar evoked potentials), auditory (brainstem auditory evoked responses), and visual functions. Visual function assessment included pattern elicited visual evoked potentials (VEP), VEP contrast sensitivity, dark-adapted (scotopic) electroretinograms (ERGs), light-adapted (photopic) ERGs, and green flicker ERGs. The results included sporadic statistically significant effects, but the observations were not consistently concentration-related and appeared to be statistical Type 1 errors related to multiple dependent measures evaluated. The exposure concentrations were much higher than can be reasonably expected from typical exposures to the general population during refueling or other common exposure situations. Overall the results indicate that gestational exposure of male rats to ethanol/gasoline vapor combinations did not cause detectable changes in peripheral nerve, somatosensory, auditory, or visual function when the offspring were assessed as adults. Published by Elsevier Inc.

75 FR 75681 - Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-06

... of [beta]-amyloid (beta-amyloid) aggregates in the brain to help rule out Alzheimer's disease. On... children (2 years of age and older) to detect and visualize areas with disrupted blood brain barrier (BBB... bloodstream into the brain. FDA intends to make background material available to the public no later than 2...

Vision-related fitness to drive mobility scooters: A practical driving test.

PubMed

Cordes, Christina; Heutink, Joost; Tucha, Oliver M; Brookhuis, Karel A; Brouwer, Wiebo H; Melis-Dankers, Bart J M

2017-03-06

To investigate practical fitness to drive mobility scooters, comparing visually impaired participants with healthy controls. Between-subjects design. Forty-six visually impaired (13 with very low visual acuity, 10 with low visual acuity, 11 with peripheral field defects, 12 with multiple visual impairment) and 35 normal-sighted controls. Participants completed a practical mobility scooter test-drive, which was recorded on video. Two independent occupational therapists specialized in orientation and mobility evaluated the videos systematically. Approximately 90% of the visually impaired participants passed the driving test. On average, participants with visual impairments performed worse than normal-sighted controls, but were judged sufficiently safe. In particular, difficulties were observed in participants with peripheral visual field defects and those with a combination of low visual acuity and visual field defects. People with visual impairment are, in practice, fit to drive mobility scooters; thus visual impairment on its own should not be viewed as a determinant of safety to drive mobility scooters. However, special attention should be paid to individuals with visual field defects with or without a combined low visual acuity. The use of an individual practical fitness-to-drive test is advised.

Peripheral Refraction, Peripheral Eye Length, and Retinal Shape in Myopia.

PubMed

Verkicharla, Pavan K; Suheimat, Marwan; Schmid, Katrina L; Atchison, David A

2016-09-01

To investigate how peripheral refraction and peripheral eye length are related to retinal shape. Relative peripheral refraction (RPR) and relative peripheral eye length (RPEL) were determined in 36 young adults (M +0.75D to -5.25D) along horizontal and vertical visual field meridians out to ±35° and ±30°, respectively. Retinal shape was determined in terms of vertex radius of curvature Rv, asphericity Q, and equivalent radius of curvature REq using a partial coherence interferometry method involving peripheral eye lengths and model eye raytracing. Second-order polynomial fits were applied to RPR and RPEL as functions of visual field position. Linear regressions were determined for the fits' second order coefficients and for retinal shape estimates as functions of central spherical refraction. Linear regressions investigated relationships of RPR and RPEL with retinal shape estimates. Peripheral refraction, peripheral eye lengths, and retinal shapes were significantly affected by meridian and refraction. More positive (hyperopic) relative peripheral refraction, more negative RPELs, and steeper retinas were found along the horizontal than along the vertical meridian and in myopes than in emmetropes. RPR and RPEL, as represented by their second-order fit coefficients, correlated significantly with retinal shape represented by REq. Effects of meridian and refraction on RPR and RPEL patterns are consistent with effects on retinal shape. Patterns derived from one of these predict the others: more positive (hyperopic) RPR predicts more negative RPEL and steeper retinas, more negative RPEL predicts more positive relative peripheral refraction and steeper retinas, and steeper retinas derived from peripheral eye lengths predict more positive RPR.

The BHVI-EyeMapper: peripheral refraction and aberration profiles.

PubMed

Fedtke, Cathleen; Ehrmann, Klaus; Falk, Darrin; Bakaraju, Ravi C; Holden, Brien A

2014-10-01

The aim of this article was to present the optical design of a new instrument (BHVI-EyeMapper, EM), which is dedicated to rapid peripheral wavefront measurements across the visual field for distance and near, and to compare the peripheral refraction and higher-order aberration profiles obtained in myopic eyes with and without accommodation. Central and peripheral refractive errors (M, J180, and J45) and higher-order aberrations (C[3, 1], C[3, 3], and C[4, 0]) were measured in 26 myopic participants (mean [±SD] age, 20.9 [±2.0] years; mean [±SD] spherical equivalent, -3.00 [±0.90] diopters [D]) corrected for distance. Measurements were performed along the horizontal visual field with (-2.00 to -5.00 D) and without (+1.00 D fogging) accommodation. Changes as a function of accommodation were compared using tilt and curvature coefficients of peripheral refraction and aberration profiles. As accommodation increased, the relative peripheral refraction profiles of M and J180 became significantly (p < 0.05) more negative and the profile of M became significantly (p < 0.05) more asymmetric. No significant differences were found for the J45 profiles (p > 0.05). The peripheral aberration profiles of C[3, 1], C[3, 3], and C[4, 0] became significantly (p < 0.05) less asymmetric as accommodation increased, but no differences were found in the curvature. The current study showed that significant changes in peripheral refraction and higher-order aberration profiles occurred during accommodation in myopic eyes. With its extended measurement capabilities, that is, permitting rapid peripheral refraction and higher-order aberration measurements up to visual field angles of ±50 degrees for distance and near (up to -5.00 D), the EM is a new advanced instrument that may provide additional insights in the ongoing quest to understand and monitor myopia development.

The BHVI-EyeMapper: Peripheral Refraction and Aberration Profiles

PubMed Central

Fedtke, Cathleen; Ehrmann, Klaus; Falk, Darrin; Bakaraju, Ravi C.; Holden, Brien A.

2014-01-01

ABSTRACT Purpose The aim of this article was to present the optical design of a new instrument (BHVI-EyeMapper, EM), which is dedicated to rapid peripheral wavefront measurements across the visual field for distance and near, and to compare the peripheral refraction and higher-order aberration profiles obtained in myopic eyes with and without accommodation. Methods Central and peripheral refractive errors (M, J180, and J45) and higher-order aberrations (C[3, 1], C[3, 3], and C[4, 0]) were measured in 26 myopic participants (mean [±SD] age, 20.9 [±2.0] years; mean [±SD] spherical equivalent, −3.00 [±0.90] diopters [D]) corrected for distance. Measurements were performed along the horizontal visual field with (−2.00 to −5.00 D) and without (+1.00 D fogging) accommodation. Changes as a function of accommodation were compared using tilt and curvature coefficients of peripheral refraction and aberration profiles. Results As accommodation increased, the relative peripheral refraction profiles of M and J180 became significantly (p < 0.05) more negative and the profile of M became significantly (p < 0.05) more asymmetric. No significant differences were found for the J45 profiles (p > 0.05). The peripheral aberration profiles of C[3, 1], C[3, 3], and C[4, 0] became significantly (p < 0.05) less asymmetric as accommodation increased, but no differences were found in the curvature. Conclusions The current study showed that significant changes in peripheral refraction and higher-order aberration profiles occurred during accommodation in myopic eyes. With its extended measurement capabilities, that is, permitting rapid peripheral refraction and higher-order aberration measurements up to visual field angles of ±50 degrees for distance and near (up to −5.00 D), the EM is a new advanced instrument that may provide additional insights in the ongoing quest to understand and monitor myopia development. PMID:25105690

Patterns of peripheral retinal and central macula ischemia in diabetic retinopathy as evaluated by ultra-widefield fluorescein angiography.

PubMed

Sim, Dawn A; Keane, Pearse A; Rajendram, Ranjan; Karampelas, Michael; Selvam, Senthil; Powner, Michael B; Fruttiger, Marcus; Tufail, Adnan; Egan, Catherine A

2014-07-01

To investigate the association between peripheral and central ischemia in diabetic retinopathy. Retrospective, cross-sectional. Consecutive ultra-widefield fluorescein angiography images were collected from patients with diabetes over a 12-month period. Parameters quantified include the foveal avascular zone (FAZ) area, peripheral ischemic index, peripheral leakage index, and central retinal thickness measurements, as well as visual acuity. The peripheral ischemia or leakage index was calculated as the area of capillary nonperfusion or leakage, expressed as a percentage of the total retinal area. Forty-seven eyes of 47 patients were included. A moderate correlation was observed between the peripheral ischemia index and FAZ area (r = 0.49, P = .0001). A moderate correlation was also observed between the peripheral leakage index and FAZ area, but only in eyes that were laser naïve (r = 0.44, P = .02). A thinner retina was observed in eyes with macular ischemia (217 ± 81.8 μm vs 272 ± 36.0 μm) (P = .02), but not peripheral ischemia (258 ± 76.3 μm vs 276 ± 68.0 μm) (P = .24). The relationships between different patterns of peripheral and central macular pathology and visual acuity were evaluated in a step-wise multivariable regression model, and the variables that remained independently associated were age (r = 0.33, P = .03), FAZ area (r = 0.45, P = .02), and central retinal thickness (r = 0.38, P = .01), (R(2)-adjusted = 0.36). Ultra-widefield fluorescein angiography provides an insight into the relationships between diabetic vascular complications in the retinal periphery and central macula. Although we observed relationships between ischemia and vascular leakage in the macula and periphery, it was only macular ischemia and retinal thinning that was independently associated with a reduced visual function. Copyright © 2014 Elsevier Inc. All rights reserved.

Assistive peripheral phosphene arrays deliver advantages in obstacle avoidance in simulated end-stage retinitis pigmentosa: a virtual-reality study

NASA Astrophysics Data System (ADS)

Zapf, Marc Patrick H.; Boon, Mei-Ying; Lovell, Nigel H.; Suaning, Gregg J.

2016-04-01

Objective. The prospective efficacy of peripheral retinal prostheses for guiding orientation and mobility in the absence of residual vision, as compared to an implant for the central visual field (VF), was evaluated using simulated prosthetic vision (SPV). Approach. Sighted volunteers wearing a head-mounted display performed an obstacle circumvention task under SPV. Mobility and orientation performance with three layouts of prosthetic vision were compared: peripheral prosthetic vision of higher visual acuity (VA) but limited VF, of wider VF but limited VA, as well as centrally restricted prosthetic vision. Learning curves using these layouts were compared fitting an exponential model to the mobility and orientation measures. Main results. Using peripheral layouts, performance was superior to the central layout. Walking speed with both higher-acuity and wider-angle layouts was 5.6% higher, and mobility errors reduced by 46.4% and 48.6%, respectively, as compared to the central layout. The wider-angle layout yielded the least number of collisions, 63% less than the higher-acuity and 73% less than the central layout. Using peripheral layouts, the number of visual-scanning related head movements was 54.3% (higher-acuity) and 60.7% (wider-angle) lower, as compared to the central layout, and the ratio of time standing versus time walking was 51.9% and 61.5% lower, respectively. Learning curves did not differ between layouts, except for time standing versus time walking, where both peripheral layouts achieved significantly lower asymptotic values compared to the central layout. Significance. Beyond complementing residual vision for an improved performance, peripheral prosthetic vision can effectively guide mobility in the later stages of retinitis pigmentosa (RP) without residual vision. Further, the temporal dynamics of learning peripheral and central prosthetic vision are similar. Therefore, development of a peripheral retinal prosthesis and early implantation to alleviate VF constriction in RP should be considered to extend the target group and the time of benefit for potential retinal prosthesis implantees.

Development of a new extracorporeal whole-liver perfusion system.

PubMed

Naruse, Katsutoshi; Sakai, Yasuyuki; Guo, Lei; Natori, Takeshi; Shindoh, Junichi; Karasawa, Yasuaki; Iida, Yuhki; Kojima, Kentaro; Michishita, Kazuya; Makuuchi, Masatoshi

2003-01-01

We have developed a new extracorporeal whole-liver accommodation device in which a whole swine liver is placed in a physiological state by modeling the intraabdominal arrangement in the pig body, with the liver supported by a special inferior vena cava tube. Furthermore, we employed a diaphragm-type artificial heart in our system to produce pulsatile blood flow through the hepatic artery, which is considered to be indispensable to dilate peripheral vessels and supply oxygenated whole blood to the peripheral liver tissue. Beneficial effects were demonstrated in visual findings and bile juice secretion. The color of the liver surface in our system remained bright red, indicating that the liver vessels were well drained and free from congestion, and bile juice secretion was maintained at more than 10 ml/h throughout the perfusion period. Our system exhibited excellent ammonia removal and urea nitrogen synthesis, and serum aspartate aminotransferase levels showed no increase, indicating the absence of hepatocyte destruction. Histological findings showed that the liver could expand appropriately and was free from compression caused by its own weight. In conclusion, our original liver accommodation device enabled appropriate expansion of the whole liver and supplied adequate oxygenated blood to peripheral areas by means of a pulsatile pump.

Signal evaluation environment: a new method for the design of peripheral in-vehicle warning signals.

PubMed

Werneke, Julia; Vollrath, Mark

2011-06-01

An evaluation method called the Signal Evaluation Environment (SEE) was developed for use in the early stages of the design process of peripheral warning signals while driving. Accident analyses have shown that with complex driving situations such as intersections, the visual scan strategies of the driver contribute to overlooking other road users who have the right of way. Salient peripheral warning signals could disrupt these strategies and direct drivers' attention towards these road users. To select effective warning signals, the SEE was developed as a laboratory task requiring visual-cognitive processes similar to those used at intersections. For validation of the SEE, four experiments were conducted using different stimulus characteristics (size, colour contrast, shape, flashing) that influence peripheral vision. The results confirm that the SEE is able to differentiate between the selected stimulus characteristics. The SEE is a useful initial tool for designing peripheral signals, allowing quick and efficient preselection of beneficial signals.

Decreased visual detection during subliminal stimulation.

PubMed

Bareither, Isabelle; Villringer, Arno; Busch, Niko A

2014-10-17

What is the perceptual fate of invisible stimuli-are they processed at all and does their processing have consequences for the perception of other stimuli? As has been shown previously in the somatosensory system, even stimuli that are too weak to be consciously detected can influence our perception: Subliminal stimulation impairs perception of near-threshold stimuli and causes a functional deactivation in the somatosensory cortex. In a recent study, we showed that subliminal visual stimuli lead to similar responses, indicated by an increase in alpha-band power as measured with electroencephalography (EEG). In the current study, we investigated whether a behavioral inhibitory mechanism also exists within the visual system. We tested the detection of peripheral visual target stimuli under three different conditions: Target stimuli were presented alone or embedded in a concurrent train of subliminal stimuli either at the same location as the target or in the opposite hemifield. Subliminal stimuli were invisible due to their low contrast, not due to a masking procedure. We demonstrate that target detection was impaired by the subliminal stimuli, but only when they were presented at the same location as the target. This finding indicates that subliminal, low-intensity stimuli induce a similar inhibitory effect in the visual system as has been observed in the somatosensory system. In line with previous reports, we propose that the function underlying this effect is the inhibition of spurious noise by the visual system. © 2014 ARVO.

A novel computational model to probe visual search deficits during motor performance

PubMed Central

Singh, Tarkeshwar; Fridriksson, Julius; Perry, Christopher M.; Tryon, Sarah C.; Ross, Angela; Fritz, Stacy

2016-01-01

Successful execution of many motor skills relies on well-organized visual search (voluntary eye movements that actively scan the environment for task-relevant information). Although impairments of visual search that result from brain injuries are linked to diminished motor performance, the neural processes that guide visual search within this context remain largely unknown. The first objective of this study was to examine how visual search in healthy adults and stroke survivors is used to guide hand movements during the Trail Making Test (TMT), a neuropsychological task that is a strong predictor of visuomotor and cognitive deficits. Our second objective was to develop a novel computational model to investigate combinatorial interactions between three underlying processes of visual search (spatial planning, working memory, and peripheral visual processing). We predicted that stroke survivors would exhibit deficits in integrating the three underlying processes, resulting in deteriorated overall task performance. We found that normal TMT performance is associated with patterns of visual search that primarily rely on spatial planning and/or working memory (but not peripheral visual processing). Our computational model suggested that abnormal TMT performance following stroke is associated with impairments of visual search that are characterized by deficits integrating spatial planning and working memory. This innovative methodology provides a novel framework for studying how the neural processes underlying visual search interact combinatorially to guide motor performance. NEW & NOTEWORTHY Visual search has traditionally been studied in cognitive and perceptual paradigms, but little is known about how it contributes to visuomotor performance. We have developed a novel computational model to examine how three underlying processes of visual search (spatial planning, working memory, and peripheral visual processing) contribute to visual search during a visuomotor task. We show that deficits integrating spatial planning and working memory underlie abnormal performance in stroke survivors with frontoparietal damage. PMID:27733596

Positive mood broadens visual attention to positive stimuli.

PubMed

Wadlinger, Heather A; Isaacowitz, Derek M

2006-03-01

In an attempt to investigate the impact of positive emotions on visual attention within the context of Fredrickson's (1998) broaden-and-build model, eye tracking was used in two studies to measure visual attentional preferences of college students (n=58, n=26) to emotional pictures. Half of each sample experienced induced positive mood immediately before viewing slides of three similarly-valenced images, in varying central-peripheral arrays. Attentional breadth was determined by measuring the percentage viewing time to peripheral images as well as by the number of visual saccades participants made per slide. Consistent with Fredrickson's theory, the first study showed that individuals induced into positive mood fixated more on peripheral stimuli than did control participants; however, this only held true for highly-valenced positive stimuli. Participants under induced positive mood also made more frequent saccades for slides of neutral and positive valence. A second study showed that these effects were not simply due to differences in emotional arousal between stimuli. Selective attentional broadening to positive stimuli may act both to facilitate later building of resources as well as to maintain current positive affective states.

Binocular summation and peripheral visual response time

NASA Technical Reports Server (NTRS)

Gilliland, K.; Haines, R. F.

1975-01-01

Six males were administered a peripheral visual response time test to the onset of brief small stimuli imaged in 10-deg arc separation intervals across the dark adapted horizontal retinal meridian under both binocular and monocular viewing conditions. This was done in an attempt to verify the existence of peripheral binocular summation using a response time measure. The results indicated that from 50-deg arc right to 50-deg arc left of the line of sight binocular summation is a reasonable explanation for the significantly faster binocular data. The stimulus position by viewing eye interaction was also significant. A discussion of these and other analyses is presented along with a review of related literature.

Computer-based route-definition system for peripheral bronchoscopy.

PubMed

Graham, Michael W; Gibbs, Jason D; Higgins, William E

2012-04-01

Multi-detector computed tomography (MDCT) scanners produce high-resolution images of the chest. Given a patient's MDCT scan, a physician can use an image-guided intervention system to first plan and later perform bronchoscopy to diagnostic sites situated deep in the lung periphery. An accurate definition of complete routes through the airway tree leading to the diagnostic sites, however, is vital for avoiding navigation errors during image-guided bronchoscopy. We present a system for the robust definition of complete airway routes suitable for image-guided bronchoscopy. The system incorporates both automatic and semiautomatic MDCT analysis methods for this purpose. Using an intuitive graphical user interface, the user invokes automatic analysis on a patient's MDCT scan to produce a series of preliminary routes. Next, the user visually inspects each route and quickly corrects the observed route defects using the built-in semiautomatic methods. Application of the system to a human study for the planning and guidance of peripheral bronchoscopy demonstrates the efficacy of the system.

Developmental visual perception deficits with no indications of prosopagnosia in a child with abnormal eye movements.

PubMed

Gilaie-Dotan, Sharon; Doron, Ravid

2017-06-01

Visual categories are associated with eccentricity biases in high-order visual cortex: Faces and reading with foveally-biased regions, while common objects and space with mid- and peripherally-biased regions. As face perception and reading are among the most challenging human visual skills, and are often regarded as the peak achievements of a distributed neural network supporting common objects perception, it is unclear why objects, which also rely on foveal vision to be processed, are associated with mid-peripheral rather than with a foveal bias. Here, we studied BN, a 9 y.o. boy who has normal basic-level vision, abnormal (limited) oculomotor pursuit and saccades, and shows developmental object and contour integration deficits but with no indication of prosopagnosia. Although we cannot infer causation from the data presented here, we suggest that normal pursuit and saccades could be critical for the development of contour integration and object perception. While faces and perhaps reading, when fixated upon, take up a small portion of central visual field and require only small eye movements to be properly processed, common objects typically prevail in mid-peripheral visual field and rely on longer-distance voluntary eye movements as saccades to be brought to fixation. While retinal information feeds into early visual cortex in an eccentricity orderly manner, we hypothesize that propagation of non-foveal information to mid and high-order visual cortex critically relies on circuitry involving eye movements. Limited or atypical eye movements, as in the case of BN, may hinder normal information flow to mid-eccentricity biased high-order visual cortex, adversely affecting its development and consequently inducing visual perceptual deficits predominantly for categories associated with these regions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Identification of real-time diagnostic measures of visual distraction with an automatic eye-tracking system.

PubMed

Zhang, Harry; Smith, Matthew R H; Witt, Gerald J

2006-01-01

This study was conducted to identify eye glance measures that are diagnostic of visual distraction. Visual distraction degrades performance, but real-time diagnostic measures have not been identified. In a driving simulator, 14 participants responded to a lead vehicle braking at -2 or -2.7 m/s2 periodically while reading a varying number of words (6-15 words every 13 s) on peripheral displays (with diagonal eccentricities of 24 degrees, 43 degrees, and 75 degrees). As the number of words and display eccentricity increased, total glance duration and reaction time increased and driving performance suffered. Correlation coefficients between several glance measures and reaction time or performance variables were reliably high, indicating that these glance measures are diagnostic of visual distraction. It is predicted that for every 25% increase in total glance duration, reaction time is increased by 0.39 s and standard deviation of lane position is increased by 0.06 m. Potential applications of this research include assessing visual distraction in real time, delivering advisories to distracted drivers to reorient their attention to driving, and using distraction information to adapt forward collision and lane departure warning systems to enhance system effectiveness.

A Computational Model of Afterimage Rotation in the Peripheral Drift Illusion Based on Retinal ON/OFF Responses

PubMed Central

Hayashi, Yuichiro; Ishii, Shin; Urakubo, Hidetoshi

2014-01-01

Human observers perceive illusory rotations after the disappearance of circularly repeating patches containing dark-to-light luminance. This afterimage rotation is a very powerful phenomenon, but little is known about the mechanisms underlying it. Here, we use a computational model to show that the afterimage rotation can be explained by a combination of fast light adaptation and the physiological architecture of the early visual system, consisting of ON- and OFF-type visual pathways. In this retinal ON/OFF model, the afterimage rotation appeared as a rotation of focus lines of retinal ON/OFF responses. Focus lines rotated clockwise on a light background, but counterclockwise on a dark background. These findings were consistent with the results of psychophysical experiments, which were also performed by us. Additionally, the velocity of the afterimage rotation was comparable with that observed in our psychophysical experiments. These results suggest that the early visual system (including the retina) is responsible for the generation of the afterimage rotation, and that this illusory rotation may be systematically misinterpreted by our high-level visual system. PMID:25517906

Perceptual load in different regions of the visual scene and its relevance for driving.

PubMed

Marciano, Hadas; Yeshurun, Yaffa

2015-06-01

The aim of this study was to better understand the role played by perceptual load, at both central and peripheral regions of the visual scene, in driving safety. Attention is a crucial factor in driving safety, and previous laboratory studies suggest that perceptual load is an important factor determining the efficiency of attentional selectivity. Yet, the effects of perceptual load on driving were never studied systematically. Using a driving simulator, we orthogonally manipulated the load levels at the road (central load) and its sides (peripheral load), while occasionally introducing critical events at one of these regions. Perceptual load affected driving performance at both regions of the visual scene. Critically, the effect was different for central versus peripheral load: Whereas load levels on the road mainly affected driving speed, load levels on its sides mainly affected the ability to detect critical events initiating from the roadsides. Moreover, higher levels of peripheral load impaired performance but mainly with low levels of central load, replicating findings with simple letter stimuli. Perceptual load has a considerable effect on driving, but the nature of this effect depends on the region of the visual scene at which the load is introduced. Given the observed importance of perceptual load, authors of future studies of driving safety should take it into account. Specifically, these findings suggest that our understanding of factors that may be relevant for driving safety would benefit from studying these factors under different levels of load at different regions of the visual scene. © 2014, Human Factors and Ergonomics Society.

Visualization of Sensory Neurons and Their Projections in an Upper Motor Neuron Reporter Line.

PubMed

Genç, Barış; Lagrimas, Amiko Krisa Bunag; Kuru, Pınar; Hess, Robert; Tu, Michael William; Menichella, Daniela Maria; Miller, Richard J; Paller, Amy S; Özdinler, P Hande

2015-01-01

Visualization of peripheral nervous system axons and cell bodies is important to understand their development, target recognition, and integration into complex circuitries. Numerous studies have used protein gene product (PGP) 9.5 [a.k.a. ubiquitin carboxy-terminal hydrolase L1 (UCHL1)] expression as a marker to label sensory neurons and their axons. Enhanced green fluorescent protein (eGFP) expression, under the control of UCHL1 promoter, is stable and long lasting in the UCHL1-eGFP reporter line. In addition to the genetic labeling of corticospinal motor neurons in the motor cortex and degeneration-resistant spinal motor neurons in the spinal cord, here we report that neurons of the peripheral nervous system are also fluorescently labeled in the UCHL1-eGFP reporter line. eGFP expression is turned on at embryonic ages and lasts through adulthood, allowing detailed studies of cell bodies, axons and target innervation patterns of all sensory neurons in vivo. In addition, visualization of both the sensory and the motor neurons in the same animal offers many advantages. In this report, we used UCHL1-eGFP reporter line in two different disease paradigms: diabetes and motor neuron disease. eGFP expression in sensory axons helped determine changes in epidermal nerve fiber density in a high-fat diet induced diabetes model. Our findings corroborate previous studies, and suggest that more than five months is required for significant skin denervation. Crossing UCHL1-eGFP with hSOD1G93A mice generated hSOD1G93A-UeGFP reporter line of amyotrophic lateral sclerosis, and revealed sensory nervous system defects, especially towards disease end-stage. Our studies not only emphasize the complexity of the disease in ALS, but also reveal that UCHL1-eGFP reporter line would be a valuable tool to visualize and study various aspects of sensory nervous system development and degeneration in the context of numerous diseases.

Reading speed in the peripheral visual field of older adults: Does it benefit from perceptual learning?

PubMed

Yu, Deyue; Cheung, Sing-Hang; Legge, Gordon E; Chung, Susana T L

2010-04-21

Enhancing reading ability in peripheral vision is important for the rehabilitation of people with central-visual-field loss from age-related macular degeneration (AMD). Previous research has shown that perceptual learning, based on a trigram letter-recognition task, improved peripheral reading speed among normally-sighted young adults (Chung, Legge, & Cheung, 2004). Here we ask whether the same happens in older adults in an age range more typical of the onset of AMD. Eighteen normally-sighted subjects, aged 55-76years, were randomly assigned to training or control groups. Visual-span profiles (plots of letter-recognition accuracy as a function of horizontal letter position) and RSVP reading speeds were measured at 10 degrees above and below fixation during pre- and post-tests for all subjects. Training consisted of repeated measurements of visual-span profiles at 10 degrees below fixation, in four daily sessions. The control subjects did not receive any training. Perceptual learning enlarged the visual spans in both trained (lower) and untrained (upper) visual fields. Reading speed improved in the trained field by 60% when the trained print size was used. The training benefits for these older subjects were weaker than the training benefits for young adults found by Chung et al. Despite the weaker training benefits, perceptual learning remains a potential option for low-vision reading rehabilitation among older adults. Copyright 2010 Elsevier Ltd. All rights reserved.

Upright face-preferential high-gamma responses in lower-order visual areas: evidence from intracranial recordings in children

PubMed Central

Matsuzaki, Naoyuki; Schwarzlose, Rebecca F.; Nishida, Masaaki; Ofen, Noa; Asano, Eishi

2015-01-01

Behavioral studies demonstrate that a face presented in the upright orientation attracts attention more rapidly than an inverted face. Saccades toward an upright face take place in 100-140 ms following presentation. The present study using electrocorticography determined whether upright face-preferential neural activation, as reflected by augmentation of high-gamma activity at 80-150 Hz, involved the lower-order visual cortex within the first 100 ms post-stimulus presentation. Sampled lower-order visual areas were verified by the induction of phosphenes upon electrical stimulation. These areas resided in the lateral-occipital, lingual, and cuneus gyri along the calcarine sulcus, roughly corresponding to V1 and V2. Measurement of high-gamma augmentation during central (circular) and peripheral (annular) checkerboard reversal pattern stimulation indicated that central-field stimuli were processed by the more polar surface whereas peripheral-field stimuli by the more anterior medial surface. Upright face stimuli, compared to inverted ones, elicited up to 23% larger augmentation of high-gamma activity in the lower-order visual regions at 40-90 ms. Upright face-preferential high-gamma augmentation was more highly correlated with high-gamma augmentation for central than peripheral stimuli. Our observations are consistent with the hypothesis that lower-order visual regions, especially those for the central field, are involved in visual cues for rapid detection of upright face stimuli. PMID:25579446

Zif268 mRNA Expression Patterns Reveal a Distinct Impact of Early Pattern Vision Deprivation on the Development of Primary Visual Cortical Areas in the Cat.

PubMed

Laskowska-Macios, Karolina; Zapasnik, Monika; Hu, Tjing-Tjing; Kossut, Malgorzata; Arckens, Lutgarde; Burnat, Kalina

2015-10-01

Pattern vision deprivation (BD) can induce permanent deficits in global motion perception. The impact of timing and duration of BD on the maturation of the central and peripheral visual field representations in cat primary visual areas 17 and 18 remains unknown. We compared early BD, from eye opening for 2, 4, or 6 months, with late onset BD, after 2 months of normal vision, using the expression pattern of the visually driven activity reporter gene zif268 as readout. Decreasing zif268 mRNA levels between months 2 and 4 characterized the normal maturation of the (supra)granular layers of the central and peripheral visual field representations in areas 17 and 18. In general, all BD conditions had higher than normal zif268 levels. In area 17, early BD induced a delayed decrease, beginning later in peripheral than in central area 17. In contrast, the decrease occurred between months 2 and 4 throughout area 18. Lack of pattern vision stimulation during the first 4 months of life therefore has a different impact on the development of areas 17 and 18. A high zif268 expression level at a time when normal vision is restored seems to predict the capacity of a visual area to compensate for BD. © The Author 2014. Published by Oxford University Press.

Peripheral refraction and image blur in four meridians in emmetropes and myopes.

PubMed

Shen, Jie; Spors, Frank; Egan, Donald; Liu, Chunming

2018-01-01

The peripheral refractive error of the human eye has been hypothesized to be a major stimulus for the development of its central refractive error. The purpose of this study was to investigate the changes in the peripheral refractive error across horizontal, vertical and two diagonal meridians in emmetropic and low, moderate and high myopic adults. Thirty-four adult subjects were recruited and aberration was measured using a modified commercial aberrometer. We then computed the refractive error in power vector notation from second-order Zernike terms. Statistical analysis was performed to evaluate the statistical differences in refractive error profiles between the subject groups and across all measured visual field meridians. Small amounts of relative myopic shift were observed in emmetropic and low myopic subjects. However, moderate and high myopic subjects exhibited a relative hyperopic shift in all four meridians. Astigmatism J 0 and J 45 had quadratic or linear changes dependent on the visual field meridians. Peripheral Sphero-Cylindrical Retinal Image Blur increased in emmetropic eyes in most of the measured visual fields. The findings indicate an overall emmetropic or slightly relative myopic periphery (spherical or oblate retinal shape) formed in emmetropes and low myopes, while moderate and high myopes form relative hyperopic periphery (prolate, or less oblate, retinal shape). In general, human emmetropic eyes demonstrate higher amount of peripheral retinal image blur.

The risk of pedestrian collisions with peripheral visual field loss.

PubMed

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.

Factors associated with developing a fear of falling in subjects with primary open-angle glaucoma.

PubMed

Adachi, Sayaka; Yuki, Kenya; Awano-Tanabe, Sachiko; Ono, Takeshi; Shiba, Daisuke; Murata, Hiroshi; Asaoka, Ryo; Tsubota, Kazuo

2018-02-13

To investigate the relationship between clinical risk factors, including visual field (VF) defects and visual acuity, and a fear of falling, among patients with primary open-angle glaucoma (POAG). All participants answered the following question at a baseline ophthalmic examination: Are you afraid of falling? The same question was then answered every 12 months for 3 years. A binocular integrated visual field was calculated by merging a patient's monocular Humphrey field analyzer VFs, using the 'best sensitivity' method. The means of total deviation values in the whole, superior peripheral, superior central, inferior central, and inferior peripheral VFs were calculated. The relationship between these mean VF measurements, and various clinical factors, against patients' baseline fear of falling and future fear of falling was analyzed using multiple logistic regression. Among 392 POAG subjects, 342 patients (87.2%) responded to the fear of falling question at least twice in the 3 years study period. The optimal regression model for patients' baseline fear of falling included age, gender, mean of total deviation values in the inferior peripheral VF and number of previous falls. The optimal regression equation for future fear of falling included age, gender, mean of total deviation values in the inferior peripheral VF and number of previous falls. Defects in the inferior peripheral VF area are significantly related to the development of a fear of falling.

Clinical and Laboratory Evaluation of Peripheral Prism Glasses for Hemianopia

PubMed Central

Giorgi, Robert G.; Woods, Russell L.; Peli, Eli

2008-01-01

Purpose Homonymous hemianopia (the loss of vision on the same side in each eye) impairs the ability to navigate and walk safely. We evaluated peripheral prism glasses as a low vision optical device for hemianopia in an extended wearing trial. Methods Twenty-three patients with complete hemianopia (13 right) with neither visual neglect nor cognitive deficit enrolled in the 5-visit study. To expand the horizontal visual field, patients’ spectacles were fitted with both upper and lower Press-On™ Fresnel prism segments (each 40 prism diopters) across the upper and lower portions of the lens on the hemianopic (“blind”) side. Patients were asked to wear these spectacles as much as possible for the duration of the study, which averaged 9 (range: 5 to 13) weeks. Clinical success (continued wear, indicating perceived overall benefit), visual field expansion, perceived direction and perceived quality of life were measured. Results Clinical Success: 14 of 21 (67%) patients chose to continue to wear the peripheral prism glasses at the end of the study (2 patients did not complete the study for non-vision reasons). At long-term follow-up (8 to 51 months), 5 of 12 (42%) patients reported still wearing the device. Visual Field Expansion: Expansion of about 22 degrees in both the upper and lower quadrants was demonstrated for all patients (binocular perimetry, Goldmann V4e). Perceived Direction: Two patients demonstrated a transient adaptation to the change in visual direction produced by the peripheral prism glasses. Quality of Life: At study end, reduced difficulty noticing obstacles on the hemianopic side was reported. Conclusions The peripheral prism glasses provided reported benefits (usually in obstacle avoidance) to 2/3 of the patients completing the study, a very good success rate for a vision rehabilitation device. Possible reasons for long-term discontinuation and limited adaptation of perceived direction are discussed. PMID:19357552

Symmetry and asymmetry of reaction time and body tissue composition of upper limbs in young female basketball players.

PubMed

Poliszczuk, Tatiana; Mańkowska, Maja; Poliszczuk, Dmytro; Wiśniewski, Andrzej

2013-01-01

The role of psychomotor abilities and their relationship to the morphofunctional characteristics of athletes is becoming more and more emphasized in studies on the subject, especially for disciplines that require athletes to notice and to respond to signals originating in dynamically changing conditions. At the same time, athletes who perform symmetrically are more effective and less likely to sustain an injury through unilateral strain. Assessment of the degree of symmetry and asymmetry of reaction time to stimuli in the central and peripheral visual fields, and assessment of body composition of upper limbs in young female basketball players. Participants of the study comprised 17 young female basketball players. Their average age was 18.11-0.8 years. On average, they had been training basketball for 6.83-1.75 years. Body tissue composition was measured using the bioelectrical impedance method. The degree of symmetry and asymmetry of reaction time to signals in the central and peripheral visual fields were measured using the Reaction Test (RT-S1) and a modified Peripheral Perception (PP) test within the Vienna Test System. An analysis of body tissue composition of the upper right and upper left limbs found an asymmetry (p<0.01 and p<0.05) in the FAT [%], FAT MASS [kg], and FFM [kg] parameters. The values of these parameters were higher for the non-dominant arm. No statistically significant differences were found in reaction time and motor time for the dominant and non-dominant arm. A correlation was found between motor time and the FFM [kg] (r=-0.62; p<0.05) and PMM [kg] (r=-0.63; p<0.05) parameters. A significant asymmetry was found in the body tissue composition of the upper limbs. Asymmetry of reaction time was found only for signals in the peripheral visual field.

Ultra-widefield fluorescein angiography of white without pressure

PubMed Central

Orlin, Anton; Fatoo, Aalya; Ehrlich, Joshua; D’Amico, Donald J; Chan, RV Paul; Kiss, Szilárd

2013-01-01

Purpose To describe ultra-widefield fluorescein angiography (UWFA) findings in eyes with white without pressure (WWOP) and in eyes without any obvious peripheral chorioretinal disease, and to determine if a difference exists between these two groups. Methods A retrospective review of 379 eyes undergoing diagnostic UWFA using the Optos 200Tx imaging system. Eyes were excluded if the quality of the color photograph or UWFA prevented reliable evaluation. Eyes were also excluded if there was any evidence of peripheral retinal or choroidal disease, which was thought to have an effect on UWFA (eg, peripheral background diabetic or hypertensive retinopathy, vein occlusion, or any other peripheral vascular disorder). Eyes were determined to have WWOP, based on a dilated fundus examination and color fundus photography that contained areas of peripheral retinal whitening consistent with the diagnosis. UWFA was evaluated by trained masked graders, and determined to have or not have peripheral vascular leakage and/or staining. Results Of the 379 eyes evaluated, 45 eyes were included in the study. Twelve eyes were determined to have peripheral WWOP; 33 eyes did not have WWOP on examination or color fundus photography. Three common UWFA peripheral patterns were visualized. Eyes with and without WWOP were grouped into one of three patterns. The majority of eyes without WWOP demonstrated UWFA pattern one (69.7%), while those in the WWOP group demonstrated pattern three (50%). The distribution of UWFA patterns is statistically different between those with and without WWOP (P = 0.002). In eyes without WWOP, in patients with no documented systemic microvascular disease (diabetes, hypertension), 71.4% of eyes had UWFA pattern one while 14.3% had both patterns two and three. Conclusion This study is one of the first to specifically evaluate peripheral vascular leakage/staining in eyes with WWOP as well as in eyes without any obvious peripheral chorioretinal disease. We demonstrate that a significant portion of WWOP eyes exhibit peripheral findings on UWFA (pattern one) compared to eyes without WWOP. Importantly, even in eyes that are apparently unremarkable in the periphery on exam and color photography, UWFA can still show peripheral vascular abnormalities. These results warrant further investigation. PMID:23737658

Peripheral refraction profiles in subjects with low foveal refractive errors.

PubMed

Tabernero, Juan; Ohlendorf, Arne; Fischer, M Dominik; Bruckmann, Anna R; Schiefer, Ulrich; Schaeffel, Frank

2011-03-01

To study the variability of peripheral refraction in a population of 43 subjects with low foveal refractive errors. A scan of the refractive error in the vertical pupil meridian of the right eye of 43 subjects (age range, 18 to 80 years, foveal spherical equivalent, < ± 2.5 diopter) over the central ± 45° of the visual field was performed using a recently developed angular scanning photorefractor. Refraction profiles across the visual field were fitted with four different models: (1) "flat model" (refractions about constant across the visual field), (2) "parabolic model" (refractions follow about a parabolic function), (3) "bi-linear model" (linear change of refractions with eccentricity from the fovea to the periphery), and (4) "box model" ("flat" central area with a linear change in refraction from a certain peripheral angle). Based on the minimal residuals of each fit, the subjects were classified into one of the four models. The "box model" accurately described the peripheral refractions in about 50% of the subjects. Peripheral refractions in six subjects were better characterized by a "linear model," in eight subjects by a "flat model," and in eight by the "parabolic model." Even after assignment to one of the models, the variability remained strikingly large, ranging from -0.75 to 6 diopter in the temporal retina at 45° eccentricity. The most common peripheral refraction profile (observed in nearly 50% of our population) was best described by the "box model." The high variability among subjects may limit attempts to reduce myopia progression with a uniform lens design and may rather call for a customized approach.

Peripheral myopization and visual performance with experimental rigid gas permeable and soft contact lens design.

PubMed

Pauné, J; Queiros, A; Quevedo, L; Neves, H; Lopes-Ferreira, D; González-Méijome, J M

2014-12-01

To evaluate the performance of two experimental contact lenses (CL) designed to induce relative peripheral myopic defocus in myopic eyes. Ten right eyes of 10 subjects were fitted with three different CL: a soft experimental lens (ExpSCL), a rigid gas permeable experimental lens (ExpRGP) and a standard RGP lens made of the same material (StdRGP). Central and peripheral refraction was measured using a Grand Seiko open-field autorefractometer across the central 60° of the horizontal visual field. Ocular aberrations were measured with a Hartman-Shack aberrometer, and monocular contrast sensitivity function (CSF) was measured with a VCTS6500 without and with the three contact lenses. Both experimental lenses were able to increase significantly the relative peripheral myopic defocus up to -0.50 D in the nasal field and -1.00 D in the temporal field (p<0.05). The ExpRGP induced a significantly higher myopic defocus in the temporal field compared to the ExpSCL. ExpSCL induced significantly lower levels of Spherical-like HOA than ExpRGP for the 5mm pupil size (p<0.05). Both experimental lenses kept CSF within normal limits without any statistically significant change from baseline (p>0.05). RGP lens design seems to be more effective to induce a significant myopic change in the relative peripheral refractive error. Both lenses preserve a good visual performance. The worsened optical quality observed in ExpRGP was due to an increased coma-like and spherical-like HOA. However, no impact on the visual quality as measured by CSF was observed. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

The role of peripheral vision in saccade planning: learning from people with tunnel vision.

PubMed

Luo, Gang; Vargas-Martin, Fernando; Peli, Eli

2008-12-22

Both visually salient and top-down information are important in eye movement control, but their relative roles in the planning of daily saccades are unclear. We investigated the effect of peripheral vision loss on saccadic behaviors in patients with tunnel vision (visual field diameters 7 degrees-16 degrees) in visual search and real-world walking experiments. The patients made up to two saccades per second to their pre-saccadic blind areas, about half of which had no overlap between the post- and pre-saccadic views. In the visual search experiment, visual field size and the background (blank or picture) did not affect the saccade sizes and direction of patients (n = 9). In the walking experiment, the patients (n = 5) and normal controls (n = 3) had similar distributions of saccade sizes and directions. These findings might provide a clue about the large extent of the top-down mechanism influence on eye movement control.

Role of peripheral vision in saccade planning: Learning from people with tunnel vision

PubMed Central

Luo, Gang; Vargas-Martin, Fernando; Peli, Eli

2008-01-01

Both visually salient and top-down information are important in eye movement control, but their relative roles in the planning of daily saccades are unclear. We investigated the effect of peripheral vision loss on saccadic behaviors in patients with tunnel vision (visual field diameters 7°–16°) in visual search and real-world walking experiments. The patients made up to two saccades per second to their pre-saccadic blind areas, about half of which had no overlap between the post- and pre-saccadic views. In the visual search experiment, visual field size and the background (blank or picture) did not affect the saccade sizes and direction of patients (n=9). In the walking experiment, the patients (n=5) and normal controls (n=3) had similar distributions of saccade sizes and directions. These findings might provide a clue about the extent of the top-down mechanism influence on eye movement control. PMID:19146326

Infants' Visual Localization of Visual and Auditory Targets.

ERIC Educational Resources Information Center

Bechtold, A. Gordon; And Others

This study is an investigation of 2-month-old infants' abilities to visually localize visual and auditory peripheral stimuli. Each subject (N=40) was presented with 50 trials; 25 of these visual and 25 auditory. The infant was placed in a semi-upright infant seat positioned 122 cm from the center speaker of an arc formed by five loudspeakers. At…

Optoelectronic aid for patients with severely restricted visual fields in daylight conditions

NASA Astrophysics Data System (ADS)

Peláez-Coca, María Dolores; Sobrado-Calvo, Paloma; Vargas-Martín, Fernando

2011-11-01

In this study we evaluated the immediate effectiveness of an optoelectronic visual field expander in a sample of subjects with retinitis pigmentosa suffering from a severe peripheral visual field restriction. The aid uses the augmented view concept and provides subjects with visual information from outside their visual field. The tests were carried out in daylight conditions. The optoelectronic aid comprises a FPGA (real-time video processor), a wide-angle mini camera and a transparent see-through head-mounted display. This optoelectronic aid is called SERBA (Sistema Electro-óptico Reconfigurable de Ayuda para Baja Visión). We previously showed that, without compromising residual vision, the SERBA system provides information about objects within an area about three times greater on average than the remaining visual field of the subjects [1]. In this paper we address the effects of the device on mobility under daylight conditions with and without SERBA. The participants were six subjects with retinitis pigmentosa. In this mobility test, better results were obtained when subjects were wearing the SERBA system; specifically, both the number of contacts with low-level obstacles and mobility errors decreased significantly. A longer training period with the device might improve its usefulness.

[Impact of hypoglycemic episodes on nerves conduction and auditory and visual evoked potentials in children with type 1 diabetes].

PubMed

Wysocka-Mincewicz, Marta; Trippenbach-Dulska, Hanna; Emeryk-Szajewska, Barbara; Zakrzewska-Pniewska, Beata; Kochanek, Krzysztof; Pańkowska, Ewa

2007-01-01

Hypoglycemia is an acute disturbance of energy, especially impacting the central nervous system, but direct influence on peripheral nervous function is not detected. The aim of the study was to establish the influence of hypoglycemic moderate and severe episodes on the function of peripheral nerves, hearing and visual pathway. 97 children with type 1 diabetes (mean age 15.4+/-2.16 years, mean duration of diabetes 8.11+/-2.9 years, mean HbA1c 8,58+/-1.06%), at least 10 years old and with at least 3 years duration of diabetes, were included to study. Nerve conduction studies, visual (VEP) and auditory (ABR) evoked potentials were performed with standard surface stimulating and recording techniques. Moderate hypoglycemic episodes were defined as events of low glycemia requiring help of another person but without loss of consciousness and/or convulsions but recurrent frequently in at least one year. Severe hypoglycemia was defined as events with loss of consciousness and/or convulsions. Univariate ANOVA tests of significance or H Kruskal-Wallis test were used, depending on normality of distribution. The subgroups with a history of hypoglycemic episodes had significant delay in all conduction parameters in the sural nerve (amplitude p<0.05, sensory latency p<0.05, and velocity p<0.005) and in motor potential amplitude of tibial nerve (p<0.005). In ABR wave III latency and interval I-III in subgroups with episodes of hypoglycemia (p<0,05) were significantly prolonged. In analyses of VEP parameters no differences were detected. The study showed influence of hypoglycemic episodes on function of all sural nerve parameters and tibial motor amplitude, and in ABR on wave III and interval I-III. Frequent moderate hypoglycemic episodes were strong risk factors for damage of the peripheral and central nervous systems, comparable with impact of several severe hypoglycemias.

The Effect of Acute Sleep Deprivation on Visual Evoked Potentials in Professional Drivers

PubMed Central

Jackson, Melinda L.; Croft, Rodney J.; Owens, Katherine; Pierce, Robert J.; Kennedy, Gerard A.; Crewther, David; Howard, Mark E.

2008-01-01

Study Objectives: Previous studies have demonstrated that as little as 18 hours of sleep deprivation can cause deleterious effects on performance. It has also been suggested that sleep deprivation can cause a “tunnel-vision” effect, in which attention is restricted to the center of the visual field. The current study aimed to replicate these behavioral effects and to examine the electrophysiological underpinnings of these changes. Design: Repeated-measures experimental study. Setting: University laboratory. Patients or Participants: Nineteen professional drivers (1 woman; mean age = 45.3 ± 9.1 years). Interventions: Two experimental sessions were performed; one following 27 hours of sleep deprivation and the other following a normal night of sleep, with control for circadian effects. Measurements & Results: A tunnel-vision task (central versus peripheral visual discrimination) and a standard checkerboard-viewing task were performed while 32-channel EEG was recorded. For the tunnel-vision task, sleep deprivation resulted in an overall slowing of reaction times and increased errors of omission for both peripheral and foveal stimuli (P < 0.05). These changes were related to reduced P300 amplitude (indexing cognitive processing) but not measures of early visual processing. No evidence was found for an interaction effect between sleep deprivation and visual-field position, either in terms of behavior or electrophysiological responses. Slower processing of the sustained parvocellular visual pathway was demonstrated. Conclusions: These findings suggest that performance deficits on visual tasks during sleep deprivation are due to higher cognitive processes rather than early visual processing. Sleep deprivation may differentially impair processing of more-detailed visual information. Features of the study design (eg, visual angle, duration of sleep deprivation) may influence whether peripheral visual-field neglect occurs. Citation: Jackson ML; Croft RJ; Owens K; Pierce RJ; Kennedy GA; Crewther D; Howard ME. The effect of acute sleep deprivation on visual evoked potentials in professional drivers. SLEEP 2008;31(9):1261-1269. PMID:18788651

Optoacoustic angiography of peripheral vasculature

NASA Astrophysics Data System (ADS)

Ermilov, Sergey; Su, Richard; Zamora, Mario; Hernandez, Travis; Nadvoretsky, Vyacheslav; Oraevsky, Alexander

2012-02-01

We developed a new optoacoustic microangiography system (OmAS) intended for in-vivo vascular imaging of a human finger. The system employs an arc-shaped acoustic array that is rotated 360 degrees around the finger providing optoacoustic data necessary for tomographic reconstruction of the three-dimensional images of a finger. A near-infrared Q-switched laser is used to generate optoacoustic signals with increased contrast of blood vessels. The laser is coupled through two randomized fiberoptic bundles oriented in orthogonal optoacoustic mode. To demonstrate OmAS capabilities, we present a time-series of optoacoustic images of a human finger taken after the hypothermia stress test. The images show a detailed vascular anatomy of a finger down to the capillary level. A series of quick 30s scans allowed us to visualize the thermoregulatory response within the studied finger as it was manifested via vasomotor activity during the hypothermia recovery. We propose that the developed system can be used for diagnostics of various medical conditions that are manifested in change of the peripheral (finger) blood flow. Examples of the medical conditions that could be diagnosed and staged using the OmAS include the peripheral arterial disease (PAD), thrombosis, frostbite, and traumas.

The Place of Nailfold Capillaroscopy Among Instrumental Methods for Assessment of Some Peripheral Ischaemic Syndromes in Rheumatology.

PubMed

Lambova, Sevdalina N

2016-01-01

Micro- and macrovascular pathology is a frequent finding in a number of common rheumatic diseases. Secondary Raynaud's phenomenon (RP) is among the most common symptoms in systemic sclerosis and several other systemic autoimmune diseases including a broad differential diagnosis. It should be also differential from other peripheral vascular syndromes such as embolism, thrombosis, etc., some of which lead to clinical manifestation of the blue toe syndrome. The current review discusses the instrumental methods for vascular assessments. Nailfold capillaroscopy is the only method among the imaging techniques that can be used for morphological assessment of the nutritive capillaries in the nailfold area. Laser-Doppler flowmetry and laser-Doppler imaging are methods for functional assessment of microcirculation, while thermography and plethysmography reflect both blood flow in peripheral arteries and microcirculation. Doppler ultrasound and angiography visualize peripheral arteries. The choice of the appropriate instrumental method is guided by the clinical presentation. The main role of capillaroscopy is to provide differential diagnosis between primary and secondary RP. In rheumatology, capillaroscopic changes in systemic sclerosis have been recently defined as diagnostic. The appearance of abnormal capillaroscopic pattern inherits high positive predictive value for the development of a connective tissue disease that is higher than the predictive value of antinuclear antibodies. In cases of abrupt onset of peripheral ischaemia, clinical signs of critical ischaemia, unilateral or lower limb involvement, Doppler ultrasound and angiography are indicated. The most common causes for such clinical picture that may be referred to rheumatologic consultation are the antiphospholipid syndrome, mimickers of vasculitides such as atherosclerosis with cholesterol emboli, and neoplasms.

Driving with visual field loss : an exploratory simulation study

DOT National Transportation Integrated Search

2009-01-01

The goal of this study was to identify the influence of peripheral visual field loss (VFL) on driving performance in a motion-based driving simulator. Sixteen drivers (6 with VFL and 10 with normal visual fields) completed a 14 km simulated drive. Th...

The effects of alcohol intoxication on attention and memory for visual scenes.

PubMed

Harvey, Alistair J; Kneller, Wendy; Campbell, Alison C

2013-01-01

This study tests the claim that alcohol intoxication narrows the focus of visual attention on to the more salient features of a visual scene. A group of alcohol intoxicated and sober participants had their eye movements recorded as they encoded a photographic image featuring a central event of either high or low salience. All participants then recalled the details of the image the following day when sober. We sought to determine whether the alcohol group would pay less attention to the peripheral features of the encoded scene than their sober counterparts, whether this effect of attentional narrowing was stronger for the high-salience event than for the low-salience event, and whether it would lead to a corresponding deficit in peripheral recall. Alcohol was found to narrow the focus of foveal attention to the central features of both images but did not facilitate recall from this region. It also reduced the overall amount of information accurately recalled from each scene. These findings demonstrate that the concept of alcohol myopia originally posited to explain the social consequences of intoxication (Steele & Josephs, 1990) may be extended to explain the relative neglect of peripheral information during the processing of visual scenes.

Occlusion properties of prosthetic contact lenses for the treatment of amblyopia.

PubMed

Collins, Randall S; McChesney, Megan E; McCluer, Craig A; Schatz, Martha P

2008-12-01

The efficacy of opaque contact lenses as occlusion therapy for amblyopia has been established in the literature. Prosthetic contact lenses use similar tints to improve cosmesis in scarred or deformed eyes and may be an alternative in occlusion therapy. To test this idea, we determined the degree of vision penalization elicited by prosthetic contact lenses and their effect on peripheral fusion. We tested 19 CIBA Vision DuraSoft 3 Prosthetic soft contact lenses with varying iris prints, underprints, and opaque pupil sizes in 10 volunteers with best-corrected Snellen distance visual acuity of 20/20 or better in each eye. Snellen visual acuity and peripheral fusion using the Worth 4-Dot test at near were measured on each subject wearing each of the 19 lenses. Results were analyzed with 3-factor analysis of variance. Mean visual acuity through the various lenses ranged from 20/79 to 20/620. Eight lenses allowed preservation of peripheral fusion in 50% or more of the subjects tested. Iris print pattern and opaque pupil size were significant factors in determining visual acuity (p < 0.05). Sufficient vision penalization can be achieved to make occlusion with prosthetic contact lenses a viable therapy for amblyopia. The degree of penalization can be varied and different iris print patterns and pupil sizes, using peripheral fusion, can be preserved with some lenses. Prosthetic contact lenses can be more cosmetically appealing and more tolerable than other amblyopia treatment modalities. These factors may improve compliance in occlusion therapy.

Neuronal network-based mathematical modeling of perceived verticality in acute unilateral vestibular lesions: from nerve to thalamus and cortex.

PubMed

Glasauer, S; Dieterich, M; Brandt, T

2018-05-29

Acute unilateral lesions of vestibular graviceptive pathways from the otolith organs and semicircular canals via vestibular nuclei and the thalamus to the parieto-insular vestibular cortex regularly cause deviations of perceived verticality in the frontal roll plane. These tilts are ipsilateral in peripheral and in ponto-medullary lesions and contralateral in ponto-mesencephalic lesions. Unilateral lesions of the vestibular thalamus or cortex cause smaller tilts of the perceived vertical, which may be either ipsilateral or contralateral. Using a neural network model, we previously explained why unilateral vestibular midbrain lesions rarely manifest with rotational vertigo. We here extend this approach, focussing on the direction-specific deviations of perceived verticality in the roll plane caused by acute unilateral vestibular lesions from the labyrinth to the cortex. Traditionally, the effect of unilateral peripheral lesions on perceived verticality has been attributed to a lesion-based bias of the otolith system. We here suggest, on the basis of a comparison of model simulations with patient data, that perceived visual tilt after peripheral lesions is caused by the effect of a torsional semicircular canal bias on the central gravity estimator. We further argue that the change of gravity coding from a peripheral/brainstem vectorial representation in otolith coordinates to a distributed population coding at thalamic and cortical levels can explain why unilateral thalamic and cortical lesions have a variable effect on perceived verticality. Finally, we propose how the population-coding network for gravity direction might implement the elements required for the well-known perceptual underestimation of the subjective visual vertical in tilted body positions.

Study of Auditory, Visual Reaction Time and Glycemic Control (HBA1C) in Chronic Type II Diabetes Mellitus.

PubMed

M, Muhil; Sembian, Umapathy; Babitha; N, Ethiya; K, Muthuselvi

2014-09-01

Diabetes mellitus is a disease of insulin deficiencyleads to micro and macro vascular disorder. Neuropathy is one of the major complication of chronic uncontrolled Diabetes affecting the Reaction time. To study the correlation between the glycosylated HbA1C and Auditory, visual Reaction time in chronic Type II diabetes (40-60y) of on oral hypoglycemic drugs of>10 y duration in two groups (n-100 in each group , both Males & females) and compared within the study groups and also with the age matched control group (100). HbA1C-Glycosylated HbA1C was measured by Particle enhanced immunoturbidimetric test method. Auditory and visual reaction time (ART, VRT) were measured by PC 1000 Reaction timer for control & study groups i.e. Group-I - Chronic Type II DM for >10 y with HbA1c < 7.0, and Group II - chronic Type-IIDM for >10 y with HbA1c > 7.0 ie impaired glycemic control. Exclusion Criteria- Subjects with Auditory and visual disturbances, alcoholism and smoking. Statistical Analysis - One-way ANOVA. Using SPSS 21 software. Both the groups had prolonged ART and VRT than controls. Among the study group, G-II (DM with HbA1C >7) had increased Auditory & Visual Reaction time than Group I which is statistically significant p-value <0.05. Impairment of sensory motor function of peripheral nervous system is more in chronic diabetic with less glycemic control ie., HbA1C>7 who have shown increased Auditory and Visual Reaction time than chronic DM with HbA1C<7.Severity of Peripheral neuropathy in Type II Diabetics could be due to elevated HbA1C.

Effectiveness of conventional versus virtual reality based vestibular rehabilitation in the treatment of dizziness, gait and balance impairment in adults with unilateral peripheral vestibular loss: a randomised controlled trial.

PubMed

Meldrum, Dara; Herdman, Susan; Moloney, Roisin; Murray, Deirdre; Duffy, Douglas; Malone, Kareena; French, Helen; Hone, Stephen; Conroy, Ronan; McConn-Walsh, Rory

2012-03-26

Unilateral peripheral vestibular loss results in gait and balance impairment, dizziness and oscillopsia. Vestibular rehabilitation benefits patients but optimal treatment remains unknown. Virtual reality is an emerging tool in rehabilitation and provides opportunities to improve both outcomes and patient satisfaction with treatment. The Nintendo Wii Fit Plus® (NWFP) is a low cost virtual reality system that challenges balance and provides visual and auditory feedback. It may augment the motor learning that is required to improve balance and gait, but no trials to date have investigated efficacy. In a single (assessor) blind, two centre randomised controlled superiority trial, 80 patients with unilateral peripheral vestibular loss will be randomised to either conventional or virtual reality based (NWFP) vestibular rehabilitation for 6 weeks. The primary outcome measure is gait speed (measured with three dimensional gait analysis). Secondary outcomes include computerised posturography, dynamic visual acuity, and validated questionnaires on dizziness, confidence and anxiety/depression. Outcome will be assessed post treatment (8 weeks) and at 6 months. Advances in the gaming industry have allowed mass production of highly sophisticated low cost virtual reality systems that incorporate technology previously not accessible to most therapists and patients. Importantly, they are not confined to rehabilitation departments, can be used at home and provide an accurate record of adherence to exercise. The benefits of providing augmented feedback, increasing intensity of exercise and accurately measuring adherence may improve conventional vestibular rehabilitation but efficacy must first be demonstrated. Clinical trials.gov identifier: NCT01442623.

4D phase contrast flow imaging for in-stent flow visualization and assessment of stent patency in peripheral vascular stents--a phantom study.

PubMed

Bunck, Alexander C; Jüttner, Alena; Kröger, Jan Robert; Burg, Matthias C; Kugel, Harald; Niederstadt, Thomas; Tiemann, Klaus; Schnackenburg, Bernhard; Crelier, Gerard R; Heindel, Walter; Maintz, David

2012-09-01

4D phase contrast flow imaging is increasingly used to study the hemodynamics in various vascular territories and pathologies. The aim of this study was to assess the feasibility and validity of MRI based 4D phase contrast flow imaging for the evaluation of in-stent blood flow in 17 commonly used peripheral stents. 17 different peripheral stents were implanted into a MR compatible flow phantom. In-stent visibility, maximal velocity and flow visualization were assessed and estimates of in-stent patency obtained from 4D phase contrast flow data sets were compared to a conventional 3D contrast-enhanced magnetic resonance angiography (CE-MRA) as well as 2D PC flow measurements. In all but 3 of the tested stents time-resolved 3D particle traces could be visualized inside the stent lumen. Quality of 4D flow visualization and CE-MRA images depended on stent type and stent orientation relative to the magnetic field. Compared to the visible lumen area determined by 3D CE-MRA, estimates of lumen patency derived from 4D flow measurements were significantly higher and less dependent on stent type. A higher number of stents could be assessed for in-stent patency by 4D phase contrast flow imaging (n=14) than by 2D phase contrast flow imaging (n=10). 4D phase contrast flow imaging in peripheral vascular stents is feasible and appears advantageous over conventional 3D contrast-enhanced MR angiography and 2D phase contrast flow imaging. It allows for in-stent flow visualization and flow quantification with varying quality depending on stent type. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Individual differences in the shape of the nasal visual field.

PubMed

Swanson, William H; Dul, Mitchell W; Horner, Douglas G; Malinovsky, Victor E

2017-12-01

Between-subject differences in the shape of the nasal visual field were assessed for 103 volunteers 21-85years of age and free of visual disorder. Perimetry was conducted with a stimulus for which contrast sensitivity is minimally affected by peripheral defocus and decreased retinal illumination. One eye each was tested for 103 volunteers free of eye disease in a multi-center prospective longitudinal study. A peripheral deviation index was computed as the difference in log contrast sensitivity at outer (25-29° nasal) and inner (8° from fixation) locations. Values for this index ranged from 0.01 (outer sensitivity slightly greater than inner sensitivity) to -0.7 log unit (outer sensitivity much lower than inner sensitivity). Mean sensitivity for the inner locations was independent of the deviation index (R 2 <1%), while mean sensitivity for the outer locations was not (R 2 =38%, p<0.0005). Age was only modestly related to the index, with a decline by 0.017 log unit per decade (R 2 =10%). Test-retest data for 21 volunteers who completed 7-10 visits yielded standard deviations for the index from 0.04 to 0.17 log unit, with a mean of 0.09 log unit. Between-subject differences in peripheral deviation persisted over two years of longitudinal testing. Peripheral deviation indices were correlated with indices for three other perimetric stimuli used in a subset of 24 volunteers (R 2 from 20% to 49%). Between-subject variability in shape of the visual field raises concerns about current clinical visual field indices, and further studies are needed to develop improved indices. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Visual Sensory and Visual-Cognitive Function and Rate of Crash and Near-Crash Involvement Among Older Drivers Using Naturalistic Driving Data

PubMed Central

Huisingh, Carrie; Levitan, Emily B.; Irvin, Marguerite R.; MacLennan, Paul; Wadley, Virginia; Owsley, Cynthia

2017-01-01

Purpose An innovative methodology using naturalistic driving data was used to examine the association between visual sensory and visual-cognitive function and rates of future crash or near-crash involvement among older drivers. Methods The Strategic Highway Research Program (SHRP2) Naturalistic Driving Study was used for this prospective analysis. The sample consisted of N = 659 drivers aged ≥70 years and study participation lasted 1 or 2 years for most participants. Distance and near visual acuity, contrast sensitivity, peripheral vision, visual processing speed, and visuospatial skills were assessed at baseline. Crash and near-crash involvement were based on video recordings and vehicle sensors. Poisson regression models were used to generate crude and adjusted rate ratios (RRs) and 95% confidence intervals, while accounting for person-miles of travel. Results After adjustment, severe impairment of the useful field of view (RR = 1.33) was associated with an increased rate of near-crash involvement. Crash, severe crash, and at-fault crash involvement were associated with impaired contrast sensitivity in the worse eye (RRs = 1.38, 1.54, and 1.44, respectively) and far peripheral field loss in both eyes (RRs = 1.74, 2.32, and 1.73, respectively). Conclusions Naturalistic driving data suggest that contrast sensitivity in the worse eye and far peripheral field loss in both eyes elevate the rates of crash involvement, and impaired visual processing speed elevates rates of near-crash involvement among older drivers. Naturalistic driving data may ultimately be critical for understanding the relationship between vision and driving safety. PMID:28605807

Imaging anatomy of the vestibular and visual systems.

PubMed

Gunny, Roxana; Yousry, Tarek A

2007-02-01

This review will outline the imaging anatomy of the vestibular and visual pathways, using computed tomography and magnetic resonance imaging, with emphasis on the more recent developments in neuroimaging. Technical advances in computed tomography and magnetic resonance imaging, such as the advent of multislice computed tomography and newer magnetic resonance imaging techniques such as T2-weighted magnetic resonance cisternography, have improved the imaging of the vestibular and visual pathways, allowing better visualization of the end organs and peripheral nerves. Higher field strength magnetic resonance imaging is a promising tool, which has been used to evaluate and resolve fine anatomic detail in vitro, as in the labyrinth. Advanced magnetic resonance imaging techniques such as functional magnetic resonance imaging and diffusion tractography have been used to identify cortical areas of activation and associated white matter pathways, and show potential for the future identification of complex neuronal relays involved in integrating these pathways. The assessment of the various components of the vestibular and the visual systems has improved with more detailed research on the imaging anatomy of these systems, the advent of high field magnetic resonance scanners and multislice computerized tomography, and the wider use of specific techniques such as tractography which displays white matter tracts not directly accessible until now.

Improved Visual Cognition through Stroboscopic Training

PubMed Central

Appelbaum, L. Gregory; Schroeder, Julia E.; Cain, Matthew S.; Mitroff, Stephen R.

2011-01-01

Humans have a remarkable capacity to learn and adapt, but surprisingly little research has demonstrated generalized learning in which new skills and strategies can be used flexibly across a range of tasks and contexts. In the present work we examined whether generalized learning could result from visual–motor training under stroboscopic visual conditions. Individuals were assigned to either an experimental condition that trained with stroboscopic eyewear or to a control condition that underwent identical training with non-stroboscopic eyewear. The training consisted of multiple sessions of athletic activities during which participants performed simple drills such as throwing and catching. To determine if training led to generalized benefits, we used computerized measures to assess perceptual and cognitive abilities on a variety of tasks before and after training. Computer-based assessments included measures of visual sensitivity (central and peripheral motion coherence thresholds), transient spatial attention (a useful field of view – dual task paradigm), and sustained attention (multiple-object tracking). Results revealed that stroboscopic training led to significantly greater re-test improvement in central visual field motion sensitivity and transient attention abilities. No training benefits were observed for peripheral motion sensitivity or peripheral transient attention abilities, nor were benefits seen for sustained attention during multiple-object tracking. These findings suggest that stroboscopic training can effectively improve some, but not all aspects of visual perception and attention. PMID:22059078

Pilot response to peripheral vision cues during instrument flying tasks.

DOT National Transportation Integrated Search

1968-02-01

In an attempt to more closely associate the visual aspects of instrument flying with that of contact flight, a study was made of human response to peripheral vision cues relating to aircraft roll attitude. Pilots, ranging from 52 to 12,000 flying hou...

Acute painless monocular visual loss due to central retinal artery occlusion in a patient with Churg-Strauss vasculitis.

PubMed

Skrapari, Ioanna; Kagkelari, Eleftheria; Charitatos, Evangelos; Pantelidaki, Catherine; Gounaris, Theodoros; Sioula, Evagelia

2008-01-01

Ocular involvement in Churg-Strauss syndrome (CSS) is infrequent. We describe a case of a 50-year-old woman, with blood eosinophilia, involvement of the respiratory tract, skin, and peripheral nervous system, fulfilling the American College of Rheumatology criteria for CSS, who presented with left foot drop followed by left acute painless visual loss. Central retinal artery occlusion was diagnosed by fundoscopic findings (retinal whitening with a cherry-red spot). CSS was confirmed by sural nerve biopsy. Despite treatment with high-dose corticosteroids, cyclophosphamide, and anticoagulant therapy, visual acuity was not substantially improved. Acute blindness in CSS has been rarely described. Even more rarely, central retinal artery occlusion has been found to be the underlying cause of this infrequent clinical manifestation in CSS.

Developmental outcome, including setback, in young children with severe visual impairment.

PubMed

Dale, Naomi; Sonksen, Patricia

2002-09-01

This study retrospectively investigated the developmental perspective of 69 children (40 males, 29 females) with 'potentially simple' congenital disorders of the peripheral visual system: development was examined in the context of degree of visual impairment. Developmental and visual assessments were carried out at 10 to 16 months (Time 1) and 27 to 54 months of age (Time 2). Participants were grouped according to (1) visual status: profound visual impairment (PVI), severe visual impairment (SVI); (2) developmental status on the Reynell-Zinkin scales. A majority of the sample showed normal development on all subscales (62% Time 1, 57% Time 2). Those with PVI were more developmentally vulnerable than SVI with a greater incidence of (1) uneven developmental profile at Time 1 (48% PVI, 16% SVI); (2) global learning difficulties at Time 2 (37% PVI, 0% SVI); (3) delay on individual subscales at Time 2 (p<0.02 PVI versus SVI); (4) deceleration (verbal comprehension 74% PVI, 24% SVI, sensorimotor understanding 70% PVI, 27% SVI); and (5) severe developmental setback (33% PVI, 7% SVI). Risk factors of visual level, age, and sex for poor developmental outcome in infants with visual impairment were established.

Display technology - Human factors concepts

NASA Astrophysics Data System (ADS)

Stokes, Alan; Wickens, Christopher; Kite, Kirsten

1990-03-01

Recent advances in the design of aircraft cockpit displays are reviewed, with an emphasis on their applicability to automobiles. The fundamental principles of display technology are introduced, and individual chapters are devoted to selective visual attention, command and status displays, foveal and peripheral displays, navigational displays, auditory displays, color and pictorial displays, head-up displays, automated systems, and dual-task performance and pilot workload. Diagrams, drawings, and photographs of typical displays are provided.

[Clinico-pathologic correlation of dementia produced by thinner and cocaine].

PubMed

Barroso Moguel, R; Méndez Armenta, M; Villeda Hernández, J

1993-01-01

Industrial solvents mixed from thinner, used in paints, leathers, rubber, varnishes, have neurotoxic action. By laboral inhalation or spontaneously these are absorbed from the lungs, transported by blood and because of this high lipophilic section are retained within the lipid rich nervous system. Euphoric effects appear accompanied with visual and additive halucinations. In chronic abusers it produce schizophrenic-paranoid consequences with encephalic and peripheral neuronal and nervous fibers destruction, accompanied of blindness and paralysis. Cocaine is another neurotoxic drug. At first it produces euphoria, arterial hypertension and symptoms suggestive of underlying psychiatric diseases. The cocaine addicts often suffer depression, paranoia, hallucinations, seizures and suicidal ideation. The morphological base of the symptomatology is the encephalic and peripheral neuronal and nerve fibers destruction.

Optimizing MRI for imaging peripheral arthritis.

PubMed

Hodgson, Richard J; O'Connor, Philip J; Ridgway, John P

2012-11-01

MRI is increasingly used for the assessment of both inflammatory arthritis and osteoarthritis. The wide variety of MRI systems in use ranges from low-field, low-cost extremity units to whole-body high-field 7-T systems, each with different strengths for specific applications. The availability of dedicated radiofrequency phased-array coils allows the rapid acquisition of high-resolution images of one or more peripheral joints. MRI is uniquely flexible in its ability to manipulate image contrast, and individual MR sequences may be combined into protocols to sensitively visualize multiple features of arthritis including synovitis, bone marrow lesions, erosions, cartilage changes, and tendinopathy. Careful choice of the imaging parameters allows images to be generated with optimal quality while minimizing unwanted artifacts. Finally, there are many novel MRI techniques that can quantify disease levels in arthritis in tissues including synovitis and cartilage. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Unconscious analyses of visual scenes based on feature conjunctions.

PubMed

Tachibana, Ryosuke; Noguchi, Yasuki

2015-06-01

To efficiently process a cluttered scene, the visual system analyzes statistical properties or regularities of visual elements embedded in the scene. It is controversial, however, whether those scene analyses could also work for stimuli unconsciously perceived. Here we show that our brain performs the unconscious scene analyses not only using a single featural cue (e.g., orientation) but also based on conjunctions of multiple visual features (e.g., combinations of color and orientation information). Subjects foveally viewed a stimulus array (duration: 50 ms) where 4 types of bars (red-horizontal, red-vertical, green-horizontal, and green-vertical) were intermixed. Although a conscious perception of those bars was inhibited by a subsequent mask stimulus, the brain correctly analyzed the information about color, orientation, and color-orientation conjunctions of those invisible bars. The information of those features was then used for the unconscious configuration analysis (statistical processing) of the central bars, which induced a perceptual bias and illusory feature binding in visible stimuli at peripheral locations. While statistical analyses and feature binding are normally 2 key functions of the visual system to construct coherent percepts of visual scenes, our results show that a high-level analysis combining those 2 functions is correctly performed by unconscious computations in the brain. (c) 2015 APA, all rights reserved).

Foveal and peripheral fields of vision influences perceptual skill in anticipating opponents' attacking position in volleyball.

PubMed

Schorer, Jörg; Rienhoff, Rebecca; Fischer, Lennart; Baker, Joseph

2013-09-01

The importance of perceptual-cognitive expertise in sport has been repeatedly demonstrated. In this study we examined the role of different sources of visual information (i.e., foveal versus peripheral) in anticipating volleyball attack positions. Expert (n = 11), advanced (n = 13) and novice (n = 16) players completed an anticipation task that involved predicting the location of volleyball attacks. Video clips of volleyball attacks (n = 72) were spatially and temporally occluded to provide varying amounts of information to the participant. In addition, participants viewed the attacks under three visual conditions: full vision, foveal vision only, and peripheral vision only. Analysis of variance revealed significant between group differences in prediction accuracy with higher skilled players performing better than lower skilled players. Additionally, we found significant differences between temporal and spatial occlusion conditions. Both of those factors interacted separately, but not combined with expertise. Importantly, for experts the sum of both fields of vision was superior to either source in isolation. Our results suggest different sources of visual information work collectively to facilitate expert anticipation in time-constrained sports and reinforce the complexity of expert perception.

The Role of the Caudal Superior Parietal Lobule in Updating Hand Location in Peripheral Vision: Further Evidence from Optic Ataxia

PubMed Central

Granek, Joshua A.; Pisella, Laure; Blangero, Annabelle; Rossetti, Yves; Sergio, Lauren E.

2012-01-01

Patients with optic ataxia (OA), who are missing the caudal portion of their superior parietal lobule (SPL), have difficulty performing visually-guided reaches towards extra-foveal targets. Such gaze and hand decoupling also occurs in commonly performed non-standard visuomotor transformations such as the use of a computer mouse. In this study, we test two unilateral OA patients in conditions of 1) a change in the physical location of the visual stimulus relative to the plane of the limb movement, 2) a cue that signals a required limb movement 180° opposite to the cued visual target location, or 3) both of these situations combined. In these non-standard visuomotor transformations, the OA deficit is not observed as the well-documented field-dependent misreach. Instead, OA patients make additional eye movements to update hand and goal location during motor execution in order to complete these slow movements. Overall, the OA patients struggled when having to guide centrifugal movements in peripheral vision, even when they were instructed from visual stimuli that could be foveated. We propose that an intact caudal SPL is crucial for any visuomotor control that involves updating ongoing hand location in space without foveating it, i.e. from peripheral vision, proprioceptive or predictive information. PMID:23071599

Change in peripheral refraction and curvature of field of the human eye with accommodation

NASA Astrophysics Data System (ADS)

Ho, Arthur; Zimmermann, Frederik; Whatham, Andrew; Martinez, Aldo; Delgado, Stephanie; Lazon de la Jara, Percy; Sankaridurg, Padmaja

2009-02-01

Recent research showed that the peripheral refractive state is a sufficient stimulus for myopia progression. This finding led to the suggestion that devices that control peripheral refraction may be efficacious in controlling myopia progression. This study aims to understand whether the optical effect of such devices may be affected by near focus. In particular, we seek to understand the influence of accommodation on peripheral refraction and curvature of field of the eye. Refraction was measured in twenty young subjects using an autorefractor at 0° (i.e. along visual axis), and 20°, 30° and 40° field angles both nasal and temporal to the visual axis. All measurements were conducted at 2.5 m, 40 cm and 30 cm viewing distances. Refractive errors were corrected using a soft contact lens during all measurements. As field angle increased, refraction became less hyperopic. Peripheral refraction also became less hyperopic at nearer viewing distances (i.e. with increasing accommodation). Astigmatism (J180) increased with field angle as well as with accommodation. Adopting a third-order aberration theory approach, the position of the Petzval surface relative to the retinal surface was estimated by considering the relative peripheral refractive error (RPRE) and J180 terms of peripheral refraction. Results for the estimated dioptric position of the Petzval surface relative to the retina showed substantial asymmetry. While temporal field tended to agree with theoretical predictions, nasal response departed dramatically from the model eye predictions. With increasing accommodation, peripheral refraction becomes less hyperopic while the Petzval surface showed asymmetry in its change in position. The change in the optical components (i.e. cornea and/or lens as opposed to retinal shape or position) is implicated as at least one of the contributors of this shift in peripheral refraction during accommodation.

A Pilot Study of Perceptual-Motor Training for Peripheral Prisms

PubMed Central

Houston, Kevin E.; Bowers, Alex R.; Fu, Xianping; Liu, Rui; Goldstein, Robert B.; Churchill, Jeff; Wiegand, Jean-Paul; Soo, Tim; Tang, Qu; Peli, Eli

2016-01-01

Purpose Peripheral prisms (p-prisms) shift peripheral portions of the visual field of one eye, providing visual field expansion for patients with hemianopia. However, patients rarely show adaption to the shift, incorrectly localizing objects viewed within the p-prisms. A pilot evaluation of a novel computerized perceptual-motor training program aiming to promote p-prism adaption was conducted. Methods Thirteen patients with hemianopia fitted with 57Δ oblique p-prisms completed the training protocol. They attended six 1-hour visits reaching and touching peripheral checkerboard stimuli presented over videos of driving scenes while fixating a central target. Performance was measured at each visit and after 3 months. Results There was a significant reduction in touch error (P = 0.01) for p-prism zone stimuli from pretraining median of 16.6° (IQR 12.1°–19.6°) to 2.7° ( IQR 1.0°–8.5°) at the end of training. P-prism zone reaction times did not change significantly with training (P > 0.05). P-prism zone detection improved significantly (P = 0.01) from a pretraining median 70% (IQR 50%–88%) to 95% at the end of training (IQR 73%–98%). Three months after training improvements had regressed but performance was still better than pretraining. Conclusions Improved pointing accuracy for stimuli detected in prism-expanded vision of patients with hemianopia wearing 57Δ oblique p-prisms is possible and training appears to further improve detection. Translational Relevance This is the first use of this novel software to train adaptation of visual direction in patients with hemianopia wearing peripheral prisms. PMID:26933522

Assessing idiopathic pulmonary fibrosis (IPF) with bronchoscopic OCT (Conference Presentation)

NASA Astrophysics Data System (ADS)

Hariri, Lida P.; Adams, David C.; Colby, Thomas V.; Tager, Andrew M.; Suter, Melissa J.

2016-03-01

Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal form of fibrotic lung disease, with a significantly worse prognosis than other forms of pulmonary fibrosis (3-year survival rate of 50%). Distinguishing IPF from other fibrotic diseases is essential to patient care because it stratifies prognosis and therapeutic decision-making. However, making the diagnosis often requires invasive, high-risk surgical procedures to look for microscopic features not seen on chest CT, such as characteristic cystic honeycombing in the peripheral lung. Optical coherence tomography (OCT) provides rapid 3D visualization of large tissue volumes with microscopic resolutions well beyond the capabilities of CT. We aim to determine whether bronchoscopic OCT can provide a low-risk, non-surgical method for IPF diagnosis. We have developed bronchoscopic OCT catheters that access the peripheral lung and conducted in vivo peripheral lung imaging in patients, including those with pulmonary fibrosis. We also conducted bronchoscopic OCT in ex vivo lung from pulmonary fibrosis patients, including IPF, to determine if OCT could successfully visualize features of IPF through the peripheral airways. Our results demonstrate that OCT is able to visualize characteristic features of IPF through the airway, including microscopic honeycombing (< 1 mm diameter) not visible by CT, dense peripheral fibrosis, and spatial disease heterogeneity. We also found that OCT has potential to distinguish mimickers of IPF honeycombing, such as traction bronchiectasis and emphysema, from true honeycombing. These findings support the potential of bronchoscopic OCT as a minimally-invasive method for in vivo IPF diagnosis. However, future clinical studies are needed to validate these findings.

Cell Death, Neuronal Plasticity and Functional Loading in the Development of the Central Nervous System

NASA Technical Reports Server (NTRS)

Keefe, J. R.

1985-01-01

Research on the precise timing and regulation of neuron production and maturation in the vestibular and visual systems of Wistar rats and several inbred strains of mice (C57B16 and Pallid mutant) concentrated upon establishing a timing baseline for mitotic development of the neurons of the vestibular nuclei and the peripheral vestibular sensory structures (maculae, cristae). This involved studies of the timing and site of neuronal cell birth and preliminary studies of neuronal cell death in both central and peripheral elements of the mammalian vestibular system. Studies on neuronal generation and maturation in the retina were recently added to provide a mechanism for more properly defining the in utero' developmental age of the individual fetal subject and to closely monitor potential transplacental effects of environmentally stressed maternal systems. Information is given on current efforts concentrating upon the (1) perinatal period of development (E18 thru P14) and (2) the role of cell death in response to variation in the functional loading of the vestibular and proprioreceptive systems in developing mammalian organisms.

Sequential involvement of the nervous system in subacute combined degeneration.

PubMed

Minn, Yang-Ki; Kim, Seung-Min; Kim, Se-Hoon; Kwon, Ki-Han; Sunwoo, Il-Nam

2012-03-01

Subacute combined degeneration (SCD) involves progressive degeneration of the spinal cord, optic nerve, and peripheral nerves. Vitamin B12 (VB12) is a co-factor in myelin synthesis. Because each cell that constitutes the myelin component in the central nervous system and peripheral nervous system is different, it is improbable that these cells undergo simultaneous degeneration. However, the sequence of degeneration in SCD has not been established. In this study, we analysed medical records and electrophysiological data of patients who showed neurological symptoms and whose serum VB12 levels were lower than 200 pg/mL. We enrolled 49 patients in this study. Their mean VB12 level was 68.3 pg/mL. Somatosensory evoked potential (SEP) study showed abnormal findings in 38 patients. Of the 40 patients who underwent visual evoked potential (VEP) study, 14 showed abnormal responses. Eighteen patients showed abnormal findings on a nerve conduction study (NCS). In this study, abnormal posterior tibial nerve SEPs only were seen in 16 patients, median nerve SEPs only were seen in 3 patients, abnormal VEPs only in two, and abnormal NCS responses in one patient. No patient complained of cognitive symptoms. In SCD, degeneration appears to progress in the following order: lower spinal cord, cervical spinal cord, peripheral nerve/optic nerve, and finally, the brain.

Screening for Electrophysiological Abnormalities in Chronic Hepatitis C Infection: Peripheral Neuropathy and Optic Neuropathy.

PubMed

Köşkderelioğlu, Aslı; Ortan, Pınar; Ari, Alpay; Gedizlioğlu, Muhteşem

2016-03-01

To investigate the existence of peripheral and optic neuropathies in asymptomatic individuals with hepatitis C infection. Thirty consecutive patients who were followed in a hepatitis C outpatient clinic were recruited for electrophysiological evaluation together with 30 age- and gender-compatible healthy controls. All patients had a detailed neurological examination. The information regarding the disease duration and management with interferons were collected. Nerve conduction studies and visual evoked potentials (VEP) were recorded in all subjects. The results of the patient and control groups were statistically compared. Of the patients with hepatitis C infection, 16 were females and 14 males. The mean age was 57.5 years, and the average disease duration was 6.43 years. The P100 latencies in the patient group were within normal limits, while the amplitudes were meaningfully small by comparison with the controls. There were some abnormalities in the nerve conduction studies of 15 patients. Sensorial neuropathy was detected in two patients, sensorimotor polyneuropathy in four, carpal tunnel syndrome in seven, and carpal tunnel syndrome and sensorimotor polyneuropathy as comorbid states in another two patients. The nerve conduction studies and VEP parameters were entirely normal in the control group. Hepatitis C-related neurological abnormalities may occur both in the central and peripheral nervous system. Mononeuritis multiplex, sensorial axonal neuropathy, and multiple mononeuropathies are some of the presentations of the peripheral nervous system involvement. The mode of infection is considered to be via vasculitic mechanisms. In addition, optic neuropathy is a known complication of interferon treatment. Autoantibodies, cytokines, chemokines, and cryoglobulins are accused to play roles in the pathogenesis. In this study, we investigated the involvement of the peripheral nervous system and optic nerves in a group of patients with hepatitis C. The results were in favor of peripheral nerve injury of various types and optic neuropathy of the axonal type.

Screening for Electrophysiological Abnormalities in Chronic Hepatitis C Infection: Peripheral Neuropathy and Optic Neuropathy

PubMed Central

KÖŞKDERELİOĞLU, Aslı; ORTAN, Pınar; ARI, Alpay; GEDİZLİOĞLU, Muhteşem

2016-01-01

Introduction To investigate the existence of peripheral and optic neuropathies in asymptomatic individuals with hepatitis C infection. Methods Thirty consecutive patients who were followed in a hepatitis C outpatient clinic were recruited for electrophysiological evaluation together with 30 age- and gender-compatible healthy controls. All patients had a detailed neurological examination. The information regarding the disease duration and management with interferons were collected. Nerve conduction studies and visual evoked potentials (VEP) were recorded in all subjects. The results of the patient and control groups were statistically compared. Results Of the patients with hepatitis C infection, 16 were females and 14 males. The mean age was 57.5 years, and the average disease duration was 6.43 years. The P100 latencies in the patient group were within normal limits, while the amplitudes were meaningfully small by comparison with the controls. There were some abnormalities in the nerve conduction studies of 15 patients. Sensorial neuropathy was detected in two patients, sensorimotor polyneuropathy in four, carpal tunnel syndrome in seven, and carpal tunnel syndrome and sensorimotor polyneuropathy as comorbid states in another two patients. The nerve conduction studies and VEP parameters were entirely normal in the control group. Conclusion Hepatitis C-related neurological abnormalities may occur both in the central and peripheral nervous system. Mononeuritis multiplex, sensorial axonal neuropathy, and multiple mononeuropathies are some of the presentations of the peripheral nervous system involvement. The mode of infection is considered to be via vasculitic mechanisms. In addition, optic neuropathy is a known complication of interferon treatment. Autoantibodies, cytokines, chemokines, and cryoglobulins are accused to play roles in the pathogenesis. In this study, we investigated the involvement of the peripheral nervous system and optic nerves in a group of patients with hepatitis C. The results were in favor of peripheral nerve injury of various types and optic neuropathy of the axonal type. PMID:28360761

The role of lower peripheral visual cues in the visuomotor coordination of locomotion and prehension.

PubMed

Graci, Valentina

2011-10-01

It has been previously suggested that coupled upper and limb movements need visuomotor coordination to be achieved. Previous studies have not investigated the role that visual cues may play in the coordination of locomotion and prehension. The aim of this study was to investigate if lower peripheral visual cues provide online control of the coordination of locomotion and prehension as they have been showed to do during adaptive gait and level walking. Twelve subjects reached a semi-empty or a full glass with their dominant or non-dominant hand at gait termination. Two binocular visual conditions were investigated: normal vision and lower visual occlusion. Outcome measures were determined using 3D motion capture techniques. Results showed that although the subjects were able to successfully complete the task without spilling the water from the glass under lower visual occlusion, they increased the margin of safety between final foot placements and glass. These findings suggest that lower visual cues are mainly used online to fine tune the trajectory of the upper and lower limbs moving toward the target. Copyright © 2011 Elsevier B.V. All rights reserved.

Interocular Difference of Peripheral Refraction in Anisomyopic Eyes of Schoolchildren

PubMed Central

Chen, Junhong; He, Ji C.; Chen, Yunyun; Xu, Jingjing; Wu, Haoran; Wang, Feifu; Lu, Fan; Jiang, Jun

2016-01-01

Purpose Refraction in the peripheral visual field is believed to play an important role in the development of myopia. The purpose of this study was to investigate the differences in peripheral refraction among anisomyopia, isomyopia, and isoemmetropia for schoolchildren. Methods Thirty-eight anisomyopic children were recruited and divided into two groups: (1) both eyes were myopic (anisomyopic group, AM group) and (2) one eye was myopic and the contralateral eye was emmetropic (emmetropic anisomyopic group, EAM group). As controls, 45 isomyopic and isoemmetropic children were also recruited with age and central spherical equivalent (SE) matched to those of the AM and EAM groups. The controls were divided into three groups: (1) intermediate myopia group (SE matched to the more myopic eye of AM group), (2) low myopia group (SE matched to the less myopic eye of AM group and the more myopic eye of EAM group), and (3) emmetropia group (SE matched to the less myopic eye of EAM group). Peripheral refraction at 7 points across the central ±30° on the horizontal visual field with a 10° interval was measured with an autorefractor. Axial length (AL), corneal curvature (CC), and anterior chamber depth (ACD) were also determined by using the Zeiss IOL-Master. Results The relative peripheral spherical equivalent [RPR(M)] and relative peripheral spherical value [RPR(S)] of the more myopic eye was shifted more hyperopically than the contralateral eye in both the AM and the EAM groups (both p<0.0001). The RPR(M, S) of the less myopic eyes in the AM and EAM groups showed a relatively flat trend across the visual field and were not significantly different from the emmetropia group. The RPR(M, S) of less myopic eyes in the AM group were shifted less hyperopically than in the isomyopic low myopia group and the more myopic eye of the EAM group [RPR(M), p = 0.007; RPR(S), p = 0.001], although the central SEs of the three groups were not significantly different from each other. However, RPR(M, S) of the more myopic eyes were not different from the corresponding isomyopic groups. There was also no significant difference in the relative peripheral astigmatism [RPR(J0, J45)] between the more and the less myopic eyes in either the AM or the EAM group. Conclusion Refraction of anisomyopia differs between the two eyes not only at the central visual field but also at the off-axis periphery. The relative peripheral refraction of the more myopic eye of anisomyopia was shifted hyperopically, as occurs in isomyopia with similar central subjective SE values. Less myopic eyes were much less hyperopically shifted in relative peripheral refraction than the corresponding isomyopic eyes, but are comparable to emmetropic eyes. This emmetropia-like relative peripheral refraction in less myopic eyes might be a factor responsible for slowing down the progression of myopia. PMID:26881745

Interocular Difference of Peripheral Refraction in Anisomyopic Eyes of Schoolchildren.

PubMed

Chen, Junhong; He, Ji C; Chen, Yunyun; Xu, Jingjing; Wu, Haoran; Wang, Feifu; Lu, Fan; Jiang, Jun

2016-01-01

Refraction in the peripheral visual field is believed to play an important role in the development of myopia. The purpose of this study was to investigate the differences in peripheral refraction among anisomyopia, isomyopia, and isoemmetropia for schoolchildren. Thirty-eight anisomyopic children were recruited and divided into two groups: (1) both eyes were myopic (anisomyopic group, AM group) and (2) one eye was myopic and the contralateral eye was emmetropic (emmetropic anisomyopic group, EAM group). As controls, 45 isomyopic and isoemmetropic children were also recruited with age and central spherical equivalent (SE) matched to those of the AM and EAM groups. The controls were divided into three groups: (1) intermediate myopia group (SE matched to the more myopic eye of AM group), (2) low myopia group (SE matched to the less myopic eye of AM group and the more myopic eye of EAM group), and (3) emmetropia group (SE matched to the less myopic eye of EAM group). Peripheral refraction at 7 points across the central ±30° on the horizontal visual field with a 10° interval was measured with an autorefractor. Axial length (AL), corneal curvature (CC), and anterior chamber depth (ACD) were also determined by using the Zeiss IOL-Master. The relative peripheral spherical equivalent [RPR(M)] and relative peripheral spherical value [RPR(S)] of the more myopic eye was shifted more hyperopically than the contralateral eye in both the AM and the EAM groups (both p<0.0001). The RPR(M, S) of the less myopic eyes in the AM and EAM groups showed a relatively flat trend across the visual field and were not significantly different from the emmetropia group. The RPR(M, S) of less myopic eyes in the AM group were shifted less hyperopically than in the isomyopic low myopia group and the more myopic eye of the EAM group [RPR(M), p = 0.007; RPR(S), p = 0.001], although the central SEs of the three groups were not significantly different from each other. However, RPR(M, S) of the more myopic eyes were not different from the corresponding isomyopic groups. There was also no significant difference in the relative peripheral astigmatism [RPR(J0, J45)] between the more and the less myopic eyes in either the AM or the EAM group. Refraction of anisomyopia differs between the two eyes not only at the central visual field but also at the off-axis periphery. The relative peripheral refraction of the more myopic eye of anisomyopia was shifted hyperopically, as occurs in isomyopia with similar central subjective SE values. Less myopic eyes were much less hyperopically shifted in relative peripheral refraction than the corresponding isomyopic eyes, but are comparable to emmetropic eyes. This emmetropia-like relative peripheral refraction in less myopic eyes might be a factor responsible for slowing down the progression of myopia.

[Eccentricity-dependent influence of amodal completion on visual search].

PubMed

Shirama, Aya; Ishiguchi, Akira

2009-06-01

Does amodal completion occur homogeneously across the visual field? Rensink and Enns (1998) found that visual search for efficiently-detected fragments became inefficient when observers perceived the fragments as a partially-occluded version of a distractor due to a rapid completion process. We examined the effect of target eccentricity in Rensink and Enns's tasks and a few additional tasks by magnifying the stimuli in the peripheral visual field to compensate for the loss of spatial resolution (M-scaling; Rovamo & Virsu, 1979). We found that amodal completion disrupted the efficient search for the salient fragments (i.e., target) even when the target was presented at high eccentricity (within 17 deg). In addition, the configuration effect of the fragments, which produced amodal completion, increased with eccentricity while the same target was detected efficiently at the lowest eccentricity. This eccentricity effect is different from a previously-reported eccentricity effect where M-scaling was effective (Carrasco & Frieder, 1997). These findings indicate that the visual system has a basis for rapid completion across the visual field, but the stimulus representations constructed through amodal completion have eccentricity-dependent properties.

Mobility scooter driving ability in visually impaired individuals.

PubMed

Cordes, Christina; Heutink, Joost; Brookhuis, Karel A; Brouwer, Wiebo H; Melis-Dankers, Bart J M

2018-06-01

To investigate how well visually impaired individuals can learn to use mobility scooters and which parts of the driving task deserve special attention. A mobility scooter driving skill test was developed to compare driving skills (e.g. reverse driving, turning) between 48 visually impaired (very low visual acuity = 14, low visual acuity = 10, peripheral field defects = 11, multiple visual impairments = 13) and 37 normal-sighted controls without any prior experience with mobility scooters. Performance on this test was rated on a three-point scale. Furthermore, the number of extra repetitions on the different elements were noted. Results showed that visually impaired participants were able to gain sufficient driving skills to be able to use mobility scooters. Participants with visual field defects combined with low visual acuity showed most problems learning different skills and needed more training. Reverse driving and stopping seemed to be most difficult. The present findings suggest that visually impaired individuals are able to learn to drive mobility scooters. Mobility scooter allocators should be aware that these individuals might need more training on certain elements of the driving task. Implications for rehabilitation Visual impairments do not necessarily lead to an inability to acquire mobility scooter driving skills. Individuals with peripheral field defects (especially in combination with reduced visual acuity) need more driving ability training compared to normal-sighted people - especially to accomplish reversing. Individual assessment of visually impaired people is recommended, since participants in this study showed a wide variation in ability to learn driving a mobility scooter.

Noninvasive identification of peripheral vessels of oral and maxillofacial regions by using electrocardiography-triggered three-dimensional fast asymmetric spin-echo sequences.

PubMed

Tanaka, Tatsurou; Oda, Masafumi; Kito, Shinji; Wakasugi-Sato, Nao; Matsumoto-Takeda, Shinobu; Otsuka, Kozue; Yoshioka, Izumi; Habu, Manabu; Kokuryo, Shinya; Kodama, Masaaki; Nogami, Shinnosuke; Miyamoto, Ikuya; Yamamoto, Noriaki; Ishikawa, Ayataka; Matsuo, Kou; Shiiba, Shunji; Seta, Yuji; Yamashita, Yoshihiro; Takahashi, Tetsu; Tominaga, Kazuhiro; Morimoto, Yasuhiro

2011-10-01

The aim of this study was to evaluate the 3-dimensional images of thinner main peripheral vessels in oral and maxillofacial regions made without contrast medium by using a new technique, fresh blood imaging (FBI). A second objective was to discern arteries from veins by using the combination of FBI with the subtraction technique. Images from FBI were compared with those from 3-dimensional phase-contrast magnetic resonance angiography (MRA) of blood vessels in 20 healthy subjects. All images were scored for visualization and image quality of the main blood vessels. In addition, appropriate flow-spoiled gradient pulses were applied to differentiate arteries from veins in the peripheral vasculature using a combination of FBI sequences and subtraction between systole- and diastole-triggered images. The scores of MRA using FBI for the visualization of thin blood vessels were significantly better than those using phase contrast, whereas scores for the visualization of main blood vessels were equal. Additionally, we succeeded in our initial attempt to differentiate arteries from veins with a reasonable acquisition time. Our initial experience shows that FBI could be a useful method to identify 3-dimensional vasculature and to differentiate arteries from veins among thinner peripheral vessels in the oral and maxillofacial regions without using contrast medium. Copyright © 2011 Mosby, Inc. All rights reserved.

Assessing idiopathic pulmonary fibrosis (IPF) with bronchoscopic OCT (Conference Presentation)

NASA Astrophysics Data System (ADS)

Hariri, Lida P.; Adams, David C.; Colby, Thomas V.; Tager, Andrew M.; Suter, Melissa J.

2016-03-01

Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal form of fibrotic lung disease, with a 3 year survival rate of 50%. Diagnostic certainty of IPF is essential to determine the most effective therapy for patients, but often requires surgery to resect lung tissue and look for microscopic honeycombing not seen on chest computed tomography (CT). Unfortunately, surgical lung resection has high risks of associated morbidity and mortality in this patient population. We aim to determine whether bronchoscopic optical coherence tomography (OCT) can serve as a novel, low-risk paradigm for in vivo IPF diagnosis without surgery or tissue removal. OCT provides rapid 3D visualization of large tissue volumes with microscopic resolutions well beyond the capabilities of CT. We have designed bronchoscopic OCT catheters to effectively and safely access the peripheral lung, and conducted in vivo peripheral lung imaging in patients, including those with pulmonary fibrosis. We utilized these OCT catheters to perform bronchoscopic imaging in lung tissue from patients with pulmonary fibrosis to determine if bronchoscopic OCT could successfully visualize features of IPF through the peripheral airways. OCT was able to visualize characteristic features of IPF through the airway, including microscopic honeycombing (< 1 mm diameter) not visible by CT, dense peripheral fibrosis, and spatial disease heterogeneity. These findings support the potential of bronchoscopic OCT as a minimally-invasive method for in vivo IPF diagnosis. However, future clinical studies are needed to validate these findings.

Cortical metabolic activity matches the pattern of visual suppression in strabismus.

PubMed

Adams, Daniel L; Economides, John R; Sincich, Lawrence C; Horton, Jonathan C

2013-02-27

When an eye becomes deviated in early childhood, a person does not experience double vision, although the globes are aimed at different targets. The extra image is prevented from reaching perception in subjects with alternating exotropia by suppression of each eye's peripheral temporal retina. To test the impact of visual suppression on neuronal activity in primary (striate) visual cortex, the pattern of cytochrome oxidase (CO) staining was examined in four macaques raised with exotropia by disinserting the medial rectus muscles shortly following birth. No ocular dominance columns were visible in opercular cortex, where the central visual field is represented, indicating that signals coming from the central retina in each eye were perceived. However, the border strips at the edges of ocular dominance columns appeared pale, reflecting a loss of activity in binocular cells from disruption of fusion. In calcarine cortex, where the peripheral visual field is represented, there were alternating pale and dark bands resembling ocular dominance columns. To interpret the CO staining pattern, [(3)H]proline was injected into the right eye in two monkeys. In the right calcarine cortex, the pale CO columns matched the labeled proline columns of the right eye. In the left calcarine cortex, the pale CO columns overlapped the unlabeled columns of the left eye in the autoradiograph. Therefore, metabolic activity was reduced in the ipsilateral eye's ocular dominance columns which serve peripheral temporal retina, in a fashion consistent with the topographic organization of suppression scotomas in humans with exotropia.

A selective impairment of perception of sound motion direction in peripheral space: A case study.

PubMed

Thaler, Lore; Paciocco, Joseph; Daley, Mark; Lesniak, Gabriella D; Purcell, David W; Fraser, J Alexander; Dutton, Gordon N; Rossit, Stephanie; Goodale, Melvyn A; Culham, Jody C

2016-01-08

It is still an open question if the auditory system, similar to the visual system, processes auditory motion independently from other aspects of spatial hearing, such as static location. Here, we report psychophysical data from a patient (female, 42 and 44 years old at the time of two testing sessions), who suffered a bilateral occipital infarction over 12 years earlier, and who has extensive damage in the occipital lobe bilaterally, extending into inferior posterior temporal cortex bilaterally and into right parietal cortex. We measured the patient's spatial hearing ability to discriminate static location, detect motion and perceive motion direction in both central (straight ahead), and right and left peripheral auditory space (50° to the left and right of straight ahead). Compared to control subjects, the patient was impaired in her perception of direction of auditory motion in peripheral auditory space, and the deficit was more pronounced on the right side. However, there was no impairment in her perception of the direction of auditory motion in central space. Furthermore, detection of motion and discrimination of static location were normal in both central and peripheral space. The patient also performed normally in a wide battery of non-spatial audiological tests. Our data are consistent with previous neuropsychological and neuroimaging results that link posterior temporal cortex and parietal cortex with the processing of auditory motion. Most importantly, however, our data break new ground by suggesting a division of auditory motion processing in terms of speed and direction and in terms of central and peripheral space. Copyright © 2015 Elsevier Ltd. All rights reserved.

Common constraints limit Korean and English character recognition in peripheral vision.

PubMed

He, Yingchen; Kwon, MiYoung; Legge, Gordon E

2018-01-01

The visual span refers to the number of adjacent characters that can be recognized in a single glance. It is viewed as a sensory bottleneck in reading for both normal and clinical populations. In peripheral vision, the visual span for English characters can be enlarged after training with a letter-recognition task. Here, we examined the transfer of training from Korean to English characters for a group of bilingual Korean native speakers. In the pre- and posttests, we measured visual spans for Korean characters and English letters. Training (1.5 hours × 4 days) consisted of repetitive visual-span measurements for Korean trigrams (strings of three characters). Our training enlarged the visual spans for Korean single characters and trigrams, and the benefit transferred to untrained English symbols. The improvement was largely due to a reduction of within-character and between-character crowding in Korean recognition, as well as between-letter crowding in English recognition. We also found a negative correlation between the size of the visual span and the average pattern complexity of the symbol set. Together, our results showed that the visual span is limited by common sensory (crowding) and physical (pattern complexity) factors regardless of the language script, providing evidence that the visual span reflects a universal bottleneck for text recognition.

Common constraints limit Korean and English character recognition in peripheral vision

PubMed Central

He, Yingchen; Kwon, MiYoung; Legge, Gordon E.

2018-01-01

The visual span refers to the number of adjacent characters that can be recognized in a single glance. It is viewed as a sensory bottleneck in reading for both normal and clinical populations. In peripheral vision, the visual span for English characters can be enlarged after training with a letter-recognition task. Here, we examined the transfer of training from Korean to English characters for a group of bilingual Korean native speakers. In the pre- and posttests, we measured visual spans for Korean characters and English letters. Training (1.5 hours × 4 days) consisted of repetitive visual-span measurements for Korean trigrams (strings of three characters). Our training enlarged the visual spans for Korean single characters and trigrams, and the benefit transferred to untrained English symbols. The improvement was largely due to a reduction of within-character and between-character crowding in Korean recognition, as well as between-letter crowding in English recognition. We also found a negative correlation between the size of the visual span and the average pattern complexity of the symbol set. Together, our results showed that the visual span is limited by common sensory (crowding) and physical (pattern complexity) factors regardless of the language script, providing evidence that the visual span reflects a universal bottleneck for text recognition. PMID:29327041

Visualization of newt aragonitic otoconial matrices using transmission electron microscopy

NASA Technical Reports Server (NTRS)

Steyger, P. S.; Wiederhold, M. L.

1995-01-01

Otoconia are calcified protein matrices within the gravity-sensing organs of the vertebrate vestibular system. These protein matrices are thought to originate from the supporting or hair cells in the macula during development. Previous studies of mammalian calcitic, barrel-shaped otoconia revealed an organized protein matrix consisting of a thin peripheral layer, a well-defined organic core and a flocculent matrix inbetween. No studies have reported the microscopic organization of the aragonitic otoconial matrix, despite its protein characterization. Pote et al. (1993b) used densitometric methods and inferred that prismatic (aragonitic) otoconia have a peripheral protein distribution, compared to that described for the barrel-shaped, calcitic otoconia of birds, mammals, and the amphibian utricle. By using tannic acid as a negative stain, we observed three kinds of organic matrices in preparations of fixed, decalcified saccular otoconia from the adult newt: (1) fusiform shapes with a homogenous electron-dense matrix; (2) singular and multiple strands of matrix; and (3) more significantly, prismatic shapes outlined by a peripheral organic matrix. These prismatic shapes remain following removal of the gelatinous matrix, revealing an internal array of organic matter. We conclude that prismatic otoconia have a largely peripheral otoconial matrix, as inferred by densitometry.

Adaptation of velocity encoding in synaptically coupled neurons in the fly visual system.

PubMed

Kalb, Julia; Egelhaaf, Martin; Kurtz, Rafael

2008-09-10

Although many adaptation-induced effects on neuronal response properties have been described, it is often unknown at what processing stages in the nervous system they are generated. We focused on fly visual motion-sensitive neurons to identify changes in response characteristics during prolonged visual motion stimulation. By simultaneous recordings of synaptically coupled neurons, we were able to directly compare adaptation-induced effects at two consecutive processing stages in the fly visual motion pathway. This allowed us to narrow the potential sites of adaptation effects within the visual system and to relate them to the properties of signal transfer between neurons. Motion adaptation was accompanied by a response reduction, which was somewhat stronger in postsynaptic than in presynaptic cells. We found that the linear representation of motion velocity degrades during adaptation to a white-noise velocity-modulated stimulus. This effect is caused by an increasingly nonlinear velocity representation rather than by an increase of noise and is similarly strong in presynaptic and postsynaptic neurons. In accordance with this similarity, the dynamics and the reliability of interneuronal signal transfer remained nearly constant. Thus, adaptation is mainly based on processes located in the presynaptic neuron or in more peripheral processing stages. In contrast, changes of transfer properties at the analyzed synapse or in postsynaptic spike generation contribute little to changes in velocity coding during motion adaptation.

Identification of peripheral vessels in oral and maxillofacial regions on magnetic resonance angiography obtained using a balanced steady-state free-precession sequence with a time-spatial labeling inversion pulse and using fresh blood imaging.

PubMed

Oda, Masafumi; Tanaka, Tatsurou; Yamashita, Yoshihiro; Kito, Shinji; Wakasugi-Sato, Nao; Matsumoto-Takeda, Shinobu; Nishimura, Shun; Habu, Manabu; Kodama, Masaaki; Uehara, Masataka; Kaneuji, Tsuyoshi; Kokuryo, Shinya; Miyamoto, Ikuya; Yoshiga, Daigo; Seta, Yuji; Tominaga, Kazuhiro; Yoshioka, Izumi; Morimoto, Yasuhiro

2013-12-01

To elucidate the characteristics of visualizing thin main peripheral vessels in oral and maxillofacial regions of 3-dimensional magnetic resonance angiography (MRA) using a balanced steady-state free-precession (SSFP) sequence with a time-spatial labeling inversion pulse (time-SLIP) and using fresh blood imaging (FBI). The conspicuity of blood vessels and the characteristics on MRA using SSFP with a time-SLIP was compared with those on MRA using FBI in 20 healthy participants. The conspicuity of the main peripheral arteries was significantly higher on MRA using SSFP with a time-SLIP than on MRA using FBI. MRA scans using SSFP were obtained in all participants, and scans using FBI were obtained in 16 of 20 participants. An electrocardiogram was unnecessary when using SSFP but was necessary when using FBI. MRA obtained using SSFP with a time-SLIP is a useful technique to visualize thin main peripheral arteries in the oral and maxillofacial regions without contrast medium. Copyright © 2013 Elsevier Inc. All rights reserved.

Balance rehabilitation: promoting the role of virtual reality in patients with diabetic peripheral neuropathy.

PubMed

Grewal, Gurtej S; Sayeed, Rashad; Schwenk, Michael; Bharara, Manish; Menzies, Robert; Talal, Talal K; Armstrong, David G; Najafi, Bijan

2013-01-01

Individuals with diabetic peripheral neuropathy frequently experience concomitant impaired proprioception and postural instability. Conventional exercise training has been demonstrated to be effective in improving balance but does not incorporate visual feedback targeting joint perception, which is an integral mechanism that helps compensate for impaired proprioception in diabetic peripheral neuropathy. This prospective cohort study recruited 29 participants (mean ± SD: age, 57 ± 10 years; body mass index [calculated as weight in kilograms divided by height in meters squared], 26.9 ± 3.1). Participants satisfying the inclusion criteria performed predefined ankle exercises through reaching tasks, with visual feedback from the ankle joint projected on a screen. Ankle motion in the mediolateral and anteroposterior directions was captured using wearable sensors attached to the participant's shank. Improvements in postural stability were quantified by measuring center of mass sway area and the reciprocal compensatory index before and after training using validated body-worn sensor technology. Findings revealed a significant reduction in center of mass sway after training (mean, 22%; P = .02). A higher postural stability deficit (high body sway) at baseline was associated with higher training gains in postural balance (reduction in center of mass sway) (r = -0.52, P < .05). In addition, significant improvement was observed in postural coordination between the ankle and hip joints (mean, 10.4%; P = .04). The present research implemented a novel balance rehabilitation strategy based on virtual reality technology. The method included wearable sensors and an interactive user interface for real-time visual feedback based on ankle joint motion, similar to a video gaming environment, for compensating impaired joint proprioception. These findings support that visual feedback generated from the ankle joint coupled with motor learning may be effective in improving postural stability in patients with diabetic peripheral neuropathy.

Concentric retinitis pigmentosa: clinicopathologic correlations.

PubMed

Milam, A H; De Castro, E B; Smith, J E; Tang, W X; John, S K; Gorin, M B; Stone, E M; Aguirre, G D; Jacobson, S G

2001-10-01

Progressive concentric (centripetal) loss of vision is one pattern of visual field loss in retinitis pigmentosa. This study provides the first clinicopathologic correlations for this form of retinitis pigmentosa. A family with autosomal dominant concentric retinitis pigmentosa was examined clinically and with visual function tests. A post-mortem eye of an affected 94 year old family member was processed for histopathology and immunocytochemistry with retinal cell specific antibodies. Unrelated simplex/multiplex patients with concentric retinitis pigmentosa were also examined. Affected family members of the eye donor and patients from the other families had prominent peripheral pigmentary retinopathy with more normal appearing central retina, good visual acuity, concentric field loss, normal or near normal rod and cone sensitivity within the preserved visual field, and reduced rod and cone electroretinograms. The eye donor, at age 90, had good acuity and function in a central island. Grossly, the central region of the donor retina appeared thinned but otherwise normal, while the far periphery contained heavy bone spicule pigment. Microscopically the central retina showed photoreceptor outer segment shortening and some photoreceptor cell loss. The mid periphery had a sharp line of demarcation where more central photoreceptors were near normal except for very short outer segments and peripheral photoreceptors were absent. Rods and cones showed abrupt loss of outer segments and cell death at this interface. It is concluded that concentric retinitis pigmentosa is a rare but recognizable phenotype with slowly progressive photoreceptor death from the far periphery toward the central retina. The disease is retina-wide but shows regional variation in severity of degeneration; photoreceptor death is severe in the peripheral retina with an abrupt edge between viable and degenerate photoreceptors. Peripheral to central gradients of unknown retinal molecule(s) may be defective or modify photoreceptor degeneration in concentric retinitis pigmentosa.

Attentional capture decreases when distractors remain visible during rapid serial visual presentations.

PubMed

Inukai, Tomoe; Kumada, Takatsune; Kawahara, Jun-ichiro

2010-05-01

The identification of a central visual target is impaired by the onset of a peripheral distractor. This impairment is said to occur because attentional focus is diverted to the peripheral distractor. We examined whether distractor offset would enhance or reduce attentional capture by manipulating the duration of the distractor. Observers identified a color singleton among a rapid stream of homogeneous nontargets. Peripheral distractors disappeared 43 or 172 msec after onset (the short- and long-duration conditions, respectively). Identification accuracy was greater in the long-duration condition than in the short-duration condition. The same pattern of results was obtained when participants identified a target of a designated color among heterogeneous nontargets when the color of the distractor was the same as that of the target. These findings suggest that attentional capture consists of stimulus onset and offset, both of which are susceptible to top-down attentional set.

How virtual reality works: illusions of vision in "real" and virtual environments

NASA Astrophysics Data System (ADS)

Stark, Lawrence W.

1995-04-01

Visual illusions abound in normal vision--illusions of clarity and completeness, of continuity in time and space, of presence and vivacity--and are part and parcel of the visual world inwhich we live. These illusions are discussed in terms of the human visual system, with its high- resolution fovea, moved from point to point in the visual scene by rapid saccadic eye movements (EMs). This sampling of visual information is supplemented by a low-resolution, wide peripheral field of view, especially sensitive to motion. Cognitive-spatial models controlling perception, imagery, and 'seeing,' also control the EMs that shift the fovea in the Scanpath mode. These illusions provide for presence, the sense off being within an environment. They equally well lead to 'Telepresence,' the sense of being within a virtual display, especially if the operator is intensely interacting within an eye-hand and head-eye human-machine interface that provides for congruent visual and motor frames of reference. Interaction, immersion, and interest compel telepresence; intuitive functioning and engineered information flows can optimize human adaptation to the artificial new world of virtual reality, as virtual reality expands into entertainment, simulation, telerobotics, and scientific visualization and other professional work.

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

PubMed Central

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. PMID:23801970

Isolated primary central nervous system lymphoma arising from the optic chiasm.

PubMed

Vassal, F; Pommier, B; Boutet, C; Forest, F; Campolmi, N; Nuti, C

2014-12-01

A 58-year-old previously healthy woman rapidly developed progressive bilateral visual loss. Magnetic resonance imaging revealed a bulging appearance of the optic chiasm, with homogeneous enhancement after gadolinium administration, which suggested an optic glioma or inflammatory disease. In the absence of (para)clinical clues for a specific diagnosis despite extensive investigation, a biopsy of one optic nerve was performed, resulting in a diagnosis of non-Hodgkin B-cell lymphoma. There was no evidence of any other ocular or systemic involvement, therefore the conclusion was that this immunocompetent patient had a primary central nervous system lymphoma isolated in the anterior visual pathway. Treatment included two cycles of polychemotherapy (rituximab, methotrexate, carmustine, etoposide, methylprednisolone), followed by autologous peripheral blood stem cell transplantation and rituximab plus cytarabine consolidation therapy. Subsequently, the patient exhibited significant improvement in vision, and was still disease-free at the 1-year follow-up examination. The aim of the present paper was to provide well-documented clinical, radiological, and intraoperative features of isolated primary malignant lymphoma arising from the anterior visual pathway. A better recognition of this rare pathological entity is necessary for clinicians who may encounter similar presentations, as prompt management is crucial for both a visual and vital prognosis. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Development of Ultra-Super Sensitive Immunohistochemistry and Its Application to the Etiological Study of Adult T-Cell Leukemia/Lymphoma

PubMed Central

Hasui, Kazuhisa; Wang, Jia; Tanaka, Yuetsu; Izumo, Shuji; Eizuru, Yoshito; Matsuyama, Takami

2012-01-01

Antigen retrieval (AR) and ultra-super sensitive immunohistochemistry (ultra-IHC) have been established for application to archival human pathology specimens. The original ultra-IHC was the ImmunoMax method or the catalyzed signal amplification system (ImmunoMax/CSA method), comprising the streptavidin-biotin complex (sABC) method and catalyzed reporter deposition (CARD) reaction with visualization of its deposition. By introducing procedures to diminish non-specific staining in the original ultra-IHC method, we developed the modified ImmunoMax/CSA method with AR heating sections in an AR solution (heating-AR). The heating-AR and modified ImmunoMax/CSA method visualized expression of the predominantly simple present form of HTLV-1 proviral DNA pX region p40Tax protein (Tax) in adult T-cell leukemia/lymphoma (ATLL) cells in archival pathology specimens in approximately 75% of cases. The simple present form of Tax detected exhibited a close relation with ATLL cell proliferation. We also established a new simplified CSA (nsCSA) system by replacing the sABC method with the secondary antibody- and horse radish peroxidase-labeled polymer reagent method, introducing the pretreatments blocking non-specific binding of secondary antibody reagent, and diminishing the diffusion of deposition in the CARD reaction. Combined with AR treating sections with proteinase K solution (enzymatic-AR), the nsCSA system visualized granular immunostaining of the complex present form of Tax in a small number of ATLL cells in most cases, presenting the possibility of etiological pathological diagnosis of ATLL and suggesting that the complex present form of Tax-positive ATLL cells were young cells derived from ATLL stem cells. The heating-AR and ultra-IHC detected physiological expression of the p53 protein and its probable phosphorylation by Tax in peripheral blood mononuclear cells of peripheral blood tissue specimens from HTLV-1 carriers, as well as physiological and pathological expression of the molecules involved with G1 phase progression and G1–S phase transition (E2F-1, E2F-4, DP-1, and cyclin E) in ATLL and peripheral T-cell lymphoma cells. The ultra-IHC with AR is useful for etiological pathological diagnosis of ATLL since HTLV-1 pathogenicity depends on that of Tax, and can be a useful tool for studies translating advanced molecular biology and pathology to human pathology. PMID:22685351

Direct visualization of antigen-specific T cells: HTLV-1 Tax11-19- specific CD8(+) T cells are activated in peripheral blood and accumulate in cerebrospinal fluid from HAM/TSP patients.

PubMed

Greten, T F; Slansky, J E; Kubota, R; Soldan, S S; Jaffee, E M; Leist, T P; Pardoll, D M; Jacobson, S; Schneck, J P

1998-06-23

Human T lymphotropic virus type 1 (HTLV-1) -associated myelopathy/tropic spastic paraparesis is a demyelinating inflammatory neurologic disease associated with HTLV-1 infection. HTLV-1 Tax11-19-specific cytotoxic T cells have been isolated from HLA-A2-positive patients. We have used a peptide-loaded soluble HLA-A2-Ig complex to directly visualize HTLV-1 Tax11-19-specific T cells from peripheral blood and cerebrospinal fluid without in vitro stimulation. Five of six HTLV-1-associated myelopathy/tropic spastic paraparesis patients carried a significant number (up to 13.87%) of CD8(+) lymphocytes specific for the HTLV-1 Tax11-19 peptide in their peripheral blood, which were not found in healthy controls. Simultaneous comparison of peripheral blood and cerebrospinal fluid from one patient revealed 2.5-fold more Tax11-19-specific T cells in the cerebrospinal fluid (23.7% vs. 9.4% in peripheral blood lymphocyte). Tax11-19-specific T cells were seen consistently over a 9-yr time course in one patient as far as 19 yrs after the onset of clinical symptoms. Further analysis of HTLV-1 Tax11-19-specific CD8(+) T lymphocytes in HAM/TSP patients showed different expression patterns of activation markers, intracellular TNF-alpha and gamma-interferon depending on the severity of the disease. Thus, visualization of antigen-specific T cells demonstrates that HTLV-1 Tax11-19-specific CD8(+) T cells are activated, persist during the chronic phase of the disease, and accumulate in cerebrospinal fluid, showing their pivotal role in the pathogenesis of this neurologic disease.

Orienting Attention within Visual Short-Term Memory: Development and Mechanisms

ERIC Educational Resources Information Center

Shimi, Andria; Nobre, Anna C.; Astle, Duncan; Scerif, Gaia

2014-01-01

How does developing attentional control operate within visual short-term memory (VSTM)? Seven-year-olds, 11-year-olds, and adults (total n = 205) were asked to report whether probe items were part of preceding visual arrays. In Experiment 1, central or peripheral cues oriented attention to the location of to-be-probed items either prior to…

Responses to Targets in the Visual Periphery in Deaf and Normal-Hearing Adults

ERIC Educational Resources Information Center

Rothpletz, Ann M.; Ashmead, Daniel H.; Tharpe, Anne Marie

2003-01-01

The purpose of this study was to compare the response times of deaf and normal-hearing individuals to the onset of target events in the visual periphery in distracting and nondistracting conditions. Visual reaction times to peripheral targets placed at 3 eccentricities to the left and right of a center fixation point were measured in prelingually…

Which Aspects of Visual Attention Are Changed by Deafness? The Case of the Attentional Network Test

ERIC Educational Resources Information Center

Dye, Matthew W. G.; Baril, Dara E.; Bavelier, Daphne

2007-01-01

The loss of one sensory modality can lead to a reorganization of the other intact sensory modalities. In the case of individuals who are born profoundly deaf, there is growing evidence of changes in visual functions. Specifically, deaf individuals demonstrate enhanced visual processing in the periphery, and in particular enhanced peripheral visual…

The Development of a Two-Dimensional Multielectrode Array for Visual Perception Research in the Mammalian Brain.

DTIC Science & Technology

1980-12-01

primary and secondary visual cortex or in the secondary visual cortex itself. When the secondary visual cortex is electrically stimulated , the subject...effect enhances their excitability, which reduces the additional stimulation ( electrical or chemical) required to elicit an action potential. These...and the peripheral area with rods. The rods have a very low light intensity threshold and provide stimulation to optic nerve fibers for low light

Central and peripheral vision loss differentially affects contextual cueing in visual search.

PubMed

Geringswald, Franziska; Pollmann, Stefan

2015-09-01

Visual search for targets in repeated displays is more efficient than search for the same targets in random distractor layouts. Previous work has shown that this contextual cueing is severely impaired under central vision loss. Here, we investigated whether central vision loss, simulated with gaze-contingent displays, prevents the incidental learning of contextual cues or the expression of learning, that is, the guidance of search by learned target-distractor configurations. Visual search with a central scotoma reduced contextual cueing both with respect to search times and gaze parameters. However, when the scotoma was subsequently removed, contextual cueing was observed in a comparable magnitude as for controls who had searched without scotoma simulation throughout the experiment. This indicated that search with a central scotoma did not prevent incidental context learning, but interfered with search guidance by learned contexts. We discuss the role of visuospatial working memory load as source of this interference. In contrast to central vision loss, peripheral vision loss was expected to prevent spatial configuration learning itself, because the restricted search window did not allow the integration of invariant local configurations with the global display layout. This expectation was confirmed in that visual search with a simulated peripheral scotoma eliminated contextual cueing not only in the initial learning phase with scotoma, but also in the subsequent test phase without scotoma. (c) 2015 APA, all rights reserved).

The role of the amygdala and the basal ganglia in visual processing of central vs. peripheral emotional content.

PubMed

Almeida, Inês; van Asselen, Marieke; Castelo-Branco, Miguel

2013-09-01

In human cognition, most relevant stimuli, such as faces, are processed in central vision. However, it is widely believed that recognition of relevant stimuli (e.g. threatening animal faces) at peripheral locations is also important due to their survival value. Moreover, task instructions have been shown to modulate brain regions involved in threat recognition (e.g. the amygdala). In this respect it is also controversial whether tasks requiring explicit focus on stimulus threat content vs. implicit processing differently engage primitive subcortical structures involved in emotional appraisal. Here we have addressed the role of central vs. peripheral processing in the human amygdala using animal threatening vs. non-threatening face stimuli. First, a simple animal face recognition task with threatening and non-threatening animal faces, as well as non-face control stimuli, was employed in naïve subjects (implicit task). A subsequent task was then performed with the same stimulus categories (but different stimuli) in which subjects were told to explicitly detect threat signals. We found lateralized amygdala responses both to the spatial location of stimuli and to the threatening content of faces depending on the task performed: the right amygdala showed increased responses to central compared to left presented stimuli specifically during the threat detection task, while the left amygdala was better prone to discriminate threatening faces from non-facial displays during the animal face recognition task. Additionally, the right amygdala responded to faces during the threat detection task but only when centrally presented. Moreover, we have found no evidence for superior responses of the amygdala to peripheral stimuli. Importantly, we have found that striatal regions activate differentially depending on peripheral vs. central processing of threatening faces. Accordingly, peripheral processing of these stimuli activated more strongly the putaminal region, while central processing engaged mainly the caudate nucleus. We conclude that the human amygdala has a central bias for face stimuli, and that visual processing recruits different striatal regions, putaminal or caudate based, depending on the task and on whether peripheral or central visual processing is involved. © 2013 Elsevier Ltd. All rights reserved.

Receptive fields for smooth pursuit eye movements and motion perception.

PubMed

Debono, Kurt; Schütz, Alexander C; Spering, Miriam; Gegenfurtner, Karl R

2010-12-01

Humans use smooth pursuit eye movements to track moving objects of interest. In order to track an object accurately, motion signals from the target have to be integrated and segmented from motion signals in the visual context. Most studies on pursuit eye movements used small visual targets against a featureless background, disregarding the requirements of our natural visual environment. Here, we tested the ability of the pursuit and the perceptual system to integrate motion signals across larger areas of the visual field. Stimuli were random-dot kinematograms containing a horizontal motion signal, which was perturbed by a spatially localized, peripheral motion signal. Perturbations appeared in a gaze-contingent coordinate system and had a different direction than the main motion including a vertical component. We measured pursuit and perceptual direction discrimination decisions and found that both steady-state pursuit and perception were influenced most by perturbation angles close to that of the main motion signal and only in regions close to the center of gaze. The narrow direction bandwidth (26 angular degrees full width at half height) and small spatial extent (8 degrees of visual angle standard deviation) correspond closely to tuning parameters of neurons in the middle temporal area (MT). Copyright © 2010 Elsevier Ltd. All rights reserved.

Alteration of the microsaccadic velocity-amplitude main sequence relationship after visual transients: implications for models of saccade control

PubMed Central

Chen, Chih-Yang; Tian, Xiaoguang; Idrees, Saad; Münch, Thomas A.

2017-01-01

Microsaccades occur during gaze fixation to correct for miniscule foveal motor errors. The mechanisms governing such fine oculomotor control are still not fully understood. In this study, we explored microsaccade control by analyzing the impacts of transient visual stimuli on these movements’ kinematics. We found that such kinematics can be altered in systematic ways depending on the timing and spatial geometry of visual transients relative to the movement goals. In two male rhesus macaques, we presented peripheral or foveal visual transients during an otherwise stable period of fixation. Such transients resulted in well-known reductions in microsaccade frequency, and our goal was to investigate whether microsaccade kinematics would additionally be altered. We found that both microsaccade timing and amplitude were modulated by the visual transients, and in predictable manners by these transients’ timing and geometry. Interestingly, modulations in the peak velocity of the same movements were not proportional to the observed amplitude modulations, suggesting a violation of the well-known “main sequence” relationship between microsaccade amplitude and peak velocity. We hypothesize that visual stimulation during movement preparation affects not only the saccadic “Go” system driving eye movements but also a “Pause” system inhibiting them. If the Pause system happens to be already turned off despite the new visual input, movement kinematics can be altered by the readout of additional visually evoked spikes in the Go system coding for the flash location. Our results demonstrate precise control over individual microscopic saccades and provide testable hypotheses for mechanisms of saccade control in general. NEW & NOTEWORTHY Microsaccadic eye movements play an important role in several aspects of visual perception and cognition. However, the mechanisms for microsaccade control are still not fully understood. We found that microsaccade kinematics can be altered in a systematic manner by visual transients, revealing a previously unappreciated and exquisite level of control by the oculomotor system of even the smallest saccades. Our results suggest precise temporal interaction between visual, motor, and inhibitory signals in microsaccade control. PMID:28202573

Anomalous coagulation factors in non-arteritic anterior ischemic optic neuropathy with central retinal vein occlusion: A case report.

PubMed

Kim, Ji Hong; Kang, Min Ho; Seong, Mincheol; Cho, Heeyoon; Shin, Yong Un

2018-04-01

Non-arteritic anterior ischemic optic neuropathy (NAION) is characterized by sudden, painless visual loss and optic disc edema. NAION occurs mainly in the presence of cardiovascular disease and hypercoagulability, mainly in patients over 50 years of age. We experienced a case of NAION associated with central retinal vein occlusion (CRVO) in a young man with no underlying disease. A 46-year-old man was referred to our clinic following a sudden loss of vision in his right eye. The patient exhibited no underlying disease and reported no ongoing medication. Significant visual loss and visual disturbance of the right eye were observed. The pupil of the right eye was enlarged and an afferent pupillary defect was observed. On fundus examination, retinal hemorrhage was observed in the peripheral retina; macular edema was observed in optical coherence tomography analysis. However, optic disc edema was not evident. No abnormal findings were found in routine blood tests for hypercoagulability. After 3 days of steroid intravenous injection, macular edema disappeared and visual acuity was improved, but optic disc edema began to appear. One week later, optic disc edema was evident and visual acuity was significantly reduced; thus, the patient was diagnosed with NAION. In fluorescein angiography, peripheral retinal ischemia was observed, suggesting that CRVO was complicated. Blood tests, including analysis of coagulation factors, were performed again, showing that coagulation factors IX and XI were increased. Anomalous coagulation factors in non-arteritic anterior ischemic optic neuropathy with central retinal vein occlusion. Systemic steroids were administered. One month later, optic disc edema and retinal hemorrhage gradually diminished and eventually disappeared; however, visual acuity did not recover. In young patients without underlying disease, cases of NAION require careful screening for coagulation disorders. Even if there is no abnormality in the test for routine coagulation status, it may be necessary to confirm a coagulation defect through an additional coagulation factor assay.

Uptake of Fluorescent Gentamicin by Peripheral Vestibular Cells after Systemic Administration

PubMed Central

Liu, Jianping; Kachelmeier, Allan; Dai, Chunfu; Li, Hongzhe; Steyger, Peter S.

2015-01-01

Objective In addition to cochleotoxicity, systemic aminoglycoside pharmacotherapy causes vestibulotoxicity resulting in imbalance and visual dysfunction. The underlying trafficking routes of systemically-administered aminoglycosides from the vasculature to the vestibular sensory hair cells are largely unknown. We investigated the trafficking of systemically-administered gentamicin into the peripheral vestibular system in C56Bl/6 mice using fluorescence-tagged gentamicin (gentamicin-Texas-Red, GTTR) imaged by scanning laser confocal microscopy to determine the cellular distribution and intensity of GTTR fluorescence in the three semicircular canal cristae, utricular, and saccular maculae at 5 time points over 4 hours. Results Low intensity GTTR fluorescence was detected at 0.5 hours as both discrete puncta and diffuse cytoplasmic fluorescence. The intensity of cytoplasmic fluorescence peaked at 3 hours, while punctate fluorescence was plateaued after 3 hours. At 0.5 and 1 hour, higher levels of diffuse GTTR fluorescence were present in transitional cells compared to hair cells and supporting cells. Sensory hair cells typically exhibited only diffuse cytoplasmic fluorescence at all time-points up to 4 hours in this study. In contrast, non-sensory cells rapidly exhibited both intense fluorescent puncta and weaker, diffuse fluorescence throughout the cytosol. The numbers and size of fluorescent puncta in dark cells and transitional cells increased over time. There is no preferential GTTR uptake by the five peripheral vestibular organs’ sensory cells. Control vestibular tissues exposed to Dulbecco’s phosphate-buffered saline or hydrolyzed Texas Red had negligible fluorescence. Conclusions All peripheral vestibular cells rapidly take up systemically-administered GTTR, reaching peak intensity 3 hours after injection. Sensory hair cells exhibited only diffuse fluorescence, while non-sensory cells displayed both diffuse and punctate fluorescence. Transitional cells may act as a primary pathway for trafficking of systemic GTTR from the vasculature to endolymph prior to entering hair cells. PMID:25793391

Models of Speed Discrimination

NASA Technical Reports Server (NTRS)

1997-01-01

The prime purpose of this project was to investigate various theoretical issues concerning the integration of information across visual space. To date, most of the research efforts in the study of the visual system seem to have been focused in two almost non-overlaping directions. One research focus has been the low level perception as studied by psychophysics. The other focus has been the study of high level vision exemplified by the study of object perception. Most of the effort in psychophysics has been devoted to the search for the fundamental "features" of perception. The general idea is that the most peripheral processes of the visual system decompose the input into features that are then used for classification and recognition. The experimental and theoretical focus has been on finding and describing these analyzers that decompose images into useful components. Various models are then compared to the physiological measurements performed on neurons in the sensory systems. In the study of higher level perception, the work has been focused on the representation of objects and on the connections between various physical effects and object perception. In this category we find the perception of 3D from a variety of physical measurements including motion, shading and other physical phenomena. With few exceptions, there seem to be very limited development of theories describing how the visual system might combine the output of the analyzers to form the representation of visual objects. Therefore, the processes underlying the integration of information over space represent critical aspects of vision system. The understanding of these processes will have implications on our expectations for the underlying physiological mechanisms, as well as for our models of the internal representation for visual percepts. In this project, we explored several mechanisms related to spatial summation, attention, and eye movements. The project comprised three components: 1. Modeling visual search for the detection of speed deviation. 2. Perception of moving objects. 3. Exploring the role of eye movements in various visual tasks.

Modeling human perception and estimation of kinematic responses during aircraft landing

NASA Technical Reports Server (NTRS)

Schmidt, David K.; Silk, Anthony B.

1988-01-01

The thrust of this research is to determine estimation accuracy of aircraft responses based on observed cues. By developing the geometric relationships between the outside visual scene and the kinematics during landing, visual and kinesthetic cues available to the pilot were modeled. Both fovial and peripheral vision was examined. The objective was to first determine estimation accuracy in a variety of flight conditions, and second to ascertain which parameters are most important and lead to the best achievable accuracy in estimating the actual vehicle response. It was found that altitude estimation was very sensitive to the FOV. For this model the motion cue of perceived vertical acceleration was shown to be less important than the visual cues. The inclusion of runway geometry in the visual scene increased estimation accuracy in most cases. Finally, it was shown that for this model if the pilot has an incorrect internal model of the system kinematics the choice of observations thought to be 'optimal' may in fact be suboptimal.

Reorganization of neural systems mediating peripheral visual selective attention in the deaf: An optical imaging study.

PubMed

Seymour, Jenessa L; Low, Kathy A; Maclin, Edward L; Chiarelli, Antonio M; Mathewson, Kyle E; Fabiani, Monica; Gratton, Gabriele; Dye, Matthew W G

2017-01-01

Theories of brain plasticity propose that, in the absence of input from the preferred sensory modality, some specialized brain areas may be recruited when processing information from other modalities, which may result in improved performance. The Useful Field of View task has previously been used to demonstrate that early deafness positively impacts peripheral visual attention. The current study sought to determine the neural changes associated with those deafness-related enhancements in visual performance. Based on previous findings, we hypothesized that recruitment of posterior portions of Brodmann area 22, a brain region most commonly associated with auditory processing, would be correlated with peripheral selective attention as measured using the Useful Field of View task. We report data from severe to profoundly deaf adults and normal-hearing controls who performed the Useful Field of View task while cortical activity was recorded using the event-related optical signal. Behavioral performance, obtained in a separate session, showed that deaf subjects had lower thresholds (i.e., better performance) on the Useful Field of View task. The event-related optical data indicated greater activity for the deaf adults than for the normal-hearing controls during the task in the posterior portion of Brodmann area 22 in the right hemisphere. Furthermore, the behavioral thresholds correlated significantly with this neural activity. This work provides further support for the hypothesis that cross-modal plasticity in deaf individuals appears in higher-order auditory cortices, whereas no similar evidence was obtained for primary auditory areas. It is also the only neuroimaging study to date that has linked deaf-related changes in the right temporal lobe to visual task performance outside of the imaging environment. The event-related optical signal is a valuable technique for studying cross-modal plasticity in deaf humans. The non-invasive and relatively quiet characteristics of this technique have great potential utility in research with clinical populations such as deaf children and adults who have received cochlear or auditory brainstem implants. Copyright © 2016 Elsevier B.V. All rights reserved.

Fast scanning photoretinoscope for measuring peripheral refraction as a function of accommodation.

PubMed

Tabernero, Juan; Schaeffel, Frank

2009-10-01

A new device was designed to provide fast measurements (4 s) of the peripheral refraction (90 degrees central horizontal field). Almost-continuous traces are obtained with high angular resolution (0.4 degrees) while the subject is fixating a central stimulus. Three-dimensional profiles can also be measured. The peripheral refractions in 10 emmetropic subjects were studied as a function of accommodation (200 cm, 50 cm, and 25 cm viewing distances). Peripheral refraction profiles were largely preserved during accommodation but were different in each individual. Apparently, the accommodating lens changes its focal length evenly over the central 90 degrees of the visual field.

Reaching a Moveable Visual Target: Dissociations in Brain Tumour Patients

ERIC Educational Resources Information Center

Buiatti, Tania; Skrap, Miran; Shallice, Tim

2013-01-01

Damage to the posterior parietal cortex (PPC) can lead to Optic Ataxia (OA), in which patients misreach to peripheral targets. Recent research suggested that the PPC might be involved not only in simple reaching tasks toward peripheral targets, but also in changing the hand movement trajectory in real time if the target moves. The present study…

Binocular pattern deprivation interferes with the expression of proteins involved in primary visual cortex maturation in the cat.

PubMed

Laskowska-Macios, Karolina; Nys, Julie; Hu, Tjing-Tjing; Zapasnik, Monika; Van der Perren, Anke; Kossut, Malgorzata; Burnat, Kalina; Arckens, Lutgarde

2015-08-14

Binocular pattern deprivation from eye opening (early BD) delays the maturation of the primary visual cortex. This delay is more pronounced for the peripheral than the central visual field representation within area 17, particularly between the age of 2 and 4 months [Laskowska-Macios, Cereb Cortex, 2014]. In this study, we probed for related dynamic changes in the cortical proteome. We introduced age, cortical region and BD as principal variables in a 2-D DIGE screen of area 17. In this way we explored the potential of BD-related protein expression changes between central and peripheral area 17 of 2- and 4-month-old BD (2BD, 4BD) kittens as a valid parameter towards the identification of brain maturation-related molecular processes. Consistent with the maturation delay, distinct developmental protein expression changes observed for normal kittens were postponed by BD, especially in the peripheral region. These BD-induced proteomic changes suggest a negative regulation of neurite outgrowth, synaptic transmission and clathrin-mediated endocytosis, thereby implicating these processes in normal experience-induced visual cortex maturation. Verification of the expression of proteins from each of the biological processes via Western analysis disclosed that some of the transient proteomic changes correlate to the distinct behavioral outcome in adult life, depending on timing and duration of the BD period [Neuroscience 2013;255:99-109]. Taken together, the plasticity potential to recover from BD, in relation to ensuing restoration of normal visual input, appears to rely on specific protein expression changes and cellular processes induced by the loss of pattern vision in early life.

Emotional stress recognition using a new fusion link between electroencephalogram and peripheral signals

PubMed Central

Hosseini, Seyyed Abed; Khalilzadeh, Mohammad Ali; Naghibi-Sistani, Mohammad Bagher; Homam, Seyyed Mehran

2015-01-01

Background: This paper proposes a new emotional stress assessment system using multi-modal bio-signals. Electroencephalogram (EEG) is the reflection of brain activity and is widely used in clinical diagnosis and biomedical research. Methods: We design an efficient acquisition protocol to acquire the EEG signals in five channels (FP1, FP2, T3, T4 and Pz) and peripheral signals such as blood volume pulse, skin conductance (SC) and respiration, under images induction (calm-neutral and negatively excited) for the participants. The visual stimuli images are selected from the subset International Affective Picture System database. The qualitative and quantitative evaluation of peripheral signals are used to select suitable segments of EEG signals for improving the accuracy of signal labeling according to emotional stress states. After pre-processing, wavelet coefficients, fractal dimension, and Lempel-Ziv complexity are used to extract the features of the EEG signals. The vast number of features leads to the problem of dimensionality, which is solved using the genetic algorithm as a feature selection method. Results: The results show that the average classification accuracy is 89.6% for two categories of emotional stress states using the support vector machine (SVM). Conclusion: This is a great improvement in results compared to other similar researches. We achieve a noticeable improvement of 11.3% in accuracy using SVM classifier, in compared to previous studies. Therefore, a new fusion between EEG and peripheral signals are more robust in comparison to the separate signals. PMID:26622979

Emotional stress recognition using a new fusion link between electroencephalogram and peripheral signals.

PubMed

Hosseini, Seyyed Abed; Khalilzadeh, Mohammad Ali; Naghibi-Sistani, Mohammad Bagher; Homam, Seyyed Mehran

2015-07-06

This paper proposes a new emotional stress assessment system using multi-modal bio-signals. Electroencephalogram (EEG) is the reflection of brain activity and is widely used in clinical diagnosis and biomedical research. We design an efficient acquisition protocol to acquire the EEG signals in five channels (FP1, FP2, T3, T4 and Pz) and peripheral signals such as blood volume pulse, skin conductance (SC) and respiration, under images induction (calm-neutral and negatively excited) for the participants. The visual stimuli images are selected from the subset International Affective Picture System database. The qualitative and quantitative evaluation of peripheral signals are used to select suitable segments of EEG signals for improving the accuracy of signal labeling according to emotional stress states. After pre-processing, wavelet coefficients, fractal dimension, and Lempel-Ziv complexity are used to extract the features of the EEG signals. The vast number of features leads to the problem of dimensionality, which is solved using the genetic algorithm as a feature selection method. The results show that the average classification accuracy is 89.6% for two categories of emotional stress states using the support vector machine (SVM). This is a great improvement in results compared to other similar researches. We achieve a noticeable improvement of 11.3% in accuracy using SVM classifier, in compared to previous studies. Therefore, a new fusion between EEG and peripheral signals are more robust in comparison to the separate signals.

Anterior ischemic optic neuropathy in a patient with Churg-Strauss syndrome.

PubMed

Lee, Ji Eun; Lee, Seung Uk; Kim, Soo Young; Jang, Tae Won; Lee, Sang Joon

2012-12-01

We describe a patient with Churg-Strauss syndrome who developed unilateral anterior ischemic optic neuropathy. A 54-year-old man with a history of bronchial asthma, allergic rhinitis, and sinusitis presented with sudden decreased visual acuity in his right eye that had begun 2 weeks previously. The visual acuity of his right eye was 20 / 50. Ophthalmoscopic examination revealed a diffusely swollen right optic disc and splinter hemorrhages at its margin. Goldmann perimetry showed central scotomas in the right eye and fluorescein angiography showed remarkable hyperfluorescence of the right optic nerve head. Marked peripheral eosinphilia, extravascular eosinophils in a bronchial biopsy specimen, and an increased sedimentation rate supported the diagnosis of Churg-Strauss syndrome. Therapy with methylprednisolone corrected the laboratory abnormalities, improved clinical features, and preserved vision, except for the right central visual field defect. Early recognition of this systemic disease by ophthalmologists may help in preventing severe ocular complications.

Anterior Ischemic Optic Neuropathy in a Patient with Churg-Strauss Syndrome

PubMed Central

Lee, Ji Eun; Lee, Seung Uk; Kim, Soo Young; Jang, Tae Won

2012-01-01

We describe a patient with Churg-Strauss syndrome who developed unilateral anterior ischemic optic neuropathy. A 54-year-old man with a history of bronchial asthma, allergic rhinitis, and sinusitis presented with sudden decreased visual acuity in his right eye that had begun 2 weeks previously. The visual acuity of his right eye was 20 / 50. Ophthalmoscopic examination revealed a diffusely swollen right optic disc and splinter hemorrhages at its margin. Goldmann perimetry showed central scotomas in the right eye and fluorescein angiography showed remarkable hyperfluorescence of the right optic nerve head. Marked peripheral eosinphilia, extravascular eosinophils in a bronchial biopsy specimen, and an increased sedimentation rate supported the diagnosis of Churg-Strauss syndrome. Therapy with methylprednisolone corrected the laboratory abnormalities, improved clinical features, and preserved vision, except for the right central visual field defect. Early recognition of this systemic disease by ophthalmologists may help in preventing severe ocular complications. PMID:23204805

Visualization of Motor Axon Navigation and Quantification of Axon Arborization In Mouse Embryos Using Light Sheet Fluorescence Microscopy.

PubMed

Liau, Ee Shan; Yen, Ya-Ping; Chen, Jun-An

2018-05-11

Spinal motor neurons (MNs) extend their axons to communicate with their innervating targets, thereby controlling movement and complex tasks in vertebrates. Thus, it is critical to uncover the molecular mechanisms of how motor axons navigate to, arborize, and innervate their peripheral muscle targets during development and degeneration. Although transgenic Hb9::GFP mouse lines have long served to visualize motor axon trajectories during embryonic development, detailed descriptions of the full spectrum of axon terminal arborization remain incomplete due to the pattern complexity and limitations of current optical microscopy. Here, we describe an improved protocol that combines light sheet fluorescence microscopy (LSFM) and robust image analysis to qualitatively and quantitatively visualize developing motor axons. This system can be easily adopted to cross genetic mutants or MN disease models with Hb9::GFP lines, revealing novel molecular mechanisms that lead to defects in motor axon navigation and arborization.

Visual spatial attention enhances the amplitude of positive and negative fMRI responses to visual stimulation in an eccentricity-dependent manner

PubMed Central

Bressler, David W.; Fortenbaugh, Francesca C.; Robertson, Lynn C.; Silver, Michael A.

2013-01-01

Endogenous visual spatial attention improves perception and enhances neural responses to visual stimuli at attended locations. Although many aspects of visual processing differ significantly between central and peripheral vision, little is known regarding the neural substrates of the eccentricity dependence of spatial attention effects. We measured amplitudes of positive and negative fMRI responses to visual stimuli as a function of eccentricity in a large number of topographically-organized cortical areas. Responses to each stimulus were obtained when the stimulus was attended and when spatial attention was directed to a stimulus in the opposite visual hemifield. Attending to the stimulus increased both positive and negative response amplitudes in all cortical areas we studied: V1, V2, V3, hV4, VO1, LO1, LO2, V3A/B, IPS0, TO1, and TO2. However, the eccentricity dependence of these effects differed considerably across cortical areas. In early visual, ventral, and lateral occipital cortex, attentional enhancement of positive responses was greater for central compared to peripheral eccentricities. The opposite pattern was observed in dorsal stream areas IPS0 and putative MT homolog TO1, where attentional enhancement of positive responses was greater in the periphery. Both the magnitude and the eccentricity dependence of attentional modulation of negative fMRI responses closely mirrored that of positive responses across cortical areas. PMID:23562388

Sequential Involvement of the Nervous System in Subacute Combined Degeneration

PubMed Central

Minn, Yang-Ki; Kim, Seung-Min; Kim, Se-Hoon; Kwon, Ki-Han

2012-01-01

Purpose Subacute combined degeneration (SCD) involves progressive degeneration of the spinal cord, optic nerve, and peripheral nerves. Vitamin B12 (VB12) is a co-factor in myelin synthesis. Because each cell that constitutes the myelin component in the central nervous system and peripheral nervous system is different, it is improbable that these cells undergo simultaneous degeneration. However, the sequence of degeneration in SCD has not been established. Materials and Methods In this study, we analysed medical records and electrophysiological data of patients who showed neurological symptoms and whose serum VB12 levels were lower than 200 pg/mL. Results We enrolled 49 patients in this study. Their mean VB12 level was 68.3 pg/mL. Somatosensory evoked potential (SEP) study showed abnormal findings in 38 patients. Of the 40 patients who underwent visual evoked potential (VEP) study, 14 showed abnormal responses. Eighteen patients showed abnormal findings on a nerve conduction study (NCS). In this study, abnormal posterior tibial nerve SEPs only were seen in 16 patients, median nerve SEPs only were seen in 3 patients, abnormal VEPs only in two, and abnormal NCS responses in one patient. No patient complained of cognitive symptoms. Conclusion In SCD, degeneration appears to progress in the following order: lower spinal cord, cervical spinal cord, peripheral nerve/optic nerve, and finally, the brain. PMID:22318813

Identification of a Peripheral Nerve Neurite Growth-Promoting Activity by Development and Use of an in vitro Bioassay

NASA Astrophysics Data System (ADS)

Sandrock, Alfred W.; Matthew, William D.

1987-10-01

The effective regeneration of severed neuronal axons in the peripheral nerves of adult mammals may be explained by the presence of molecules in situ that promote the effective elongation of neurites. The absence of such molecules in the central nervous system of these animals may underlie the relative inability of axons to regenerate in this tissue after injury. In an effort to identify neurite growth-promoting molecules in tissues that support effective axonal regeneration, we have developed an in vitro bioassay that is sensitive to substrate-bound factors of peripheral nerve that influence the growth of neurites. In this assay, neonatal rat superior cervical ganglion explants are placed on longitudinal cryostat sections of fresh-frozen sciatic nerve, and the regrowing axons are visualized by catecholamine histofluorescence. Axons are found to regenerate effectively over sciatic nerve tissue sections. When ganglia are similarly explanted onto cryostat sections of adult rat central nervous system tissue, however, axonal regeneration is virtually absent. We have begun to identify the molecules in peripheral nerve that promote effective axonal regeneration by examining the effect of antibodies that interfere with the activity of previously described neurite growth-promoting factors. Axonal elongation over sciatic nerve tissue was found to be sensitive to the inhibitory effects of INO (for inhibitor of neurite outgrowth), a monoclonal antibody that recognizes and inhibits a neurite growth-promoting activity from PC-12 cell-conditioned medium. The INO antigen appears to be a molecular complex of laminin and heparan sulfate proteoglycan. In contrast, a rabbit antiserum that recognizes laminin purified from mouse Engelbreth-Holm-Swarm (EHS) sarcoma, stains the Schwann cell basal lamina of peripheral nerve, and inhibits neurite growth over purified laminin substrata has no detectable effect on the rate of axonal regeneration in our assay.

[The Efficacy of Near-Infrared Devices in Facilitating Peripheral Intravenous Access in Children: A Systematic Review and Subgroup Meta-Analysis].

PubMed

Kuo, Chia-Chi; Feng, I-Jung; Lee, Wei-Jing

2017-10-01

Peripheral intravenous access is a common and invasive procedure that is performed in pediatric clinical settings. Children often have difficult intravenous-access problems that may not only increase staff stress but also affect the timeliness of immediate treatments. To determine the efficacy of near-infrared devices in facilitating peripheral intravenous access in children, using a systematic review and meta-analysis. Six databases, namely the Index to Taiwan Periodical Literature System, Airiti Library, CINAHL, Cochrane Library, PubMed/MEDLINE, and ProQuest were searched for related articles that were published between the earliest year available and February 2017. The search was limited to studies on populations of children that used either a randomized controlled trial or controlled clinical trial approach and used the key words "near-infrared devices" AND "peripheral intravenous access." The 12 articles that met these criteria were included in the analysis. The Cochrane Collaboration bias assessment tool was used to assess the methodological quality. In addition, RevMan 5.3.5 software was used to conduct the meta-analysis. The near-infrared devices did not significantly improve the first-attempt success rate, number of attempts, or the procedural time of peripheral intravenous access in children. However, the subgroup analysis of difficult intravenous-access factors revealed a significant improvement in the first-attempt success rate of children with difficult intravenous access scores (OR = 1.83, p = .03). Near-infrared devices may improve the first-attempt success rate in children with difficult intravenous access by allowing healthcare professionals to visualize the peripheral veins. Therefore, we suggest that the difficult intravenous-access score be used as a screening tool to suggest when to apply near-infrared devices to children with difficult peripheral intravenous access in order to maximize efficacy of treatment.

Short-term and long-term plasticity in the visual-attention system: Evidence from habituation of attentional capture.

PubMed

Turatto, Massimo; Pascucci, David

2016-04-01

Attention is known to be crucial for learning and to regulate activity-dependent brain plasticity. Here we report the opposite scenario, with plasticity affecting the onset-driven automatic deployment of spatial attention. Specifically, we showed that attentional capture is subject to habituation, a fundamental form of plasticity consisting in a response decrement to repeated stimulations. Participants performed a visual discrimination task with focused attention, while being occasionally exposed to a distractor consisting of a high-luminance peripheral onset. With practice, short-term and long-term habituation of attentional capture emerged, making the visual-attention system fully immune to distraction. Furthermore, spontaneous recovery of attentional capture was found when the distractor was temporarily removed. Capture, however, once habituated was surprisingly resistant to spontaneous recovery, taking from several minutes to days to recover. The results suggest that the mechanisms subserving exogenous attentional orienting are subject to profound and enduring plastic changes based on previous experience, and that habituation can impact high-order cognitive functions. Copyright © 2016 Elsevier Inc. All rights reserved.

A neurophysiologically plausible population code model for feature integration explains visual crowding.

PubMed

van den Berg, Ronald; Roerdink, Jos B T M; Cornelissen, Frans W

2010-01-22

An object in the peripheral visual field is more difficult to recognize when surrounded by other objects. This phenomenon is called "crowding". Crowding places a fundamental constraint on human vision that limits performance on numerous tasks. It has been suggested that crowding results from spatial feature integration necessary for object recognition. However, in the absence of convincing models, this theory has remained controversial. Here, we present a quantitative and physiologically plausible model for spatial integration of orientation signals, based on the principles of population coding. Using simulations, we demonstrate that this model coherently accounts for fundamental properties of crowding, including critical spacing, "compulsory averaging", and a foveal-peripheral anisotropy. Moreover, we show that the model predicts increased responses to correlated visual stimuli. Altogether, these results suggest that crowding has little immediate bearing on object recognition but is a by-product of a general, elementary integration mechanism in early vision aimed at improving signal quality.

Ultra-wide-field imaging in diabetic retinopathy; an overview.

PubMed

Ghasemi Falavarjani, Khalil; Wang, Kang; Khadamy, Joobin; Sadda, Srinivas R

2016-06-01

To present an overview on ultra-wide-field imaging in diabetic retinopathy. A comprehensive search of the pubmed database was performed using the search terms of "ultra-wide-field imaging", "ultra-wide-field fluorescein angiography" and "diabetic retinopathy". The relevant original articles were reviewed. New advances in ultra-wide-field imaging allow for precise measurements of the peripheral retinal lesions. A consistent finding amongst these articles was that ultra-wide-field imaging improved detection of peripheral lesion. There was discordance among the studies, however, on the correlation between peripheral diabetic lesions and diabetic macular edema. Visualization of the peripheral retina using ultra-wide-field imaging improves diagnosis and classification of diabetic retinopathy. Additional studies are needed to better define the association of peripheral diabetic lesions with diabetic macular edema.

The Charles F. Prentice Award Lecture 2010: A Case for Peripheral Optical Treatment Strategies for Myopia

PubMed Central

Smith, Earl L.

2011-01-01

It is well established that refractive development is regulated by visual feedback. However, most optical treatment strategies designed to reduce myopia progression have not produced the desired results, primarily because some of our assumptions concerning the operating characteristics of the vision-dependent mechanisms that regulate refractive development have been incorrect. In particular, because of the prominence of central vision in primates, it has generally been assumed that signals from the fovea determine the effects of vision on refractive development. However, experiments in laboratory animals demonstrate that ocular growth and emmetropization are mediated by local retinal mechanisms and that foveal vision is not essential for many vision-dependent aspects of refractive development. On the other hand, the peripheral retina, in isolation, can effectively regulate emmetropization and mediate many of the effects of vision on the eye’s refractive status. Moreover, when there are conflicting visual signals between the fovea and the periphery, peripheral vision can dominate refractive development. The overall pattern of results suggests that optical treatment strategies for myopia that take into account the effects of peripheral vision are likely to be more successful than strategies that effectively manipulate only central vision. PMID:21747306

Sub-lethal Ocular Trauma (SLOT): Establishing a Standardized Blast Threshold to Facilitate Diagnostic, Early Treatment, and Recovery Studies for Blast Injuries to the Eye and Optic Nerve

DTIC Science & Technology

2015-11-01

delamination, cyclodialysis, peripheral chorioretinal detachments and radial peripapillary retinal detachments. Petras et al., (1997) observed a...Methods in Biomechanics and Biomedical Engineering, 16: 612–621. Petras , J.M., Bauman, R.A., and Elsayed, N.M., 1997, Visual system degeneration...Sanchez, R., Martin , R., Ussa, F., and Fernandez-Bueno, I., 2011, The parameters of the porcine eyeball. Graefe’s Archive for Clinical and

Novel Combinatory Approaches to Repair Visual System after Optic Nerve Damage

DTIC Science & Technology

2014-09-01

Intravitreal Viral Treatment Outcome Measures PTEN/SOCS3f/f AAV-GFP (Control) RGC staining and axon tracing PTEN/SOCS3f/f AAV-Cre “ “ CHOP-/- AAV-XBP1...survival and axon regeneration using immunohistochemistry and axon tracing methods used in our previous studies. At 4 and 8 weeks after injury, retinas...the cell body. After peripheral nerve injury, phosphorylated (i.e., active) STAT3 is detected in the injured axons and later in the soma (Lee, Neitzel

Congruent representation of visual and acoustic space in the superior colliculus of the echolocating bat Phyllostomus discolor.

PubMed

Hoffmann, Susanne; Vega-Zuniga, Tomas; Greiter, Wolfgang; Krabichler, Quirin; Bley, Alexandra; Matthes, Mariana; Zimmer, Christiane; Firzlaff, Uwe; Luksch, Harald

2016-11-01

The midbrain superior colliculus (SC) commonly features a retinotopic representation of visual space in its superficial layers, which is congruent with maps formed by multisensory neurons and motor neurons in its deep layers. Information flow between layers is suggested to enable the SC to mediate goal-directed orienting movements. While most mammals strongly rely on vision for orienting, some species such as echolocating bats have developed alternative strategies, which raises the question how sensory maps are organized in these animals. We probed the visual system of the echolocating bat Phyllostomus discolor and found that binocular high acuity vision is frontally oriented and thus aligned with the biosonar system, whereas monocular visual fields cover a large area of peripheral space. For the first time in echolocating bats, we could show that in contrast with other mammals, visual processing is restricted to the superficial layers of the SC. The topographic representation of visual space, however, followed the general mammalian pattern. In addition, we found a clear topographic representation of sound azimuth in the deeper collicular layers, which was congruent with the superficial visual space map and with a previously documented map of orienting movements. Especially for bats navigating at high speed in densely structured environments, it is vitally important to transfer and coordinate spatial information between sensors and motor systems. Here, we demonstrate first evidence for the existence of congruent maps of sensory space in the bat SC that might serve to generate a unified representation of the environment to guide motor actions. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Ocular vascular occlusive disorders: Natural history of visual outcome☆

PubMed Central

Hayreh, Sohan Singh

2014-01-01

Ocular vascular occlusive disorders collectively constitute the most common cause of visual disability. Before a disease can be managed, it is essential to understand its natural history, so as to be able to assess the likely effectiveness of any intervention. I investigated natural history of visual outcome in prospective studies of 386 eyes with non-arteritic anterior ischemic optic neuropathy (NA-AION), 16 eyes with non-arteritic posterior ischemic optic neuropathy, 697 eyes with central retinal vein occlusion (CRVO), 67 eyes with hemi-CRVO (HCRVO), 216 eyes with branch retinal vein occlusion (BRVO), 260 eyes with central retinal artery occlusion (CRAO), 151 eyes with branch retinal artery occlusion (BRAO) and 61 eyes with cilioretinal artery occlusion (CLRAO). My studies have shown that every one of these disorders consists of multiple distinct clinical sub-categories with different visual findings. When an ocular vascular occlusive disorder is caused by giant cell arteritis, which is an ophthalmic emergency, it would be unethical to do a natural history study of visual outcome in them, because in this case early diagnosis and immediate, intensive high-dose steroid therapy is essential to prevent any further visual loss, not only in the involved eye but also in the fellow, normal eye. In NA-AION in eyes seen ≤2 weeks after the onset, visual acuity (VA) improved in 41% of those with VA 20/70 or worse, and visual field (VF) improved in 26% of those with moderate to severe VF defect. In non-ischemic CRVO eyes with VA 20/70 or worse, VA improved in 47% and in ischemic CRVO in 23%; moderate to severe VF defect improved in 79% in non-ischemic CRVO and in 27% in ischemic CRVO. In HCRVO, overall findings demonstrated that initial VA and VF defect and the final visual outcome were different in non-ischemic from ischemic HCRVO – much better in the former than the latter. In major BRVO, in eyes with initial VA of 20/70 or worse, VA improved in 69%, and moderate to severe VF defect improved in 52%. In macular BRVO with 20/70 or worse initial VA, it improved in 53%, and initial minimal-mild VF defect was stable or improved in 85%. In various types of CRAO there are significant differences in both initial and final VA and VF defects. In CRAO eyes seen within 7 days of onset and initial VA of counting fingers or worse, VA improved in 82% with transient non-arteritic CRAO, 67% with non-arteritic CRAO with cilioretinal artery sparing, 22% with non-arteritic CRAO. Central VF improved in 39% of transient non-arteritic CRAO, 25% of non-arteritic CRAO with cilioretinal artery sparing and 21% of non-arteritic CRAO. Peripheral VF improved in non-arteritic CRAO in 39% and in transient non-arteritic CRAO in 39%. In transient CRAO, finally peripheral VFs were normal in 93%. In non-arteritic CRAO eyes initially 22% had normal peripheral VF and in the rest it improved in 39%. Final VA of 20/40 or better was seen in 89% of permanent BRAO, and in 100% of transient BRAO and non-arteritic CLRAO. In permanent BRAO eyes, among those seen within 7 days of onset, central VF defect improved in 47% and peripheral VF in 52%, and in transient BRAO central and peripheral VFs were normal at follow-up. My studies showed that AION, CRVO, BRVO, CRAO and BRAO, each consist of multiple distinct clinical sub-categories with different visual outcome. Contrary to the prevalent impression, these studies on the natural history of visual outcome have shown that there is a statistically significant spontaneous visual improvement in each category. The factors which influence the visual outcome in various ocular vascular occlusive disorders are discussed. PMID:24769221

Virtual bronchoscopic navigation without X-ray fluoroscopy to diagnose peripheral pulmonary lesions: a randomized trial.

PubMed

Asano, Fumihiro; Ishida, Takashi; Shinagawa, Naofumi; Sukoh, Noriaki; Anzai, Masaki; Kanazawa, Kenya; Tsuzuku, Akifumi; Morita, Satoshi

2017-12-11

Transbronchial biopsy for peripheral pulmonary lesions is generally performed under X-ray fluoroscopy. Virtual bronchoscopic navigation (VBN) is a method in which virtual images of the bronchial route to the lesion are produced based on CT images obtained before VBN, and the bronchoscope is guided using these virtual images, improving the diagnostic yield of peripheral pulmonary lesions. VBN has the possibility of eliminating the need for X-ray fluoroscopy in the bronchoscopic diagnosis of peripheral lesions. To determine whether VBN can be a substitute for X-ray fluoroscopy, a randomized multicenter trial (non-inferiority trial) was performed in VBN and X-ray fluoroscopy (XRF) -assisted groups. The non-inferiority margin in the VBN-assisted group compared with the XRF-assisted group was set at 15%. The subjects consisted of 140 patients with peripheral pulmonary lesions with a mean diameter > 3 cm. In the VBN-assisted group, the bronchoscope was guided to the lesion using a VBN system without X-ray fluoroscopy. In the XRF-assisted group, the same bronchoscope was guided to the lesion under X-ray fluoroscopy. Subsequently, in both groups, the lesion was visualized using endobronchial ultrasonography with a guide sheath (EBUS/GS), and biopsy was performed. In this serial procedure, X-ray fluoroscopy was not used in the VBNA group. The subjects of analysis consisted of 129 patients. The diagnostic yield was 76.9% (50/65) in the VBN-assisted group and 85.9% (55/64) in the XRF-assisted group. The difference in the diagnostic yield between the two groups was -9.0% (95% confidence interval: -22.3% ~ 4.3%). The non-inferiority of the VBN-assisted group could not be confirmed. The rate of visualizing lesions by EBUS was 95.4% (62/65) in the VBN-assisted group and 96.9% (62/64) in the XRF-assisted group, being high in both groups. On EBUS/GS, a bronchoscope and biopsy instruments may be guided to the lesions using VBN without X-ray fluoroscopy, but X-ray fluoroscopy is necessary to improve the accuracy of sample collection from lesions. During transbronchial biopsy for peripheral pulmonary lesions, VBN cannot be a substitute for X-ray fluoroscopy. UMIN-CTR (UMIN000001710); registered 16 February 2009.

Intravenous immunoglobulin for chronic residual peripheral neuropathy in eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome): a multicenter, double-blind trial.

PubMed

Koike, Haruki; Akiyama, Kazuo; Saito, Toyokazu; Sobue, Gen

2015-03-01

Eosinophilic granulomatosis with polyangiitis (EGPA), previously called Churg-Strauss syndrome, frequently affects the peripheral nervous system. We conducted a multicenter, double-blind, three-arm treatment period, randomized, pre-post trial to assess the efficacy of intravenous immunoglobulin (IVIg) administration for residual peripheral neuropathy in patients with EGPA that is in remission, indicated by laboratory indices. Twenty-three patients were randomly assigned into three groups, in which the timing of IVIg and placebo administration was different. Each group received one course of intervention and two courses of placebo at 2-week intervals. Treatment effects were assessed every 2 weeks for 8 weeks. The primary outcome measure, the amount of change in the manual muscle testing sum score 2 weeks after IVIg administration, significantly increased (p = 0.002). The results over time suggested that this effect continued until the last assessment was done 8 weeks later. The number of muscles with manual muscle testing scores of three or less (p = 0.004) and the neuropathic pain scores represented by the visual analogue scale (p = 0.005) also improved significantly 2 weeks after IVIg administration. This study indicates that IVIg treatment for EGPA patients with residual peripheral neuropathy should be considered even when laboratory indices suggest remission of the disease.

Left, right, left, right, eyes to the front! Müller-Lyer bias in grasping is not a function of hand used, hand preferred or visual hemifield, but foveation does matter.

PubMed

van der Kamp, John; de Wit, Matthieu M; Masters, Rich S W

2012-04-01

We investigated whether the control of movement of the left hand is more likely to involve the use of allocentric information than movements performed with the right hand. Previous studies (Gonzalez et al. in J Neurophys 95:3496-3501, 2006; De Grave et al. in Exp Br Res 193:421-427, 2009) have reported contradictory findings in this respect. In the present study, right-handed participants (N = 12) and left-handed participants (N = 12) made right- and left-handed grasps to foveated objects and peripheral, non-foveated objects that were located in the right or left visual hemifield and embedded within a Müller-Lyer illusion. They were also asked to judge the size of the object by matching their hand aperture to its length. Hand apertures did not show significant differences in illusory bias as a function of hand used, handedness or visual hemifield. However, the illusory effect was significantly larger for perception than for action, and for the non-foveated compared to foveated objects. No significant illusory biases were found for reach movement times. These findings are consistent with the two-visual system model that holds that the use of allocentric information is more prominent in perception than in movement control. We propose that the increased involvement of allocentric information in movements toward peripheral, non-foveated objects may be a consequence of more awkward, less automatized grasps of nonfoveated than foveated objects. The current study does not support the conjecture that the control of left-handed and right-handed grasps is predicated on different sources of information.

Attentional Modulation of Change Detection ERP Components by Peripheral Retro-Cueing

PubMed Central

Pazo-Álvarez, Paula; Roca-Fernández, Adriana; Gutiérrez-Domínguez, Francisco-Javier; Amenedo, Elena

2017-01-01

Change detection is essential for visual perception and performance in our environment. However, observers often miss changes that should be easily noticed. A failure in any of the processes involved in conscious detection (encoding the pre-change display, maintenance of that information within working memory, and comparison of the pre and post change displays) can lead to change blindness. Given that unnoticed visual changes in a scene can be easily detected once attention is drawn to them, it has been suggested that attention plays an important role on visual awareness. In the present study, we used behavioral and electrophysiological (ERPs) measures to study whether the manipulation of retrospective spatial attention affects performance and modulates brain activity related to the awareness of a change. To that end, exogenous peripheral cues were presented during the delay period (retro-cues) between the first and the second array using a one-shot change detection task. Awareness of a change was associated with a posterior negative amplitude shift around 228–292 ms (“Visual Awareness Negativity”), which was independent of retrospective spatial attention, as it was elicited to both validly and invalidly cued change trials. Change detection was also associated with a larger positive deflection around 420–580 ms (“Late Positivity”), but only when the peripheral retro-cues correctly predicted the change. Present results confirm that the early and late ERP components related to change detection can be functionally dissociated through manipulations of exogenous retro-cueing using a change blindness paradigm. PMID:28270759

Evaluation of peripheral binocular visual field in patients with glaucoma: a pilot study.

PubMed

Ana, Banc; Cristina, Stan; Dorin, Chiselita

2016-01-01

The objective of this study was to evaluate the peripheral binocular visual field (PBVF) in patients with glaucoma using the threshold strategy of Humphrey Field Analyzer. We conducted a case-control pilot study in which we enrolled 59 patients with glaucoma and 20 controls. All participants were evaluated using a custom PBVF test and central 24 degrees monocular visual field tests for each eye using the threshold strategy. The central binocular visual field (CBVF) was predicted from the monocular tests using the most sensitive point at each field location. The glaucoma patients were grouped according to Hodapp classification and age. The PBVF was compared to controls and the relationship between the PBVF and CBVF was tested. The areas of frame-induced artefacts were determined (over 50 degrees in each temporal field, 24 degrees superiorly and 45 degrees inferiorly) and excluded from interpretation. The patients presented a statistically significant generalized decrease of the peripheral retinal sensitivity compared to controls for Hodapp initial stage--groups aged 50-59 (t = 11.93 > 2.06; p < 0.05) and 60-69 (t = 7.55 > 2.06; p < 0.05). For the initial Hodapp stage there was no significant relationship between PBVF and CBVF (r = 0.39). For the moderate and advanced Hodapp stages, the interpretation of data was done separately for each patient. This pilot study suggests that glaucoma patients present a decrease of PBVF compared to controls and CBVF cannot predict the PBVF in glaucoma.

Two-stage perceptual learning to break visual crowding.

PubMed

Zhu, Ziyun; Fan, Zhenzhi; Fang, Fang

2016-01-01

When a target is presented with nearby flankers in the peripheral visual field, it becomes harder to identify, which is referred to as crowding. Crowding sets a fundamental limit of object recognition in peripheral vision, preventing us from fully appreciating cluttered visual scenes. We trained adult human subjects on a crowded orientation discrimination task and investigated whether crowding could be completely eliminated by training. We discovered a two-stage learning process with this training task. In the early stage, when the target and flankers were separated beyond a certain distance, subjects acquired a relatively general ability to break crowding, as evidenced by the fact that the breaking of crowding could transfer to another crowded orientation, even a crowded motion stimulus, although the transfer to the opposite visual hemi-field was weak. In the late stage, like many classical perceptual learning effects, subjects' performance gradually improved and showed specificity to the trained orientation. We also found that, when the target and flankers were spaced too finely, training could only reduce, rather than completely eliminate, the crowding effect. This two-stage learning process illustrates a learning strategy for our brain to deal with the notoriously difficult problem of identifying peripheral objects in clutter. The brain first learned to solve the "easy and general" part of the problem (i.e., improving the processing resolution and segmenting the target and flankers) and then tackle the "difficult and specific" part (i.e., refining the representation of the target).

A deep (learning) dive into visual search behaviour of breast radiologists

NASA Astrophysics Data System (ADS)

Mall, Suneeta; Brennan, Patrick C.; Mello-Thoms, Claudia

2018-03-01

Visual search, the process of detecting and identifying objects using the eye movements (saccades) and the foveal vision, has been studied for identification of root causes of errors in the interpretation of mammography. The aim of this study is to model visual search behaviour of radiologists and their interpretation of mammograms using deep machine learning approaches. Our model is based on a deep convolutional neural network, a biologically-inspired multilayer perceptron that simulates the visual cortex, and is reinforced with transfer learning techniques. Eye tracking data obtained from 8 radiologists (of varying experience levels in reading mammograms) reviewing 120 two-view digital mammography cases (59 cancers) have been used to train the model, which was pre-trained with the ImageNet dataset for transfer learning. Areas of the mammogram that received direct (foveally fixated), indirect (peripherally fixated) or no (never fixated) visual attention were extracted from radiologists' visual search maps (obtained by a head mounted eye tracking device). These areas, along with the radiologists' assessment (including confidence of the assessment) of suspected malignancy were used to model: 1) Radiologists' decision; 2) Radiologists' confidence on such decision; and 3) The attentional level (i.e. foveal, peripheral or none) obtained by an area of the mammogram. Our results indicate high accuracy and low misclassification in modelling such behaviours.

Solar retinopathy. A study from Nepal and from Germany.

PubMed

Rai, N; Thuladar, L; Brandt, F; Arden, G B; Berninger, T A

1998-01-01

319 patients with a solar retinopathy were seen in an eye clinic in Nepal within 20 months. All patients had either a positive history of sun-gazing or typical circumscribed scars in the foveal area. In more than 80% of the patients the visual acuity was 6/12 or better and did not deteriorate over time. 126 (40%) patients had a history of gazing at the sun during an eclipse, 33 (10%) were sun worshipers and 4 (1%) were in both categories. Three years later 29 patients were re-examined in a follow-up study. Only 16 had had visual disturbances directly after they had gazed into the sun. No colour vision defects were seen in any of the 44 affected eyes, when tested with Panel D 15, while four patients (6 eyes) had some uncertainty with the tritan plates of the Ishihara test charts. Metamorphopsia were recorded in 11 eyes. Five German patients with solar retinopathy were examined in more detail. Colour contrast sensitivity (CCS) was tested for the central and the peripheral visual field. CCS for tritan axis was raised in all patients for the central visual field, while it was normal for the peripheral visual field.

Visual skills involved in decision making by expert referees.

PubMed

Ghasemi, Abdollah; Momeni, Maryam; Jafarzadehpur, Ebrahim; Rezaee, Meysam; Taheri, Hamid

2011-02-01

Previous studies have compared visual skills of expert and novice athletes; referees' performance has not been addressed. Visual skills of two groups of expert referees, successful and unsuccessful in decision making, were compared. Using video clips of soccer matches to assess decision-making success of 41 national and international referees from 31 to 42 years of age, 10 top referees were selected as the Successful group and 10 as the Unsuccessful group. Visual tests included visual memory, visual reaction time, peripheral vision, recognition speed, saccadic eye movement, and facility of accommodation. The Successful group had better visual skills than the Unsuccessful group. Such visual skills enhance soccer referees' performance and may be recommended for young referees.

Effect of prolonged bedrest and plus Gz acceleration on peripheral visual response time

NASA Technical Reports Server (NTRS)

Haines, R. F.

1973-01-01

Peripheral visual response time changes during +G sub z acceleration following fourteen days of bedrest are considered as well as what effect prolonged bedrest has upon this response. Eighteen test lights, placed 10 deg are apart along the horizontal meridian of the subject's field of view, were presented in a random sequence. The subject was instructed to press a button as soon as a light appeared. Response time testing occurred periodically during bedrest and continuously during centrifugation testing. The results indicate that: (1) mean response time is significantly longer to stimuli imaged in the far periphery than to stimuli imaged closer to the line of sight; (2) mean response time at each stimulus position tends to be longer at plateau g than during the preacceleration baseline period; (3) mean response time tends to lengthen as the g level is increased; (4) peripheral visual response time during +G sub x acceleration at 2, 3.2, and 3.8 g was not a reliable advanced indicator that blackout was going to occur; and (5) the subject's field of view collapsed rapidly just before blackout. Bedrest data showed that the distribution of response times to stimuli imaged across the subject's horizontal retinal meridian remained remarkably constant from day to day during both the bedrest and recovery periods.

Peripheral prism glasses: effects of moving and stationary backgrounds.

PubMed

Shen, Jieming; Peli, Eli; Bowers, Alex R

2015-04-01

Unilateral peripheral prisms for homonymous hemianopia (HH) expand the visual field through peripheral binocular visual confusion, a stimulus for binocular rivalry that could lead to reduced predominance and partial suppression of the prism image, thereby limiting device functionality. Using natural-scene images and motion videos, we evaluated whether detection was reduced in binocular compared with monocular viewing. Detection rates of nine participants with HH or quadranopia and normal binocularity wearing peripheral prisms were determined for static checkerboard perimetry targets briefly presented in the prism expansion area and the seeing hemifield. Perimetry was conducted under monocular and binocular viewing with targets presented over videos of real-world driving scenes and still frame images derived from those videos. With unilateral prisms, detection rates in the prism expansion area were significantly lower in binocular than in monocular (prism eye) viewing on the motion background (medians, 13 and 58%, respectively, p = 0.008) but not the still frame background (medians, 63 and 68%, p = 0.123). When the stimulus for binocular rivalry was reduced by fitting prisms bilaterally in one HH and one normally sighted subject with simulated HH, prism-area detection rates on the motion background were not significantly different (p > 0.6) in binocular and monocular viewing. Conflicting binocular motion appears to be a stimulus for reduced predominance of the prism image in binocular viewing when using unilateral peripheral prisms. However, the effect was only found for relatively small targets. Further testing is needed to determine the extent to which this phenomenon might affect the functionality of unilateral peripheral prisms in more real-world situations.

Characterization of Soft Contact Lens Edge Fitting during Daily Wear Using Ultrahigh-Resolution Optical Coherence Tomography.

PubMed

Cui, Lele; Chen, Sisi; Zhou, Weihe; Sheng, Kaixuan; Zhang, Lei; Shen, Meixiao; Li, Ming

2018-01-01

To determine conjunctival overlap over the edge of soft contact lens and to visualize the peripheral postlens tear film (PoLTF) underneath soft contact lenses using ultrahigh-resolution optical coherence tomography (UHR-OCT). Twenty participants (4 males and 16 females, 23.0 ± 3.7 years) were fitted with two different types of soft contact lenses randomly. The limbus with lens was imaged with the UHR-OCT at the horizontal meridian every two hours up to 6 hours during lens wear. The conjunctival overlap was ranked as the percentage of the edge covered by the conjunctiva. The frequency of occurrence for visualized peripheral PoLTF was determined. The average conjunctival overlaps at insertion were 49% and 73% for galyfilcon A and balafilcon A lenses and increased significantly to 84% and 90% by 6 hours of lens wear ( P < 0.001). Lenses with rounded edges had more conjunctival overlap than the lenses with angled edges ( P =0.014). There were significant decreases for PoLTF on the conjunctiva ( P =0.014) and peripheral cornea ( P =0.004) over the study period compared to insertion. The percentage of subjects with PoLTF on the conjunctiva (32.5%) and peripheral cornea (36%) were greater in subjects wearing balafilcon A lenses ( P =0.017). Increased conjunctival overlap over the lens edges and reduced PoLTF underneath the peripheral region of soft contact lenses were shown during lens daily wear. The lens edge configuration may play a role in conjunctival response and peripheral PoLTF.

Peripheral Prism Glasses: Effects of Moving and Stationary Backgrounds

PubMed Central

Shen, Jieming; Peli, Eli; Bowers, Alex R.

2015-01-01

Purpose Unilateral peripheral prisms for homonymous hemianopia (HH) expand the visual field through peripheral binocular visual confusion, a stimulus for binocular rivalry that could lead to reduced predominance (partial local suppression) of the prism image and limit device functionality. Using natural-scene images and motion videos, we evaluated whether detection was reduced in binocular compared to monocular viewing. Methods Detection rates of nine participants with HH or quadranopia and normal binocularity wearing peripheral prisms were determined for static checkerboard perimetry targets briefly presented in the prism expansion area and the seeing hemifield. Perimetry was conducted under monocular and binocular viewing with targets presented over videos of real-world driving scenes and still frame images derived from those videos. Results With unilateral prisms, detection rates in the prism expansion area were significantly lower in binocular than monocular (prism eye) viewing on the motion background (medians 13% and 58%, respectively, p = 0.008), but not the still frame background (63% and 68%, p = 0.123). When the stimulus for binocular rivalry was reduced by fitting prisms bilaterally in 1 HH and 1 normally-sighted subject with simulated HH, prism-area detection rates on the motion background were not significantly different (p > 0.6) in binocular and monocular viewing. Conclusions Conflicting binocular motion appears to be a stimulus for reduced predominance of the prism image in binocular viewing when using unilateral peripheral prisms. However, the effect was only found for relatively small targets. Further testing is needed to determine the extent to which this phenomenon might affect the functionality of unilateral peripheral prisms in more real-world situations. PMID:25785533

Optic ataxia and the function of the dorsal stream: contributions to perception and action.

PubMed

Pisella, Laure; Sergio, Lauren; Blangero, Annabelle; Torchin, Héloïse; Vighetto, Alain; Rossetti, Yves

2009-12-01

Optic ataxia (OA) is one of the symptoms pertaining to Bálint's Syndrome. It has been described clinically for nearly 80 years before it became a cornerstone of the most popular dual stream theory of the visual brain. Over the last 10 years a regain of interest for this neurological condition lead to a number of precise analyses of the deficits found in optic ataxia, giving rise to a renewed outline of its very definition and hence of the function(s) of the occipito-parietal (dorsal) stream. In absence of concomitant clinical symptoms, we review evidence that misreaching errors in central vision result from the "hand effect": an erroneous dynamic spatial processing of proprioceptive information from the hand. When visual feedback of the hand is provided (closed-loop condition), pure optic ataxia is restricted to peripheral vision. This central versus peripheral vision distinction is repeatedly used to argue that action and perception are not unique and dissociated systems. New assessments of optic ataxia patients are provided, confirming on one hand that their visuomotor deficit is specific to peripheral vision (i.e. when the gaze and the hand goals are dissociated), on the other hand that they disclose perceptual deficits in peripheral vision. These results are coherent with the recent demonstration that optic ataxia patients exhibit a general contralesional deficit for dynamic visuo-spatial processing, affecting both hand and eye movements [Gaveau, V., Pélisson, D., Blangero, A., Urquizar, C., Prablanc, C.,Vighetto, A., et al. (2008). A common parietal module for saccade and reach: Eye-hand coordination and saccadic control in optic ataxia. Neuropsychologia, 46, 475-486]. Such module(s) within the dorsal stream could be used for both action and perception in the periphery. It is concluded that optic ataxia cannot be considered as a unitary and specific visuo-manual deficit, and that the modular organisation of the dorsal stream allows for numerous dorsal-ventral interactions for perception and action.

The Visual Impairment Intracranial Pressure Syndrome in Long Duration NASA Astronauts: An Integrated Approach

NASA Technical Reports Server (NTRS)

Otto, C. A.; Norsk, P.; Shelhamer, M. J.; Davis, J. R.

2015-01-01

The Visual Impairment Intracranial Pressure (VIIP) syndrome is currently NASA's number one human space flight risk. The syndrome, which is related to microgravity exposure, manifests with changes in visual acuity (hyperopic shifts, scotomas), changes in eye structure (optic disc edema, choroidal folds, cotton wool spots, globe flattening, and distended optic nerve sheaths). In some cases, elevated cerebrospinal fluid pressure has been documented postflight reflecting increased intracranial pressure (ICP). While the eye appears to be the main affected end organ of this syndrome, the ocular affects are thought to be related to the effect of cephalad fluid shift on the vascular system and the central nervous system. The leading hypotheses for the development of VIIP involve microgravity induced head-ward fluid shifts along with a loss of gravity-assisted drainage of venous blood from the brain, both leading to cephalic congestion and increased ICP. Although not all crewmembers have manifested clinical signs or symptoms of the VIIP syndrome, it is assumed that all astronauts exposed to microgravity have some degree of ICP elevation in-flight. Prolonged elevations of ICP can cause long-term reduced visual acuity and loss of peripheral visual fields, and has been reported to cause mild cognitive impairment in the analog terrestrial population of Idiopathic Intracranial Hypertension (IIH). These potentially irreversible health consequences underscore the importance of identifying the factors that lead to this syndrome and mitigating them.

The Development and Temporal Dynamics of Spatial Orienting in Infants.

ERIC Educational Resources Information Center

Johnson, Mark H.; Tucker, Leslie A.

1996-01-01

Discusses changes occurring in two-, four-, and six-month-old infants' visual attention span, through a series of experiments examining their ability to orient to peripheral visual stimuli. The results obtained were consistent with the hypothesis that infants get faster with age in shifting attention to a spatial location. (AA)

Central and Peripheral Vision Loss Differentially Affects Contextual Cueing in Visual Search

ERIC Educational Resources Information Center

Geringswald, Franziska; Pollmann, Stefan

2015-01-01

Visual search for targets in repeated displays is more efficient than search for the same targets in random distractor layouts. Previous work has shown that this contextual cueing is severely impaired under central vision loss. Here, we investigated whether central vision loss, simulated with gaze-contingent displays, prevents the incidental…

Optical treatment strategies to slow myopia progression: Effects of the visual extent of the optical treatment zone

PubMed Central

Smith, Earl L.

2013-01-01

In order to develop effective optical treatment strategies for myopia, it is important to understand how visual experience influences refractive development. Beginning with the discovery of the phenomenon of form deprivation myopia, research involving many animal species has demonstrated that refractive development is regulated by visual feedback. In particular, animal studies have shown that optically imposed myopic defocus slows axial elongation, that the effects of vision are dominated by local retinal mechanisms, and that peripheral vision can dominate central refractive development. In this review, the results obtained from clinical trials of traditional optical treatment strategies employed in efforts to slow myopia progression in children are interpreted in light of the results from animal studies and are compared to the emerging results from preliminary clinical studies of optical treatment strategies that manipulate the effective focus of the peripheral retina. Overall, the results suggest that imposed myopic defocus can slow myopia progression in children and that the effectiveness of an optical treatment strategy in reducing myopia progression is influenced by the extent of the visual field that is manipulated. PMID:23290590

Vestibular signals in macaque extrastriate visual cortex are functionally appropriate for heading perception

PubMed Central

Liu, Sheng; Angelaki, Dora E.

2009-01-01

Visual and vestibular signals converge onto the dorsal medial superior temporal area (MSTd) of the macaque extrastriate visual cortex, which is thought to be involved in multisensory heading perception for spatial navigation. Peripheral otolith information, however, is ambiguous and cannot distinguish linear accelerations experienced during self-motion from those due to changes in spatial orientation relative to gravity. Here we show that, unlike peripheral vestibular sensors but similar to lobules 9 and 10 of the cerebellar vermis (nodulus and uvula), MSTd neurons respond selectively to heading and not to changes in orientation relative to gravity. In support of a role in heading perception, MSTd vestibular responses are also dominated by velocity-like temporal dynamics, which might optimize sensory integration with visual motion information. Unlike the cerebellar vermis, however, MSTd neurons also carry a spatial orientation-independent rotation signal from the semicircular canals, which could be useful in compensating for the effects of head rotation on the processing of optic flow. These findings show that vestibular signals in MSTd are appropriately processed to support a functional role in multisensory heading perception. PMID:19605631

Visual spatial attention enhances the amplitude of positive and negative fMRI responses to visual stimulation in an eccentricity-dependent manner.

PubMed

Bressler, David W; Fortenbaugh, Francesca C; Robertson, Lynn C; Silver, Michael A

2013-06-07

Endogenous visual spatial attention improves perception and enhances neural responses to visual stimuli at attended locations. Although many aspects of visual processing differ significantly between central and peripheral vision, little is known regarding the neural substrates of the eccentricity dependence of spatial attention effects. We measured amplitudes of positive and negative fMRI responses to visual stimuli as a function of eccentricity in a large number of topographically-organized cortical areas. Responses to each stimulus were obtained when the stimulus was attended and when spatial attention was directed to a stimulus in the opposite visual hemifield. Attending to the stimulus increased both positive and negative response amplitudes in all cortical areas we studied: V1, V2, V3, hV4, VO1, LO1, LO2, V3A/B, IPS0, TO1, and TO2. However, the eccentricity dependence of these effects differed considerably across cortical areas. In early visual, ventral, and lateral occipital cortex, attentional enhancement of positive responses was greater for central compared to peripheral eccentricities. The opposite pattern was observed in dorsal stream areas IPS0 and putative MT homolog TO1, where attentional enhancement of positive responses was greater in the periphery. Both the magnitude and the eccentricity dependence of attentional modulation of negative fMRI responses closely mirrored that of positive responses across cortical areas. Copyright © 2013 Elsevier Ltd. All rights reserved.

Functional neural substrates of posterior cortical atrophy patients.

PubMed

Shames, H; Raz, N; Levin, Netta

2015-07-01

Posterior cortical atrophy (PCA) is a neurodegenerative syndrome in which the most pronounced pathologic involvement is in the occipito-parietal visual regions. Herein, we aimed to better define the cortical reflection of this unique syndrome using a thorough battery of behavioral and functional MRI (fMRI) tests. Eight PCA patients underwent extensive testing to map their visual deficits. Assessments included visual functions associated with lower and higher components of the cortical hierarchy, as well as dorsal- and ventral-related cortical functions. fMRI was performed on five patients to examine the neuronal substrate of their visual functions. The PCA patient cohort exhibited stereopsis, saccadic eye movements and higher dorsal stream-related functional impairments, including simultant perception, image orientation, figure-from-ground segregation, closure and spatial orientation. In accordance with the behavioral findings, fMRI revealed intact activation in the ventral visual regions of face and object perception while more dorsal aspects of perception, including motion and gestalt perception, revealed impaired patterns of activity. In most of the patients, there was a lack of activity in the word form area, which is known to be linked to reading disorders. Finally, there was evidence of reduced cortical representation of the peripheral visual field, corresponding to the behaviorally assessed peripheral visual deficit. The findings are discussed in the context of networks extending from parietal regions, which mediate navigationally related processing, visually guided actions, eye movement control and working memory, suggesting that damage to these networks might explain the wide range of deficits in PCA patients.

Reading speed benefits from increased vertical word spacing in normal peripheral vision.

PubMed

Chung, Susana T L

2004-07-01

Crowding, the adverse spatial interaction due to proximity of adjacent targets, has been suggested as an explanation for slow reading in peripheral vision. The purposes of this study were to (1) demonstrate that crowding exists at the word level and (2) examine whether or not reading speed in central and peripheral vision can be enhanced with increased vertical word spacing. Five normal observers read aloud sequences of six unrelated four-letter words presented on a computer monitor, one word at a time, using rapid serial visual presentation (RSVP). Reading speeds were calculated based on the RSVP exposure durations yielding 80% correct. Testing was conducted at the fovea and at 5 degrees and 10 degrees in the inferior visual field. Critical print size (CPS) for each observer and at each eccentricity was first determined by measuring reading speeds for four print sizes using unflanked words. We then presented words at 0.8x or 1.4x CPS, with each target word flanked by two other words, one above and one below the target word. Reading speeds were determined for vertical word spacings (baseline-to-baseline separation between two vertically separated words) ranging from 0.8x to 2x the standard single-spacing, as well as the unflanked condition. At the fovea, reading speed increased with vertical word spacing up to about 1.2x to 1.5x the standard spacing and remained constant and similar to the unflanked reading speed at larger vertical word spacings. In the periphery, reading speed also increased with vertical word spacing, but it remained below the unflanked reading speed for all spacings tested. At 2x the standard spacing, peripheral reading speed was still about 25% lower than the unflanked reading speed for both eccentricities and print sizes. Results from a control experiment showed that the greater reliance of peripheral reading speed on vertical word spacing was also found in the right visual field. Increased vertical word spacing, which presumably decreases the adverse effect of crowding between adjacent lines of text, benefits reading speed. This benefit is greater in peripheral than central vision.

A nationwide survey of combined central and peripheral demyelination in Japan.

PubMed

Ogata, Hidenori; Matsuse, Dai; Yamasaki, Ryo; Kawamura, Nobutoshi; Matsushita, Takuya; Yonekawa, Tomomi; Hirotani, Makoto; Murai, Hiroyuki; Kira, Jun-ichi

2016-01-01

To clarify the clinical features of combined central and peripheral demyelination (CCPD) via a nationwide survey. The following characteristics were used to define CCPD: T2 high-signal intensity lesions in the brain, optic nerves or spinal cord on MRI, or abnormalities on visual-evoked potentials; conduction delay, conduction block, temporal dispersion or F-wave abnormalities suggesting demyelinating neuropathy based on nerve conduction studies; exclusion of secondary demyelination. We conducted a nationwide survey in 2012, sending questionnaires to 1332 adult and paediatric neurology institutions in Japan. We collated 40 CCPD cases, including 29 women. Age at onset was 31.7±14.1 years (mean±SD). Sensory disturbance (94.9%), motor weakness (92.5%) and gait disturbance (79.5%) were common. Although cerebrospinal fluid protein levels were increased in 82.5%, oligoclonal IgG bands and elevated IgG indices were detected in 7.4% and 18.5% of cases, respectively. Fifteen of 21 patients (71.4%) had abnormal visual-evoked potentials. Antineurofascin 155 antibodies were positive in 5/11 (45.5%). Corticosteroids, intravenous immunoglobulins and plasmapheresis resulted in an 83.3%, 66.7% and 87.5% improvement, respectively, whereas interferon-β was effective in only 10% of cases. CCPD cases with simultaneous onset of central nervous system (CNS) and peripheral nervous system (PNS) involvement exhibited greater disability, but less recurrence and more frequent extensive cerebral and spinal cord MRI lesions compared to those with temporarily separated onset, whereas optic nerve involvement was more common in the latter. CCPD shows different characteristics from classical demyelinating diseases, and distinctive features exist between cases with simultaneous and temporarily separated onset of CNS and PNS involvement. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

The first radiographic image of a peripheral nerve disorder? Lipomatous macrodactyly (unrecognized lipomatosis of nerve).

PubMed

Mahan, Mark A; Prasad, Nikhil; Spinner, Robert J

2015-06-01

Lipomatosis of nerves (LN) involves benign fibro-fatty infiltration and is often associated with territorial overgrowth of soft tissue and bone; this distinctive disease pattern can be visualized on plain radiographs. We recently discovered a case (presented by Sir Robert Jones in 1898 to the Pathological Society of London) that indirectly represents a historical landmark in the imaging of peripheral nerves. The clinical findings and image, with obvious soft tissue and bone overgrowth, are pathognomonic for LN, making this one of the earliest radiological observations of a peripheral nerve lesion.

Fish allergy causing angioedema and secondary angle-closure glaucoma.

PubMed

Calder, Donovan; Calder, Jennifer

2013-03-06

A 56-year-old woman with a history of primary angle-closure glaucoma presented with acute generalised swelling, and facial angioedema following a fish meal. She complained of nausea, vomiting, headache, pain in both eyes and acute loss of vision. Her visual acuity was reduced and intraocular pressures (IOP) were elevated. Gonioscopy revealed complete angle closure in the left eye and complete to partial closure in the right eye. Through existing peripheral iridotomies the anterior capsules were seen pressed up against the iris of both eyes. A diagnosis of angle-closure glaucoma was made, medications were started to reduce the elevated intraocular pressure and systemic antihistamine to counter the allergic reaction. She was hospitalised for further management. A follow-up at 2 years revealed her visual acuities and IOP had remained normal.

Blast exposure and dual sensory impairment: an evidence review and integrated rehabilitation approach.

PubMed

Saunders, Gabrielle H; Echt, Katharina V

2012-01-01

Combat exposures to blast can result in both peripheral damage to the ears and eyes and central damage to the auditory and visual processing areas in the brain. The functional effects of the latter include visual, auditory, and cognitive processing difficulties that manifest as deficits in attention, memory, and problem solving--symptoms similar to those seen in individuals with visual and auditory processing disorders. Coexisting damage to the auditory and visual system is referred to as dual sensory impairment (DSI). The number of Operation Iraqi Freedom/Operation Enduring Freedom Veterans with DSI is vast; yet currently no established models or guidelines exist for assessment, rehabilitation, or service-delivery practice. In this article, we review the current state of knowledge regarding blast exposure and DSI and outline the many unknowns in this area. Further, we propose a model for clinical assessment and rehabilitation of blast-related DSI that includes development of a coordinated team-based approach to target activity limitations and participation restrictions in order to enhance reintegration, recovery, and quality of life.

[Vigilance and beta blockade. The influence of the beta blocker atenolol and other substances on the reaction time of the visual system].

PubMed

Harms, D; Pachale, E; Nechvatal, D

1981-03-05

Visual reaction times as a measure of vigilance and of the psycho-physiological condition of subjects was determined after combined physical and mental stress to examine beta-blocker influence. Using the technique of electrooculography 40 subjects aged 25,7 +/- 6 with a mean blood pressure to 126/79 mmHg were measured in a double-blind cross-over design after application of placebo or 50 mg of atenolol (Tenormin) for 3 days. Visual reaction time was defined as the time between display of a peripheral light signal and the start of the eye movement that shifts the direction of gaze from the reference point to the stimulus. The results of the study show, that under these experimental conditions there is a positive effect of beta-blocker medication on vigilance. Findings of other authors are discussed. To prove the sensitivity of the test method in a preliminary study, the effects of the well-described drugs fenetyllinhydrochloride, diazepam, oxazepam and alcohol on visual reaction time were investigated.

Interval timing in children: effects of auditory and visual pacing stimuli and relationships with reading and attention variables.

PubMed

Birkett, Emma E; Talcott, Joel B

2012-01-01

Motor timing tasks have been employed in studies of neurodevelopmental disorders such as developmental dyslexia and ADHD, where they provide an index of temporal processing ability. Investigations of these disorders have used different stimulus parameters within the motor timing tasks that are likely to affect performance measures. Here we assessed the effect of auditory and visual pacing stimuli on synchronised motor timing performance and its relationship with cognitive and behavioural predictors that are commonly used in the diagnosis of these highly prevalent developmental disorders. Twenty-one children (mean age 9.6 years) completed a finger tapping task in two stimulus conditions, together with additional psychometric measures. As anticipated, synchronisation to the beat (ISI 329 ms) was less accurate in the visually paced condition. Decomposition of timing variance indicated that this effect resulted from differences in the way that visual and auditory paced tasks are processed by central timekeeping and associated peripheral implementation systems. The ability to utilise an efficient processing strategy on the visual task correlated with both reading and sustained attention skills. Dissociations between these patterns of relationship across task modality suggest that not all timing tasks are equivalent.

A novel bFGF-GH injection therapy for two patients with severe ischemic limb pain.

PubMed

Ito, Naomi; Saito, Shigeru; Yamada, Makiko Hardy; Koizuka, Shiro; Obata, Hideaki; Nishikawa, Koichi; Tabata, Yasuhiko

2008-01-01

Severe ischemic pain is difficult to treat with a single therapy. Although modern angiogenic therapies have been used in patients with peripheral arterial occlusive diseases, a regimen combining novel angiogenic therapy and classic nerve blocks, including sympathectomy, has not been discussed to date. In this case report, we present two patients with peripheral arterial occlusive disease who were first treated with medication and lumbar sympathectomy, and then with a novel gelatin hydrogel drug-delivery system loaded with basic fibroblast growth factor. The gelatin hydrogel combined with recombinant basic fibroblast growth factor was injected intramuscularly into the ischemic limbs. In the first patient, with arteriosclerosis obliterans, a foot ulcer was healed, and the original score for resting pain (visual analogue scale, 5/10) was decreased to 0/10. In the second patient, with Buerger's disease, a large toe ulcer was healed, and his resting pain (visual analogue scale, 8/10) was decreased to 1/10. Some other parameters, such as skin surface temperature, transcutaneous oxygen partial pressure, and pain-free walking distance, were also improved in both patients after the combined therapy. A multimodal approach is necessary to treat severe ischemic pain. Novel angiogenic therapy combined with nerve blocks seems to be a promising option in patients with severe pain.

Visual symptoms and retinal straylight after laser peripheral iridotomy: the Zhongshan Angle-Closure Prevention Trial.

PubMed

Congdon, Nathan; Yan, Xixi; Friedman, David S; Foster, Paul J; van den Berg, Thomas J T P; Peng, Michelle; Gangwani, Rita; He, Mingguang

2012-07-01

To assess the impact of laser peripheral iridotomy (LPI) on forward-scatter of light and subjective visual symptoms and to identify LPI parameters influencing these phenomena. Cohort study derived from a randomized trial, using an external control group. Chinese subjects initially aged 50 or older and 70 years or younger with bilateral narrow angles undergoing LPI in 1 eye selected at random, and age- and gender-matched controls. Eighteen months after laser, LPI-treated subjects underwent digital iris photography and photogrammetry to characterize the size and location of the LPI, Lens Opacity Classification System III cataract grading, and measurement of retinal straylight (C-Quant; OCULUS, Wetzlar, Germany) in the treated and untreated eyes and completed a visual symptoms questionnaire. Controls answered the questionnaire and underwent straylight measurement and (in a random one-sixth sample) cataract grading. Retinal straylight levels and subjective visual symptoms. Among 230 LPI-treated subjects (121 [58.8%] with LPI totally covered by the lid, 43 [19.8%] with LPI partly covered by the lid, 53 [24.4%] with LPI uncovered by the lid), 217 (94.3%) completed all testing, as did 250 (93.3%) of 268 controls. Age, gender, and prevalence of visual symptoms did not differ between treated subjects and controls, although nuclear (P<0.01) and cortical (P = 0.03) cataract were less common among controls. Neither presenting visual acuity nor straylight score differed between the treated and untreated eyes among all treated persons, nor among those (n = 96) with LPI partially or totally uncovered. Prevalence of subjective glare did not differ significantly between participants with totally covered LPI (6.61%; 95% confidence interval [CI], 3.39%-12.5%), partially covered LPI (11.6%; 95% CI, 5.07%-24.5%), or totally uncovered LPI (9.43%; 95% CI, 4.10%-10.3%). In regression models, only worse cortical cataract grade (P = 0.01) was associated significantly with straylight score, and no predictors were associated with subjective glare. None of the LPI size or location parameters were associated with straylight or subjective symptoms. These results suggests that LPI is safe regarding measures of straylight and visual symptoms. This randomized design provides strong evidence that treatment programs for narrow angles would be unlikely to result in important medium-term visual disability. Copyright © 2012 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Micro-calibration of space and motion by photoreceptors synchronized in parallel with cortical oscillations: A unified theory of visual perception.

PubMed

Jerath, Ravinder; Cearley, Shannon M; Barnes, Vernon A; Jensen, Mike

2018-01-01

A fundamental function of the visual system is detecting motion, yet visual perception is poorly understood. Current research has determined that the retina and ganglion cells elicit responses for motion detection; however, the underlying mechanism for this is incompletely understood. Previously we proposed that retinogeniculo-cortical oscillations and photoreceptors work in parallel to process vision. Here we propose that motion could also be processed within the retina, and not in the brain as current theory suggests. In this paper, we discuss: 1) internal neural space formation; 2) primary, secondary, and tertiary roles of vision; 3) gamma as the secondary role; and 4) synchronization and coherence. Movement within the external field is instantly detected by primary processing within the space formed by the retina, providing a unified view of the world from an internal point of view. Our new theory begins to answer questions about: 1) perception of space, erect images, and motion, 2) purpose of lateral inhibition, 3) speed of visual perception, and 4) how peripheral color vision occurs without a large population of cones located peripherally in the retina. We explain that strong oscillatory activity influences on brain activity and is necessary for: 1) visual processing, and 2) formation of the internal visuospatial area necessary for visual consciousness, which could allow rods to receive precise visual and visuospatial information, while retinal waves could link the lateral geniculate body with the cortex to form a neural space formed by membrane potential-based oscillations and photoreceptors. We propose that vision is tripartite, with three components that allow a person to make sense of the world, terming them "primary, secondary, and tertiary roles" of vision. Finally, we propose that Gamma waves that are higher in strength and volume allow communication among the retina, thalamus, and various areas of the cortex, and synchronization brings cortical faculties to the retina, while the thalamus is the link that couples the retina to the rest of the brain through activity by gamma oscillations. This novel theory lays groundwork for further research by providing a theoretical understanding that expands upon the functions of the retina, photoreceptors, and retinal plexus to include parallel processing needed to form the internal visual space that we perceive as the external world. Copyright © 2017 Elsevier Ltd. All rights reserved.

Automated ultrasound scanning on a dual-modality breast imaging system: coverage and motion issues and solutions.

PubMed

Sinha, Sumedha P; Goodsitt, Mitchell M; Roubidoux, Marilyn A; Booi, Rebecca C; LeCarpentier, Gerald L; Lashbrook, Christine R; Thomenius, Kai E; Chalek, Carl L; Carson, Paul L

2007-05-01

We are developing an automated ultrasound imaging-mammography system wherein a digital mammography unit has been augmented with a motorized ultrasound transducer carriage above a special compression paddle. Challenges of this system are acquiring complete coverage of the breast and minimizing motion. We assessed these problems and investigated methods to increase coverage and stabilize the compressed breast. Visual tracings of the breast-to-paddle contact area and breast periphery were made for 10 patients to estimate coverage area. Various motion artifacts were evaluated in 6 patients. Nine materials were tested for coupling the paddle to the breast. Fourteen substances were tested for coupling the transducer to the paddle in lateral-to-medial and medial-to-lateral views and filling the gap between the peripheral breast and paddle. In-house image registration software was used to register adjacent ultrasound sweeps. The average breast contact area was 56%. The average percentage of the peripheral air gap filled with ultrasound gel was 61%. Shallow patient breathing proved equivalent to breath holding, whereas speech and sudden breathing caused unacceptable artifacts. An adhesive spray that preserves image quality was found to be best for coupling the breast to the paddle and minimizing motion. A highly viscous ultrasound gel proved most effective for coupling the transducer to the paddle for lateral-to-medial and medial-to-lateral views and for edge fill-in. The challenges of automated ultrasound scanning in a multimodality breast imaging system have been addressed by developing methods to fill in peripheral gaps, minimize patient motion, and register and reconstruct multisweep ultrasound image volumes.

Exploring What's Missing: What Do Target Absent Trials Reveal about Autism Search Superiority?

ERIC Educational Resources Information Center

Keehn, Brandon; Joseph, Robert M.

2016-01-01

We used eye-tracking to investigate the roles of enhanced discrimination and peripheral selection in superior visual search in autism spectrum disorder (ASD). Children with ASD were faster at visual search than their typically developing peers. However, group differences in performance and eye-movements did not vary with the level of difficulty of…

Interlateral Asymmetry in the Time Course of the Effect of a Peripheral Prime Stimulus

ERIC Educational Resources Information Center

Castro-Barros, B. A.; Righi, L. L.; Grechi, G.; Ribeiro-do-Valle, L. E.

2008-01-01

Evidence exists that both right and left hemisphere attentional mechanisms are mobilized when attention is directed to the right visual hemifield and only right hemisphere attentional mechanisms are mobilized when attention is directed to the left visual hemifield. This arrangement might lead to a rightward bias of automatic attention. The…

Real-time decoding of the direction of covert visuospatial attention

NASA Astrophysics Data System (ADS)

Andersson, Patrik; Ramsey, Nick F.; Raemaekers, Mathijs; Viergever, Max A.; Pluim, Josien P. W.

2012-08-01

Brain-computer interfaces (BCIs) make it possible to translate a person’s intentions into actions without depending on the muscular system. Brain activity is measured and classified into commands, thereby creating a direct link between the mind and the environment, enabling, e.g., cursor control or navigation of a wheelchair or robot. Most BCI research is conducted with scalp EEG but recent developments move toward intracranial electrodes for paralyzed people. The vast majority of BCI studies focus on the motor system as the appropriate target for recording and decoding movement intentions. However, properties of the visual system may make the visual system an attractive and intuitive alternative. We report on a study investigating feasibility of decoding covert visuospatial attention in real time, exploiting the full potential of a 7 T MRI scanner to obtain the necessary signal quality, capitalizing on earlier fMRI studies indicating that covert visuospatial attention changes activity in the visual areas that respond to stimuli presented in the attended area of the visual field. Healthy volunteers were instructed to shift their attention from the center of the screen to one of four static targets in the periphery, without moving their eyes from the center. During the first part of the fMRI-run, the relevant brain regions were located using incremental statistical analysis. During the second part, the activity in these regions was extracted and classified, and the subject was given visual feedback of the result. Performance was assessed as the number of trials where the real-time classifier correctly identified the direction of attention. On average, 80% of trials were correctly classified (chance level <25%) based on a single image volume, indicating very high decoding performance. While we restricted the experiment to five attention target regions (four peripheral and one central), the number of directions can be higher provided the brain activity patterns can be distinguished. In summary, the visual system promises to be an effective target for BCI control.

Peripheral vision and perceptual asymmetries in young and older martial arts athletes and nonathletes.

PubMed

Muiños, Mónica; Ballesteros, Soledad

2014-11-01

The present study investigated peripheral vision (PV) and perceptual asymmetries in young and older martial arts athletes (judo and karate athletes) and compared their performance with that of young and older nonathletes. Stimuli were dots presented at three different eccentricities along the horizontal, oblique, and vertical diameters and three interstimulus intervals. Experiment 1 showed that although the two athlete groups were faster in almost all conditions, karate athletes performed significantly better than nonathlete participants when stimuli were presented in the peripheral visual field. Experiment 2 showed that older participants who had practiced a martial art at a competitive level when they were young were significantly faster than sedentary older adults of the same age. The practiced sport (judo or karate) did not affect performance differentially, suggesting that it is the practice of martial arts that is the crucial factor, rather than the type of martial art. Importantly, older athletes lose their PV advantage, as compared with young athletes. Finally, we found that physical activity (young and older athletes) and age (young and older adults) did not alter the visual asymmetries that vary as a function of spatial location; all participants were faster for stimuli presented along the horizontal than for those presented along the vertical meridian and for those presented at the lower rather than at the upper locations within the vertical meridian. These results indicate that the practice of these martial arts is an effective way of counteracting the processing speed decline of visual stimuli appearing at any visual location and speed.

Learning of goal-relevant and -irrelevant complex visual sequences in human V1.

PubMed

Rosenthal, Clive R; Mallik, Indira; Caballero-Gaudes, Cesar; Sereno, Martin I; Soto, David

2018-06-12

Learning and memory are supported by a network involving the medial temporal lobe and linked neocortical regions. Emerging evidence indicates that primary visual cortex (i.e., V1) may contribute to recognition memory, but this has been tested only with a single visuospatial sequence as the target memorandum. The present study used functional magnetic resonance imaging to investigate whether human V1 can support the learning of multiple, concurrent complex visual sequences involving discontinous (second-order) associations. Two peripheral, goal-irrelevant but structured sequences of orientated gratings appeared simultaneously in fixed locations of the right and left visual fields alongside a central, goal-relevant sequence that was in the focus of spatial attention. Pseudorandom sequences were introduced at multiple intervals during the presentation of the three structured visual sequences to provide an online measure of sequence-specific knowledge at each retinotopic location. We found that a network involving the precuneus and V1 was involved in learning the structured sequence presented at central fixation, whereas right V1 was modulated by repeated exposure to the concurrent structured sequence presented in the left visual field. The same result was not found in left V1. These results indicate for the first time that human V1 can support the learning of multiple concurrent sequences involving complex discontinuous inter-item associations, even peripheral sequences that are goal-irrelevant. Copyright © 2018. Published by Elsevier Inc.

Adaptive Gaze Strategies for Locomotion with Constricted Visual Field

PubMed Central

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

What Do Patients With Glaucoma See? Visual Symptoms Reported by Patients With Glaucoma

PubMed Central

Hu, Cindy X.; Zangalli, Camila; Hsieh, Michael; Gupta, Lalita; Williams, Alice L.; Richman, Jesse

2014-01-01

Abstract: Background: Vision loss from glaucoma has traditionally been described as loss of “peripheral vision.” In this prospective study, we aimed to improve our clinical understanding of the visual symptoms caused by glaucoma by asking patients specific detailed questions about how they see. Methods: Patients who were clinically diagnosed with various types and stages of glaucoma were included. All had a comprehensive ocular examination, including Octopus visual field testing. Patients were excluded if they had other ocular conditions that affected their vision, including cornea, lens or retina pathologies. Patients responded to an oral questionnaire about their visual symptoms. We investigated the visual symptoms described by patients with glaucoma and correlated the severity of visual field loss with visual symptoms reported. Results: Ninety-nine patients completed the questionnaire. Most patients (76%) were diagnosed with primary open-angle glaucoma. The most common symptoms reported by all patients, including patients with early or moderate glaucoma, were needing more light and blurry vision. Patients with a greater amount of field loss (Octopus mean defect >+9.4 dB) were more likely to report difficulty seeing objects to one or both sides, as if looking through dirty glasses and trouble differentiating boundaries and colors. Conclusions: Vision loss in patients with glaucoma is not as simple as the traditional view of loss of peripheral vision. Needing more light and blurry vision were the most common symptoms reported by patients with glaucoma. PMID:24992392

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

PubMed

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.

Local infiltration analgesia adds no clinical benefit in pain control to peripheral nerve blocks after total knee arthroplasty.

PubMed

Hinarejos, Pedro; Capurro, Bruno; Santiveri, Xavier; Ortiz, Pere; Leal, Joan; Pelfort, Xavier; Torres-Claramunt, Raul; Sánchez-Soler, Juan; Monllau, Joan C

2016-10-01

To evaluate the effect of the local infiltration of analgesics for pain after total knee arthroplasty in patients treated with femoral and sciatic peripheral nerve blocks. The secondary objective was to detect differences in analgesic consumption as well as blood loss after local infiltration of analgesics. Prospective randomized double-blinded study in patients who underwent a TKA for knee osteoarthritis under spinal anesthesia and treated with femoral and sciatic nerve blocks. This study compared 50 patients treated with local infiltration with ropivacaine, epinephrine, ketorolac and clonidine and 50 patients treated with a placebo with the same technique. The visual analogic score was registered postoperatively at 2, 6, 12, 24, 36, 48 and 72 h after surgery. Analgesic consumption was also registered. Both groups of patients were treated with the same surgical and rehabilitation protocols. A significant difference of one point was found in the visual analogic pain scores 12 h after surgery (0.6 ± 1.5 vs. 1.7 ± 2.3). There were no significant differences in the visual analogic pain scores evaluated at any other time between 2 and 72 h after surgery. No significant differences were found in the required doses of tramadol or morphine in the postoperative period. Postoperative hemoglobin and blood loss were also similar in both groups. Adding local infiltration of analgesics to peripheral nerve blocks after TKA surgery only provides minimal benefit for pain control. This benefit may be considered as non-clinically relevant. Moreover, the need for additional analgesics was the same in both groups. Therefore, the use of local infiltration of analgesics treatment in TKA surgery cannot be recommended if peripheral nerve blocks are used. I.

A Neurophysiologically Plausible Population Code Model for Feature Integration Explains Visual Crowding

PubMed Central

van den Berg, Ronald; Roerdink, Jos B. T. M.; Cornelissen, Frans W.

2010-01-01

An object in the peripheral visual field is more difficult to recognize when surrounded by other objects. This phenomenon is called “crowding”. Crowding places a fundamental constraint on human vision that limits performance on numerous tasks. It has been suggested that crowding results from spatial feature integration necessary for object recognition. However, in the absence of convincing models, this theory has remained controversial. Here, we present a quantitative and physiologically plausible model for spatial integration of orientation signals, based on the principles of population coding. Using simulations, we demonstrate that this model coherently accounts for fundamental properties of crowding, including critical spacing, “compulsory averaging”, and a foveal-peripheral anisotropy. Moreover, we show that the model predicts increased responses to correlated visual stimuli. Altogether, these results suggest that crowding has little immediate bearing on object recognition but is a by-product of a general, elementary integration mechanism in early vision aimed at improving signal quality. PMID:20098499

Differences in neural responses to ipsilateral stimuli in wide-view fields between face- and house-selective areas

PubMed Central

Li, Ting; Niu, Yan; Xiang, Jie; Cheng, Junjie; Liu, Bo; Zhang, Hui; Yan, Tianyi; Kanazawa, Susumu; Wu, Jinglong

2018-01-01

Category-selective brain areas exhibit varying levels of neural activity to ipsilaterally presented stimuli. However, in face- and house-selective areas, the neural responses evoked by ipsilateral stimuli in the peripheral visual field remain unclear. In this study, we displayed face and house images using a wide-view visual presentation system while performing functional magnetic resonance imaging (fMRI). The face-selective areas (fusiform face area (FFA) and occipital face area (OFA)) exhibited intense neural responses to ipsilaterally presented images, whereas the house-selective areas (parahippocampal place area (PPA) and transverse occipital sulcus (TOS)) exhibited substantially smaller and even negative neural responses to the ipsilaterally presented images. We also found that the category preferences of the contralateral and ipsilateral neural responses were similar. Interestingly, the face- and house-selective areas exhibited neural responses to ipsilateral images that were smaller than the responses to the contralateral images. Multi-voxel pattern analysis (MVPA) was implemented to evaluate the difference between the contralateral and ipsilateral responses. The classification accuracies were much greater than those expected by chance. The classification accuracies in the FFA were smaller than those in the PPA and TOS. The closer eccentricities elicited greater classification accuracies in the PPA and TOS. We propose that these ipsilateral neural responses might be interpreted by interhemispheric communication through intrahemispheric connectivity of white matter connection and interhemispheric connectivity via the corpus callosum and occipital white matter connection. Furthermore, the PPA and TOS likely have weaker interhemispheric communication than the FFA and OFA, particularly in the peripheral visual field. PMID:29451872

Satisfactory rate of post-processing visualization of fetal cerebral axial, sagittal, and coronal planes from three-dimensional volumes acquired in routine second trimester ultrasound practice by sonographers of peripheral centers.

PubMed

Rizzo, Giuseppe; Pietrolucci, Maria Elena; Capece, Giuseppe; Cimmino, Ernesto; Colosi, Enrico; Ferrentino, Salvatore; Sica, Carmine; Di Meglio, Aniello; Arduini, Domenico

2011-08-01

The aim of this study was to evaluate the feasibility to visualize central nervous system (CNS) diagnostic planes from three-dimensional (3D) brain volumes obtained in ultrasound facilities with no specific experience in fetal neurosonography. Five sonographers prospectively recorded transabdominal 3D CNS volumes starting from an axial approach on 500 consecutive pregnancies at 19-24 weeks of gestation undergoing routine ultrasound examination. Volumes were sent to the referral center (Department of Obstetrics and Gynecology, Università Roma Tor Vergata, Italy) and two independent reviewers with experience in 3D ultrasound assessed their quality in the display of axial, coronal, and sagittal planes. CNS volumes were acquired in 491/500 pregnancies (98.2%). The two reviewers acknowledged the presence of satisfactory images with a visualization rate ranging respectively between 95.1% and 97.14% for axial planes, 73.72% and 87.16% for coronal planes, and 78.41% and 94.29% for sagittal planes. The agreement rate between the two reviewers as expressed by Cohen's kappa coefficient was >0.87 for axial planes, >0.89 for coronal planes, and >0.94 for sagittal planes. The presence of a maternal body mass index >30 alters the probability of achieving satisfactory CNS views, while existence of previous maternal lower abdomen surgery does not affect the quality of the reconstructed planes. CNS volumes acquired by 3D ultrasonography in peripheral centers showed a quality high enough to allow a detailed fetal neurosonogram.

Can long-term corticosteriods lead to blindness? A case series of central serous chorioretinopathy induced by corticosteroids.

PubMed

Loo, Jing-Liang; Lee, Shu-Yen; Ang, Chong-Lye

2006-07-01

Long-term, high-dose corticosteroid therapy is well-known to cause systemic and ocular complications. A lesser known complication is chronic central serous chorioretinopathy (CSCR). Although idiopathic central serous chorioretinopathy (CSCR) is known to be mild with spontaneous recovery and minimal effects on the final visual acuity, chronic CSCR as a complication of long- term steroid therapy behaves differently, and may cause irreversible visual impairment. Three cases of chronic, recurrent CSCR were precipitated by longterm corticosteroids prescribed for post-renal transplant immunosuppressive therapy, postpituitary surgery and pemphigus vulgaris. Two cases resolved with tapering of corticosteroids while one case was treated by focal laser photocoagulation. Two eyes had severe impairment of vision as a result of subretinal scar formation while the other 4 eyes had mild reduction of visual acuity from retinal epithelium pigment atrophy. Long-term corticosteroid therapy can be complicated by severe, chronic and recurrent CSCR and occasionally peripheral exudative retinal detachment. This may result in subretinal fibrosis and permanent loss of vision.

Developing a schedule to identify social communication difficulties and autism spectrum disorder in young children with visual impairment.

PubMed

Absoud, Michael; Parr, Jeremy R; Salt, Alison; Dale, Naomi

2011-03-01

Available observational tools used in the identification of social communication difficulties and diagnosis of autism spectrum disorder (ASD) rely partly on visual behaviours and therefore may not be valid in children with visual impairment. A pilot observational instrument, the Visual Impairment and Social Communication Schedule (VISS), was developed to aid in identifying social communication difficulties and ASD in young children with visual impairment affected by congenital disorders of the peripheral visual system (disorders of the globe, retina, and anterior optic nerve). The VISS was administered to 23 consecutive children (age range 1 y 9 mo-6 y 11 mo, mean 4 y 1 mo [SD 1.6]; 12 males, 11 females) with visual impairment (nine with severe and 14 with profound visual impairment). Item analysis was carried out by fit of the items to the Rasch model. Validity of the VISS was explored by comparison with the Childhood Autism Rating Scale (CARS) score, and the clinical ASD diagnosis (n=9). Correlation between the VISS and CARS total scores was highly significant (Spearman's rho=-0.89; p=0.01). Below threshold rating on the VISS (score of 35) showed good agreement with the clinical ASD diagnosis (sensitivity 89%, specificity 100%). This preliminary study shows the VISS to be a promising schedule to aid the identification of ASD in young children with visual impairment. © The Authors. Journal compilation © Mac Keith Press 2010.

Brain activity during auditory and visual phonological, spatial and simple discrimination tasks.

PubMed

Salo, Emma; Rinne, Teemu; Salonen, Oili; Alho, Kimmo

2013-02-16

We used functional magnetic resonance imaging to measure human brain activity during tasks demanding selective attention to auditory or visual stimuli delivered in concurrent streams. Auditory stimuli were syllables spoken by different voices and occurring in central or peripheral space. Visual stimuli were centrally or more peripherally presented letters in darker or lighter fonts. The participants performed a phonological, spatial or "simple" (speaker-gender or font-shade) discrimination task in either modality. Within each modality, we expected a clear distinction between brain activations related to nonspatial and spatial processing, as reported in previous studies. However, within each modality, different tasks activated largely overlapping areas in modality-specific (auditory and visual) cortices, as well as in the parietal and frontal brain regions. These overlaps may be due to effects of attention common for all three tasks within each modality or interaction of processing task-relevant features and varying task-irrelevant features in the attended-modality stimuli. Nevertheless, brain activations caused by auditory and visual phonological tasks overlapped in the left mid-lateral prefrontal cortex, while those caused by the auditory and visual spatial tasks overlapped in the inferior parietal cortex. These overlapping activations reveal areas of multimodal phonological and spatial processing. There was also some evidence for intermodal attention-related interaction. Most importantly, activity in the superior temporal sulcus elicited by unattended speech sounds was attenuated during the visual phonological task in comparison with the other visual tasks. This effect might be related to suppression of processing irrelevant speech presumably distracting the phonological task involving the letters. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparative Discussion on Psychophysiological Effect of Self-administered Facial Massage by Treatment Method

NASA Astrophysics Data System (ADS)

Nozawa, Akio; Takei, Yuya

The aim of study was to quantitatively evaluate the effects of self-administered facial massage, which was done by hand or facial roller. In this study, the psychophysiological effects of facial massage were evaluated. The central nerves system and the autonomic nervous system were administered to evaluate physiological system. The central nerves system was assessed by Electroencephalogram (EEG). The autonomic nervous system were assessed by peripheral skin temperature(PST) and heart rate variability (HRV) with spectral analysis. In the spectral analysis of HRV, the high-frequency components (HF) were evaluated. State-Trait Anxiety Inventory (STAI), Profile of Mood Status (POMS) and subjective sensory amount with Visual Analog Scale (VAS) were administered to evaluate psychological status. These results suggest that kept brain activity and had strong effects on stress alleviation.

Central nervous system involvement in eosinophilic granulomatosis with polyangiitis (Churg-Strauss): Report of 26 patients and review of the literature.

PubMed

André, Raphaël; Cottin, Vincent; Saraux, Jean-Luc; Blaison, Gilles; Bienvenu, Boris; Cathebras, Pascal; Dhote, Robin; Foucher, Aurélie; Gil, Helder; Lapoirie, Joëlle; Launay, David; Loustau, Valentine; Maurier, François; Pertuiset, Edouard; Zénone, Thierry; Seebach, Jörg; Costedoat-Chalumeau, Nathalie; Puéchal, Xavier; Mouthon, Luc; Guillevin, Loïc; Terrier, Benjamin

2017-09-01

Although peripheral nervous system involvement is common in eosinophilic granulomatosis with polyangiitis (EGPA), central nervous system (CNS) manifestations are poorly described. This study aimed to describe CNS involvement in EGPA. This retrospective, observational, multicenter study included patients with EGPA and CNS involvement affecting cranial nerves, brain and/or spinal cord. We also undertook a systematic literature review. We analyzed 26 personal cases and 62 previously reported cases. At EGPA diagnosis, asthma was noted in 97%, eosinophilia in 98%, peripheral neuropathy in 55% and cardiac involvement in 41%. 38/71 (54%) were ANCA-positive, with a perinuclear-labeling pattern and/or anti-MPO specificity. CNS was involved in 86% at EGPA diagnosis, preceded EGPA in 2%, and occurred during follow-up in 12% after a median of 24months. Main neurological manifestations were ischemic cerebrovascular lesions in 46 (52%), intracerebral hemorrhage and/or subarachnoid hemorrhage in 21 (24%), loss of visual acuity in 28 (33%) (15 with optic neuritis, 9 with central retinal artery occlusion, 4 with cortical blindness), and cranial nerves palsies in 18 (21%), with 25 patients having ≥1 of these clinical CNS manifestations. Among the 81 patients with assessable neurological responses, 43% had complete responses without sequelae, 43% had partial responses with long-term sequelae and 14% refractory disease. After a mean follow-up of 36months, 11 patients died including 5 from intracerebral hemorrhages. EGPA-related CNS manifestations form 4 distinct neurological pictures: ischemic lesions, intracerebral hemorrhages, cranial nerve palsies and loss of visual acuity. Such manifestation should prompt practitioners to consider EGPA in such conditions. Long-term neurological sequelae were common, and intracerebral hemorrhages had the worst prognostic impact. Copyright © 2017 Elsevier B.V. All rights reserved.

Peripheral dysgraphia: dissociations of lowercase from uppercase letters and of print from cursive writing.

PubMed

Ingles, Janet L; Fisk, John D; Fleetwood, Ian; Burrell, Steven; Darvesh, Sultan

2014-03-01

Clinical analyses of patients with acquired dysgraphia provide unique opportunities to understand the cognitive and neural organization of written language production. We report J.B., a 50-year-old woman with peripheral dysgraphia who had prominent dissociations in her ability to write in lowercase versus uppercase and print versus cursive. We gave J.B. a series of tasks that evaluated her skills at writing uppercase and lowercase print and cursive, spelling aloud and in writing, writing numbers and symbols, and visual letter recognition and imagery. She was impaired in printing letters, with lowercase more affected than uppercase, but her cursive writing was relatively intact. This pattern was consistent across letter, word, and nonword writing tasks. She was unimpaired on tasks assessing her visual recognition and imagery of lowercase and uppercase letters. Her writing of numbers was preserved. J.B.'s handwriting disorder was accompanied by a central phonological dysgraphia. Our findings indicate functional independence of graphomotor programs for print and cursive letter styles and for letters and numbers. We discuss the relationship between peripheral and central writing disorders.

Comparison of two scanning instruments to measure peripheral refraction in the human eye.

PubMed

Jaeken, Bart; Tabernero, Juan; Schaeffel, Frank; Artal, Pablo

2012-03-01

To better understand how peripheral refraction affects development of myopia in humans, specialized instruments are fundamental for precise and rapid measurements of refraction over the visual field. We compare here two prototype instruments that measure in a few seconds the peripheral refraction in the eye with high angular resolution over a range of about ±45 deg. One instrument is based on the continuous recording of Hartmann-Shack (HS) images (HS scanner) and the other is based on the photorefraction (PR) principle (PR scanner). On average, good correlations were found between the refraction results provided by the two devices, although it varied across subjects. A detailed statistical analysis of the differences between both instruments was performed based on measurements in 35 young subjects. Both instruments have advantages and disadvantages. The HS scanner also provides the high-order aberration data, while the PR scanner is more compact and has a lower cost. Both instruments are current prototypes, and further optimization is possible to make them even more suitable tools for future visual optics and myopia research and also for different ophthalmic applications.

Retinotopic patterns of background connectivity between V1 and fronto-parietal cortex are modulated by task demands

PubMed Central

Griffis, Joseph C.; Elkhetali, Abdurahman S.; Burge, Wesley K.; Chen, Richard H.; Visscher, Kristina M.

2015-01-01

Attention facilitates the processing of task-relevant visual information and suppresses interference from task-irrelevant information. Modulations of neural activity in visual cortex depend on attention, and likely result from signals originating in fronto-parietal and cingulo-opercular regions of cortex. Here, we tested the hypothesis that attentional facilitation of visual processing is accomplished in part by changes in how brain networks involved in attentional control interact with sectors of V1 that represent different retinal eccentricities. We measured the strength of background connectivity between fronto-parietal and cingulo-opercular regions with different eccentricity sectors in V1 using functional MRI data that were collected while participants performed tasks involving attention to either a centrally presented visual stimulus or a simultaneously presented auditory stimulus. We found that when the visual stimulus was attended, background connectivity between V1 and the left frontal eye fields (FEF), left intraparietal sulcus (IPS), and right IPS varied strongly across different eccentricity sectors in V1 so that foveal sectors were more strongly connected than peripheral sectors. This retinotopic gradient was weaker when the visual stimulus was ignored, indicating that it was driven by attentional effects. Greater task-driven differences between foveal and peripheral sectors in background connectivity to these regions were associated with better performance on the visual task and faster response times on correct trials. These findings are consistent with the notion that attention drives the configuration of task-specific functional pathways that enable the prioritized processing of task-relevant visual information, and show that the prioritization of visual information by attentional processes may be encoded in the retinotopic gradient of connectivty between V1 and fronto-parietal regions. PMID:26106320

Contrasting the use of 2 vision-specific quality of life questionnaires in subjects with open-angle glaucoma.

PubMed

Wren, Patricia A; Musch, David C; Janz, Nancy K; Niziol, Leslie M; Guire, Kenneth E; Gillespie, Brenda W

2009-01-01

To compare 2 vision-specific functional status measures to each other and to clinical parameters in the Collaborative Initial Glaucoma Treatment Study (CIGTS). CIGTS participants completed the Visual Activities Questionnaire (VAQ) and the National Eye Institute-Visual Function Questionnaire (NEI-VFQ) and were tested for visual field (VF) and visual acuity (VA). In all, 426 subjects contributed the VAQ and NEI-VFQ scores at 54 months. Pearson correlations were used to assess associations. The VAQ subscales (range, 0 to 100) that assessed light-dark adaptation (mean=66.1), glare disability (66.4), and acuity/spatial vision (67.7) indicated vision-related functions that CIGTS participants found most difficult. On the NEI-VFQ, subjects reported high levels of visual functioning, with mean >/=90 (out of 100) on the total score and in 9 of 12 subscales. General vision (mean=82.6) received the lowest subscale score. Two subscales common to both questionnaires were highly correlated: VA (r=0.68) and peripheral vision (r=0.77) (both P<0.0001). Correlations between participants' perceptions and clinical measures of visual function were in the expected direction, but weaker. Stronger associations were found between clinical measures and the NEI-VFQ than the VAQ. Better eye VF and worse eye VA had the highest number of significant correlations with subjects' perceptions of their visual function. Increasing VF loss was associated with a significant decrease in the overall and peripheral vision subscale scores from both questionnaires, and also several other subscales. CIGTS patients reported excellent visual function on both the NEI-VFQ and VAQ. These findings will help researchers interested in assessing patients' perceptions of their visual function make an informed selection when choosing between the VAQ and the NEI-VFQ.

Detecting target changes in multiple object tracking with peripheral vision: More pronounced eccentricity effects for changes in form than in motion.

PubMed

Vater, Christian; Kredel, Ralf; Hossner, Ernst-Joachim

2017-05-01

In the current study, dual-task performance is examined with multiple-object tracking as a primary task and target-change detection as a secondary task. The to-be-detected target changes in conditions of either change type (form vs. motion; Experiment 1) or change salience (stop vs. slowdown; Experiment 2), with changes occurring at either near (5°-10°) or far (15°-20°) eccentricities (Experiments 1 and 2). The aim of the study was to test whether changes can be detected solely with peripheral vision. By controlling for saccades and computing gaze distances, we could show that participants used peripheral vision to monitor the targets and, additionally, to perceive changes at both near and far eccentricities. Noticeably, gaze behavior was not affected by the actual target change. Detection rates as well as response times generally varied as a function of change condition and eccentricity, with faster detections for motion changes and near changes. However, in contrast to the effects found for motion changes, sharp declines in detection rates and increased response times were observed for form changes as a function of the eccentricities. This result can be ascribed to properties of the visual system, namely to the limited spatial acuity in the periphery and the comparably receptive motion sensitivity of peripheral vision. These findings show that peripheral vision is functional for simultaneous target monitoring and target-change detection as saccadic information suppression can be avoided and covert attention can be optimally distributed to all targets. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Subjective Perception of Visual Distortions or Scotomas in Individuals with Retinitis Pigmentosa

ERIC Educational Resources Information Center

Wittich, Walter; Watanabe, Donald H.; Kapusta, Michael A.; Overbury, Olga

2011-01-01

It is often assumed that persons who develop ocular disease have some form of visual experience that makes them aware of their deficits. However, in the case of peripheral field loss or decreasing vision in dim lighting, as in retinitis pigmentosa, for example, symptoms are more obscure and may not be as easily identified by the persons who have…

Fundamental Visual Representations of Social Cognition in ASD

DTIC Science & Technology

2015-10-01

autism spectrum disorder as assessed by high density electrical mapping...C., Russo, N. N., & Foxe, J. J. (2013). Atypical cortical representation of peripheral visual space in children with an autism spectrum disorder . European Journal of Neuroscience, 38(1), 2125-2138. ...Sensory processing issues are prevalent in the autism spectrum (ASD) population, and sensory adaptation can be a potential biomarker - a

In vivo imaging of pulmonary nodule and vasculature using endoscopic co-registered optical coherence tomography and autofluorescence imaging (Conference Presentation)

NASA Astrophysics Data System (ADS)

Pahlevaninezhad, Hamid; Lee, Anthony; Hohert, Geoffrey; Schwartz, Carely; Shaipanich, Tawimas; Ritchie, Alexander J.; Zhang, Wei; MacAulay, Calum E.; Lam, Stephen; Lane, Pierre M.

2016-03-01

Peripheral lung nodules found by CT-scans are difficult to localize and biopsy bronchoscopically particularly for those ≤ 2 cm in diameter. In this work, we present the results of endoscopic co-registered optical coherence tomography and autofluorescence imaging (OCT-AFI) of normal and abnormal peripheral airways from 40 patients using 0.9 mm diameter fiber optic rotary pullback catheter. Optical coherence tomography (OCT) can visualize detailed airway morphology endoscopically in the lung periphery. Autofluorescence imaging (AFI) can visualize fluorescing tissue components such as collagen and elastin, enabling the detection of airway lesions with high sensitivity. Results indicate that AFI of abnormal airways is different from that of normal airways, suggesting that AFI can provide a sensitive visual presentation for rapidly identifying possible sites of pulmonary nodules. AFI can also rapidly visualize in vivo vascular networks using fast scanning parameters resulting in vascular-sensitive imaging with less breathing/cardiac motion artifacts compared to Doppler OCT imaging. It is known that tumor vasculature is structurally and functionally different from normal vessels. Thus, AFI can be potentially used for differentiating normal and abnormal lung vasculature for studying vascular remodeling.

[Diagnosis and treatment options in vertigo syndromes].

PubMed

Strupp, M; Dieterich, M; Zwergal, A; Brandt, T

2015-10-01

The key to diagnosing vertigo and balance disorders is systematic analysis of case history with clinical examination of the vestibular, oculomotor, and cerebral systems in particular. Important criteria for differentiating between the various vertigo syndromes are 1) the time course of symptoms, 2) the type of symptoms, 3) modulating factors, and 4) associated symptoms. For clinical examination of the vestibular system, six important tests are available: assessment of spontaneous nystagmus, head impulse test, dynamic visual acuity, subjective visual verticality, positioning manoeuvre, and the Romberg test/gait analysis with eyes open and closed. On the basis of five clinical signs (vertical divergence, central fixation nystagmus, gaze-evoked nystagmus, saccades, normal head impulse test), the clinical examination is able to differentiate between acute central and peripheral vestibular syndromes with a sensitivity and specificity of over 90%. The most relevant laboratory examinations are caloric irrigation and the video head-impulse test for canal function and the vestibular evoked myogenic potentials for otolith function. Finally, treatment is based upon four therapeutic principles: physiotherapy, pharmacotherapy, psychotherapy, and in rare cases, surgery.

The Perception of Multiple Images

ERIC Educational Resources Information Center

Goldstein, E. Bruce

1975-01-01

A discussion of visual field, foveal and peripheral vision, eye fixations, recognition and recall of pictures, memory for meaning of pictures, and the relation between speed of presentation and memory. (Editor)

Peripheral Faulting of Eden Patera: Potential Evidence in Support of a New Volcanic Construct on Mars

NASA Astrophysics Data System (ADS)

Harlow, J.

2016-12-01

Arabia Terra's (AT) pock-marked topography in the expansive upland region of Mars Northern Hemisphere has been assumed to be the result of impact crater bombardment. However, examination of several craters by researchers revealed morphologies inconsistent with neighboring craters of similar size and age. These 'craters' share features with terrestrial super-eruption calderas, and are considered a new volcanic construct on Mars called `plains-style' caldera complexes. Eden Patera (EP), located on the northern boundary of AT is a reference type for these calderas. EP lacks well-preserved impact crater morphologies, including a decreasing depth to diameter ratio. Conversely, Eden shares geomorphological attributes with terrestrial caldera complexes such as Valles Caldera (New Mexico): arcuate caldera walls, concentric fracturing/faulting, flat-topped benches, irregular geometric circumferences, etc. This study focuses on peripheral fractures surrounding EP to provide further evidence of calderas within the AT region. Scaled balloon experiments mimicking terrestrial caldera analogs have showcased fracturing/faulting patterns and relationships of caldera systems. These experiments show: 1) radial fracturing (perpendicular to caldera rim) upon inflation, 2) concentric faulting (parallel to sub-parallel to caldera rim) during evacuation, and 3) intersecting radial and concentric peripheral faulting from resurgence. Utilizing Mars Reconnaissance Orbiter Context Camera (CTX) imagery, peripheral fracturing is analyzed using GIS to study variations in peripheral fracture geometries relative to the caldera rim. Visually, concentric fractures dominate within 20 km, radial fractures prevail between 20 and 50 km, followed by gradation into randomly oriented and highly angular intersections in the fretted terrain region. Rose diagrams of orientation relative to north expose uniformly oriented mean regional stresses, but do not illuminate localized caldera stresses. Further examination of orientation relative to caldera rim reveals expected orientations of ±30° on rose diagrams, taking into account the geometric nature of concentric faulting. These results establish a quantitative geometric system to differentiate localized from regional faulting surrounding Eden Patera.

Vision related quality of life in patients with type 2 diabetes in the EUROCONDOR trial.

PubMed

Trento, Marina; Durando, Olga; Lavecchia, Sonia; Charrier, Lorena; Cavallo, Franco; Costa, Miguel Angelo; Hernández, Cristina; Simó, Rafael; Porta, Massimo

2017-07-01

To evaluate vision related quality of life in the patients enrolled in The European Consortium for the Early Treatment of Diabetic Retinopathy, a clinical trial on prevention of diabetic retinopathy. Four-hundred-forty-nine patients, 153 women, with type 2 Diabetes and no or mild diabetic retinopathy were enrolled in a 2-year multicenter randomized controlled trial. The 25-item National Eye Institute Visual Functioning Questionnaire was used to explore 12 subscales of vision related quality of life. The patients were 62.8 ± 6.7 years old and had 11.1 ± 5.6 years known disease duration. Diabetic retinopathy was absent in 193 (43.0 %) and mild in 256 (57.0 %). Patients without diabetic retinopathy were older, had shorter diabetes duration and used less insulin and glucose-lowering agents but did not differ by gender, best corrected visual acuity or any subscale, except vision specific mental health and vision specific role difficulties. Patients with reduced retinal thickness at the ganglion cell layer (n = 36) did not differ for diabetic retinopathy but were older, had lower best corrected visual acuity and worse scores for ocular pain, color vision and peripheral vision. On multivariable analysis, worse scores for general vision remained associated with reduced retinal thickness, diabetes duration and best corrected visual acuity, and scores for visual specific mental health with diabetic retinopathy and lower best corrected visual acuity. Visual specific role difficulties were only associated with reduced best corrected visual acuity. Scores for driving decreased among females, with worsening of Hemoglobin A1c and best corrected visual acuity. Color vision depended only on reduced retinal thickness, and peripheral vision on both reduced thickness and best corrected visual acuity. The National Eye Institute Visual Functioning Questionnaire could detect subtle changes in patients' perception of visual function, despite absent/minimal diabetic retinopathy.

A longitudinal study of visual function in carriers of X-linked recessive retinitis pigmentosa.

PubMed

Grover, S; Fishman, G A; Anderson, R J; Lindeman, M

2000-02-01

This study was carried out to evaluate the progression of visual function impairment in carriers of X-linked recessive retinitis pigmentosa. We also assessed the relationship between the retinal findings at presentation and the extent of deterioration. Observational, retrospective, case series. Twenty-seven carriers of X-linked recessive retinitis pigmentosa. Each carrier was clinically categorized into one of four grades (grades 0 through 3) depending on the presence or absence of a tapetal-like retinal reflex and the extent of peripheral pigmentary degeneration. A complete ophthalmologic examination was performed and data for visual acuity, visual field area, and electroretinographic measurements were collected on the most recent visit in both eyes. These were then compared with similar data obtained on their initial visits. A comparison of visual function was carried out between the initial visit and the most recent visit on each carrier. The visual acuity was measured with Snellen's acuity charts. The visual fields to targets V-4-e and II-4-e were planimeterized and used for the analysis. The electroretinographic (ERG) measures used were light-adapted single-flash b-wave amplitudes and 30-Hz red flicker for cone function, dark-adapted maximal b-wave amplitudes, and response to a low intensity blue-flash for rod function. None of the 11 carriers with a tapetal-like reflex only (grade 1) showed any significant change in visual acuity or fields as compared with 3 of 7 (43%) carriers with diffuse peripheral pigmentary findings (grade 3) who showed significant deterioration in visual acuity in at least one eye, and 6 of 7 (86%) who showed a significant decrease in visual field area with at least one target size in at least one eye. By comparison, only 1 of 10 carriers with a grade 1 fundus finding demonstrated a significant decrease in maximal dark-adapted ERG function as compared with 5 of 6 (83%) carriers with grade 3 in response to a single-flash stimulus and with 4 of 5 (80%) carriers in response to a single-flash blue stimulus. For the single-flash photopic response, none of the 10 carriers with grade 1 showed any significant deterioration, whereas 2 of 4 (50%) with grade 3 did show such deterioration. The ERG responses for carriers with grade 2 were in between the extent of decrease in ERG amplitudes of those in carriers with grades 1 and 3. In our cohort of X-linked retinitis pigmentosa carriers, those with only a tapetal-like retinal reflex at presentation had a better prognosis to retain visual function than those with peripheral retinal pigmentation. These data are useful in counseling such carriers as to their visual prognosis.

Effect of Pupil Size on Wavefront Refraction during Orthokeratology.

PubMed

Faria-Ribeiro, Miguel; Navarro, Rafael; González-Méijome, José Manuel

2016-11-01

It has been hypothesized that central and peripheral refraction, in eyes treated with myopic overnight orthokeratology, might vary with changes in pupil diameter. The aim of this work was to evaluate the axial and peripheral refraction and optical quality after orthokeratology, using ray tracing software for different pupil sizes. Zemax-EE was used to generate a series of 29 semi-customized model eyes based on the corneal topography changes from 29 patients who had undergone myopic orthokeratology. Wavefront refraction in the central 80 degrees of the visual field was calculated using three different quality metrics criteria: Paraxial curvature matching, minimum root mean square error (minRMS), and the Through Focus Visual Strehl of the Modulation Transfer Function (VSMTF), for 3- and 6-mm pupil diameters. The three metrics predicted significantly different values for foveal and peripheral refractions. Compared with the Paraxial criteria, the other two metrics predicted more myopic refractions on- and off-axis. Interestingly, the VSMTF predicts only a marginal myopic shift in the axial refraction as the pupil changes from 3 to 6 mm. For peripheral refraction, minRMS and VSMTF metric criteria predicted a higher exposure to peripheral defocus as the pupil increases from 3 to 6 mm. The results suggest that the supposed effect of myopic control produced by ortho-k treatments might be dependent on pupil size. Although the foveal refractive error does not seem to change appreciably with the increase in pupil diameter (VSMTF criteria), the high levels of positive spherical aberration will lead to a degradation of lower spatial frequencies, that is more significant under low illumination levels.

Peripheral Visual Fields in ABCA4 Stargardt Disease and Correlation With Disease Extent on Ultra-widefield Fundus Autofluorescence.

PubMed

Abalem, Maria Fernanda; Otte, Benjamin; Andrews, Chris; Joltikov, Katherine A; Branham, Kari; Fahim, Abigail T; Schlegel, Dana; Qian, Cynthia X; Heckenlively, John R; Jayasundera, Thiran

2017-12-01

To evaluate the disease extent on ultra-widefield fundus autofluorescence (UWF-FAF) in patients with ABCA4 Stargardt disease (STGD) and correlate these data with functional outcome measures. Retrospective cross-sectional study. Setting: Kellogg Eye Center, University of Michigan. Sixty-five patients with clinical diagnosis and proven pathogenic variants in the ABCA4 gene. Observational Procedures: The UWF-FAF images were obtained using Optos (200 degrees) and classified into 3 types. Functional testing included kinetic widefield perimetry, full-field electroretinogram (ffERG), and visual acuity (VA). All results were evaluated with respect to UWF-FAF classification. Classification of UWF-FAF; area comprising the I4e, III4e, and IV4e isopters; ffERG patterns; and VA. For UWF-FAF, 27 subjects (41.5%) were classified as type I, 17 (26.2%) as type II, and 21 (32.4%) as type III. The area of each isopter correlated inversely with the extent of the disease and all isopters were able to detect differences among UWF-FAF types (IV4e, P = .0013; III4e, P = .0003; I4e, P < .0001 = 3.93e -8 ). ffERG patterns and VA were also different among the 3 UWF-FAF types (P < .001 = 6.61e- 6 and P < .001 = 7.3e -5 , respectively). Patients with widespread disease presented with more constriction of peripheral visual fields and had more dysfunction on ffERG and worse VA compared to patients with disease confined to the macula. UWF-FAF images may provide information for estimating peripheral and central visual function in STGD. Copyright © 2017. Published by Elsevier Inc.

Prospective Observational Study of Ocular Health in ISS Crews - The Ocular Health Study

NASA Technical Reports Server (NTRS)

Otto, C.; Barr, Y.; Platts, S.; Ploutz-Snyder, R.; Sargsyan, A.; Alexander, D.; Riascos, R.; Gibson, C.; Patel, N.

2015-01-01

The Visual Impairment Intracranial Pressure (VIIP) syndrome is currently NASA's number one human space flight risk. The syndrome, which is related to microgravity exposure, manifests with changes in visual acuity (hyperopic shifts, scotomas), changes in eye structure (optic disc edema, choroidal folds, cotton wool spots, globe flattening, and dilated optic nerve sheaths), and in some cases with documented increased intracranial pressure (ICP) postflight. While the eye appears to be the main affected end organ of this syndrome, the ocular effects are thought to be related to underlying changes in the vascular system and the central nervous system. The leading hypotheses for the development of VIIP involve microgravity-induced head-ward fluid shifts along with a loss of gravity-assisted drainage of venous blood from the brain, leading to cephalic congestion, decreased CSF resorption and increased ICP. Since 70% of ISS crewmembers have manifested clinical signs or symptoms of the VIIP syndrome, it is assumed that the majority have some degree of ICP elevation in-flight compared to the ground. Prolonged elevations of ICP can cause long-term reduced visual acuity and loss of peripheral visual fields, and have been reported to cause mild cognitive impairment in the analog terrestrial population of Idiopathic Intracranial Hypertension (IIH). These potentially irreversible health consequences underscore the importance of identifying the factors that lead to this syndrome and mitigating them.

Comparative proteomic analyses of macular and peripheral retina of cynomolgus monkeys (Macaca fascicularis).

PubMed

Okamoto, Haru; Umeda, Shinsuke; Nozawa, Takehiro; Suzuki, Michihiro T; Yoshikawa, Yasuhiro; Matsuura, Etsuko T; Iwata, Takeshi

2010-01-01

The central region of the primate retina is called the macula. The fovea is located at the center of the macula, where the photoreceptors are concentrated to create a neural network adapted for high visual acuity. Damage to the fovea, e.g., by macular dystrophies and age-related macular degeneration, can reduce central visual acuity. The molecular mechanisms leading to these diseases are most likely dependent on the proteins in the macula which differ from those in the peripheral retina in expression level. To investigate whether the distribution of proteins in the macula is different from the peripheral retina, proteomic analyses of tissues from these two regions of cynomolgus monkeys were compared. Two-dimensional gel electrophoresis and mass spectrometry identified 26 proteins that were present only in the macular gel spots. The expression levels of five proteins, cone photoreceptor specific arrestin-C, gamma-synuclein, epidermal fatty acid binding protein, tropomyosin 1alpha chain, and heterogeneous nuclear ribonucleoproteins A2/B1, were significantly higher in the macula than in the peripheral retina. Immunostaining of macula sections by antibodies to each identified protein revealed unique localization in the retina, retinal pigment epithelial cells and the choroidal layer. Some of these proteins were located in cells with higher densities in the macula. We suggest that it will be important to study these proteins to determine their contribution to the pathogenesis and progression of macula diseases.

Feeling good: autonomic nervous system responding in five positive emotions.

PubMed

Shiota, Michelle N; Neufeld, Samantha L; Yeung, Wan H; Moser, Stephanie E; Perea, Elaine F

2011-12-01

Although dozens of studies have examined the autonomic nervous system (ANS) aspects of negative emotions, less is known about ANS responding in positive emotion. An evolutionary framework was used to define five positive emotions in terms of fitness-enhancing function, and to guide hypotheses regarding autonomic responding. In a repeated measures design, participants viewed sets of visual images eliciting these positive emotions (anticipatory enthusiasm, attachment love, nurturant love, amusement, and awe) plus an emotionally neutral state. Peripheral measures of sympathetic and vagal parasympathetic activation were assessed. Results indicated that the emotion conditions were characterized by qualitatively distinct profiles of autonomic activation, suggesting the existence of multiple, physiologically distinct positive emotions. (c) 2011 APA, all rights reserved.

Rehabilitation Approaches in Macular Degeneration Patients

PubMed Central

Maniglia, Marcello; Cottereau, Benoit R.; Soler, Vincent; Trotter, Yves

2016-01-01

Age related macular degeneration (AMD) is a visual disease that affects elderly population. It entails a progressive loss of central vision whose consequences are dramatic for the patient’s quality of life. Current rehabilitation programs are restricted to technical aids based on visual devices. They only temporarily improve specific visual functions such as reading skills. Considering the rapid increase of the aging population worldwide, it is crucial to intensify clinical research on AMD in order to develop simple and efficient methods that improve the patient’s visual performances in many different contexts. One very promising approach to face this challenge is based on perceptual learning (PL). Through intensive practice, PL can induce neural plasticity in sensory cortices and result in long-lasting enhancements for various perceptual tasks in both normal and visually impaired populations. A growing number of studies showed how appropriate PL protocols improve visual functions in visual disorders, namely amblyopia, presbyopia or myopia. In order to successfully apply these approaches to more severe conditions such as AMD, numerous challenges have to be overcome. Indeed, the overall elderly age of patients and the reduced cortical surface that is devoted to peripheral vision potentially limit neural plasticity in this population. In addition, ocular fixation becomes much less stable because patients have to rely on peripheral fixation spots outside the scotoma whose size keeps on evolving. The aim of this review article is to discuss the recent literature on this topic and to offer a unified approach for developing new rehabilitation programs of AMD using PL. We argue that with an appropriate experimental and training protocol that is adapted to each patient needs, PL can offer fascinating opportunities for the development of simple, non-expensive rehabilitation approaches a large spectrum of visual functions in AMD patients. PMID:28082876

Temporally flexible feedback signal to foveal cortex for peripheral object recognition

PubMed Central

Fan, Xiaoxu; Wang, Lan; Shao, Hanyu; Kersten, Daniel; He, Sheng

2016-01-01

Recent studies have shown that information from peripherally presented images is present in the human foveal retinotopic cortex, presumably because of feedback signals. We investigated this potential feedback signal by presenting noise in fovea at different object–noise stimulus onset asynchronies (SOAs), whereas subjects performed a discrimination task on peripheral objects. Results revealed a selective impairment of performance when foveal noise was presented at 250-ms SOA, but only for tasks that required comparing objects’ spatial details, suggesting a task- and stimulus-dependent foveal processing mechanism. Critically, the temporal window of foveal processing was shifted when mental rotation was required for the peripheral objects, indicating that the foveal retinotopic processing is not automatically engaged at a fixed time following peripheral stimulation; rather, it occurs at a stage when detailed information is required. Moreover, fMRI measurements using multivoxel pattern analysis showed that both image and object category-relevant information of peripheral objects was represented in the foveal cortex. Taken together, our results support the hypothesis of a temporally flexible feedback signal to the foveal retinotopic cortex when discriminating objects in the visual periphery. PMID:27671651

Approaches to a cortical vision prosthesis: implications of electrode size and placement

NASA Astrophysics Data System (ADS)

Christie, Breanne P.; Ashmont, Kari R.; House, Paul A.; Greger, Bradley

2016-04-01

Objective. In order to move forward with the development of a cortical vision prosthesis, the critical issues in the field must be identified. Approach. To begin this process, we performed a brief review of several different cortical and retinal stimulation techniques that can be used to restore vision. Main results. Intracortical microelectrodes and epicortical macroelectrodes have been evaluated as the basis of a vision prosthesis. We concluded that an important knowledge gap necessitates an experimental in vivo performance evaluation of microelectrodes placed on the surface of the visual cortex. A comparison of the level of vision restored by intracortical versus epicortical microstimulation is necessary. Because foveal representation in the primary visual cortex involves more cortical columns per degree of visual field than does peripheral vision, restoration of foveal vision may require a large number of closely spaced microelectrodes. Based on previous studies of epicortical macrostimulation, it is possible that stimulation via surface microelectrodes could produce a lower spatial resolution, making them better suited for restoring peripheral vision. Significance. The validation of epicortical microstimulation in addition to the comparison of epicortical and intracortical approaches for vision restoration will fill an important knowledge gap and may have important implications for surgical strategies and device longevity. It is possible that the best approach to vision restoration will utilize both epicortical and intracortical microstimulation approaches, applying them appropriately to different visual representations in the primary visual cortex.

Instrument Display Visual Angles for Conventional Aircraft and the MQ-9 Ground Control Station

NASA Technical Reports Server (NTRS)

Bendrick, Gregg A.; Kamine, Tovy Haber

2008-01-01

Aircraft instrument panels should be designed such that primary displays are in optimal viewing location to minimize pilot perception and response time. Human Factors engineers define three zones (i.e. "cones") of visual location: 1) "Easy Eye Movement" (foveal vision); 2) "Maximum Eye Movement" (peripheral vision with saccades), and 3) "Head Movement" (head movement required). Instrument display visual angles were measured to determine how well conventional aircraft (T-34, T-38, F- 15B, F-16XL, F/A-18A, U-2D, ER-2, King Air, G-III, B-52H, DC-10, B747-SCA) and the MQ-9 ground control station (GCS) complied with these standards, and how they compared with each other. Methods: Selected instrument parameters included: attitude, pitch, bank, power, airspeed, altitude, vertical speed, heading, turn rate, slip/skid, AOA, flight path, latitude, longitude, course, bearing, range and time. Vertical and horizontal visual angles for each component were measured from the pilot s eye position in each system. Results: The vertical visual angles of displays in conventional aircraft lay within the cone of "Easy Eye Movement" for all but three of the parameters measured, and almost all of the horizontal visual angles fell within this range. All conventional vertical and horizontal visual angles lay within the cone of "Maximum Eye Movement". However, most instrument vertical visual angles of the MQ-9 GCS lay outside the cone of "Easy Eye Movement", though all were within the cone of "Maximum Eye Movement". All the horizontal visual angles for the MQ-9 GCS were within the cone of "Easy Eye Movement". Discussion: Most instrument displays in conventional aircraft lay within the cone of "Easy Eye Movement", though mission-critical instruments sometimes displaced less important instruments outside this area. Many of the MQ-9 GCS systems lay outside this area. Specific training for MQ-9 pilots may be needed to avoid increased response time and potential error during flight.

Multi-modal distraction: insights from children's limited attention.

PubMed

Matusz, Pawel J; Broadbent, Hannah; Ferrari, Jessica; Forrest, Benjamin; Merkley, Rebecca; Scerif, Gaia

2015-03-01

How does the multi-sensory nature of stimuli influence information processing? Cognitive systems with limited selective attention can elucidate these processes. Six-year-olds, 11-year-olds and 20-year-olds engaged in a visual search task that required them to detect a pre-defined coloured shape under conditions of low or high visual perceptual load. On each trial, a peripheral distractor that could be either compatible or incompatible with the current target colour was presented either visually, auditorily or audiovisually. Unlike unimodal distractors, audiovisual distractors elicited reliable compatibility effects across the two levels of load in adults and in the older children, but high visual load significantly reduced distraction for all children, especially the youngest participants. This study provides the first demonstration that multi-sensory distraction has powerful effects on selective attention: Adults and older children alike allocate attention to potentially relevant information across multiple senses. However, poorer attentional resources can, paradoxically, shield the youngest children from the deleterious effects of multi-sensory distraction. Furthermore, we highlight how developmental research can enrich the understanding of distinct mechanisms controlling adult selective attention in multi-sensory environments. Copyright © 2014 Elsevier B.V. All rights reserved.

Neurophysiological intraoperative monitoring during an optic nerve schwannoma removal.

PubMed

San-Juan, Daniel; Escanio Cortés, Manuel; Tena-Suck, Martha; Orozco Garduño, Adolfo Josué; López Pizano, Jesús Alejandro; Villanueva Domínguez, Jonathan; Fernández Gónzalez-Aragón, Maricarmen; Gómez-Amador, Juan Luis

2017-10-01

This paper reports the case of a patient with optic nerve schwannoma and the first use of neurophysiological intraoperative monitoring of visual evoked potentials during the removal of such tumor with no postoperative visual damage. Schwannomas are benign neoplasms of the peripheral nervous system arising from the neural crest-derived Schwann cells, these tumors are rarely located in the optic nerve and the treatment consists on surgical removal leading to high risk of damage to the visual pathway. Case report of a thirty-year-old woman with an optic nerve schwannoma. The patient underwent surgery for tumor removal on the left optic nerve through a left orbitozygomatic approach with intraoperative monitoring of left II and III cranial nerves. We used Nicolet Endeavour CR IOM (Carefusion, Middleton WI, USA) to performed visual evoked potentials stimulating binocularly with LED flash goggles with the patient´s eyes closed and direct epidural optic nerve stimulation delivering rostral to the tumor a rectangular current pulse. At follow up examinations 7 months later, the left eye visual acuity was 20/60; Ishihara score was 8/8 in both eyes; the right eye photomotor reflex was normal and left eye was mydriatic and arreflectic; optokinetic reflex and ocular conjugate movements were normal. In this case, the epidural direct electrical stimulation of optic nerve provided stable waveforms during optic nerve schwannoma resection without visual loss.

Low Vision Training in Sweden.

ERIC Educational Resources Information Center

Inde, Krister

1978-01-01

The article describes the team work approach used in Sweden to provide services to the four main categories of visual impairment: central scotoma, nystagmus, loss of peripheral vision while retaining central vision, and amblyopia. (Author/PHR)

Bilateral foveal retinoschisis accompanying unilateral peripheral retinoschisis.

PubMed

Kocak, Nilufer; Ozturk, Taylan A; Kaynak, Suleyman

2014-04-01

X-linked juvenile retinoschisis is a rare hereditary retinal disease characterized by a tangential splitting of the neurosensory retina which may cause early-onset visual impairment. Existence of the retinal neurosensory layer splitting on cross-sectional images of optical coherance tomography (OCT) and the absence of leakage on fluorescein angiography (FA) help confirming the diagnosis. Such diagnostic tests are also helpful in determining the management of the disease. However, most of the retinoschisis cavities remain stable and rarely extend to the posterior pole, many authors suggest laser prophylaxis to avoid the potential risk of retinal detachment due to holes in the outer retinal layer. Herein, we report a case with bilateral foveal retinoschisis accompanying unilateral peripheral retinoschisis who was evaluated with detailed ophthalmologic examination. Visual acuity, fundoscopy, OCT, and FA remained stable in the second year of follow-up after prophylactic argon laser treatment.

Global Enhancement but Local Suppression in Feature-based Attention.

PubMed

Forschack, Norman; Andersen, Søren K; Müller, Matthias M

2017-04-01

A key property of feature-based attention is global facilitation of the attended feature throughout the visual field. Previously, we presented superimposed red and blue randomly moving dot kinematograms (RDKs) flickering at a different frequency each to elicit frequency-specific steady-state visual evoked potentials (SSVEPs) that allowed us to analyze neural dynamics in early visual cortex when participants shifted attention to one of the two colors. Results showed amplification of the attended and suppression of the unattended color as measured by SSVEP amplitudes. Here, we tested whether the suppression of the unattended color also operates globally. To this end, we presented superimposed flickering red and blue RDKs in the center of a screen and a red and blue RDK in the left and right periphery, respectively, also flickering at different frequencies. Participants shifted attention to one color of the superimposed RDKs in the center to discriminate coherent motion events in the attended from the unattended color RDK, whereas the peripheral RDKs were task irrelevant. SSVEP amplitudes elicited by the centrally presented RDKs confirmed the previous findings of amplification and suppression. For peripherally located RDKs, we found the expected SSVEP amplitude increase, relative to precue baseline when color matched the one of the centrally attended RDK. We found no reduction in SSVEP amplitude relative to precue baseline, when the peripheral color matched the unattended one of the central RDK, indicating that, while facilitation in feature-based attention operates globally, suppression seems to be linked to the location of focused attention.

Comparison of Octopus Semi-Automated Kinetic Perimetry and Humphrey Peripheral Static Perimetry in Neuro-Ophthalmic Cases

PubMed Central

Rowe, Fiona J.; Noonan, Carmel; Manuel, Melanie

2013-01-01

Aim. To compare semikinetic perimetry (SKP) on Octopus 900 perimetry to a peripheral static programme with Humphrey automated perimetry. Methods. Prospective cross-section study comparing Humphrey full field (FF) 120 two zone programme to a screening protocol for SKP on Octopus perimetry. Results were independently graded for presence/absence of field defect plus type and location of defect. Results. 64 patients (113 eyes) underwent dual perimetry assessment. Mean duration of assessment for SKP was 4.54 minutes ±0.18 and 6.17 ± 0.12 for FF120 (P = 0.0001). 80% of results were correctly matched for normal or abnormal visual fields using the I4e target versus FF120, and 73.5% were correctly matched using the I2e target versus FF120. When comparing Octopus results with combined I4e and I2e isopters to the FF120 result, a match for normal or abnormal fields was recorded in 87%. Conclusions. Humphrey perimetry test duration was generally longer than Octopus SKP. In the absence of kinetic perimetry, peripheral static suprathreshold programme options such as FF120 may be useful for detection of visual field defects. However, statokinetic dissociation may occur. Octopus SKP utilising both I4e and I2e targets provides detailed information of both the defect depth and size and may provide a more representative view of the actual visual field defect. PMID:24558605

[Individual differences in sense of direction and psychological stress associated with mobility in visually impaired people].

PubMed

Matsunaka, Kumiko; Shibata, Yuki; Yamamoto, Toshikazu

2008-08-01

Study 1 investigated individual differences in spatial cognition amongst visually impaired students and sighted controls, as well as the extent to which visual status contributes to these individual differences. Fifty-eight visually impaired and 255 sighted university students evaluated their sense of direction via self-ratings. Visual impairment contributed to the factors associated with the use and understanding of maps, confirming that maps are generally unfamiliar to visually impaired people. The relationship between psychological stress associated with mobility and individual differences in sense of direction was investigated in Study 2. A stress checklist was administered to the 51 visually impaired students who participated in Study 1. Psychological stress level was related to understanding and use of maps, as well as orientation and renewal, that is, course correction after being got lost. Central visual field deficits were associated with greater mobility-related stress levels than peripheral visual field deficits.

Peripheral Visual Cues: Their Fate in Processing and Effects on Attention and Temporal-Order Perception.

PubMed

Tünnermann, Jan; Scharlau, Ingrid

2016-01-01

Peripheral visual cues lead to large shifts in psychometric distributions of temporal-order judgments. In one view, such shifts are attributed to attention speeding up processing of the cued stimulus, so-called prior entry. However, sometimes these shifts are so large that it is unlikely that they are caused by attention alone. Here we tested the prevalent alternative explanation that the cue is sometimes confused with the target on a perceptual level, bolstering the shift of the psychometric function. We applied a novel model of cued temporal-order judgments, derived from Bundesen's Theory of Visual Attention. We found that cue-target confusions indeed contribute to shifting psychometric functions. However, cue-induced changes in the processing rates of the target stimuli play an important role, too. At smaller cueing intervals, the cue increased the processing speed of the target. At larger intervals, inhibition of return was predominant. Earlier studies of cued TOJs were insensitive to these effects because in psychometric distributions they are concealed by the conjoint effects of cue-target confusions and processing rate changes.

Crowding by Invisible Flankers

PubMed Central

Ho, Cristy; Cheung, Sing-Hang

2011-01-01

Background Human object recognition degrades sharply as the target object moves from central vision into peripheral vision. In particular, one's ability to recognize a peripheral target is severely impaired by the presence of flanking objects, a phenomenon known as visual crowding. Recent studies on how visual awareness of flanker existence influences crowding had shown mixed results. More importantly, it is not known whether conscious awareness of the existence of both the target and flankers are necessary for crowding to occur. Methodology/Principal Findings Here we show that crowding persists even when people are completely unaware of the flankers, which are rendered invisible through the continuous flash suppression technique. Contrast threshold for identifying the orientation of a grating pattern was elevated in the flanked condition, even when the subjects reported that they were unaware of the perceptually suppressed flankers. Moreover, we find that orientation-specific adaptation is attenuated by flankers even when both the target and flankers are invisible. Conclusions These findings complement the suggested correlation between crowding and visual awareness. What's more, our results demonstrate that conscious awareness and attention are not prerequisite for crowding. PMID:22194919

Gene mapping of the Usher syndromes.

PubMed

Kimberling, W; Smith, R J

1992-10-01

USH is an autosomal recessive group of diseases characterized by auditory impairment and visual loss owing to RP. Two common types of USH are known, types I and II. USH type I is characterized by a congenital severe to profound hearing impairment, absent vestibular function, and a progressive pigmentary retinopathy. Persons with type I do not find hearing aids useful, have delayed motor development, and experience progressive night blindness and peripheral visual loss, which usually begins in their second decade. USH type II is characterized by a congenital moderate to severe hearing loss with a down-sloping audiogram, normal vestibular function, and a progressive pigmentary retinopathy. Persons with USH2 find hearing aids beneficial, have normal psychomotor development, and experience progressive night blindness and peripheral visual loss, which usually begins in their third decade. Vestibular dysfunction is the best distinguishing hallmark to differentiate USH type I from type II. One USH type II gene (called USH2) has been assigned to chromosome 1q. One USH type I gene has been tentatively assigned to chromosome 14q. There are other USH genes that have not yet been localized.

Peripheral visual response time and retinal luminance-area relations

NASA Technical Reports Server (NTRS)

Haines, R. F.

1975-01-01

Experiments were undertaken to elucidate the stimulus luminance-retinal area relationship that underlies response time (RT) behavior. Mean RT was significantly faster to stimuli imaged beyond about 70 deg of arc from the fovea when their luminance was increased by an amount equal to the foveal stimulus luminance multiplied by the cosine of the angle between the peripheral stimuli and the line of sight. This and additional data are discussed in relation to previous psychophysical data and to possible response mechanisms.

Visual loss after spine surgery: a population-based study.

PubMed

Patil, Chirag G; Lad, Eleonora M; Lad, Shivanand P; Ho, Chris; Boakye, Maxwell

2008-06-01

Retrospective cohort study using National inpatient sample administrative data. To determine national estimates of visual impairment and ischemic optic neuropathy after spine surgery. Loss of vision after spine surgery is rare but has devastating complications that has gained increasing recognition in the recent literature. National population-based studies of visual complications after spine surgery are lacking. All patients from 1993 to 2002 who underwent spine surgery (Clinical Classifications software procedure code: 3, 158) and who had ischemic optic neuropathy (ION) (ICD9-CM code 377.41), central retinal artery occlusion (CRAO) (ICD9-CM code 362.31) or non-ION, non-CRAO perioperative visual impairment (ICD9-CM codes: 369, 368.4, 368.8-9368.11-13) were included. Univariate and multivariate analysis were performed to identify potential risk factors. The overall incidence of visual disturbance after spine surgery was 0.094%. Spine surgery for scoliosis correction and posterior lumbar fusion had the highest rates of postoperative visual loss of 0.28% and 0.14% respectively. Pediatric patients (<18 years) were 5.8 times and elderly patients (>84 years) were 3.2 times more likely than, patients 18 to 44 years of age to develop non-ION, non-CRAO visual loss after spine surgery. Patients with peripheral vascular disease (OR = 2.0), hypertension (OR = 1.3), and those who received blood transfusion (OR = 2.2) were more likely to develop non-ION, non-CRAO vision loss after spine surgery. Ischemic optic neuropathy was present in 0.006% of patients. Hypotension (OR = 10.1), peripheral vascular disease (OR = 6.3) and anemia (OR = 5.9) were the strongest risk factors identified for the development of ION. We used multivariate analysis to identify significant risk factors for visual loss after spine surgery. National population-based estimate of visual impairment after spine surgery confirms that ophthalmic complications after spine surgery are rare. Since visual loss may be reversible in the early stages, awareness, evaluation and prompt management of this rare but potentially devastating complication is critical.

Are evoked potentials in patients with adult-onset pompe disease indicative of clinically relevant central nervous system involvement?

PubMed

Wirsching, Andreas; Müller-Felber, Wolfgang; Schoser, Benedikt

2014-08-01

Pompe disease is a multisystem autosomal recessive glycogen storage disease. Autoptic findings in patients with classic infantile and late-onset Pompe disease have proven that accumulation of glycogen can also be found in the peripheral and central nervous system. To assess the functional role of these pathologic findings, multimodal sensory evoked potentials were analyzed. Serial recordings for brainstem auditory, visual, and somatosensory evoked potentials of 11 late-onset Pompe patients were reviewed. Data at the onset of the enzyme replacement therapy with alglucosidase alfa were compared with follow-up recordings at 12 and 24 months. Brainstem auditory evoked potentials showed a delayed peak I in 1/10 patients and an increased I-III and I-V interpeak latency in 1/10 patients, respectively. The III-V interpeak latencies were in the normal range. Visual evoked potentials were completely normal. Median somatosensory evoked potentials showed an extended interpeak latency in 3/9 patients. Wilcoxon tests comparing age-matched subgroups found significant differences in brainstem auditory evoked potentials and visual evoked potentials. We found that the majority of recordings for evoked potentials were within the ranges for standard values, therefore reflecting the lack of clinically relevant central nervous system involvement. Regular surveillance by means of evoked potentials does not seem to be appropriate in late-onset Pompe patients.

Adaptive attunement of selective covert attention to evolutionary-relevant emotional visual scenes.

PubMed

Fernández-Martín, Andrés; Gutiérrez-García, Aída; Capafons, Juan; Calvo, Manuel G

2017-05-01

We investigated selective attention to emotional scenes in peripheral vision, as a function of adaptive relevance of scene affective content for male and female observers. Pairs of emotional-neutral images appeared peripherally-with perceptual stimulus differences controlled-while viewers were fixating on a different stimulus in central vision. Early selective orienting was assessed by the probability of directing the first fixation towards either scene, and the time until first fixation. Emotional scenes selectively captured covert attention even when they were task-irrelevant, thus revealing involuntary, automatic processing. Sex of observers and specific emotional scene content (e.g., male-to-female-aggression, families and babies, etc.) interactively modulated covert attention, depending on adaptive priorities and goals for each sex, both for pleasant and unpleasant content. The attentional system exhibits domain-specific and sex-specific biases and attunements, probably rooted in evolutionary pressures to enhance reproductive and protective success. Emotional cues selectively capture covert attention based on their bio-social significance. Copyright © 2017 Elsevier Inc. All rights reserved.

GPS Usage in a Population of Low-Vision Drivers.

PubMed

Cucuras, Maria; Chun, Robert; Lee, Patrick; Jay, Walter M; Pusateri, Gregg

2017-01-01

We surveyed bioptic and non-bioptic low-vision drivers in Illinois, USA, to determine their usage of global positioning system (GPS) devices. Low-vision patients completed an IRB-approved phone survey regarding driving demographics and usage of GPS while driving. Participants were required to be active drivers with an Illinois driver's license, and met one of the following criteria: best-corrected visual acuity (BCVA) less than or equal to 20/40, central or significant peripheral visual field defects, or a combination of both. Of 27 low-vision drivers, 10 (37%) used GPS while driving. The average age for GPS users was 54.3 and for non-users was 77.6. All 10 drivers who used GPS while driving reported increased comfort or safety level. Since non-GPS users were significantly older than GPS users, it is likely that older participants would benefit from GPS technology training from their low-vision eye care professionals.

Comparing the fixational and functional preferred retinal location in a pointing task

PubMed Central

Sullivan, Brian; Walker, Laura

2016-01-01

Patients with central vision loss (CVL) typically adopt eccentric viewing strategies using a preferred retinal locus (PRL) in peripheral retina. Clinically, the PRL is defined monocularly as the area of peripheral retina used to fixate small stimuli. It is not clear if this fixational PRL describes the same portion of peripheral retina used during dynamic binocular eye-hand coordination tasks. We studied this question with four participants each with a unique CVL history. Using a scanning laser ophthalmoscope, we measured participants’ monocular visual fields and the location and stability of their fixational PRLs. Participants’ monocular and binocular visual fields were also evaluated using a computer monitor and eye tracker. Lastly, eye-hand coordination was tested over several trials where participants pointed to and touched a small target on a touchscreen monitor. Trials were blocked and carried out monocularly and binocularly, with a target appearing at 5° or 15° from screen center, in one of 8 locations. During pointing, our participants often exhibited long movement durations, an increased number of eye movements and impaired accuracy, especially in monocular conditions. However, these compensatory changes in behavior did not consistently worsen when loci beyond the fixational PRL were used. While fixational PRL size, location and fixation stability provide a necessary description of behavior, they are not sufficient to capture the pointing PRL used in this task. Generally, patients use a larger portion of peripheral retina than one might expect from measures of the fixational PRL alone, when pointing to a salient target without time constraints. While the fixational and pointing PRLs often overlap, the fixational PRL does not predict the large area of peripheral retina that can be used. PMID:26440864

Electromagnetic navigational bronchoscopy with dye marking for identification of small peripheral lung nodules during minimally invasive surgical resection

PubMed Central

Muñoz-Largacha, Juan A.; Ebright, Michael I.; Litle, Virginia R.

2017-01-01

Background Identification of small peripheral lung nodules during minimally invasive resection can be challenging. Electromagnetic navigational bronchoscopy (ENB) with injection of dye to identify nodules can be performed by the surgeon immediately prior to resection. We evaluated the effectiveness of ENB with dye marking to aid minimally invasive resection. Methods Patients with peripheral pulmonary nodules underwent ENB before planned thoracoscopic or robotic-assisted thoracoscopic resection. Methylene blue was injected directly into the lesion for pleural-based lesions or peripherally for lesions deep to the pleural surface. Surgical resection was then immediately performed. Technical success was defined as identification of the dye marking within/close to the lesion with pathological confirmation after minimally invasive surgical resection. Results Seventeen patients (19 nodules) underwent ENB with dye marking followed by minimally invasive resection. Median lesion size was 9 mm (4–32 mm) and the median distance from the pleura was 9.5 mm (1–40 mm). Overall success rate was 79% (15/19). In two cases the dye was not visualized and in the remaining two there was extravasation of dye into the pleural space. There were trends favoring technical success for nodules that were larger or closer to the pleural surface. Five patients required adhesiolysis to visualize the target lesion and all were successful. There were no significant adverse events and a definitive diagnosis was ultimately accomplished in all patients. Conclusions ENB with dye marking is useful for guiding minimally invasive resection of small peripheral lung nodules. ENB can be undertaken immediately before performing resection in the operating room. This improves workflow and avoids the need for a separate localization procedure. PMID:28449489

Neurologic complications of electrolyte disturbances and acid-base balance.

PubMed

Espay, Alberto J

2014-01-01

Electrolyte and acid-base disturbances are common occurrences in daily clinical practice. Although these abnormalities can be readily ascertained from routine laboratory findings, only specific clinical correlates may attest as to their significance. Among a wide phenotypic spectrum, acute electrolyte and acid-base disturbances may affect the peripheral nervous system as arreflexic weakness (hypermagnesemia, hyperkalemia, and hypophosphatemia), the central nervous system as epileptic encephalopathies (hypomagnesemia, dysnatremias, and hypocalcemia), or both as a mixture of encephalopathy and weakness or paresthesias (hypocalcemia, alkalosis). Disabling complications may develop not only when these derangements are overlooked and left untreated (e.g., visual loss from intracranial hypertension in respiratory or metabolic acidosis; quadriplegia with respiratory insufficiency in hypermagnesemia) but also when they are inappropriately managed (e.g., central pontine myelinolisis when rapidly correcting hyponatremia; cardiac arrhythmias when aggressively correcting hypo- or hyperkalemia). Therefore prompt identification of the specific neurometabolic syndromes is critical to correct the causative electrolyte or acid-base disturbances and prevent permanent central or peripheral nervous system injury. This chapter reviews the pathophysiology, clinical investigations, clinical phenotypes, and current management strategies in disorders resulting from alterations in the plasma concentration of sodium, potassium, calcium, magnesium, and phosphorus as well as from acidemia and alkalemia. © 2014 Elsevier B.V. All rights reserved.

Eccentric correction for off-axis vision in central visual field loss.

PubMed

Gustafsson, Jörgen; Unsbo, Peter

2003-07-01

Subjects with absolute central visual field loss use eccentric fixation and magnifying devices to utilize their residual vision. This preliminary study investigated the importance of an accurate eccentric correction of off-axis refractive errors to optimize the residual visual function for these subjects. Photorefraction using the PowerRefractor instrument was used to evaluate the ametropia in eccentric fixation angles. Methods were adapted for measuring visual acuity outside the macula using filtered optotypes from high-pass resolution perimetry. Optical corrections were implemented, and the visual function of subjects with central visual field loss was measured with and without eccentric correction. Of the seven cases reported, five experienced an improvement in visual function in their preferred retinal locus with eccentric refraction. The main result was that optical correction for better image quality on the peripheral retina is important for the vision of subjects with central visual field loss, objectively as well as subjectively.

Effects of Motion in the Far Peripheral Visual Field on Cognitive Test Performance and Cognitive Load.

PubMed

Bevilacqua, Andy; Paas, Fred; Krigbaum, Genomary

2016-04-01

Cognitive load theory posits that limited attention is in actuality a limitation in working memory resources. The load theory of selective attention and cognitive control sees the interplay between attention and awareness as separate modifying functions that act on working memory. Reconciling the theoretical differences in these two theories has important implications for learning. Thirty-nine adult participants performed a cognitively demanding test, with and without movement in the far peripheral field. Although the results for movement effects on cognitive load in this experiment were not statistically significant, men spent less time on the cognitive test in the peripheral movement condition than in the conditions without peripheral movement. No such difference was found for women. The implications of these results and recommendations for future research that extends the present study are presented. © The Author(s) 2016.

Effects of myopic spectacle correction and radial refractive gradient spectacles on peripheral refraction.

PubMed

Tabernero, Juan; Vazquez, Daniel; Seidemann, Anne; Uttenweiler, Dietmar; Schaeffel, Frank

2009-08-01

The recent observation that central refractive development might be controlled by the refractive errors in the periphery, also in primates, revived the interest in the peripheral optics of the eye. We optimized an eccentric photorefractor to measure the peripheral refractive error in the vertical pupil meridian over the horizontal visual field (from -45 degrees to 45 degrees ), with and without myopic spectacle correction. Furthermore, a newly designed radial refractive gradient lens (RRG lens) that induces increasing myopia in all radial directions from the center was tested. We found that for the geometry of our measurement setup conventional spectacles induced significant relative hyperopia in the periphery, although its magnitude varied greatly among different spectacle designs and subjects. In contrast, the newly designed RRG lens induced relative peripheral myopia. These results are of interest to analyze the effect that different optical corrections might have on the emmetropization process.

Postural Control and Gait Performance in the Diabetic Peripheral Neuropathy: A Systematic Review.

PubMed

Mustapa, Amirah; Justine, Maria; Mohd Mustafah, Nadia; Jamil, Nursuriati; Manaf, Haidzir

2016-01-01

Purpose. The aim of this paper is to review the published studies on the characteristics of impairments in the postural control and gait performance in diabetic peripheral neuropathy (DPN). Methods. A review was performed by obtaining publication of all papers reporting on the postural control and gait performance in DPN from Google Scholar, Ovid, SAGE, Springerlink, Science Direct (SD), EBSCO Discovery Service, and Web of Science databases. The keywords used for searching were "postural control," "balance," "gait performance," "diabetes mellitus," and "diabetic peripheral neuropathy." Results. Total of 4,337 studies were hit in the search. 1,524 studies were screened on their titles and citations. Then, 79 studies were screened on their abstract. Only 38 studies were eligible to be selected: 17 studies on postural control and 21 studies on the gait performance. Most previous researches were found to have strong evidence of postural control impairments and noticeable gait deficits in DPN. Deterioration of somatosensory, visual, and vestibular systems with the pathologic condition of diabetes on cognitive impairment causes further instability of postural and gait performance in DPN. Conclusions. Postural instability and gait imbalance in DPN may contribute to high risk of fall incidence, especially in the geriatric population. Thus, further works are crucial to highlight this fact in the hospital based and community adults.

[The dependence of the range of fusion on some selected functions of the visual system. Part II: Accommodation and dominance].

PubMed

Adamek, Bogdan; Karczewicz, Danuta

2006-01-01

This present study is the continuation of Part I of the research into the range of fusion in which the difference between both eyeballs as far as convergent fusion is concerned was described. The phenomenon was called "visual unevenness of the range of convergent fusion". This part of the study is devoted to the analysis of the relationship between the unevenness of the fusion, ocular dominance and accommodation. A lower range of convergent fusion was observed in the dominant eye with the higher accommodation, In contrast, a higher range of fusion was observed in the not dominant eye with lower accommodation. The authors think that the phenomenon of ocular unevenness of the range of convergent fusion does not depend on the peripheral part of visual organ. In fact, it does seem to point out to a cortical process. The authors suggest that quantitative tests on amplitude of fusion should be carried out first on the first eye and then on the other. The results obtained from both eyes should be compared with each other.

On the rules of integration of crowded orientation signals

PubMed Central

Põder, Endel

2012-01-01

Crowding is related to an integration of feature signals over an inappropriately large area in the visual periphery. The rules of this integration are still not well understood. This study attempts to understand how the orientation signals from the target and flankers are combined. A target Gabor, together with 2, 4, or 6 flanking Gabors, was briefly presented in a peripheral location (4° eccentricity). The observer's task was to identify the orientation of the target (eight-alternative forced-choice). Performance was found to be nonmonotonically dependent on the target–flanker orientation difference (a drop at intermediate differences). For small target–flanker differences, a strong assimilation bias was observed. An effect of the number of flankers was found for heterogeneous flankers only. It appears that different rules of integration are used, dependent on some salient aspects (target pop-out, homogeneity–heterogeneity) of the stimulus pattern. The strategy of combining simple rules may be explained by the goal of the visual system to encode potentially important aspects of a stimulus with limited processing resources and using statistical regularities of the natural visual environment. PMID:23145295

On the rules of integration of crowded orientation signals.

PubMed

Põder, Endel

2012-01-01

Crowding is related to an integration of feature signals over an inappropriately large area in the visual periphery. The rules of this integration are still not well understood. This study attempts to understand how the orientation signals from the target and flankers are combined. A target Gabor, together with 2, 4, or 6 flanking Gabors, was briefly presented in a peripheral location (4° eccentricity). The observer's task was to identify the orientation of the target (eight-alternative forced-choice). Performance was found to be nonmonotonically dependent on the target-flanker orientation difference (a drop at intermediate differences). For small target-flanker differences, a strong assimilation bias was observed. An effect of the number of flankers was found for heterogeneous flankers only. It appears that different rules of integration are used, dependent on some salient aspects (target pop-out, homogeneity-heterogeneity) of the stimulus pattern. The strategy of combining simple rules may be explained by the goal of the visual system to encode potentially important aspects of a stimulus with limited processing resources and using statistical regularities of the natural visual environment.

Immunocytochemical distribution of locustamyoinhibiting peptide (Lom-MIP) in the nervous system of Locusta migratoria.

PubMed

Schoofs, L; Veelaert, D; Broeck, J V; De Loof, A

1996-07-05

Locustamyoinhibiting peptide (Lom-MIP) is one of the 4 identified myoinhibiting neuropeptides, isolated from brain-corpora cardiaca-corpora allata-suboesophageal ganglion complexes of the locust, Locusta migratoria. An antiserum was raised against Lom-MIP for use in immunohistochemistry. Locustamyoinhibiting peptide-like immunoreactivity (Lom-MIP-LI) was visualized in the nervous system and peripheral organs of Locusta migratoria by means of the peroxidase-antiperoxidase method. A total of 12 specific immunoreactive neurons was found in the brain. Processes of these neurons innervate the protocerebral bridge the central body complex and distinct neuropil areas in the proto- and tritocerebrum but not in the deuterocerebrum nor in the optic lobes. The glandular cells of the corpora cardiaca, known to produce adipokinetic hormones, are contacted by Lom-MIP-LI fibers. The corpora allata were innervated by the nervus corporis allati I containing immunoreactive fibers. Lom-MIP-LI cell bodies were also found in the subesophageal ganglion, the metathoracic ganglion and the abdominal ganglia I-IV. In peripheral muscles, Lom-MIP-LI fibers innervate the heart, the oviduct, and the hindgut. In the salivary glands, Lom-MIP-LI was detected in the intracellular ductule of the parietal cells. Possible functions of Lom-MIP are discussed.

Retinal constraints on orientation specificity in cat visual cortex.

PubMed

Schall, J D; Vitek, D J; Leventhal, A G

1986-03-01

Most retinal ganglion cells (Levick and Thibos, 1982) and cortical cells (Leventhal, 1983; Leventhal et al., 1984) subserving peripheral vision respond best to stimuli that are oriented radially, i.e., like the spokes of a wheel with the area centralis at the hub. We have extended this work by comparing directly the distributions of orientations represented in topographically corresponding regions of retina and visual cortex. Both central and peripheral regions were studied. The relations between the orientations of neighboring ganglion cells and the manner in which the overrepresentation of radial orientations is accommodated in the functional architecture of visual cortex were also studied. Our results are based on an analysis of the orientations of the dendritic fields of 1296 ganglion cells throughout the retina and the preferred orientations of 1389 cells located in retinotopically corresponding regions of cortical areas 17, 18, and 19 in the cat. We find that horizontal and vertical orientations are overrepresented in regions of both retina and visual cortex subserving the central 5 degrees of vision. The distributions of the orientations of retinal ganglion cells and cortical cells subserving the horizontal, vertical, and diagonal meridians outside the area centralis differ significantly. The distribution of the preferred orientations of the S (simple) cells in areas 17, 18 and 19 subserving a given part of the retina corresponds to the distribution of the dendritic field orientations of the ganglion cells in that part of retina. The distribution of the preferred orientations of C (complex) cells with narrow receptive fields in area 17 but not C cells with wide receptive fields in areas 17, 18, or 19 subserving a given part of the retina matches the distribution of the orientations of the ganglion cells in that part of retina. The orientations of all of the alpha-cells in 5-9 mm2 patches of retina along the horizontal, vertical, and oblique meridians were determined. A comparison of the orientations of neighboring cells indicates that other than a mutual tendency to be oriented radially, ganglion cells with similar orientations are not clustered in the retina. Reconstructions of electrode penetrations into regions of visual cortex representing peripheral retina indicate that columns subserving radial orientations are wider than those subserving nonradial orientations. Our results provide evidence that the distribution of the preferred orientations of simple cells in visual cortex subserving any region of the visual field matches the distribution of the orientations of the ganglion cells subserving the same region of the visual field.(ABSTRACT TRUNCATED AT 400 WORDS)

Through-focus optical characteristics of monofocal and bifocal soft contact lenses across the peripheral visual field.

PubMed

Ji, Qiuzhi; Yoo, Young-Sik; Alam, Hira; Yoon, Geunyoung

2018-05-01

To characterise the impact of monofocal soft contact lens (SCL) and bifocal SCLs on refractive error, depth of focus (DoF) and orientation of blur in the peripheral visual field. Monofocal and two bifocal SCLs, Acuvue Bifocal (AVB, Johnson & Johnson) and Misight Dual Focus (DF, CooperVision) with +2.0 D add power were modelled using a ray tracing program (ZEMAX) based on their power maps. These SCLs were placed onto the anterior corneal surface of the simulated Atchison myopic eye model to correct for -3.0 D spherical refractive error at the fovea. To quantify through-focus retinal image quality, defocus from -3.5 D to 1.5 D in 0.5 D steps was induced at each horizontal eccentricity from 0 to 40° in 10° steps. Wavefront aberrations were computed for each visual eccentricity and defocus. The retinal images were simulated using a custom software program developed in Matlab (The MathWorks) by convolving the point spread function calculated from the aberration with a reference image. The convolved images were spatially filtered to match the spatial resolution limit of each peripheral eccentricity. Retinal image quality was then quantified by the 2-D cross-correlation between the filtered convolved retinal images and the reference image. Peripheral defocus, DoF and orientation of blur were also estimated. In comparison with the monofocal SCL, the bifocal SCLs degraded retinal image quality while DoF was increased at fovea. From 10 to 20°, a relatively small amount of myopic shift (less than 0.3 D) was induced by bifocal SCLs compared with monofocal. DoF was also increased with bifocal SCLs at peripheral vision of 10 and 20°. The trend of myopic shift became less consistent at larger eccentricity, where at 30° DF showed a 0.75 D myopic shift while AVB showed a 0.2 D hyperopic shift and both AVB and DF exhibited large relative hyperopic defocus at 40°. The anisotropy in orientation of blur was found to increase and change its direction through focus beyond central vision. This trend was found to be less dominant with bifocal SCLs compared to monofocal SCL. Bifocal SCLs have a relatively small impact on myopic shift in peripheral refractive error while DoF is increased significantly. We hypothetically suggest that a mechanism underlying myopia control with these bifocal or multifocal contact lenses is an increase in DoF and a decrease in anisotropy of peripheral optical blur. © 2018 The Authors Ophthalmic & Physiological Optics © 2018 The College of Optometrists.

Is the size of the useful field of view affected by postural demands associated with standing and stepping?

PubMed

Reed-Jones, James G; Reed-Jones, Rebecca J; Hollands, Mark A

2014-04-30

The useful field of view (UFOV) is the visual area from which information is obtained at a brief glance. While studies have examined the effects of increased cognitive load on the visual field, no one has specifically looked at the effects of postural control or locomotor activity on the UFOV. The current study aimed to examine the effects of postural demand and locomotor activity on UFOV performance in healthy young adults. Eleven participants were tested on three modified UFOV tasks (central processing, peripheral processing, and divided-attention) while seated, standing, and stepping in place. Across all postural conditions, participants showed no difference in their central or peripheral processing. However, in the divided-attention task (reporting the letter in central vision and target location in peripheral vision amongst distracter items) a main effect of posture condition on peripheral target accuracy was found for targets at 57° of eccentricity (p=.037). The mean accuracy reduced from 80.5% (standing) to 74% (seated) to 56.3% (stepping). These findings show that postural demands do affect UFOV divided-attention performance. In particular, the size of the useful field of view significantly decreases when stepping. This finding has important implications for how the results of a UFOV test are used to evaluate the general size of the UFOV during varying activities, as the traditional seated test procedure may overestimate the size of the UFOV during locomotor activities. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Bilateral foveal retinoschisis accompanying unilateral peripheral retinoschisis

PubMed Central

Kocak, Nilufer; Ozturk, Taylan A; Kaynak, Suleyman

2014-01-01

X-linked juvenile retinoschisis is a rare hereditary retinal disease characterized by a tangential splitting of the neurosensory retina which may cause early-onset visual impairment. Existence of the retinal neurosensory layer splitting on cross-sectional images of optical coherance tomography (OCT) and the absence of leakage on fluorescein angiography (FA) help confirming the diagnosis. Such diagnostic tests are also helpful in determining the management of the disease. However, most of the retinoschisis cavities remain stable and rarely extend to the posterior pole, many authors suggest laser prophylaxis to avoid the potential risk of retinal detachment due to holes in the outer retinal layer. Herein, we report a case with bilateral foveal retinoschisis accompanying unilateral peripheral retinoschisis who was evaluated with detailed ophthalmologic examination. Visual acuity, fundoscopy, OCT, and FA remained stable in the second year of follow-up after prophylactic argon laser treatment. PMID:23571248

Lean on Wii: physical rehabilitation with virtual reality Wii peripherals.

PubMed

Anderson, Fraser; Annett, Michelle; Bischof, Walter F

2010-01-01

In recent years, a growing number of occupational therapists have integrated video game technologies, such as the Nintendo Wii, into rehabilitation programs. 'Wiihabilitation', or the use of the Wii in rehabilitation, has been successful in increasing patients' motivation and encouraging full body movement. The non-rehabilitative focus of Wii applications, however, presents a number of problems: games are too difficult for patients, they mainly target upper-body gross motor functions, and they lack support for task customization, grading, and quantitative measurements. To overcome these problems, we have designed a low-cost, virtual-reality based system. Our system, Virtual Wiihab, records performance and behavioral measurements, allows for activity customization, and uses auditory, visual, and haptic elements to provide extrinsic feedback and motivation to patients.

Electrophysiological indices of surround suppression in humans

PubMed Central

Vanegas, M. Isabel; Blangero, Annabelle

2014-01-01

Surround suppression is a well-known example of contextual interaction in visual cortical neurophysiology, whereby the neural response to a stimulus presented within a neuron's classical receptive field is suppressed by surrounding stimuli. Human psychophysical reports present an obvious analog to the effects seen at the single-neuron level: stimuli are perceived as lower-contrast when embedded in a surround. Here we report on a visual paradigm that provides relatively direct, straightforward indices of surround suppression in human electrophysiology, enabling us to reproduce several well-known neurophysiological and psychophysical effects, and to conduct new analyses of temporal trends and retinal location effects. Steady-state visual evoked potentials (SSVEP) elicited by flickering “foreground” stimuli were measured in the context of various static surround patterns. Early visual cortex geometry and retinotopic organization were exploited to enhance SSVEP amplitude. The foreground response was strongly suppressed as a monotonic function of surround contrast. Furthermore, suppression was stronger for surrounds of matching orientation than orthogonally-oriented ones, and stronger at peripheral than foveal locations. These patterns were reproduced in psychophysical reports of perceived contrast, and peripheral electrophysiological suppression effects correlated with psychophysical effects across subjects. Temporal analysis of SSVEP amplitude revealed short-term contrast adaptation effects that caused the foreground signal to either fall or grow over time, depending on the relative contrast of the surround, consistent with stronger adaptation of the suppressive drive. This electrophysiology paradigm has clinical potential in indexing not just visual deficits but possibly gain control deficits expressed more widely in the disordered brain. PMID:25411464

HECTOR: A 240kV micro-CT setup optimized for research

NASA Astrophysics Data System (ADS)

Masschaele, Bert; Dierick, Manuel; Van Loo, Denis; Boone, Matthieu N.; Brabant, Loes; Pauwels, Elin; Cnudde, Veerle; Van Hoorebeke, Luc

2013-10-01

X-ray micro-CT has become a very powerful and common tool for non-destructive three-dimensional (3D) visualization and analysis of objects. Many systems are commercially available, but they are typically limited in terms of operational freedom both from a mechanical point of view as well as for acquisition routines. HECTOR is the latest system developed by the Ghent University Centre for X-ray Tomography (http://www.ugct.ugent.be) in collaboration with X-Ray Engineering (XRE bvba, Ghent, Belgium). It consists of a mechanical setup with nine motorized axes and a modular acquisition software package and combines a microfocus directional target X-ray source up to 240 kV with a large flat-panel detector. Provisions are made to install a line-detector for a maximal operational range. The system can accommodate samples up to 80 kg, 1 m long and 80 cm in diameter while it is also suited for high resolution (down to 4 μm) tomography. The bi-directional detector tiling is suited for large samples while the variable source-detector distance optimizes the signal to noise ratio (SNR) for every type of sample, even with peripheral equipment such as compression stages or climate chambers. The large vertical travel of 1 m can be used for helical scanning and a vertical detector rotation axis allows laminography experiments. The setup is installed in a large concrete bunker to allow accommodation of peripheral equipment such as pumps, chillers, etc., which can be integrated in the modular acquisition software to obtain a maximal correlation between the environmental control and the CT data taken. The acquisition software does not only allow good coupling with the peripheral equipment but its scripting feature is also particularly interesting for testing new and exotic acquisition routines.

The Effects of Optical Illusions in Perception and Action in Peripersonal and Extrapersonal Space.

PubMed

Shim, Jaeho; van der Kamp, John

2017-09-01

While the two visual system hypothesis tells a fairly compelling story about perception and action in peripersonal space (i.e., within arm's reach), its validity for extrapersonal space is very limited and highly controversial. Hence, the present purpose was to assess whether perception and action differences in peripersonal space hold in extrapersonal space and are modulated by the same factors. To this end, the effects of an optic illusion in perception and action in both peripersonal and extrapersonal space were compared in three groups that threw balls toward a target at a distance under different target eccentricity (i.e., with the target fixated and in peripheral field), viewing (i.e., binocular and monocular viewing), and delay conditions (i.e., immediate and delayed action). The illusory bias was smaller in action than in perception in peripersonal space, but this difference was significantly reduced in extrapersonal space, primarily because of a weakening bias in perception. No systematic modulation of target eccentricity, viewing, and delay arose. The findings suggest that the two visual system hypothesis is also valid for extra personal space.

Long-Lasting Enhancement of Visual Perception with Repetitive Noninvasive Transcranial Direct Current Stimulation

PubMed Central

Behrens, Janina R.; Kraft, Antje; Irlbacher, Kerstin; Gerhardt, Holger; Olma, Manuel C.; Brandt, Stephan A.

2017-01-01

Understanding processes performed by an intact visual cortex as the basis for developing methods that enhance or restore visual perception is of great interest to both researchers and medical practitioners. Here, we explore whether contrast sensitivity, a main function of the primary visual cortex (V1), can be improved in healthy subjects by repetitive, noninvasive anodal transcranial direct current stimulation (tDCS). Contrast perception was measured via threshold perimetry directly before and after intervention (tDCS or sham stimulation) on each day over 5 consecutive days (24 subjects, double-blind study). tDCS improved contrast sensitivity from the second day onwards, with significant effects lasting 24 h. After the last stimulation on day 5, the anodal group showed a significantly greater improvement in contrast perception than the sham group (23 vs. 5%). We found significant long-term effects in only the central 2–4° of the visual field 4 weeks after the last stimulation. We suspect a combination of two factors contributes to these lasting effects. First, the V1 area that represents the central retina was located closer to the polarization electrode, resulting in higher current density. Second, the central visual field is represented by a larger cortical area relative to the peripheral visual field (cortical magnification). This is the first study showing that tDCS over V1 enhances contrast perception in healthy subjects for several weeks. This study contributes to the investigation of the causal relationship between the external modulation of neuronal membrane potential and behavior (in our case, visual perception). Because the vast majority of human studies only show temporary effects after single tDCS sessions targeting the visual system, our study underpins the potential for lasting effects of repetitive tDCS-induced modulation of neuronal excitability. PMID:28860969

Comparative study of visual pathways in owls (Aves: Strigiformes).

PubMed

Gutiérrez-Ibáñez, Cristián; Iwaniuk, Andrew N; Lisney, Thomas J; Wylie, Douglas R

2013-01-01

Although they are usually regarded as nocturnal, owls exhibit a wide range of activity patterns, from strictly nocturnal, to crepuscular or cathemeral, to diurnal. Several studies have shown that these differences in the activity pattern are reflected in differences in eye morphology and retinal organization. Despite the evidence that differences in activity pattern among owl species are reflected in the peripheral visual system, there has been no attempt to correlate these differences with changes in the visual regions in the brain. In this study, we compare the relative size of nuclei in the main visual pathways in nine species of owl that exhibit a wide range of activity patterns. We found marked differences in the relative size of all visual structures among the species studied, both in the tectofugal and the thalamofugal pathway, as well in other retinorecipient nuclei, including the nucleus lentiformis mesencephali, the nucleus of the basal optic root and the nucleus geniculatus lateralis, pars ventralis. We show that the barn owl (Tyto alba), a species widely used in the study of the integration of visual and auditory processing, has reduced visual pathways compared to strigid owls. Our results also suggest there could be a trade-off between the relative size of visual pathways and auditory pathways, similar to that reported in mammals. Finally, our results show that although there is no relationship between activity pattern and the relative size of either the tectofugal or the thalamofugal pathway, there is a positive correlation between the relative size of both visual pathways and the relative number of cells in the retinal ganglion layer. Copyright © 2012 S. Karger AG, Basel.

Retinotopically specific reorganization of visual cortex for tactile pattern recognition

PubMed Central

Cheung, Sing-Hang; Fang, Fang; He, Sheng; Legge, Gordon E.

2009-01-01

Although previous studies have shown that Braille reading and other tactile-discrimination tasks activate the visual cortex of blind and sighted people [1–5], it is not known whether this kind of cross-modal reorganization is influenced by retinotopic organization. We have addressed this question by studying S, a visually impaired adult with the rare ability to read print visually and Braille by touch. S had normal visual development until age six years, and thereafter severe acuity reduction due to corneal opacification, but no evidence of visual-field loss. Functional magnetic resonance imaging (fMRI) revealed that, in S’s early visual areas, tactile information processing activated what would be the foveal representation for normally-sighted individuals, and visual information processing activated what would be the peripheral representation. Control experiments showed that this activation pattern was not due to visual imagery. S’s high-level visual areas which correspond to shape- and object-selective areas in normally-sighted individuals were activated by both visual and tactile stimuli. The retinotopically specific reorganization in early visual areas suggests an efficient redistribution of neural resources in the visual cortex. PMID:19361999

Plasticity Beyond V1: Reinforcement of Motion Perception upon Binocular Central Retinal Lesions in Adulthood.

PubMed

Burnat, Kalina; Hu, Tjing-Tjing; Kossut, Małgorzata; Eysel, Ulf T; Arckens, Lutgarde

2017-09-13

Induction of a central retinal lesion in both eyes of adult mammals is a model for macular degeneration and leads to retinotopic map reorganization in the primary visual cortex (V1). Here we characterized the spatiotemporal dynamics of molecular activity levels in the central and peripheral representation of five higher-order visual areas, V2/18, V3/19, V4/21a,V5/PMLS, area 7, and V1/17, in adult cats with central 10° retinal lesions (both sexes), by means of real-time PCR for the neuronal activity reporter gene zif268. The lesions elicited a similar, permanent reduction in activity in the center of the lesion projection zone of area V1/17, V2/18, V3/19, and V4/21a, but not in the motion-driven V5/PMLS, which instead displayed an increase in molecular activity at 3 months postlesion, independent of visual field coordinates. Also area 7 only displayed decreased activity in its LPZ in the first weeks postlesion and increased activities in its periphery from 1 month onward. Therefore we examined the impact of central vision loss on motion perception using random dot kinematograms to test the capacity for form from motion detection based on direction and velocity cues. We revealed that the central retinal lesions either do not impair motion detection or even result in better performance, specifically when motion discrimination was based on velocity discrimination. In conclusion, we propose that central retinal damage leads to enhanced peripheral vision by sensitizing the visual system for motion processing relying on feedback from V5/PMLS and area 7. SIGNIFICANCE STATEMENT Central retinal lesions, a model for macular degeneration, result in functional reorganization of the primary visual cortex. Examining the level of cortical reactivation with the molecular activity marker zif268 revealed reorganization in visual areas outside V1. Retinotopic lesion projection zones typically display an initial depression in zif268 expression, followed by partial recovery with postlesion time. Only the motion-sensitive area V5/PMLS shows no decrease, and even a significant activity increase at 3 months post-retinal lesion. Behavioral tests of motion perception found no impairment and even better sensitivity to higher random dot stimulus velocities. We demonstrate that the loss of central vision induces functional mobilization of motion-sensitive visual cortex, resulting in enhanced perception of moving stimuli. Copyright © 2017 the authors 0270-6474/17/378989-11$15.00/0.

Attention to body-parts varies with visual preference and verb-effector associations.

PubMed

Boyer, Ty W; Maouene, Josita; Sethuraman, Nitya

2017-05-01

Theories of embodied conceptual meaning suggest fundamental relations between others' actions, language, and our own actions and visual attention processes. Prior studies have found that when people view an image of a neutral body in a scene they first look toward, in order, the head, torso, hands, and legs. Other studies show associations between action verbs and the body-effectors used in performing the action (e.g., "jump" with feet/legs; "talk" with face/head). In the present experiment, the visual attention of participants was recorded with a remote eye-tracking system while they viewed an image of an actor pantomiming an action and heard a concrete action verb. Participants manually responded whether or not the action image was a good example of the verb they heard. The eye-tracking results confirmed that participants looked at the head most, followed by the hands, and the feet least of all; however, visual attention to each of the body-parts also varied as a function of the effector associated with the spoken verb on image/verb congruent trials, particularly for verbs associated with the legs. Overall, these results suggest that language influences some perceptual processes; however, hearing auditory verbs did not alter the previously reported fundamental hierarchical sequence of directed attention, and fixations on specific body-effectors may not be essential for verb comprehension as peripheral visual cues may be sufficient to perform the task.

Useful visual field in patients with schizophrenia: a choice reaction time study.

PubMed

Matsuda, Yukihisa; Matsui, Mie; Tonoya, Yasuhiro; Ebihara, Naokuni; Kurachi, Masayoshi

2011-04-01

This study examined the size of the useful visual field in patients (9 men, 6 women) with schizophrenia. A choice reaction task was conducted, and performances at 2.5, 5, 7, 10, and 25 degrees in both visual fields were measured. Three key findings were shown. First, patients had slower choice reaction times (choice RTs) than normal controls. Second, patients had slower choice RTs in the right visual field than in the left visual field. Third, patients and normal controls showed the same U-shaped choice RT pattern. The first and second findings were consistent with those of other studies. The third finding was a clear indication of the patients' performance in peripheral vision, and a comparison with normal controls suggested that there was no difference in the size of the useful visual field, at least within

Providing straw to allow exploratory behaviour in a pig experimental system does not modify putative indicators of positive welfare: peripheral oxytocin and serotonin.

PubMed

Marcet Rius, M; Cozzi, A; Bienboire-Frosini, C; Teruel, E; Chabaud, C; Monneret, P; Leclercq, J; Lafont-Lecuelle, C; Pageat, P

2018-01-22

Numerous studies have shown that providing straw to pigs can reduce undesirable behaviours such as aggression, tail biting and stereotypy. The measurement of various neuromodulators can be helpful in assessing the development of positive behaviours and overall animal welfare. The oxytocin release is frequently linked to positive emotions and positive welfare. It has been suggested that oxytocin modulates the serotoninergic system. This study aims to investigate the potential effect of straw provision in pigs on peripheral levels of oxytocin and serotonin. In total, 18 mini-pigs were involved in an exploratory study conducted in two parallel groups, Enriched (n=10) and Control (n=8) groups. Pigs were divided by group and housed in pens of two individuals. Straw was provided continuously only in Enriched group and renewed each day for 2 weeks. Two blood samples were drawn from each animal 5 to 10 min before providing the straw, and 15 min after providing straw, during the 1st week, to analyse peripheral changes in oxytocin and serotonin before and after straw provision, and determine the existence of a putative short-term effect. The same procedure was carried out for Control group, without straw provision. Long-term effects of straw provision were also examined using blood samples drawn at the same hour from each animal in the 2nd and 3rd weeks. During this time, animals had the permanent possibility to explore the straw in Enriched group but not in Control group. At the end of each week, one animal-keeper completed two visual analogue scales for each mini-pig regarding the difficulty/ease to work with and handle it and its trust in humans. Results showed peripheral oxytocin increases in both groups after 2 weeks (P=0.02). Results did not demonstrate any effect of providing straw to allow exploratory behaviour on peripheral serotonin. Other results were not significant. This preliminary study explored the relationship between peripheral oxytocin and serotonin and the presence of straw that allow pigs to perform exploratory behaviour, suggesting that there was no relationship between them. Some future studies may include crossing oxytocin and serotonin with other parameters, such as behavioural measures, to obtain more information about the true state of the animal and any possible relationship with pig welfare.

Clinical use of closed-system safety peripheral intravenous cannulas.

PubMed

Barton, Andrew

2018-04-26

Peripheral intravenous (IV) cannulas are the quickest and most effective way of gaining venous vascular access and administering IV therapy. Closed-system peripheral IV cannulas have been shown to be safe and more reliable than open, non-valved peripheral cannulas in clinical practice. This article introduces the Smiths Medical DeltaVen closed-system peripheral IV cannula and includes three case studies describing its use in clinical practice and associated patient outcomes.

The topography of primate retina: a study of the human, bushbaby, and new- and old-world monkeys.

PubMed

Stone, J; Johnston, E

1981-02-20

The distribution of ganglion cells has been studied in the retinas of four primates: the prosimian bushbaby, the New-World squirrel monkey, the Old-World crab-eating cynamolgous monkey, and the human. The sizes of ganglion cell somas were also measured at a number of retinal locations and compared with similar measurements in the cat retina to test for the presence in primates of retinal specializations such as the visual streak, and for gradients in retinal structure, such as that between temporal and nasal retina. In all four primates, ganglion cell somas in peripheral retina ranged considerably in diameter (6-16 micrometer in the bushbaby, 8-22 micrometer in the squirrel monkey, 8-23 micrometer in the cynamolgous monkey, 8-26 micrometer in the human). It seems likely that the strong physiological correlates of soma size which have been described among cat retinal ganglion cells and among the relay cells of the macaque lateral geniculate nucleus are generally present in primates. In all four primates, evidence was also obtained of a visual streak specialization; the isodensity lines in ganglion cell density maps were horizontally elongated, and small-bodied ganglion cells were relatively more common in the region of the proposed streak than in other areas of peripheral retina. However, the visual streak seems less well developed than in the cat; among the four primate species examined it was best developed in the bushbaby, at least as assessed by the shape of the isodensity lines. All four primates showed a clear foveal specialization, but this feature seemed least developed in the bushbaby. At the fovea, ganglion cells are smaller in soma size than in peripheral retina; they also seemed more uniform in size, although some distinctly larger cells persist in the human and bushbaby. Soma size measurements also provided evidence of a difference between nasal and temporal areas of peripheral retina comparable to that reported for the cat and other species. Thus the primate retinas examined show features, such as the foveal specialization, which seem unique to them among mammals. They also show features, such as nasal-temporal differences in ganglion cell size, and (though weakly developed) a visual streak, which they have in common with other mammals with widely different phylogenetic histories.

[Combination surgery for wet age-related macular degeneration and chronic peripheral uveitis].

PubMed

Zapuskalov, I V; Krivosheina, O I; Khoroshikh, Yu I

2016-01-01

To develop a combination surgery for wet age-related macular degeneration and concurrent chronic peripheral uveitis that would include intravitreal injection of Lucentis and cryocerclage of the peripheral retina. A total of 75 patients were examined and divided into 2 groups: the main group (37 patients) and the controls (38 patients). Patients from the main group underwent the new combination surgery, while the controls received intravitreal Lucentis alone (peripheral uveitis was managed therapeutically). It has been found that the new combination method provides a significant and stable improvement in visual acuity (by a factor of 10) and a decrease in the area of central scotoma (by a factor of 2.95) in the postoperative period. The period needed for recovery in the central retinal thickness is also 1.6 times shorter. The new combination surgery for wet age-related macular degeneration and concurrent chronic peripheral uveitis provides rapid reduction of inflammation in the extreme periphery of the fundus and a 1.5 times faster (as compared to traditional methods) primary restoration of topographic anatomy of the retina in the macular region.

Analysis of clinical features and visual outcomes of pars planitis.

PubMed

Berker, Nilufer; Sen, Emine; Elgin, Ufuk; Atilgan, Cemile Ucgul; Dursun, Erdem; Yilmazbas, Pelin

2018-04-01

To evaluate the demographic characteristics, clinical features, treatment and outcomes of patients with pars planitis in a tertiary referral center in Turkey. Medical records of patients with pars planitis were retrospectively reviewed. The data including demographic and ocular features and treatment outcomes were recorded. The distribution of clinical findings and complications were evaluated according to age and gender groups. The changes in final BCVA compared to the initial BCVA were noted. Statistical analysis was performed using SPSS software (Version 18.0, SPSS Inc., Chicago, USA). Twenty-seven patients (54 eyes) were included in this study. 16 patients were male (59.3%), and 11 were female (40.7%). Mean age at diagnosis was 12.84 ± 8.26 (range 4-36) years. Mean follow-up period was 61.3 ± 52.15 (range 9-172) months. Mean BCVA was 0.58 ± 0.36 (range 0.03-1.00) (0.40 ± 0.45 logMAR) at presentation, and 0.81 ± 0.28 (range 0.10-1.00) (0.14 ± 0.27 logMAR) at final visit (P = 0.001). Vitreous inflammation (100%), vitreous haze (92.6%), snowballs (74.1%), snowbanks (66.7%), anterior chamber cells (66.7%) and peripheral retinal vascular sheathing (48.1%) were the most common presentations. Ocular complications included vitreous condensation (51.9%), cystoid macular edema (22.2%), cataract (18.5%), inferior peripheral retinal detachment (11.1%), glaucoma (5.6%) and vitreous hemorrhage (3.7%). Treatments included topical, periocular, intravitreal and systemic corticosteroids, immunosuppressives, peripheral laser photocoagulation and pars plana vitrectomy when needed. Pars planitis is an idiopathic chronic intermediate uveitis mostly affecting children and adolescents. In spite of its chronic nature with high potential of causing ocular complications, adequate treatment and close follow-up lead to favorable visual outcomes.

Retinal specialization through spatially varying cell densities and opsin coexpression in cichlid fish.

PubMed

Dalton, Brian E; de Busserolles, Fanny; Marshall, N Justin; Carleton, Karen L

2017-01-15

The distinct behaviours of animals and the varied habitats in which animals live place different requirements on their visual systems. A trade-off exists between resolution and sensitivity, with these properties varying across the retina. Spectral sensitivity, which affects both achromatic and chromatic (colour) vision, also varies across the retina, though the function of this inhomogeneity is less clear. We previously demonstrated spatially varying spectral sensitivity of double cones in the cichlid fish Metriaclima zebra owing to coexpression of different opsins. Here, we map the distributions of ganglion cells and cone cells and quantify opsin coexpression in single cones to show these also vary across the retina. We identify an area centralis with peak acuity and infrequent coexpression, which may be suited for tasks such as foraging and detecting male signals. The peripheral retina has reduced ganglion cell densities and increased opsin coexpression. Modeling of cichlid visual tasks indicates that coexpression might hinder colour discrimination of foraging targets and some fish colours. But, coexpression might improve contrast detection of dark objects against bright backgrounds, which might be useful for detecting predators or zooplankton. This suggests a trade-off between acuity and colour discrimination in the central retina versus lower resolution but more sensitive contrast detection in the peripheral retina. Significant variation in the pattern of coexpression among individuals, however, raises interesting questions about the selective forces at work. © 2017. Published by The Company of Biologists Ltd.

Influence of combined visual and vestibular cues on human perception and control of horizontal rotation

NASA Technical Reports Server (NTRS)

Zacharias, G. L.; Young, L. R.

1981-01-01

Measurements are made of manual control performance in the closed-loop task of nulling perceived self-rotation velocity about an earth-vertical axis. Self-velocity estimation is modeled as a function of the simultaneous presentation of vestibular and peripheral visual field motion cues. Based on measured low-frequency operator behavior in three visual field environments, a parallel channel linear model is proposed which has separate visual and vestibular pathways summing in a complementary manner. A dual-input describing function analysis supports the complementary model; vestibular cues dominate sensation at higher frequencies. The describing function model is extended by the proposal of a nonlinear cue conflict model, in which cue weighting depends on the level of agreement between visual and vestibular cues.

Cognitive tunneling: use of visual information under stress.

PubMed

Dirkin, G R

1983-02-01

References to "tunnel vision" under stress are considered to describe a process of attentional, rather than visual, narrowing. The hypothesis of Easterbrook that the range of cue utilization is reduced under stress was tested with a primary task located in the visual periphery. High school volunteers performed a visual discrimination task with choice reaction time (RT) as the dependent variable. A 2 X 3 order of presentation by practice design, with repeated measures on the last factor, was employed. Two levels of stress, high and low, were operationalized by the subject's performing in the presence of an evaluative audience or alone. Pulse rate was employed as a manipulation check on arousal. The results partially supported the hypothesis that a peripherally visual primary task could be attended to under stress without decrement in performance.

Foveated model observers to predict human performance in 3D images

NASA Astrophysics Data System (ADS)

Lago, Miguel A.; Abbey, Craig K.; Eckstein, Miguel P.

2017-03-01

We evaluate 3D search requires model observers that take into account the peripheral human visual processing (foveated models) to predict human observer performance. We show that two different 3D tasks, free search and location-known detection, influence the relative human visual detectability of two signals of different sizes in synthetic backgrounds mimicking the noise found in 3D digital breast tomosynthesis. One of the signals resembled a microcalcification (a small and bright sphere), while the other one was designed to look like a mass (a larger Gaussian blob). We evaluated current standard models observers (Hotelling; Channelized Hotelling; non-prewhitening matched filter with eye filter, NPWE; and non-prewhitening matched filter model, NPW) and showed that they incorrectly predict the relative detectability of the two signals in 3D search. We propose a new model observer (3D Foveated Channelized Hotelling Observer) that incorporates the properties of the visual system over a large visual field (fovea and periphery). We show that the foveated model observer can accurately predict the rank order of detectability of the signals in 3D images for each task. Together, these results motivate the use of a new generation of foveated model observers for predicting image quality for search tasks in 3D imaging modalities such as digital breast tomosynthesis or computed tomography.

The association between reading abilities and visual-spatial attention in Hong Kong Chinese children.

PubMed

Liu, Sisi; Liu, Duo; Pan, Zhihui; Xu, Zhengye

2018-03-25

A growing body of research suggests that visual-spatial attention is important for reading achievement. However, few studies have been conducted in non-alphabetic orthographies. This study extended the current research to reading development in Chinese, a logographic writing system known for its visual complexity. Eighty Hong Kong Chinese children were selected and divided into poor reader and typical reader groups, based on their performance on the measures of reading fluency, Chinese character reading, and reading comprehension. The poor and typical readers were matched on age and nonverbal intelligence. A Posner's spatial cueing task was adopted to measure the exogenous and endogenous orienting of visual-spatial attention. Although the typical readers showed the cueing effect in the central cue condition (i.e., responses to targets following valid cues were faster than those to targets following invalid cues), the poor readers did not respond differently in valid and invalid conditions, suggesting an impairment of the endogenous orienting of attention. The two groups, however, showed a similar cueing effect in the peripheral cue condition, indicating intact exogenous orienting in the poor readers. These findings generally supported a link between the orienting of covert attention and Chinese reading, providing evidence for the attentional-deficit theory of dyslexia. Copyright © 2018 John Wiley & Sons, Ltd.

[The application of subjective visual gravity in assessment of vestibular compensation: a pilot study].

PubMed

Zhao, Yuan; Chen, Taisheng; Wang, Wei; Xu, Kaixu; Wen, Chao; Liu, Qiang; Han, Xi; Li, Shanshan; Li, Xiaojie; Lin, Peng

2016-05-01

To discuss the characteristics of subjective visual gravity (subjective visual vertical/horizontal, SVV/SVH) and assess its clinical application for peripheral unilateral vestibular compensation. 69 cases of acute peripheral unilateral vestibular dysfunction patients (case group) accepted SVV/SVH, spontaneous nystagmus (SN), caloric test (CT) and other vestibular function tests. 49 healthy people (control group) accepted SVV/SVH only. SVV/SVH, SN and unilateral weakness (UW) were selected as for the observation indicators. The correlations between SVV/SVH, SN, UW and courses were investigated respectively, as well as the characteristic of SVV/SVH, SN in period of vestibular compensation. Among case group SVV, SVH positive in 42 patients(60.9%) and 44 patients(63.8%), the absolute values of the skew angle were in the range between 2.1°-20.0°, 2.1°-22.2°. Skew angles of SVV/SVH in control were in the range between -1.5°-2.0° and -2.0°-1.6°, and had no statistical significance with case group(t=5.336 and 5.864, P<0.05). SN-positive 28 cases (40.6%), the range of intensities at 2.4°-17.1°; UW-positive 50 cases (72.5%). In case group, positive correlation between SVV and SVH(r=0.948, P=0.00), negatively correlated between SVV/SVH and SN respectively(r values were -0.720, -0.733, P values were 0.00), no correlation between the skew angle of SVV/SVH, strength of SN and UW value(r values were 0.191, 0.189, and 0.179, P>0.05), there was no correlation between the absolute value of SVV, SVH, SN, UW with the duration (rs values were -0.075, -0.065, -0.212, and 0.126, P>0.05). Subjective visual gravity can be used not only to assess the range of unilateral peripheral vestibular dysfunction, but also help assess the static compensatory of otolithic, guidance and assessment of vestibular rehabilitation.

Attention enhances multi-voxel representation of novel objects in frontal, parietal and visual cortices.

PubMed

Woolgar, Alexandra; Williams, Mark A; Rich, Anina N

2015-04-01

Selective attention is fundamental for human activity, but the details of its neural implementation remain elusive. One influential theory, the adaptive coding hypothesis (Duncan, 2001, An adaptive coding model of neural function in prefrontal cortex, Nature Reviews Neuroscience 2:820-829), proposes that single neurons in certain frontal and parietal regions dynamically adjust their responses to selectively encode relevant information. This selective representation may in turn support selective processing in more specialized brain regions such as the visual cortices. Here, we use multi-voxel decoding of functional magnetic resonance images to demonstrate selective representation of attended--and not distractor--objects in frontal, parietal, and visual cortices. In addition, we highlight a critical role for task demands in determining which brain regions exhibit selective coding. Strikingly, representation of attended objects in frontoparietal cortex was highest under conditions of high perceptual demand, when stimuli were hard to perceive and coding in early visual cortex was weak. Coding in early visual cortex varied as a function of attention and perceptual demand, while coding in higher visual areas was sensitive to the allocation of attention but robust to changes in perceptual difficulty. Consistent with high-profile reports, peripherally presented objects could also be decoded from activity at the occipital pole, a region which corresponds to the fovea. Our results emphasize the flexibility of frontoparietal and visual systems. They support the hypothesis that attention enhances the multi-voxel representation of information in the brain, and suggest that the engagement of this attentional mechanism depends critically on current task demands. Copyright © 2015 Elsevier Inc. All rights reserved.

Concentration: The Neural Underpinnings of How Cognitive Load Shields Against Distraction.

PubMed

Sörqvist, Patrik; Dahlström, Örjan; Karlsson, Thomas; Rönnberg, Jerker

2016-01-01

Whether cognitive load-and other aspects of task difficulty-increases or decreases distractibility is subject of much debate in contemporary psychology. One camp argues that cognitive load usurps executive resources, which otherwise could be used for attentional control, and therefore cognitive load increases distraction. The other camp argues that cognitive load demands high levels of concentration (focal-task engagement), which suppresses peripheral processing and therefore decreases distraction. In this article, we employed an functional magnetic resonance imaging (fMRI) protocol to explore whether higher cognitive load in a visually-presented task suppresses task-irrelevant auditory processing in cortical and subcortical areas. The results show that selectively attending to an auditory stimulus facilitates its neural processing in the auditory cortex, and switching the locus-of-attention to the visual modality decreases the neural response in the auditory cortex. When the cognitive load of the task presented in the visual modality increases, the neural response to the auditory stimulus is further suppressed, along with increased activity in networks related to effortful attention. Taken together, the results suggest that higher cognitive load decreases peripheral processing of task-irrelevant information-which decreases distractibility-as a side effect of the increased activity in a focused-attention network.

Concentration: The Neural Underpinnings of How Cognitive Load Shields Against Distraction

PubMed Central

Sörqvist, Patrik; Dahlström, Örjan; Karlsson, Thomas; Rönnberg, Jerker

2016-01-01

Whether cognitive load—and other aspects of task difficulty—increases or decreases distractibility is subject of much debate in contemporary psychology. One camp argues that cognitive load usurps executive resources, which otherwise could be used for attentional control, and therefore cognitive load increases distraction. The other camp argues that cognitive load demands high levels of concentration (focal-task engagement), which suppresses peripheral processing and therefore decreases distraction. In this article, we employed an functional magnetic resonance imaging (fMRI) protocol to explore whether higher cognitive load in a visually-presented task suppresses task-irrelevant auditory processing in cortical and subcortical areas. The results show that selectively attending to an auditory stimulus facilitates its neural processing in the auditory cortex, and switching the locus-of-attention to the visual modality decreases the neural response in the auditory cortex. When the cognitive load of the task presented in the visual modality increases, the neural response to the auditory stimulus is further suppressed, along with increased activity in networks related to effortful attention. Taken together, the results suggest that higher cognitive load decreases peripheral processing of task-irrelevant information—which decreases distractibility—as a side effect of the increased activity in a focused-attention network. PMID:27242485

Attention modulates trans-saccadic integration.

PubMed

Stewart, Emma E M; Schütz, Alexander C

2018-01-01

With every saccade, humans must reconcile the low resolution peripheral information available before a saccade, with the high resolution foveal information acquired after the saccade. While research has shown that we are able to integrate peripheral and foveal vision in a near-optimal manner, it is still unclear which mechanisms may underpin this important perceptual process. One potential mechanism that may moderate this integration process is visual attention. Pre-saccadic attention is a well documented phenomenon, whereby visual attention shifts to the location of an upcoming saccade before the saccade is executed. While it plays an important role in other peri-saccadic processes such as predictive remapping, the role of attention in the integration process is as yet unknown. This study aimed to determine whether the presentation of an attentional distractor during a saccade impaired trans-saccadic integration, and to measure the time-course of this impairment. Results showed that presenting an attentional distractor impaired integration performance both before saccade onset, and during the saccade, in selected subjects who showed integration in the absence of a distractor. This suggests that visual attention may be a mechanism that facilitates trans-saccadic integration. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Stages of Childhood Soft Tissue Sarcoma

MedlinePlus

... lymph nodes or to the lungs. Peripheral nervous system tumors Peripheral nervous system tumors include the following ... and surgery with or without chemotherapy . Peripheral Nervous System Tumors Ectomesenchymoma Treatment of ectomesenchymoma may include the ...

Treatment Options for Childhood Soft Tissue Sarcoma

MedlinePlus

... lymph nodes or to the lungs. Peripheral nervous system tumors Peripheral nervous system tumors include the following ... and surgery with or without chemotherapy . Peripheral Nervous System Tumors Ectomesenchymoma Treatment of ectomesenchymoma may include the ...

PLDAPS: A Hardware Architecture and Software Toolbox for Neurophysiology Requiring Complex Visual Stimuli and Online Behavioral Control.

PubMed

Eastman, Kyler M; Huk, Alexander C

2012-01-01

Neurophysiological studies in awake, behaving primates (both human and non-human) have focused with increasing scrutiny on the temporal relationship between neural signals and behaviors. Consequently, laboratories are often faced with the problem of developing experimental equipment that can support data recording with high temporal precision and also be flexible enough to accommodate a wide variety of experimental paradigms. To this end, we have developed a MATLAB toolbox that integrates several modern pieces of equipment, but still grants experimenters the flexibility of a high-level programming language. Our toolbox takes advantage of three popular and powerful technologies: the Plexon apparatus for neurophysiological recordings (Plexon, Inc., Dallas, TX, USA), a Datapixx peripheral (Vpixx Technologies, Saint-Bruno, QC, Canada) for control of analog, digital, and video input-output signals, and the Psychtoolbox MATLAB toolbox for stimulus generation (Brainard, 1997; Pelli, 1997; Kleiner et al., 2007). The PLDAPS ("Platypus") system is designed to support the study of the visual systems of awake, behaving primates during multi-electrode neurophysiological recordings, but can be easily applied to other related domains. Despite its wide range of capabilities and support for cutting-edge video displays and neural recording systems, the PLDAPS system is simple enough for someone with basic MATLAB programming skills to design their own experiments.

Suppression of spontaneous nystagmus during different visual fixation conditions.

PubMed

Hirvonen, Timo P; Juhola, Martti; Aalto, Heikki

2012-07-01

Analysis of spontaneous nystagmus is important in the evaluation of dizzy patients. The aim was to measure how different visual conditions affect the properties of nystagmus using three-dimensional video-oculography (VOG). We compared prevalence, frequency and slow phase velocity (SPV) of the spontaneous nystagmus with gaze fixation allowed, with Frenzel's glasses, and in total darkness. Twenty-five patients (35 measurements) with the peripheral vestibular pathologies were included. The prevalence of nystagmus with the gaze fixation was 40%, and it increased significantly to 66% with Frenzel's glasses and regular room lights on (p < 0.01). The prevalence increased significantly to 83% when the regular room lights were switched off (p = 0.014), and further to 100% in total darkness (p = 0.025). The mean SPV of nystagmus with visual fixation allowed was 1.0°/s. It increased to 2.4°/s with Frenzel's glasses and room lights on, and additionally to 3.1°/s, when the regular room lights were switched off. The mean SPV in total darkness was 6.9°/s. The difference was highly significant between all test conditions (p < 0.01). The frequency of nystagmus was 0.7 beats/s with gaze fixation, 0.8 beats/s in both the test conditions with Frenzel's glasses on, and 1.2 beats/s in total darkness. The frequency in total darkness was significantly higher (p < 0.05) than with Frenzel's glasses, and more so than with visual fixation (p = 0.003). The VOG in total darkness is superior in detecting nystagmus, since Frenzel's glasses allow visual suppression to happen, and this effect is reinforced with gaze fixation allowed. Strict control of visual surroundings is essential in interpreting peripheral nystagmus.

Neural basis of superior performance of action videogame players in an attention-demanding task.

PubMed

Mishra, Jyoti; Zinni, Marla; Bavelier, Daphne; Hillyard, Steven A

2011-01-19

Steady-state visual evoked potentials (SSVEPs) were recorded from action videogame players (VGPs) and from non-videogame players (NVGPs) during an attention-demanding task. Participants were presented with a multi-stimulus display consisting of rapid sequences of alphanumeric stimuli presented at rates of 8.6/12 Hz in the left/right peripheral visual fields, along with a central square at fixation flashing at 5.5 Hz and a letter sequence flashing at 15 Hz at an upper central location. Subjects were cued to attend to one of the peripheral or central stimulus sequences and detect occasional targets. Consistent with previous behavioral studies, VGPs detected targets with greater speed and accuracy than NVGPs. This behavioral advantage was associated with an increased suppression of SSVEP amplitudes to unattended peripheral sequences in VGPs relative to NVGPs, whereas the magnitude of the attended SSVEPs was equivalent in the two groups. Group differences were also observed in the event-related potentials to targets in the alphanumeric sequences, with the target-elicited P300 component being of larger amplitude in VGPS than NVGPs. These electrophysiological findings suggest that the superior target detection capabilities of the VGPs are attributable, at least in part, to enhanced suppression of distracting irrelevant information and more effective perceptual decision processes.

Peripheral vision, perceptual asymmetries and visuospatial attention in young, young-old and oldest-old adults.

PubMed

Muiños, Mónica; Palmero, Francisco; Ballesteros, Soledad

2016-03-01

The present study investigated possible changes occurring in peripheral vision, perceptual asymmetries and visuospatial attention in oldest-old adults and compared their performance with that of young and young-old adults. We examined peripheral vision (PV) and perceptual asymmetries in the three age groups for stimuli varying in eccentricity (Experiment 1). In Experiment 2, designed to investigate possible changes in spatial attention, the same participants performed an exogenous orienting attention task. Experiment 1 showed that the three age groups performed the task similarly but differed in processing speed. Importantly, the oldest-old group showed a different perceptual pattern than the other groups suggesting a lack of specificity in visual asymmetries. Experiment 2 indicated that the validity effects emerged later in the young-old and even later in the oldest-old participants, showing a delayed time course of inhibition of return (IOR). Orienting effects, however, were preserved with age. Taken together, these results indicate that the three age groups displayed similar perceptual and orienting attention patterns, but with differences in processing speed. Importantly, age (only in the oldest-old adults) altered perceptual visual asymmetries. These results suggest that some neural plasticity is still present even in oldest-old adults, but a lack of specificity occurs in advanced age. Copyright © 2015 Elsevier Inc. All rights reserved.

Treatment Option Overview (Childhood Soft Tissue Sarcoma)

MedlinePlus

... nearby lymph nodes or to the lungs. Peripheral nervous system tumors Peripheral nervous system tumors include the following ... therapy , and surgery with or without chemotherapy . Peripheral Nervous System Tumors Ectomesenchymoma Treatment of ectomesenchymoma may include the ...

Nonpenetrating glaucoma surgery with goniosynechiolysis ab interno: a surgical technique.

PubMed

Mirshahi, A; Scharioth, G B

2009-01-01

To present a surgical technique for treatment of peripheral anterior synechiae (PAS or goniosynechiae) at the operative field during nonpenetrating glaucoma surgery. After usual preparation of a superficial and a deep scleral flap with externalization of the Schlemm's canal and peeling the juxtacanalicular trabecular meshwork, the goniosynechia is transected by a spatula introduced to the anterior chamber through a paracentesis. A Descemet's window provides full visual control at the peripheral cornea at the basis of the superficial scleral flap. With this surgical technique, selective treatment of goniosynechiae is possible exactly at the area where creation of low outflow resistance is intended by the surgeon during nonpenetrating glaucoma surgery. This technique enables the surgeon to perform nonpenetrating glaucoma surgery even in the presence of peripheral anterior synechiae.

Role of Neuroactive Steroids in the Peripheral Nervous System

PubMed Central

Melcangi, Roberto Cosimo; Giatti, Silvia; Pesaresi, Marzia; Calabrese, Donato; Mitro, Nico; Caruso, Donatella; Garcia-Segura, Luis Miguel

2011-01-01

Several reviews have so far pointed out on the relevant physiological and pharmacological role exerted by neuroactive steroids in the central nervous system. In the present review we summarize observations indicating that synthesis and metabolism of neuroactive steroids also occur in the peripheral nerves. Interestingly, peripheral nervous system is also a target of their action. Indeed, as here reported neuroactive steroids are physiological regulators of peripheral nerve functions and they may also represent interesting therapeutic tools for different types of peripheral neuropathy. PMID:22654839

Cholinergic, But Not Dopaminergic or Noradrenergic, Enhancement Sharpens Visual Spatial Perception in Humans

PubMed Central

Wallace, Deanna L.

2017-01-01

The neuromodulator acetylcholine modulates spatial integration in visual cortex by altering the balance of inputs that generate neuronal receptive fields. These cholinergic effects may provide a neurobiological mechanism underlying the modulation of visual representations by visual spatial attention. However, the consequences of cholinergic enhancement on visuospatial perception in humans are unknown. We conducted two experiments to test whether enhancing cholinergic signaling selectively alters perceptual measures of visuospatial interactions in human subjects. In Experiment 1, a double-blind placebo-controlled pharmacology study, we measured how flanking distractors influenced detection of a small contrast decrement of a peripheral target, as a function of target-flanker distance. We found that cholinergic enhancement with the cholinesterase inhibitor donepezil improved target detection, and modeling suggested that this was mainly due to a narrowing of the extent of facilitatory perceptual spatial interactions. In Experiment 2, we tested whether these effects were selective to the cholinergic system or would also be observed following enhancements of related neuromodulators dopamine or norepinephrine. Unlike cholinergic enhancement, dopamine (bromocriptine) and norepinephrine (guanfacine) manipulations did not improve performance or systematically alter the spatial profile of perceptual interactions between targets and distractors. These findings reveal mechanisms by which cholinergic signaling influences visual spatial interactions in perception and improves processing of a visual target among distractors, effects that are notably similar to those of spatial selective attention. SIGNIFICANCE STATEMENT Acetylcholine influences how visual cortical neurons integrate signals across space, perhaps providing a neurobiological mechanism for the effects of visual selective attention. However, the influence of cholinergic enhancement on visuospatial perception remains unknown. Here we demonstrate that cholinergic enhancement improves detection of a target flanked by distractors, consistent with sharpened visuospatial perceptual representations. Furthermore, whereas most pharmacological studies focus on a single neurotransmitter, many neuromodulators can have related effects on cognition and perception. Thus, we also demonstrate that enhancing noradrenergic and dopaminergic systems does not systematically improve visuospatial perception or alter its tuning. Our results link visuospatial tuning effects of acetylcholine at the neuronal and perceptual levels and provide insights into the connection between cholinergic signaling and visual attention. PMID:28336568

Ultra-wide-field fundus autofluorescence in multiple evanescent white dot syndrome.

PubMed

Hashimoto, Hideaki; Kishi, Shoji

2015-04-01

To observe the progression of affected lesions using ultra-wide-field fundus autofluorescence (FAF) in multiple evanescent white dot syndrome. Retrospective, observational case series. setting: Institutional. 14 eyes of 13 patients (mean age, 35.8 years) with acute disease unilaterally. Patients underwent ultra-wide-field FAF, spectral-domain optical coherence tomography (SD OCT), multifocal electroretinography (mfERG), and Goldmann or automated perimetry; the best-corrected visual acuity (BCVA) and refractive error were measured. Ability of ultra-wide-field FAF to detect lesions with greater sensitivity compared with color fundus photography. Ultra-wide-field FAF imaging enabled improved visualization of the affected lesions and showed that the core lesion was in the posterior fundus involving the peripapillary retina and posterior pole and surrounded by hyper-autofluorescent spots outside the vascular arcade. The posterior lesions expanded rapidly and peripheral spots spread farther peripherally and reached a maximal extent during the acute stage. During follow-up, the peripheral hyper-autofluorescent spots resolved and then hyper-autofluorescence of the posterior fundus gradually faded. SD OCT showed diffuse disruption of the photoreceptor inner segment/outer segment junction (IS/OS) in the posterior fundus during the acute stage. The correlation between the IS/OS abnormality and hyper-autofluorescent areas was unclear. The disrupted IS/OS was restored with normalization of the FAF. Ultra-wide-field FAF showed that the lesions arise from the peripapillary retina and the posterior pole and spread peripherally in a centrifugal manner during the acute stage. The hyper-autofluorescent spots faded from the periphery in a centripetal manner. Copyright © 2015 Elsevier Inc. All rights reserved.

Salient sounds activate human visual cortex automatically.

PubMed

McDonald, John J; Störmer, Viola S; Martinez, Antigona; Feng, Wenfeng; Hillyard, Steven A

2013-05-22

Sudden changes in the acoustic environment enhance perceptual processing of subsequent visual stimuli that appear in close spatial proximity. Little is known, however, about the neural mechanisms by which salient sounds affect visual processing. In particular, it is unclear whether such sounds automatically activate visual cortex. To shed light on this issue, this study examined event-related brain potentials (ERPs) that were triggered either by peripheral sounds that preceded task-relevant visual targets (Experiment 1) or were presented during purely auditory tasks (Experiments 2-4). In all experiments the sounds elicited a contralateral ERP over the occipital scalp that was localized to neural generators in extrastriate visual cortex of the ventral occipital lobe. The amplitude of this cross-modal ERP was predictive of perceptual judgments about the contrast of colocalized visual targets. These findings demonstrate that sudden, intrusive sounds reflexively activate human visual cortex in a spatially specific manner, even during purely auditory tasks when the sounds are not relevant to the ongoing task.

Salient sounds activate human visual cortex automatically

PubMed Central

McDonald, John J.; Störmer, Viola S.; Martinez, Antigona; Feng, Wenfeng; Hillyard, Steven A.

2013-01-01

Sudden changes in the acoustic environment enhance perceptual processing of subsequent visual stimuli that appear in close spatial proximity. Little is known, however, about the neural mechanisms by which salient sounds affect visual processing. In particular, it is unclear whether such sounds automatically activate visual cortex. To shed light on this issue, the present study examined event-related brain potentials (ERPs) that were triggered either by peripheral sounds that preceded task-relevant visual targets (Experiment 1) or were presented during purely auditory tasks (Experiments 2, 3, and 4). In all experiments the sounds elicited a contralateral ERP over the occipital scalp that was localized to neural generators in extrastriate visual cortex of the ventral occipital lobe. The amplitude of this cross-modal ERP was predictive of perceptual judgments about the contrast of co-localized visual targets. These findings demonstrate that sudden, intrusive sounds reflexively activate human visual cortex in a spatially specific manner, even during purely auditory tasks when the sounds are not relevant to the ongoing task. PMID:23699530

Decoding Visual Location From Neural Patterns in the Auditory Cortex of the Congenitally Deaf

PubMed Central

Almeida, Jorge; He, Dongjun; Chen, Quanjing; Mahon, Bradford Z.; Zhang, Fan; Gonçalves, Óscar F.; Fang, Fang; Bi, Yanchao

2016-01-01

Sensory cortices of individuals who are congenitally deprived of a sense can exhibit considerable plasticity and be recruited to process information from the senses that remain intact. Here, we explored whether the auditory cortex of congenitally deaf individuals represents visual field location of a stimulus—a dimension that is represented in early visual areas. We used functional MRI to measure neural activity in auditory and visual cortices of congenitally deaf and hearing humans while they observed stimuli typically used for mapping visual field preferences in visual cortex. We found that the location of a visual stimulus can be successfully decoded from the patterns of neural activity in auditory cortex of congenitally deaf but not hearing individuals. This is particularly true for locations within the horizontal plane and within peripheral vision. These data show that the representations stored within neuroplastically changed auditory cortex can align with dimensions that are typically represented in visual cortex. PMID:26423461

Sweet bee venom pharmacopuncture for chemotherapy-induced peripheral neuropathy.

PubMed

Yoon, Jeungwon; Jeon, Ju-Hyun; Lee, Yeon-Weol; Cho, Chong-Kwan; Kwon, Ki-Rok; Shin, Ji-Eun; Sagar, Stephen; Wong, Raimond; Yoo, Hwa-Seung

2012-08-01

Chemotherapy-induced peripheral neuropathy (CIPN) is sensory and motor nerve damage to the peripheral nervous system caused by chemotherapeutic agents. It often causes pain and other varying degrees of neuropathic symptoms accompanied by functional limitations and reduced quality of life. Currently, there is no standard treatment protocol for the treatment of CIPN. In need of more research to develop new therapeutic options focusing on their safety, efficacy, and long-term sustained clinical effects, a pilot study of sweet bee venom pharmacopuncture (SBVP) for CIPN was conducted to build up preliminary efficacy data in the process of preparing for a future larger scale randomized controlled SBVP trial for CIPN. We conducted a prospective case series by analyzing the clinical observations made of CIPN patients treated with SBVP. A total of 11 eligible consecutive CIPN patients who visited East-West Cancer Center from June 1, 2010, to February 28, 2011, were treated with total of six SBVP treatments given within the 3-week period. The outcomes were measured using World Health Organization Common Toxicity Criteria for Peripheral neuropathy (WHO grading system), Patient Neurotoxicity Questionnaire (PNQ), Visual Analogue System (VAS), and Health-Related Quality of Life (HRQOL) collected at the baseline, post-second, fourth, and the final treatment. Patients were followed 3 weeks into no intervention to determine the sustained effects of pharmacopuncture. Both of the WHO CIPN grade and PNQ scores have shown a decrease in the level of neuropathy. VAS pain level has also shown a great decrease and improvement in patients' quality of life have also been detected though modest. Changes in WHO grade, VAS and Total HRQOL scores between the baseline and after the last treatment session were significant. Changes in WHO grade, Total PNQ, PNQ-sensory, VAS, Total HRQOL, and HRQOL-functional scores between the baseline and the 3-week follow-up were significant. The positive result of the study supports the potential value of conducting a fully powered trial to explore further efficacy of SBVP for CIPN. However a single positive result within this pilot study must be interpreted with caution. Copyright © 2012. Published by Elsevier B.V.

Peripheral choline acetyltransferase in rat skin demonstrated by immunohistochemistry.

PubMed

Hanada, Keiji; Kishimoto, Saburo; Bellier, Jean-Pierre; Kimura, Hiroshi

2013-03-01

Conventional choline acetyltransferase immunohistochemistry has been used widely for visualizing central cholinergic neurons and fibers but not often for labeling peripheral structures, probably because of their poor staining. The recent identification of the peripheral type of choline acetyltransferase (pChAT) has enabled the clear immunohistochemical detection of many known peripheral cholinergic elements. Here, we report the presence of pChAT-immunoreactive nerve fibers in rat skin. Intensely stained nerve fibers were distributed in association with eccrine sweat glands, blood vessels, hair follicles and portions just beneath the epidermis. These results suggest that pChAT-positive nerves participate in the sympathetic cholinergic innervation of eccrine sweat glands. Moreover, pChAT also appears to play a role in cutaneous sensory nerve endings. These findings are supported by the presence of many pChAT-positive neuronal cells in the sympathetic ganglion and dorsal root ganglion. Thus, pChAT immunohistochemistry should provide a novel and unique tool for studying cholinergic nerves in the skin.

Monitoring peripheral nerve degeneration in ALS by label-free stimulated Raman scattering imaging

NASA Astrophysics Data System (ADS)

Tian, Feng; Yang, Wenlong; Mordes, Daniel A.; Wang, Jin-Yuan; Salameh, Johnny S.; Mok, Joanie; Chew, Jeannie; Sharma, Aarti; Leno-Duran, Ester; Suzuki-Uematsu, Satomi; Suzuki, Naoki; Han, Steve S.; Lu, Fa-Ke; Ji, Minbiao; Zhang, Rosanna; Liu, Yue; Strominger, Jack; Shneider, Neil A.; Petrucelli, Leonard; Xie, X. Sunney; Eggan, Kevin

2016-10-01

The study of amyotrophic lateral sclerosis (ALS) and potential interventions would be facilitated if motor axon degeneration could be more readily visualized. Here we demonstrate that stimulated Raman scattering (SRS) microscopy could be used to sensitively monitor peripheral nerve degeneration in ALS mouse models and ALS autopsy materials. Three-dimensional imaging of pre-symptomatic SOD1 mouse models and data processing by a correlation-based algorithm revealed that significant degeneration of peripheral nerves could be detected coincidentally with the earliest detectable signs of muscle denervation and preceded physiologically measurable motor function decline. We also found that peripheral degeneration was an early event in FUS as well as C9ORF72 repeat expansion models of ALS, and that serial imaging allowed long-term observation of disease progression and drug effects in living animals. Our study demonstrates that SRS imaging is a sensitive and quantitative means of measuring disease progression, greatly facilitating future studies of disease mechanisms and candidate therapeutics.

Surgical treatment of advanced pellucid marginal degeneration.

PubMed

Rasheed, K; Rabinowitz, Y S

2000-10-01

To determine the efficacy of simultaneous peripheral crescentic lamellar keratoplasty (LK) and central penetrating keratoplasty (PK) for advanced pellucid marginal degeneration (PMD). Retrospective, noncomparative, interventional case series. Five patients with advanced PMD. Simultaneous peripheral crescentic LK and central PK followed by selective suture removal and astigmatic keratotomy in the postoperative period. These included interval of time required for visual rehabilitation, best spectacle-corrected visual acuity achieved, and amount of corneal astigmatism, as measured by videokeratography. Measuring the change in corneal astigmatism by videokeratography over the subsequent follow-up period after spectacle correction had been prescribed assessed stability of the achieved refraction. Visual acuity results were 20/40 in three eyes, 20/80 in one eye, and 20/400 in one eye. The latter two had decreased acuity from posterior subcapsular cataract formation, which may have been caused by topical steroid use. The time required for visual rehabilitation ranged from 5.13 to 10.93 (mean, 9.92) months, and the amount of corneal astigmatism at the end of this period ranged from 0.3 diopters (D) to 5.3 D. A tendency for an increase in "with the rule astigmatism" after the rehabilitation period was noted. Two patients had elevations of intraocular pressure that responded to reduction in topical steroid dose. The short-term results with this technique are excellent in that it provides early and stable visual rehabilitation in patients with advanced PMD. Low to moderate levels of postkeratoplasty astigmatism were achieved in all the eyes treated. The usual tendency of an increase in "against the rule astigmatism" that occurs when PK alone is done for PMD was eliminated.

Sensory and Perceptual Functions in the Cerebral Palsied. III. Some Visual Perceptual Relationships

ERIC Educational Resources Information Center

Breakey, Arnold Stewart; And Others

1974-01-01

The relationships between specific aspects of peripheral ocular defects and perceptual deficits were investigated in a cerebral palsied population of 60 spastics, 60 athetoids, and 60 non-neurologically impaired Ss, 7 to 21 years of age. (Author/MC)

Postural Control and Gait Performance in the Diabetic Peripheral Neuropathy: A Systematic Review

PubMed Central

Mustapa, Amirah; Mohd Mustafah, Nadia; Jamil, Nursuriati

2016-01-01

Purpose. The aim of this paper is to review the published studies on the characteristics of impairments in the postural control and gait performance in diabetic peripheral neuropathy (DPN). Methods. A review was performed by obtaining publication of all papers reporting on the postural control and gait performance in DPN from Google Scholar, Ovid, SAGE, Springerlink, Science Direct (SD), EBSCO Discovery Service, and Web of Science databases. The keywords used for searching were “postural control,” “balance,” “gait performance,” “diabetes mellitus,” and “diabetic peripheral neuropathy.” Results. Total of 4,337 studies were hit in the search. 1,524 studies were screened on their titles and citations. Then, 79 studies were screened on their abstract. Only 38 studies were eligible to be selected: 17 studies on postural control and 21 studies on the gait performance. Most previous researches were found to have strong evidence of postural control impairments and noticeable gait deficits in DPN. Deterioration of somatosensory, visual, and vestibular systems with the pathologic condition of diabetes on cognitive impairment causes further instability of postural and gait performance in DPN. Conclusions. Postural instability and gait imbalance in DPN may contribute to high risk of fall incidence, especially in the geriatric population. Thus, further works are crucial to highlight this fact in the hospital based and community adults. PMID:27525281

A New Font, Specifically Designed for Peripheral Vision, Improves Peripheral Letter and Word Recognition, but Not Eye-Mediated Reading Performance

PubMed Central

Bernard, Jean-Baptiste; Aguilar, Carlos; Castet, Eric

2016-01-01

Reading speed is dramatically reduced when readers cannot use their central vision. This is because low visual acuity and crowding negatively impact letter recognition in the periphery. In this study, we designed a new font (referred to as the Eido font) in order to reduce inter-letter similarity and consequently to increase peripheral letter recognition performance. We tested this font by running five experiments that compared the Eido font with the standard Courier font. Letter spacing and x-height were identical for the two monospaced fonts. Six normally-sighted subjects used exclusively their peripheral vision to run two aloud reading tasks (with eye movements), a letter recognition task (without eye movements), a word recognition task (without eye movements) and a lexical decision task. Results show that reading speed was not significantly different between the Eido and the Courier font when subjects had to read single sentences with a round simulated gaze-contingent central scotoma (10° diameter). In contrast, Eido significantly decreased perceptual errors in peripheral crowded letter recognition (-30% errors on average for letters briefly presented at 6° eccentricity) and in peripheral word recognition (-32% errors on average for words briefly presented at 6° eccentricity). PMID:27074013

A New Font, Specifically Designed for Peripheral Vision, Improves Peripheral Letter and Word Recognition, but Not Eye-Mediated Reading Performance.

PubMed

Bernard, Jean-Baptiste; Aguilar, Carlos; Castet, Eric

2016-01-01

Reading speed is dramatically reduced when readers cannot use their central vision. This is because low visual acuity and crowding negatively impact letter recognition in the periphery. In this study, we designed a new font (referred to as the Eido font) in order to reduce inter-letter similarity and consequently to increase peripheral letter recognition performance. We tested this font by running five experiments that compared the Eido font with the standard Courier font. Letter spacing and x-height were identical for the two monospaced fonts. Six normally-sighted subjects used exclusively their peripheral vision to run two aloud reading tasks (with eye movements), a letter recognition task (without eye movements), a word recognition task (without eye movements) and a lexical decision task. Results show that reading speed was not significantly different between the Eido and the Courier font when subjects had to read single sentences with a round simulated gaze-contingent central scotoma (10° diameter). In contrast, Eido significantly decreased perceptual errors in peripheral crowded letter recognition (-30% errors on average for letters briefly presented at 6° eccentricity) and in peripheral word recognition (-32% errors on average for words briefly presented at 6° eccentricity).

Sounds Activate Visual Cortex and Improve Visual Discrimination

PubMed Central

Störmer, Viola S.; Martinez, Antigona; McDonald, John J.; Hillyard, Steven A.

2014-01-01

A recent study in humans (McDonald et al., 2013) found that peripheral, task-irrelevant sounds activated contralateral visual cortex automatically as revealed by an auditory-evoked contralateral occipital positivity (ACOP) recorded from the scalp. The present study investigated the functional significance of this cross-modal activation of visual cortex, in particular whether the sound-evoked ACOP is predictive of improved perceptual processing of a subsequent visual target. A trial-by-trial analysis showed that the ACOP amplitude was markedly larger preceding correct than incorrect pattern discriminations of visual targets that were colocalized with the preceding sound. Dipole modeling of the scalp topography of the ACOP localized its neural generators to the ventrolateral extrastriate visual cortex. These results provide direct evidence that the cross-modal activation of contralateral visual cortex by a spatially nonpredictive but salient sound facilitates the discriminative processing of a subsequent visual target event at the location of the sound. Recordings of event-related potentials to the targets support the hypothesis that the ACOP is a neural consequence of the automatic orienting of visual attention to the location of the sound. PMID:25031419

Development and evaluation of vision rehabilitation devices.

PubMed

Luo, Gang; Peli, Eli

2011-01-01

We have developed a range of vision rehabilitation devices and techniques for people with impaired vision due to either central vision loss or severely restricted peripheral visual field. We have conducted evaluation studies with patients to test the utilities of these techniques in an effort to document their advantages as well as their limitations. Here we describe our work on a visual field expander based on a head mounted display (HMD) for tunnel vision, a vision enhancement device for central vision loss, and a frequency domain JPEG/MPEG based image enhancement technique. All the evaluation studies included visual search paradigms that are suitable for conducting indoor controllable experiments.

Spatial Disorientation in Military Vehicles: Causes, Consequences and Cures (Desorientation spaiale dans les vehicules militaires: causes, consequences et remedes)

DTIC Science & Technology

2003-02-01

servcice warfighters (Training devices and protocols, Onboard equipment, Cognitive and sensorimotor aids, Visual and auditory symbology, Peripheral visual...vestibular stimulation causing a decrease in cerebral blood pressure with the consequent reduction in G-tolerance and increased likelihood of ALOC or GLOC...tactile stimulators (e.g. one providing a sensation of movement) or of displays with a more complex coding (e.g. by increase in the number of tactors, or

Peripheral defocus does not necessarily affect central refractive development.

PubMed

Schippert, Ruth; Schaeffel, Frank

2006-10-01

Recent experiments in monkeys suggest that deprivation, imposed only in the periphery of the visual field, can induce foveal myopia. This raises the hypothesis that peripheral refractive errors imposed by the spectacle lens correction could influence foveal refractive development also in humans. We have tested this hypothesis in chicks. Chicks wore either full field spectacle lenses (+6.9 D/-7 D), or lenses with central holes of 4, 6, or 8mm diameter, for 4 days (n=6 for each group). Refractions were measured in the central visual field, and at -45 degrees (temporal) and +45 degrees (nasal), and axial lengths were measured by A-scan ultrasonography. As previously described, full field lenses were largely compensated within 4 days (refraction changes with positive lenses: +4.69+/-1.73 D, negative lenses: -5.98+/-1.78 D, both p<0.001, Dunnett's test, to untreated controls). With holes in the center of the lenses, the central refraction remained emmetropic and there was not even a trend of a shift in refraction (all groups: p>0.5, Dunnetts test). At +/-45 degrees , the lenses were partially compensated despite the 4/6/8mm central holes; positive lenses: +2.63 / +1.44 / +0.43 D, negative lenses: -2.57 / -1.06 / +0.06 D. There is extensive local compensation of imposed refractive errors in chickens. For the tested hole sizes, peripherally imposed defocus did not influence central refractive development. To alter central refractive development, the unobstructed part in the central visual field may have to be quite small (hole sizes smaller than 4mm, with the lenses at a vertex distance of 2-3mm).

Using task effort and pupil size to track covert shifts of visual attention independently of a pupillary light reflex.

PubMed

Brocher, Andreas; Harbecke, Raphael; Graf, Tim; Memmert, Daniel; Hüttermann, Stefanie

2018-03-07

We tested the link between pupil size and the task effort involved in covert shifts of visual attention. The goal of this study was to establish pupil size as a marker of attentional shifting in the absence of luminance manipulations. In three experiments, participants evaluated two stimuli that were presented peripherally, appearing equidistant from and on opposite sides of eye fixation. The angle between eye fixation and the peripherally presented target stimuli varied from 12.5° to 42.5°. The evaluation of more distant stimuli led to poorer performance than did the evaluation of more proximal stimuli throughout our study, confirming that the former required more effort than the latter. In addition, in Experiment 1 we found that pupil size increased with increasing angle and that this effect could not be reduced to the operation of low-level visual processes in the task. In Experiment 2 the pupil dilated more strongly overall when participants evaluated the target stimuli, which required shifts of attention, than when they merely reported on the target's presence versus absence. Both conditions yielded larger pupils for more distant than for more proximal stimuli, however. In Experiment 3, we manipulated task difficulty more directly, by changing the contrast at which the target stimuli were presented. We replicated the results from Experiment 1 only with the high-contrast stimuli. With stimuli of low contrast, ceiling effects in pupil size were observed. Our data show that the link between task effort and pupil size can be used to track the degree to which an observer covertly shifts attention to or detects stimuli in peripheral vision.

A novel wide-field-of-view display method with higher central resolution for hyper-realistic head dome projector

NASA Astrophysics Data System (ADS)

Hotta, Aira; Sasaki, Takashi; Okumura, Haruhiko

2007-02-01

In this paper, we propose a novel display method to realize a high-resolution image in a central visual field for a hyper-realistic head dome projector. The method uses image processing based on the characteristics of human vision, namely, high central visual acuity and low peripheral visual acuity, and pixel shift technology, which is one of the resolution-enhancing technologies for projectors. The projected image with our method is a fine wide-viewing-angle image with high definition in the central visual field. We evaluated the psychological effects of the projected images with our method in terms of sensation of reality. According to the result, we obtained 1.5 times higher resolution in the central visual field and a greater sensation of reality by using our method.

Recruitment of Foveal Retinotopic Cortex During Haptic Exploration of Shapes and Actions in the Dark.

PubMed

Monaco, Simona; Gallivan, Jason P; Figley, Teresa D; Singhal, Anthony; Culham, Jody C

2017-11-29

The role of the early visual cortex and higher-order occipitotemporal cortex has been studied extensively for visual recognition and to a lesser degree for haptic recognition and visually guided actions. Using a slow event-related fMRI experiment, we investigated whether tactile and visual exploration of objects recruit the same "visual" areas (and in the case of visual cortex, the same retinotopic zones) and if these areas show reactivation during delayed actions in the dark toward haptically explored objects (and if so, whether this reactivation might be due to imagery). We examined activation during visual or haptic exploration of objects and action execution (grasping or reaching) separated by an 18 s delay. Twenty-nine human volunteers (13 females) participated in this study. Participants had their eyes open and fixated on a point in the dark. The objects were placed below the fixation point and accordingly visual exploration activated the cuneus, which processes retinotopic locations in the lower visual field. Strikingly, the occipital pole (OP), representing foveal locations, showed higher activation for tactile than visual exploration, although the stimulus was unseen and location in the visual field was peripheral. Moreover, the lateral occipital tactile-visual area (LOtv) showed comparable activation for tactile and visual exploration. Psychophysiological interaction analysis indicated that the OP showed stronger functional connectivity with anterior intraparietal sulcus and LOtv during the haptic than visual exploration of shapes in the dark. After the delay, the cuneus, OP, and LOtv showed reactivation that was independent of the sensory modality used to explore the object. These results show that haptic actions not only activate "visual" areas during object touch, but also that this information appears to be used in guiding grasping actions toward targets after a delay. SIGNIFICANCE STATEMENT Visual presentation of an object activates shape-processing areas and retinotopic locations in early visual areas. Moreover, if the object is grasped in the dark after a delay, these areas show "reactivation." Here, we show that these areas are also activated and reactivated for haptic object exploration and haptically guided grasping. Touch-related activity occurs not only in the retinotopic location of the visual stimulus, but also at the occipital pole (OP), corresponding to the foveal representation, even though the stimulus was unseen and located peripherally. That is, the same "visual" regions are implicated in both visual and haptic exploration; however, touch also recruits high-acuity central representation within early visual areas during both haptic exploration of objects and subsequent actions toward them. Functional connectivity analysis shows that the OP is more strongly connected with ventral and dorsal stream areas when participants explore an object in the dark than when they view it. Copyright © 2017 the authors 0270-6474/17/3711572-20$15.00/0.

Elucidating the mechanism of posterior reversible encephalopathy syndrome: a case of transient blindness after central venous catheterization.

PubMed

Rao, Neal M; Raychev, Radoslav; Kim, Doojin; Liebeskind, David S

2012-11-01

Posterior reversible encephalopathy syndrome (PRES) is a condition characterized by reversible symptoms including headache, visual disturbances, focal neurological deficits, altered mentation, and seizures. It has been associated with circumstances that may affect the cerebrovascular system, such as hypertension, eclampsia, and immunosuppression with calcineurin inhibitors. The underlying etiology of PRES has remained unclear; however, cerebrovascular autoregulatory dysfunction, hyperperfusion, and endothelial activation have been implicated. We describe a case of a young patient with lung transplant, who presented with headache, acute binocular blindness, and seizure immediately after infusion of saline through a peripherally inserted central catheter line, which inadvertently terminated cephalad in the left internal jugular vein, near the jugular foramen. Subsequent brain magnetic resonance imaging revealed vasogenic edematous lesions in a pattern consistent with PRES--a diagnosis supported by his constellation of symptoms, history of lung transplantation on tacrolimus immunosuppression, and relative hypertension. This is the first reported case describing the development of PRES after the insertion of a peripherally inserted central catheter line. The development of PRES in a typical high-risk patient immediately after cerebral venous outflow obstruction implicates the role of the cerebral venous system and provides potential insight into the mechanism of this disorder that remains of unclear pathogenesis.

Mud extrusion and ring-fault gas seepage - upward branching fluid discharge at a deep-sea mud volcano.

PubMed

Loher, M; Pape, T; Marcon, Y; Römer, M; Wintersteller, P; Praeg, D; Torres, M; Sahling, H; Bohrmann, G

2018-04-19

Submarine mud volcanoes release sediments and gas-rich fluids at the seafloor via deeply-rooted plumbing systems that remain poorly understood. Here the functioning of Venere mud volcano, on the Calabrian accretionary prism in ~1,600 m water depth is investigated, based on multi-parameter hydroacoustic and visual seafloor data obtained using ship-borne methods, ROVs, and AUVs. Two seepage domains are recognized: mud breccia extrusion from a summit, and hydrocarbon venting from peripheral sites, hosting chemosynthetic ecosystems and authigenic carbonates indicative of long-term seepage. Pore fluids in freshly extruded mud breccia (up to 13 °C warmer than background sediments) contained methane concentrations exceeding saturation by 2.7 times and chloride concentrations up to five times lower than ambient seawater. Gas analyses indicate an underlying thermogenic hydrocarbon source with potential admixture of microbial methane during migration along ring faults to the peripheral sites. The gas and pore water analyses point to fluids sourced deep (>3 km) below Venere mud volcano. An upward-branching plumbing system is proposed to account for co-existing mud breccia extrusion and gas seepage via multiple surface vents that influence the distribution of seafloor ecosystems. This model of mud volcanism implies that methane-rich fluids may be released during prolonged phases of moderate activity.

Peripheral Refraction Validity of the Shin-Nippon SRW5000 Autorefractor.

PubMed

Osuagwu, Uchechukwu Levi; Suheimat, Marwan; Wolffsohn, James S; Atchison, David A

2016-10-01

To investigate the operation of the Shin-Nippon/Grand Seiko autorefractor and whether higher-order aberrations affect its peripheral refraction measurements. Information on instrument design, together with parameters and equations used to obtain refraction, was obtained from a patent. A model eye simulating the operating principles was tested with an optical design program. Effects of induced defocus and astigmatism on the retinal image were used to calibrate the model eye to match the patent equations. Coma and trefoil were added to assess their effects on the image. Peripheral refraction of a physical model eye was measured along four visual field meridians with the Shin-Nippon/Grand Seiko autorefractor SRW-5000 and a Hartmann-Shack aberrometer, and simulated autorefractor peripheral refraction was derived using the Zernike coefficients from the aberrometer. In simulation, the autorefractor's square image was changed in size by defocus, into rectangles or parallelograms by astigmatism, and into irregular shapes by coma and trefoil. In the presence of 1.0 D oblique astigmatism, errors in refraction were proportional to the higher-order aberrations, with up to 0.8 D sphere and 1.5 D cylinder for ±0.6 μm of coma or trefoil coefficients with a 5-mm-diameter pupil. For the physical model eye, refraction with the aberrometer was similar in all visual field meridians, but refraction with the autorefractor changed more quickly along one oblique meridian and less quickly along the other oblique meridian than along the horizontal and vertical meridians. Simulations predicted that higher-order aberrations would affect refraction in oblique meridians, and this was supported by the experimental measurements with the physical model eye. The autorefractor's peripheral refraction measurements are valid for horizontal and vertical field meridians, but not for oblique field meridians. Similar instruments must be validated before being adopted outside their design scope.

The Effects of Restricted Peripheral Field-of-View on Spatial Learning while Navigating.

PubMed

Barhorst-Cates, Erica M; Rand, Kristina M; Creem-Regehr, Sarah H

2016-01-01

Recent work with simulated reductions in visual acuity and contrast sensitivity has found decrements in survey spatial learning as well as increased attentional demands when navigating, compared to performance with normal vision. Given these findings, and previous work showing that peripheral field loss has been associated with impaired mobility and spatial memory for room-sized spaces, we investigated the role of peripheral vision during navigation using a large-scale spatial learning paradigm. First, we aimed to establish the magnitude of spatial memory errors at different levels of field restriction. Second, we tested the hypothesis that navigation under these different levels of restriction would use additional attentional resources. Normally sighted participants walked on novel real-world paths wearing goggles that restricted the field-of-view (FOV) to severe (15°, 10°, 4°, or 0°) or mild angles (60°) and then pointed to remembered target locations using a verbal reporting measure. They completed a concurrent auditory reaction time task throughout each path to measure cognitive load. Only the most severe restrictions (4° and blindfolded) showed impairment in pointing error compared to the mild restriction (within-subjects). The 10° and 4° conditions also showed an increase in reaction time on the secondary attention task, suggesting that navigating with these extreme peripheral field restrictions demands the use of limited cognitive resources. This comparison of different levels of field restriction suggests that although peripheral field loss requires the actor to use more attentional resources while navigating starting at a less extreme level (10°), spatial memory is not negatively affected until the restriction is very severe (4°). These results have implications for understanding of the mechanisms underlying spatial learning during navigation and the approaches that may be taken to develop assistance for navigation with visual impairment.

The effect of fractal contact lenses on peripheral refraction in myopic model eyes.

PubMed

Rodriguez-Vallejo, Manuel; Benlloch, Josefa; Pons, Amparo; Monsoriu, Juan A; Furlan, Walter D

2014-12-01

To test multizone contact lenses in model eyes: Fractal Contact Lenses (FCLs), designed to induce myopic peripheral refractive error (PRE). Zemax ray-tracing software was employed to simulate myopic and accommodation-dependent model eyes fitted with FCLs. PRE, defined in terms of mean sphere M and 90°-180° astigmatism J180, was computed at different peripheral positions, ranging from 0 to 35° in steps of 5°, and for different pupil diameters (PDs). Simulated visual performance and changes in the PRE were also analyzed for contact lens decentration and model eye accommodation. For comparison purposes, the same simulations were performed with another commercially available contact lens designed for the same intended use: the Dual Focus (DF). PRE was greater with FCL than with DF when both designs were tested for a 3.5 mm PD, and with and without decentration of the lenses. However, PRE depended on PD with both multizone lenses, with a remarkable reduction of the myopic relative effect for a PD of 5.5 mm. The myopic PRE with contact lenses decreased as the myopic refractive error increased, but this could be compensated by increasing the power of treatment zones. A peripheral myopic shift was also induced by the FCLs in the accommodated model eye. In regard to visual performance, a myopia under-correction with reference to the circle of least confusion was obtained in all cases for a 5.5 mm PD. The ghost images, generated by treatment zones of FCL, were dimmer than the ones produced with DF lens of the same power. FCLs produce a peripheral myopic defocus without compromising central vision in photopic conditions. FCLs have several design parameters that can be varied to obtain optimum results: lens diameter, number of zones, addition and asphericity; resulting in a very promising customized lens for the treatment of myopia progression.

Chewing side preference is associated with hemispheric laterality in healthy adults.

PubMed

Serel Arslan, Selen; İnal, Özgü; Demir, Numan; Ölmez, Merih Seval; Karaduman, Aynur Ayşe

2017-06-01

Purpose To investigate if chewing side preference (CSP) can be used as an indicator of hemispheric laterality in healthy adults. Materials and methods Seventy-five individuals were included. The visual analogue scale (VAS) was used to determine CSP and laterality test for preferred peripheral organs. Results Significant correlation between CSP and hand, foot, ear, and eye side preference was found (r = .41, p < .001; r = .34, p = .003; r = .35, p = .03; r = .36, p = .002). Conclusion Besides peripheral organs, the CSP can also be used in determination of hemispheric lateralization.

The Effects of Spatial Endogenous Pre-cueing across Eccentricities

PubMed Central

Feng, Jing; Spence, Ian

2017-01-01

Frequently, we use expectations about likely locations of a target to guide the allocation of our attention. Despite the importance of this attentional process in everyday tasks, examination of pre-cueing effects on attention, particularly endogenous pre-cueing effects, has been relatively little explored outside an eccentricity of 20°. Given the visual field has functional subdivisions that attentional processes can differ significantly among the foveal, perifoveal, and more peripheral areas, how endogenous pre-cues that carry spatial information of targets influence our allocation of attention across a large visual field (especially in the more peripheral areas) remains unclear. We present two experiments examining how the expectation of the location of the target shapes the distribution of attention across eccentricities in the visual field. We measured participants’ ability to pick out a target among distractors in the visual field after the presentation of a highly valid cue indicating the size of the area in which the target was likely to occur, or the likely direction of the target (left or right side of the display). Our first experiment showed that participants had a higher target detection rate with faster responses, particularly at eccentricities of 20° and 30°. There was also a marginal advantage of pre-cueing effects when trials of the same size cue were blocked compared to when trials were mixed. Experiment 2 demonstrated a higher target detection rate when the target occurred at the cued direction. This pre-cueing effect was greater at larger eccentricities and with a longer cue-target interval. Our findings on the endogenous pre-cueing effects across a large visual area were summarized using a simple model to assist in conceptualizing the modifications of the distribution of attention over the visual field. We discuss our finding in light of cognitive penetration of perception, and highlight the importance of examining attentional process across a large area of the visual field. PMID:28638353

The Effects of Spatial Endogenous Pre-cueing across Eccentricities.

PubMed

Feng, Jing; Spence, Ian

2017-01-01

Frequently, we use expectations about likely locations of a target to guide the allocation of our attention. Despite the importance of this attentional process in everyday tasks, examination of pre-cueing effects on attention, particularly endogenous pre-cueing effects, has been relatively little explored outside an eccentricity of 20°. Given the visual field has functional subdivisions that attentional processes can differ significantly among the foveal, perifoveal, and more peripheral areas, how endogenous pre-cues that carry spatial information of targets influence our allocation of attention across a large visual field (especially in the more peripheral areas) remains unclear. We present two experiments examining how the expectation of the location of the target shapes the distribution of attention across eccentricities in the visual field. We measured participants' ability to pick out a target among distractors in the visual field after the presentation of a highly valid cue indicating the size of the area in which the target was likely to occur, or the likely direction of the target (left or right side of the display). Our first experiment showed that participants had a higher target detection rate with faster responses, particularly at eccentricities of 20° and 30°. There was also a marginal advantage of pre-cueing effects when trials of the same size cue were blocked compared to when trials were mixed. Experiment 2 demonstrated a higher target detection rate when the target occurred at the cued direction. This pre-cueing effect was greater at larger eccentricities and with a longer cue-target interval. Our findings on the endogenous pre-cueing effects across a large visual area were summarized using a simple model to assist in conceptualizing the modifications of the distribution of attention over the visual field. We discuss our finding in light of cognitive penetration of perception, and highlight the importance of examining attentional process across a large area of the visual field.

Individual differences in peripheral physiology and implications for the real-time assessment of driver state (phase I & II).

DOT National Transportation Integrated Search

2013-05-01

Cognitively oriented in-vehicle activities (cell-phone calls, speech interfaces, audio translations of text : messages, etc.) increasingly place non-visual demands on a drivers attention. While a drivers eyes may : remain oriented towards the r...

The effects of equine peripheral blood stem cells on cutaneous wound healing: a clinical evaluation in four horses.

PubMed

Spaas, J H; Broeckx, S; Van de Walle, G R; Polettini, M

2013-04-01

Stem-cell therapy represents a promising strategy for the treatment of challenging pathologies, such as large, infected wounds that are unresponsive to conventional therapies. The present study describes the clinical application of peripheral blood stem cells (PBSCs) for the treatment of four adult Warmblood horses with naturally occurring wounds, which were unresponsive to conventional therapies for at least 3 months. A visual assessment was performed, and a number of wound-healing parameters (granulation tissue, crust formation and scar formation) were evaluated. In all cases, tissue overgrowth was visible within 4 weeks after PBSC injection, followed by the formation of crusts and small scars in the centre of the wound, with hair regeneration at the edges. In conclusion, this is the first report of PBSC therapy of skin wounds in horses, and it produced a positive visual and clinical outcome. © The Author(s) CED © 2013 British Association of Dermatologists.

The Impact and Implication of Peripheral Vascular Leakage on Ultra-Widefield Fluorescein Angiography in Uveitis.

PubMed

Thomas, Akshay S; Redd, Travis; Campbell, John P; Palejwala, Neal V; Baynham, Justin T; Suhler, Eric B; Rosenbaum, James T; Lin, Phoebe

2017-10-16

To study if peripheral vascular leakage (PVL) on ultra-widefield fluorescein angiography (UWFFA) prognosticates complications of uveitis or necessitates treatment augmentation. Retrospective cohort study of uveitis patients imaged with UWFFA and ≥1 yr of follow-up. We included 73 eyes of 42 patients with uveitis. There was no difference in baseline, intermediate, final visual acuity (p = 0.47-0.95) or rates of cystoid macular edema (CME) (p = 0.37-0.87) in eyes with PVL vs. those without. Eyes with PVL receiving baseline treatment augmentation were more likely to have baseline CME but were not more likely to have impaired visual acuity at final follow-up. PVL was independently associated with treatment augmentation on generalized estimating equation analysis with multivariable linear regression (OR: 4.39, p = 0.015). PVL did not confer an increased risk of impaired VA or CME at ≥1 yr follow-up but was possibly an independent driver of treatment augmentation.

[The neuroscientific work of Justo Gonzalo (1910-1986): the center syndrome and reversal metamorphopsia].

PubMed

Arias, M; Gonzalo, I

2004-10-01

The Spanish neuroscientist Justo Gonzalo Rodriguez-Leal (Barcelona 1910, Madrid 1986) carried out different studies on cerebral functions, highlighting those made in patients with encephalic injuries suffered during the Spanish civil war. His book "Investigaciones sobre la nueva dinámica cerebral. La actividad cerebral en función de las condiciones de excitabilidad nerviosa", published in two volumes (the first one in 1945 and the second one five years later), gathers some of his fundamental contributions, among which the so-called central syndrome stands out. A dominant parietal lesion (central) equidistant from the visual, sensorial and auditory projection areas can lead to diverse perceptive dysfunctions, among them inversions in visual, tactile and acoustic perception. As the lesion becomes more peripheral, the resulting defect will be more unisensorial and crossed, while when it approaches the central region, the disorders will be bilateral and polysensorial. Justo Gonzalo explained all these phenomena later by a gradient system.

Does It Really Matter Where You Look When Walking on Stairs? Insights from a Dual-Task Study

PubMed Central

Miyasike-daSilva, Veronica; McIlroy, William E.

2012-01-01

Although the visual system is known to provide relevant information to guide stair locomotion, there is less understanding of the specific contributions of foveal and peripheral visual field information. The present study investigated the specific role of foveal vision during stair locomotion and ground-stairs transitions by using a dual-task paradigm to influence the ability to rely on foveal vision. Fifteen healthy adults (26.9±3.3 years; 8 females) ascended a 7-step staircase under four conditions: no secondary tasks (CONTROL); gaze fixation on a fixed target located at the end of the pathway (TARGET); visual reaction time task (VRT); and auditory reaction time task (ART). Gaze fixations towards stair features were significantly reduced in TARGET and VRT compared to CONTROL and ART. Despite the reduced fixations, participants were able to successfully ascend stairs and rarely used the handrail. Step time was increased during VRT compared to CONTROL in most stair steps. Navigating on the transition steps did not require more gaze fixations than the middle steps. However, reaction time tended to increase during locomotion on transitions suggesting additional executive demands during this phase. These findings suggest that foveal vision may not be an essential source of visual information regarding stair features to guide stair walking, despite the unique control challenges at transition phases as highlighted by phase-specific challenges in dual-tasking. Instead, the tendency to look at the steps in usual conditions likely provides a stable reference frame for extraction of visual information regarding step features from the entire visual field. PMID:22970297

[RESEARCH PROGRESS OF PERIPHERAL NERVE SURGERY ASSISTED BY Da Vinci ROBOTIC SYSTEM].

PubMed

Shen, Jie; Song, Diyu; Wang, Xiaoyu; Wang, Changjiang; Zhang, Shuming

2016-02-01

To summarize the research progress of peripheral nerve surgery assisted by Da Vinci robotic system. The recent domestic and international articles about peripheral nerve surgery assisted by Da Vinci robotic system were reviewed and summarized. Compared with conventional microsurgery, peripheral nerve surgery assisted by Da Vinci robotic system has distinctive advantages, such as elimination of physiological tremors and three-dimensional high-resolution vision. It is possible to perform robot assisted limb nerve surgery using either the traditional brachial plexus approach or the mini-invasive approach. The development of Da Vinci robotic system has revealed new perspectives in peripheral nerve surgery. But it has still been at the initial stage, more basic and clinical researches are still needed.

Semantic bifurcated importance field visualization

NASA Astrophysics Data System (ADS)

Lindahl, Eric; Petrov, Plamen

2007-04-01

While there are many good ways to map sensual reality to two dimensional displays, mapping non-physical and possibilistic information can be challenging. The advent of faster-than-real-time systems allow the predictive and possibilistic exploration of important factors that can affect the decision maker. Visualizing a compressed picture of the past and possible factors can assist the decision maker summarizing information in a cognitive based model thereby reducing clutter and perhaps related decision times. Our proposed semantic bifurcated importance field visualization uses saccadic eye motion models to partition the display into a possibilistic and sensed data vertically and spatial and semantic data horizontally. Saccadic eye movement precedes and prepares decision makers before nearly every directed action. Cognitive models for saccadic eye movement show that people prefer lateral to vertical saccadic movement. Studies have suggested that saccades may be coupled to momentary problem solving strategies. Also, the central 1.5 degrees of the visual field represents 100 times greater resolution that then peripheral field so concentrating factors can reduce unnecessary saccades. By packing information according to saccadic models, we can relate important decision factors reduce factor dimensionality and present the dense summary dimensions of semantic and importance. Inter and intra ballistics of the SBIFV provide important clues on how semantic packing assists in decision making. Future directions of SBIFV are to make the visualization reactive and conformal to saccades specializing targets to ballistics, such as dynamically filtering and highlighting verbal targets for left saccades and spatial targets for right saccades.

Oculo-vestibular recoupling using galvanic vestibular stimulation to mitigate simulator sickness.

PubMed

Cevette, Michael J; Stepanek, Jan; Cocco, Daniela; Galea, Anna M; Pradhan, Gaurav N; Wagner, Linsey S; Oakley, Sarah R; Smith, Benn E; Zapala, David A; Brookler, Kenneth H

2012-06-01

Despite improvement in the computational capabilities of visual displays in flight simulators, intersensory visual-vestibular conflict remains the leading cause of simulator sickness (SS). By using galvanic vestibular stimulation (GVS), the vestibular system can be synchronized with a moving visual field in order to lessen the mismatch of sensory inputs thought to result in SS. A multisite electrode array was used to deliver combinations of GVS in 21 normal subjects. Optimal electrode combinations were identified and used to establish GVS dose-response predictions for the perception of roll, pitch, and yaw. Based on these data, an algorithm was then implemented in flight simulator hardware in order to synchronize visual and GVS-induced vestibular sensations (oculo-vestibular-recoupled or OVR simulation). Subjects were then randomly exposed to flight simulation either with or without OVR simulation. A self-report SS checklist was administered to all subjects after each session. An overall SS score was calculated for each category of symptoms for both groups. The analysis of GVS stimulation data yielded six unique combinations of electrode positions inducing motion perceptions in the three rotational axes. This provided the algorithm used for OVR simulation. The overall SS scores for gastrointestinal, central, and peripheral categories were 17%, 22.4%, and 20% for the Control group and 6.3%, 20%, and 8% for the OVR group, respectively. When virtual head signals produced by GVS are synchronized to the speed and direction of a moving visual field, manifestations of induced SS in a cockpit flight simulator are significantly reduced.

Visual function and color vision in adults with Attention-Deficit/Hyperactivity Disorder.

PubMed

Kim, Soyeon; Chen, Samantha; Tannock, Rosemary

2014-01-01

Color vision and self-reported visual function in everyday life in young adults with Attention-Deficit/Hyperactivity Disorder (ADHD) were investigated. Participants were 30 young adults with ADHD and 30 controls matched for age and gender. They were tested individually and completed the Visual Activities Questionnaire (VAQ), Farnsworth-Munsell 100 Hue Test (FMT) and A Quick Test of Cognitive Speed (AQT). The ADHD group reported significantly more problems in 4 of 8 areas on the VAQ: depth perception, peripheral vision, visual search and visual processing speed. Further analyses of VAQ items revealed that the ADHD group endorsed more visual problems associated with driving than controls. Color perception difficulties on the FMT were restricted to the blue spectrum in the ADHD group. FMT and AQT results revealed slower processing of visual stimuli in the ADHD group. A comprehensive investigation of mechanisms underlying visual function and color vision in adults with ADHD is warranted, along with the potential impact of these visual problems on driving performance. Copyright © 2013 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

A second visual rhodopsin gene, rh1-2, is expressed in zebrafish photoreceptors and found in other ray-finned fishes.

PubMed

Morrow, James M; Lazic, Savo; Dixon Fox, Monica; Kuo, Claire; Schott, Ryan K; de A Gutierrez, Eduardo; Santini, Francesco; Tropepe, Vincent; Chang, Belinda S W

2017-01-15

Rhodopsin (rh1) is the visual pigment expressed in rod photoreceptors of vertebrates that is responsible for initiating the critical first step of dim-light vision. Rhodopsin is usually a single copy gene; however, we previously discovered a novel rhodopsin-like gene expressed in the zebrafish retina, rh1-2, which we identified as a functional photosensitive pigment that binds 11-cis retinal and activates in response to light. Here, we localized expression of rh1-2 in the zebrafish retina to a subset of peripheral photoreceptor cells, which indicates a partially overlapping expression pattern with rh1 We also expressed, purified and characterized Rh1-2, including investigation of the stability of the biologically active intermediate. Using fluorescence spectroscopy, we found the half-life of the rate of retinal release of Rh1-2 following photoactivation to be more similar to that of the visual pigment rhodopsin than to the non-visual pigment exo-rhodopsin (exorh), which releases retinal around 5 times faster. Phylogenetic and molecular evolutionary analyses show that rh1-2 has ancient origins within teleost fishes, is under similar selective pressure to rh1, and likely experienced a burst of positive selection following its duplication and divergence from rh1 These findings indicate that rh1-2 is another functional visual rhodopsin gene, which contradicts the prevailing notion that visual rhodopsin is primarily found as a single copy gene within ray-finned fishes. The reasons for retention of this duplicate gene, as well as possible functional consequences for the visual system, are discussed. © 2017. Published by The Company of Biologists Ltd.

Normal and sonographic anatomy of selected peripheral nerves. Part III: Peripheral nerves of the lower limb.

PubMed

Kowalska, Berta; Sudoł-Szopińska, Iwona

2012-06-01

The ultrasonographic examination is currently increasingly used in imaging peripheral nerves, serving to supplement the physical examination, electromyography and magnetic resonance imaging. As in the case of other USG imaging studies, the examination of peripheral nerves is non-invasive and well-tolerated by patients. The typical ultrasonographic picture of peripheral nerves as well as the examination technique have been discussed in part I of this article series, following the example of the median nerve. Part II of the series presented the normal anatomy and the technique for examining the peripheral nerves of the upper limb. This part of the article series focuses on the anatomy and technique for examining twelve normal peripheral nerves of the lower extremity: the iliohypogastric and ilioinguinal nerves, the lateral cutaneous nerve of the thigh, the pudendal, sciatic, tibial, sural, medial plantar, lateral plantar, common peroneal, deep peroneal and superficial peroneal nerves. It includes diagrams showing the proper positioning of the sonographic probe, plus USG images of the successively discussed nerves and their surrounding structures. The ultrasonographic appearance of the peripheral nerves in the lower limb is identical to the nerves in the upper limb. However, when imaging the lower extremity, convex probes are more often utilized, to capture deeply-seated nerves. The examination technique, similarly to that used in visualizing the nerves of upper extremity, consists of locating the nerve at a characteristic anatomic reference point and tracking it using the "elevator technique". All 3 parts of the article series should serve as an introduction to a discussion of peripheral nerve pathologies, which will be presented in subsequent issues of the "Journal of Ultrasonography".

Effect of single vision soft contact lenses on peripheral refraction.

PubMed

Kang, Pauline; Fan, Yvonne; Oh, Kelly; Trac, Kevin; Zhang, Frank; Swarbrick, Helen

2012-07-01

To investigate changes in peripheral refraction with under-, full, and over-correction of central refraction with commercially available single vision soft contact lenses (SCLs) in young myopic adults. Thirty-four myopic adult subjects were fitted with Proclear Sphere SCLs to under-correct (+0.75 DS), fully correct, and over-correct (-0.75 DS) their manifest central refractive error. Central and peripheral refraction were measured with no lens wear and subsequently with different levels of SCL central refractive error correction. The uncorrected refractive error was myopic at all locations along the horizontal meridian. Peripheral refraction was relatively hyperopic compared to center at 30 and 35° in the temporal visual field (VF) in low myopes and at 30 and 35° in the temporal VF and 10, 30, and 35° in the nasal VF in moderate myopes. All levels of SCL correction caused a hyperopic shift in refraction at all locations in the horizontal VF. The smallest hyperopic shift was demonstrated with under-correction followed by full correction and then by over-correction of central refractive error. An increase in relative peripheral hyperopia was measured with full correction SCLs compared with no correction in both low and moderate myopes. However, no difference in relative peripheral refraction profiles were found between under-, full, and over-correction. Under-, full, and over-correction of central refractive error with single vision SCLs caused a hyperopic shift in both central and peripheral refraction at all positions in the horizontal meridian. All levels of SCL correction caused the peripheral retina, which initially experienced absolute myopic defocus at baseline with no correction, to experience absolute hyperopic defocus. This peripheral hyperopia may be a possible cause of myopia progression reported with different types and levels of myopia correction.

Normal and sonographic anatomy of selected peripheral nerves. Part III: Peripheral nerves of the lower limb

PubMed Central

Sudoł-Szopińska, Iwona

2012-01-01

The ultrasonographic examination is currently increasingly used in imaging peripheral nerves, serving to supplement the physical examination, electromyography and magnetic resonance imaging. As in the case of other USG imaging studies, the examination of peripheral nerves is non-invasive and well-tolerated by patients. The typical ultrasonographic picture of peripheral nerves as well as the examination technique have been discussed in part I of this article series, following the example of the median nerve. Part II of the series presented the normal anatomy and the technique for examining the peripheral nerves of the upper limb. This part of the article series focuses on the anatomy and technique for examining twelve normal peripheral nerves of the lower extremity: the iliohypogastric and ilioinguinal nerves, the lateral cutaneous nerve of the thigh, the pudendal, sciatic, tibial, sural, medial plantar, lateral plantar, common peroneal, deep peroneal and superficial peroneal nerves. It includes diagrams showing the proper positioning of the sonographic probe, plus USG images of the successively discussed nerves and their surrounding structures. The ultrasonographic appearance of the peripheral nerves in the lower limb is identical to the nerves in the upper limb. However, when imaging the lower extremity, convex probes are more often utilized, to capture deeply-seated nerves. The examination technique, similarly to that used in visualizing the nerves of upper extremity, consists of locating the nerve at a characteristic anatomic reference point and tracking it using the “elevator technique”. All 3 parts of the article series should serve as an introduction to a discussion of peripheral nerve pathologies, which will be presented in subsequent issues of the “Journal of Ultrasonography”. PMID:26674560

Heritability of peripheral refraction in Chinese children and adolescents: the Guangzhou Twin Eye study.

PubMed

Ding, Xiaohu; Lin, Zhi; Huang, Qunxiao; Zheng, Yingfeng; Congdon, Nathan; He, Mingguang

2012-01-10

To estimate the heritability of peripheral refraction in Chinese children and adolescents. The authors examined 72 monozygotic (MZ) twins and 48 dizygotic (DZ) twins aged 8 to 20 years from a population-based twin registry. Temporal and nasal peripheral refraction, each 40° from the visual axis, and axial refraction were measured using an autorefractor. Relative peripheral refractive error (RPRE) was defined as the peripheral refraction minus the axial refraction. Heritability was assessed by structural equation modeling after adjustment for age and sex. The mean and SD of temporal refraction (T(40)), nasal refraction (N(40)), RPRE-T(40), RPRE-N(40), and T(40)-N(40) asymmetry were -0.27 ± 2.0 D, 0.36 ± 2.19 D, 1.18 ± 1.39 D, 1.80 ± 1.69 D, and -0.62 ± 1.58 D, respectively. The intraclass correlations for T(40) refraction, N(40) refraction, RPRE-T(40), RPRE-N(40), and T(40)-N(40) asymmetry were 0.87, 0.83, 0.65, 0.74, and 0.58 for MZ pairs and 0.49, 0.42, 0.30, 0.41, and 0.32 for DZ pairs, respectively. A model with additive genetic and unique environmental effects was the most parsimonious, with heritability values estimated as 0.84, 0.76, 0.63, 0.70, and 0.55, respectively, for the peripheral refractive parameters. Additive genetic effects appear to explain most of the variance in peripheral refraction and relative peripheral refraction when adjusting for the effects of axial refraction.

Pedal angiography in peripheral arterial occlusive disease: first-pass i.v. contrast-enhanced MR angiography with blood pool contrast medium versus intraarterial digital subtraction angiography.

PubMed

Kos, Sebastian; Reisinger, Clemens; Aschwanden, Markus; Bongartz, Georg M; Jacob, Augustinus L; Bilecen, Deniz

2009-03-01

The purpose of this study was to prospectively evaluate first-pass i.v. gadofosveset-enhanced MR angiography in patients with peripheral arterial occlusive disease for visualization of the pedal arteries and stenosis or occlusion of those arteries with intraarterial digital subtraction angiography as the reference standard. Twenty patients with peripheral arterial occlusive disease (nine women, 11 men; age-range 58-83 years) were prospectively enrolled. Gadofosveset first-pass contrast-enhanced MR angiography was performed with a 1.5-T system, a dedicated foot coil, and cuff compression to the calf. Arterial segments were assessed for degree of arterial stenosis, arterial visibility, diagnostic utility, and venous contamination. Detection of vessel stenosis or occlusion was evaluated in comparison with findings at digital subtraction angiography. The unpaired Student's t test was used to test arterial visibility with the two techniques. First-pass MR angiography with gadofosveset had good diagnostic utility in 83.9% of all segments and no venous contamination in 96.8% of all segments. There was no difference between the performance of intraarterial digital subtraction angiography and that of i.v. contrast-enhanced MR angiography in arterial visibility overall (p = 0.245) or in subgroup analysis of surgical arterial bypass targets (p = 0.202). The overall sensitivity, specificity, and accuracy of i.v. gadofosveset-enhanced MR angiography for characterization of clinically significant stenosis and occlusion were 91.4%, 96.1%, and 93.9%. In the subgroup analysis, the sensitivity, specificity, and accuracy were 85.5%, 96.5%, and 92.1%. Gadofosveset-enhanced MR angiography of the pedal arteries in patients with peripheral arterial occlusive disease has arterial visibility equal to that of digital subtraction angiography and facilitates depiction of clinically significant stenosis and occlusion.

An innovative approach to near-infrared spectroscopy using a standard mobile device and its clinical application in the real-time visualization of peripheral veins.

PubMed

Juric, Simon; Zalik, Borut

2014-11-25

Excessive venipunctures are a significant problem both in emergency rooms and during hospital stays. Near-infrared (NIR) illumination devices improve venipuncture success rate but their usage is limited by their availability and economic cost. The objectives of this study were to develop a low-cost NIR spectroscopy prototype from a standard mobile device, to evaluate its efficacy and acceptance as an educational tool, and in a clinical setting. Through a user-centric design process a prototype device was developed. Its educational efficacy was evaluated through a non-invasive, observational study (20 student clinicians, 25 subjects) and its acceptance was assessed using quantitative and qualitative analysis. A smaller clinical trial was performed by a group of 4 medical professionals over a period of 6 weeks that involved 64 patients. The prototype enables real-time visualization of peripheral veins on a variety of Android-based devices. The prototype was 35.2% more successful in visualizing and locating veins (n = 500 attempts) than the nursing students. The acceptance assessment revealed high perception of usefulness, satisfaction, and ease of use. In the clinical trial, 1.6 (SD 1.3) additional veins per patient were identified compared with the traditional visualization methods. To the best of our knowledge this is the first study that describes the design, feasibility and application of an NIR spectroscopy prototype developed on a standard mobile device.

The effect of flower-like and non-flower-like visual properties on choice of unrewarding patterns by bumblebees

NASA Astrophysics Data System (ADS)

Orbán, Levente L.; Plowright, Catherine M. S.

2013-07-01

How do distinct visual stimuli help bumblebees discover flowers before they have experienced any reward outside of their nest? Two visual floral properties, type of a pattern (concentric vs radial) and its position on unrewarding artificial flowers (central vs peripheral on corolla), were manipulated in two experiments. Both visual properties showed significant effects on floral choice. When pitted against each other, pattern was more important than position. Experiment 1 shows a significant effect of concentric pattern position, and experiment 2 shows a significant preference towards radial patterns regardless of their position. These results show that the presence of markings at the center of a flower are not so important as the presence of markings that will direct bees there.

Can manipulation of orthokeratology lens parameters modify peripheral refraction?

PubMed

Kang, Pauline; Gifford, Paul; Swarbrick, Helen

2013-11-01

To investigate changes in peripheral refraction, corneal topography, and aberrations induced by changes in orthokeratology (OK) lens parameters in myopes. Subjects were fitted with standard OK lenses that were worn overnight for 2 weeks. Peripheral refraction, corneal topography, and corneal surface aberrations were measured at baseline and after 14 nights of OK lens wear. Subsequent to a 2-week washout period, subjects were refitted with another set of lenses where one eye was randomly assigned to wear an OK lens with a smaller optic zone diameter (OZD) and the other eye with a steeper peripheral tangent. Measurements were taken again at a second baseline and after 14 days of overnight wear of the second OK lens set. Standard OK lenses with a 6-mm OZD and 1/4 peripheral tangent caused significant changes in both peripheral refraction and corneal topography. Significant hyperopic shift occurred in the central visual field (VF) while a myopic shift was found at 35 degrees in the nasal VF. OK induced significant reductions in corneal power at all positions along the horizontal corneal chord except at 2.4 mm nasal where there was no significant change and at 2.8 mm nasal where there was an increase in corneal refractive power. A positive shift in spherical aberration was induced for all investigated lens designs except for the 1/2 tangent design when calculated over a 4-mm pupil. Reducing OZD and steepening the peripheral tangent did not cause significant changes in peripheral refraction or corneal topography profiles across the horizontal meridian. OK lenses caused significant changes in peripheral refraction, corneal topography, and corneal surface aberrations. Modifying OZD and peripheral tangent made no significant difference to the peripheral refraction or corneal topography profile. Attempting to customize refraction and topography changes through manipulation of OK lens parameters appears to be a difficult task.

NEUROSENSORY EFFECTS OF CHRONIC HUMAN EXPOSURE TO ARSENIC ASSOCIATED WITH BODY BURDEN AND ENVIRONMENTAL MEASURES

EPA Science Inventory

Exposure to arsenic in drinking water is known to produce a variety of health problems including peripheral neuropathy. Auditory, visual and somatosensory impairments have been reported in Mongolian farmers living in the Yellow River Valley where drinking water is contami...

Substantial adverse association of visual and vascular comorbidities on visual disability in multiple sclerosis.

PubMed

Marrie, Ruth Ann; Cutter, Gary; Tyry, Tuula

2011-12-01

Visual comorbidities are common in multiple sclerosis (MS) but the impact of visual comorbidities on visual disability is unknown. We assessed the impact of visual and vascular comorbidities on severity of visual disability in MS. In 2006, we queried participants of the North American Research Committee on Multiple Sclerosis (NARCOMS) about cataracts, glaucoma, uveitis, hypertension, hypercholesterolemia, heart disease, diabetes and peripheral vascular disease. We assessed visual disability using the Vision subscale of Performance Scales. Using Cox regression, we investigated whether visual or vascular comorbidities affected the time between MS symptom onset and the development of mild, moderate and severe visual disability. Of 8983 respondents, 1415 (15.9%) reported a visual comorbidity while 4745 (52.8%) reported a vascular comorbidity. The median (interquartile range) visual score was 1 (0-2). In a multivariable Cox model the risk of mild visual disability was higher among participants with vascular (hazard ratio [HR] 1.45; 95% confidence interval [CI]: 1.39-1.51) and visual comorbidities (HR 1.47; 95% CI: 1.37-1.59). Vascular and visual comorbidities were similarly associated with increased risks of moderate and severe visual disability. Visual and vascular comorbidities are associated with progression of visual disability in MS. Clinicians hearing reports of worsening visual symptoms in MS patients should consider visual comorbidities as contributing factors. Further study of these issues using objective, systematic neuro-ophthalmologic evaluations is warranted.

Bio-inspired approach for intelligent unattended ground sensors

NASA Astrophysics Data System (ADS)

Hueber, Nicolas; Raymond, Pierre; Hennequin, Christophe; Pichler, Alexander; Perrot, Maxime; Voisin, Philippe; Moeglin, Jean-Pierre

2015-05-01

Improving the surveillance capacity over wide zones requires a set of smart battery-powered Unattended Ground Sensors capable of issuing an alarm to a decision-making center. Only high-level information has to be sent when a relevant suspicious situation occurs. In this paper we propose an innovative bio-inspired approach that mimics the human bi-modal vision mechanism and the parallel processing ability of the human brain. The designed prototype exploits two levels of analysis: a low-level panoramic motion analysis, the peripheral vision, and a high-level event-focused analysis, the foveal vision. By tracking moving objects and fusing multiple criteria (size, speed, trajectory, etc.), the peripheral vision module acts as a fast relevant event detector. The foveal vision module focuses on the detected events to extract more detailed features (texture, color, shape, etc.) in order to improve the recognition efficiency. The implemented recognition core is able to acquire human knowledge and to classify in real-time a huge amount of heterogeneous data thanks to its natively parallel hardware structure. This UGS prototype validates our system approach under laboratory tests. The peripheral analysis module demonstrates a low false alarm rate whereas the foveal vision correctly focuses on the detected events. A parallel FPGA implementation of the recognition core succeeds in fulfilling the embedded application requirements. These results are paving the way of future reconfigurable virtual field agents. By locally processing the data and sending only high-level information, their energy requirements and electromagnetic signature are optimized. Moreover, the embedded Artificial Intelligence core enables these bio-inspired systems to recognize and learn new significant events. By duplicating human expertise in potentially hazardous places, our miniature visual event detector will allow early warning and contribute to better human decision making.

Reversible cerebellar dysfunction associated with ciguatera fish poisoning.

PubMed

Oh, Sun-Young; Kim, Do-Hyung; Seo, Man-Wook; Shin, Byoung-Soo

2012-10-01

Ciguatera-fish poisoning (or ciguatera) is a common but underdiagnosed food-borne illness related to fish consumption that is characterized by nausea, vomiting and neurologic symptoms such as tingling in the fingers or toes. We describe the case of a young man who suffered from diarrhea and abdominal pain after eating raw fish and who also developed severe ataxia with spontaneous downbeat and perverted head-shaking nystagmus. The patient experienced visual fixation suppression failure during the bithermal caloric test and bilateral smooth-pursuit impairment. Oculomotor findings suggested dysfunction of the vestibulocerebellum, especially the flocculus. These findings suggest that both the peripheral and the central nervous systems can be involved in ciguatera. Copyright © 2012 Elsevier Inc. All rights reserved.

Oxaliplatin in Treating Young Patients With Recurrent Solid Tumors That Have Not Responded to Previous Treatment

ClinicalTrials.gov

2013-06-04

Childhood Central Nervous System Germ Cell Tumor; Childhood Extragonadal Germ Cell Tumor; Childhood Hepatoblastoma; Childhood Hepatocellular Carcinoma; Childhood High-grade Cerebral Astrocytoma; Childhood Low-grade Cerebral Astrocytoma; Childhood Malignant Ovarian Germ Cell Tumor; Childhood Malignant Testicular Germ Cell Tumor; Childhood Teratoma; Recurrent Adrenocortical Carcinoma; Recurrent Childhood Brain Stem Glioma; Recurrent Childhood Cerebellar Astrocytoma; Recurrent Childhood Cerebral Astrocytoma; Recurrent Childhood Ependymoma; Recurrent Childhood Liver Cancer; Recurrent Childhood Malignant Germ Cell Tumor; Recurrent Childhood Rhabdomyosarcoma; Recurrent Childhood Soft Tissue Sarcoma; Recurrent Childhood Visual Pathway and Hypothalamic Glioma; Recurrent Colon Cancer; Recurrent Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor; Recurrent Nasopharyngeal Cancer; Recurrent Neuroblastoma; Recurrent Osteosarcoma; Recurrent Rectal Cancer; Recurrent Renal Cell Cancer

Total laparorobotic repair of abdominal aortic aneurysm with sac exclusion obliteration and aortobifemoral bypass.

PubMed

Wu, Timothy; Prema, Jateen; Zagaja, Gregory; Shalhav, Arieh; Bassiouny, Hisham S

2009-01-01

A 65-year-old man with coronary artery disease, hypertension, and peripheral vascular disease was found to have an asymptomatic abdominal aortic aneurysm (AAA) of 5.5 cm on surveillance for his peripheral vascular disease. Cardiac stress testing demonstrated no evidence of myocardial ischemia, and he opted to undergo open repair of his aneurysm. Laparorobotic repair of the infrarenal AAA using the da Vinci robotic system was performed with an aortobifemoral bypass. We describe a novel technique for AAA exclusion using a cerclage method, which greatly facilitates repair of infrarenal AAAs using laparorobotic techniques. Laparorobotic repair of infrarenal AAA can be greatly facilitated by AAA sac exclusion and obliteration without the need to ligate all lumbar arteries or to open the aneurysm. This virtually avoids blood loss from the sac and minimizes the possibility for open conversion as a result of poor visualization. Minimally invasive aortic intervention for aneurysmal disease using laparascopic methods has been reported in the literature. Problems associated with this technique include a prolonged learning curve and difficulty completing intracorporeal anastomoses. Robotic surgery provides an advantage over laparoscopic surgery in its ability to provide greater degrees of freedom in a relatively small field of view along with superior high-definition, three-dimensional visualization. To date, there have been no known reports of using robotic surgery in the United States as a sole method for repair of AAA. We report our technique of combining robotic surgery with a novel procedure for sac exclusion and obliteration to successfully repair AAA without the need for opening the aneurysm sac and endoaneurysmorrhaphy.

Computer program for analysis of hemodynamic response to head-up tilt test

NASA Astrophysics Data System (ADS)

ŚwiÄ tek, Eliza; Cybulski, Gerard; Koźluk, Edward; PiÄ tkowska, Agnieszka; Niewiadomski, Wiktor

2014-11-01

The aim of this work was to create a computer program, written in the MATLAB environment, which enables the visualization and analysis of hemodynamic parameters recorded during a passive tilt test using the CNS Task Force Monitor System. The application was created to help in the assessment of the relationship between the values and dynamics of changes of the selected parameters and the risk of orthostatic syncope. The signal analysis included: R-R intervals (RRI), heart rate (HR), systolic blood pressure (sBP), diastolic blood pressure (dBP), mean blood pressure (mBP), stroke volume (SV), stroke index (SI), cardiac output (CO), cardiac index (CI), total peripheral resistance (TPR), total peripheral resistance index (TPRI), ventricular ejection time (LVET) and thoracic fluid content (TFC). The program enables the user to visualize waveforms for a selected parameter and to perform smoothing with selected moving average parameters. It allows one to construct the graph of means for any range, and the Poincare plot for a selected time range. The program automatically determines the average value of the parameter before tilt, its minimum and maximum value immediately after changing positions and the times of their occurrence. It is possible to correct the automatically detected points manually. For the RR interval, it determines the acceleration index (AI) and the brake index (BI). It is possible to save calculated values to an XLS with a name specified by user. The application has a user-friendly graphical interface and can run on a computer that has no MATLAB software.

Surgical peripheral iridectomy via a clear-cornea phacoemulsification incision for pupillary block following cataract surgery in acute angle closure.

PubMed

Fang, Aiwu; Wang, Peijuan; He, Rui; Qu, Jia

2018-05-18

To describe a technique of surgical peripheral iridectomy via a clear-cornea tunnel incision to prevent or treat pupillary block following phacoemulsification. Description of technique and retrospective description results in 20 eyes of 20 patients with acute angle closure with coexisting visually significant cataract undergoing phacoemulsification considered at risk of postoperative papillary block as well as two pseudo-phakic eyes with acute postoperative pupillary-block. Following phacoemulsification and insertion of an intraocular lens, a needle with a bent tip was inserted behind the iris through the corneal tunnel incision. A blunt iris repositor was introduced through the paracentesis and placed above the iris to exert posterior pressure and create a puncture. The size of the puncture was enlarged using scissors. For postoperative pupillary block the same technique was carried out through the existing incisions created for phacoemulsification. Peripheral iridectomy was successfully created in all 22 eyes. At a mean follow-up of 18.77 ± 9.72 months, none of the iridectomies closed or required enlargement. Two eyes had mild intraoperative bleeding and one eye a small Descemet's detachment that did not require intervention. No clinically significant complications were observed. Visual acuity and IOP improved or was maintained in all patients. The incidence of pupillary block in our hospital was 0.09% overall, 0.6% in diabetics and 3.5% in those with diabetic retinopathy. This technique of peripheral iridectomy via the cornea tunnel incision can be safely used during phacoemulsification in eyes at high risk of pupillary block or in the treatment of acute postoperative pupillary-block after cataract surgery. The technique is likely to be especially useful in brown iris, or if a laser is not available.

Central and peripheral hemodynamic responses to passive limb movement: the role of arousal

PubMed Central

Venturelli, Massimo; Amann, M.; McDaniel, J.; Trinity, J. D.; Fjeldstad, A. S.

2012-01-01

The exact role of arousal in central and peripheral hemodynamic responses to passive limb movement in humans is unclear but has been proposed as a potential contributor. Thus, we used a human model with no lower limb afferent feedback to determine the role of arousal on the hemodynamic response to passive leg movement. In nine people with a spinal cord injury, we compared central and peripheral hemodynamic and ventilatory responses to one-leg passive knee extension with and without visual feedback (M+VF and M-VF, respectively) as well as in a third trial with no movement or visual feedback but the perception of movement (F). Ventilation (V̇e), heart rate, stroke volume, cardiac output, mean arterial pressure, and leg blood flow (LBF) were evaluated during the three protocols. V̇e increased rapidly from baseline in M+VF (55 ± 11%), M-VF (63 ± 13%), and F (48 ± 12%) trials. Central hemodynamics (heart rate, stroke volume, cardiac output, and mean arterial pressure) were unchanged in all trials. LBF increased from baseline by 126 ± 18 ml/min in the M+VF protocol and 109 ± 23 ml/min in the M-VF protocol but was unchanged in the F protocol. Therefore, with the use of model that is devoid of afferent feedback from the legs, the results of this study reveal that, although arousal is invoked by passive movement or the thought of passive movement, as evidenced by the increase in V̇e, there is no central or peripheral hemodynamic impact of this increased neural activity. Additionally, this study revealed that a central hemodynamic response is not an obligatory component of movement-induced LBF. PMID:22003056

Peripheral Vision Can Influence Eye Growth and Refractive Development in Infant Monkeys

PubMed Central

Smith, Earl L.; Kee, Chea-su; Ramamirtham, Ramkumar; Qiao-Grider, Ying; Hung, Li-Fang

2006-01-01

PURPOSE Given the prominence of central vision in humans, it has been assumed that visual signals from the fovea dominate emmetropization. The purpose of this study was to examine the impact of peripheral vision on emmetropization. METHODS Bilateral, peripheral form deprivation was produced in 12 infant monkeys by rearing them with diffusers that had either 4- or 8-mm apertures centered on the pupils of each eye, to allow 24° or 37° of unrestricted central vision, respectively. At the end of the lens-rearing period, an argon laser was used to ablate the fovea in one eye of each of seven monkeys. Subsequently, all the animals were allowed unrestricted vision. Refractive error and axial dimensions were measured along the pupillary axis by retinoscopy and A-scan ultrasonography, respectively. Control data were obtained from 21 normal monkeys and 3 infants reared with binocular plano lenses. RESULTS Nine of the 12 treated monkeys had refractive errors that fell outside the 10th- and 90th-percentile limits for the age-matched control subjects, and the average refractive error for the treated animals was more variable and significantly less hyperopic/more myopic (+0.03 ± 2.39 D vs. +2.39 ± 0.92 D). The refractive changes were symmetric in the two eyes of a given animal and axial in nature. After lens removal, all the treated monkeys recovered from the induced refractive errors. No interocular differences in the recovery process were observed in the animals with monocular foveal lesions. CONCLUSIONS On the one hand, the peripheral retina can contribute to emmetropizing responses and to ametropias produced by an abnormal visual experience. On the other hand, unrestricted central vision is not sufficient to ensure normal refractive development, and the fovea is not essential for emmetropizing responses. PMID:16249469

Positioning patients for spine surgery: Avoiding uncommon position-related complications

PubMed Central

Kamel, Ihab; Barnette, Rodger

2014-01-01

Positioning patients for spine surgery is pivotal for optimal operating conditions and operative-site exposure. During spine surgery, patients are placed in positions that are not physiologic and may lead to complications. Perioperative peripheral nerve injury (PPNI) and postoperative visual loss (POVL) are rare complications related to patient positioning during spine surgery that result in significant patient disability and functional loss. PPNI is usually due to stretch or compression of the peripheral nerve. PPNI may present as a brachial plexus injury or as an isolated injury of single nerve, most commonly the ulnar nerve. Understanding the etiology, mechanism and pattern of injury with each type of nerve injury is important for the prevention of PPNI. Intraoperative neuromonitoring has been used to detect peripheral nerve conduction abnormalities indicating peripheral nerve stress under general anesthesia and to guide modification of the upper extremity position to prevent PPNI. POVL usually results in permanent visual loss. Most cases are associated with prolonged spine procedures in the prone position under general anesthesia. The most common causes of POVL after spine surgery are ischemic optic neuropathy and central retinal artery occlusion. Posterior ischemic optic neuropathy is the most common cause of POVL after spine surgery. It is important for spine surgeons to be aware of POVL and to participate in safe, collaborative perioperative care of spine patients. Proper education of perioperative staff, combined with clear communication and collaboration while positioning patients in the operating room is the best and safest approach. The prevention of uncommon complications of spine surgery depends primarily on identifying high-risk patients, proper positioning and optimal intraoperative management of physiological parameters. Modification of risk factors extrinsic to the patient may help reduce the incidence of PPNI and POVL. PMID:25232519

Earlier saccades to task-relevant targets irrespective of relative gain between peripheral and foveal information.

PubMed

Wolf, Christian; Schütz, Alexander C

2017-06-01

Saccades bring objects of interest onto the fovea for high-acuity processing. Saccades to rewarded targets show shorter latencies that correlate negatively with expected motivational value. Shorter latencies are also observed when the saccade target is relevant for a perceptual discrimination task. Here we tested whether saccade preparation is equally influenced by informational value as it is by motivational value. We defined informational value as the probability that information is task-relevant times the ratio between postsaccadic foveal and presaccadic peripheral discriminability. Using a gaze-contingent display, we independently manipulated peripheral and foveal discriminability of the saccade target. Latencies of saccades with perceptual task were reduced by 36 ms in general, but they were not modulated by the information saccades provide (Experiments 1 and 2). However, latencies showed a clear negative linear correlation with the probability that the target is task-relevant (Experiment 3). We replicated that the facilitation by a perceptual task is spatially specific and not due to generally heightened arousal (Experiment 4). Finally, the facilitation only emerged when the perceptual task is in the visual but not in the auditory modality (Experiment 5). Taken together, these results suggest that saccade latencies are not equally modulated by informational value as by motivational value. The facilitation by a perceptual task only arises when task-relevant visual information is foveated, irrespective of whether the foveation is useful or not.

Use of pulse oximeter placed on a gastroschisis silo to monitor intestinal oxygen saturation.

PubMed

Kim, Sunghoon; Betts, James; Yedlin, Steve; Rowe, Richard; Idowu, Olajire

2006-09-01

The use of a silo for temporary coverage of exposed viscera for newborns with gastroschisis has allowed gradual reduction of the externalized intestine into the abdominal cavity. However, there has not been an easy way to monitor blood perfusion to the intestine within the silo other than with visual examination. In addition, visual examination of bowel through the silo is sometimes difficult for medical staff due to serositis and peel over the bowel. We have adopted an approach to monitor oxygen saturation of silo-contained intestine by placing a pulse oximeter sensor on the surface of the transparent silo to detect intestinal ischemia. Pulse oximeter sensors were applied on both a patient's distal extremity and the silo on five consecutive patients who were born with gastroschisis. The sensor was left on the silo during the entire period of gradual reduction. Perfusion index, pulse and oxygen saturation were observed and checked against the sensor placed on a peripheral extremity. The silo-placed pulse oximeter and peripheral pulse oximeter sensors showed a similar pulse and oxygen saturation throughout the reduction period in all five patients. In general, perfusion index was higher from the silo pulse oximeter compared to the peripheral pulse oximeter reading. A pulse oximeter can be used to monitor intestinal oxygen saturation contained within a silo and help modulate the rate of manual reduction of intestine.

Long-term Outcome of Argon Laser Peripheral Iridoplasty in the Management of Plateau Iris Syndrome Eyes.

PubMed

Peterson, Jeffrey R; Anderson, John W; Blieden, Lauren S; Chuang, Alice Z; Feldman, Robert M; Bell, Nicholas P

2017-09-01

To report long-term (>5 y) outcomes of plateau iris syndrome patients treated with argon laser peripheral iridoplasty (ALPI). A retrospective chart review was performed on all patients with plateau iris syndrome treated with ALPI from 1996 to 2007. The study included 22 eyes from 22 patients with plateau iris after peripheral iridotomy that were followed for at least 1 year after ALPI. The primary outcome was incidence of needing any intraocular pressure (IOP)-lowering medications or surgery (either a filtering procedure or phacoemulsification). Demographic and baseline clinical data were summarized by mean (±SD) or frequency (percentage). Snellen best-corrected visual acuity was converted to logMAR. The paired t test was used to compare IOP changes, number of IOP-lowering medications, and best-corrected visual acuity from baseline to annual follow-up. Mean follow-up was 76 months. Only 2 (9%) eyes maintained an IOP<21 mm Hg without requiring medication or surgery. Seventeen (77%) eyes underwent surgery at an average of 49.1±7.9 months after ALPI. Eight (36%) eyes underwent filtering surgery, and 9 (41%) eyes underwent phacoemulsification. Three months after cataract extraction, no eyes required IOP-lowering medication. The beneficial effects of ALPI last for <4 years, with the majority of patients (77%) requiring surgery. Phacoemulsification alone was a successful treatment for plateau iris in our patient population.

Objective perimetry using a four-channel multifocal VEP system: correlation with conventional perimetry and thickness of the retinal nerve fibre layer.

PubMed

Horn, Folkert K; Kaltwasser, Christoph; Jünemann, Anselm G; Kremers, Jan; Tornow, Ralf P

2012-04-01

There is evidence that multifocal visual evoked potentials (VEPs) can be used as an objective tool to detect visual field loss. The aim of this study was to correlate multifocal VEP amplitudes with standard perimetry data and retinal nerve fibre layer (RNFL) thickness. Multifocal VEP recordings were performed with a four-channel electrode array using 58 stimulus fields (pattern reversal dartboard). For each field, the recording from the channel with maximal signal-to-noise ratio (SNR) was retained, resulting in an SNR optimised virtual recording. Correlation with RNFL thickness, measured with spectral domain optical coherence tomography and with standard perimetry, was performed for nerve fibre bundle related areas. The mean amplitudes in nerve fibre related areas were smaller in glaucoma patients than in normal subjects. The differences between both groups were most significant in mid-peripheral areas. Amplitudes in these areas were significantly correlated with corresponding RNFL thickness (Spearman R=0.76) and with standard perimetry (R=0.71). The multifocal VEP amplitude was correlated with perimetric visual field data and the RNFL thickness of the corresponding regions. This method of SNR optimisation is useful for extracting data from recordings and may be appropriate for objective assessment of visual function at different locations. This study has been registered at http://www.clinicaltrials.gov (NCT00494923).

76 FR 44595 - Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-26

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2011-N-0002] Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting AGENCY: Food and Drug... Committee: Peripheral and Central Nervous System Drugs Advisory Committee. General Function of the Committee...

Off-resonance magnetic resonance angiography improves visualization of in-stent lumen in peripheral nitinol stents compared to conventional T1-weighted acquisitions: an in vitro comparison study.

PubMed

Gitsioudis, Gitsios; Fortner, Philipp; Stuber, Matthias; Missiou, Anna; Andre, Florian; Müller, Oliver J; Katus, Hugo A; Korosoglou, Grigorios

2016-11-01

To compare the value of inversion recovery with on-resonant water suppression (IRON) to conventional T1-weighted (T1w) MRA and computed tomography angiography (CTA) for visualization of peripheral nitinol stents. We visualized 14 different peripheral nitinol stents in vitro both using Gadolinium (Gd) and ultrasmall superparamagnetic iron nanoparticles (USPIOs) for conventional T1w and IRON-MRA using clinical grade 1.5T MR scanner and iodinated contrast material for CTA using a 256-slice CT scanner. Parameter assessment included signal- and contrast-to-noise ratio (S/CNR), relative in-stent signal and artificial lumen narrowing. X-ray angiography served as gold standard for diameter assessment. Gd-enhanced IRON-MRA exhibited highest in-stent SNR and CNR values compared to conventional T1w MRA (IRON (Gd/USPIO): SNR = 30 ± 3/21 ± 2, CNR = 23 ± 2/14 ± 1; T1w: SNR = 16 ± 1/14 ± 2, CNR = 12 ± 1/10 ± 1, all p < 0.05). Furthermore, IRON-MRA achieved highest relative in-stent signal both using Gd and USPIO (IRON (Gd/USPIO): 121 ± 8 %/103 ± 6 %; T1w: 73 ± 2 %/66 ± 4 %; CTA: 84 ± 6 %, all p < 0.05). However, artificial lumen narrowing appeared similar in all imaging protocols (IRON (Gd/USPIO): 21 ± 3 %/21 ± 2 %; T1w: 16 ± 4 %/17 ± 3 %; CTA: 19 ± 2 %, all p = NS). Finally, IRON-MRA provided improvement of the in-stent lumen visualization with an 'open-close-open' design, which revealed a complete in-stent signal loss in T1w MRA. IRON-MRA improves in-stent visualization in vitro compared to conventional T1w MRA and CTA. In light of the in vitro results with Gd-enhanced IRON-MRA, the clinical implementation of such an approach appears promising.

Visual Field Map Clusters in High-Order Visual Processing: Organization of V3A/V3B and a New Cloverleaf Cluster in the Posterior Superior Temporal Sulcus

PubMed Central

Barton, Brian; Brewer, Alyssa A.

2017-01-01

The cortical hierarchy of the human visual system has been shown to be organized around retinal spatial coordinates throughout much of low- and mid-level visual processing. These regions contain visual field maps (VFMs) that each follows the organization of the retina, with neighboring aspects of the visual field processed in neighboring cortical locations. On a larger, macrostructural scale, groups of such sensory cortical field maps (CFMs) in both the visual and auditory systems are organized into roughly circular cloverleaf clusters. CFMs within clusters tend to share properties such as receptive field distribution, cortical magnification, and processing specialization. Here we use fMRI and population receptive field (pRF) modeling to investigate the extent of VFM and cluster organization with an examination of higher-level visual processing in temporal cortex and compare these measurements to mid-level visual processing in dorsal occipital cortex. In human temporal cortex, the posterior superior temporal sulcus (pSTS) has been implicated in various neuroimaging studies as subserving higher-order vision, including face processing, biological motion perception, and multimodal audiovisual integration. In human dorsal occipital cortex, the transverse occipital sulcus (TOS) contains the V3A/B cluster, which comprises two VFMs subserving mid-level motion perception and visuospatial attention. For the first time, we present the organization of VFMs in pSTS in a cloverleaf cluster. This pSTS cluster contains four VFMs bilaterally: pSTS-1:4. We characterize these pSTS VFMs as relatively small at ∼125 mm2 with relatively large pRF sizes of ∼2–8° of visual angle across the central 10° of the visual field. V3A and V3B are ∼230 mm2 in surface area, with pRF sizes here similarly ∼1–8° of visual angle across the same region. In addition, cortical magnification measurements show that a larger extent of the pSTS VFM surface areas are devoted to the peripheral visual field than those in the V3A/B cluster. Reliability measurements of VFMs in pSTS and V3A/B reveal that these cloverleaf clusters are remarkably consistent and functionally differentiable. Our findings add to the growing number of measurements of widespread sensory CFMs organized into cloverleaf clusters, indicating that CFMs and cloverleaf clusters may both be fundamental organizing principles in cortical sensory processing. PMID:28293182

Retinitis pigmentosa.

PubMed

Hamel, Christian

2006-10-11

Retinitis pigmentosa (RP) is an inherited retinal dystrophy caused by the loss of photoreceptors and characterized by retinal pigment deposits visible on fundus examination. Prevalence of non syndromic RP is approximately 1/4,000. The most common form of RP is a rod-cone dystrophy, in which the first symptom is night blindness, followed by the progressive loss in the peripheral visual field in daylight, and eventually leading to blindness after several decades. Some extreme cases may have a rapid evolution over two decades or a slow progression that never leads to blindness. In some cases, the clinical presentation is a cone-rod dystrophy, in which the decrease in visual acuity predominates over the visual field loss. RP is usually non syndromic but there are also many syndromic forms, the most frequent being Usher syndrome. To date, 45 causative genes/loci have been identified in non syndromic RP (for the autosomal dominant, autosomal recessive, X-linked, and digenic forms). Clinical diagnosis is based on the presence of night blindness and peripheral visual field defects, lesions in the fundus, hypovolted electroretinogram traces, and progressive worsening of these signs. Molecular diagnosis can be made for some genes, but is not usually performed due to the tremendous genetic heterogeneity of the disease. Genetic counseling is always advised. Currently, there is no therapy that stops the evolution of the disease or restores the vision, so the visual prognosis is poor. The therapeutic approach is restricted to slowing down the degenerative process by sunlight protection and vitaminotherapy, treating the complications (cataract and macular edema), and helping patients to cope with the social and psychological impact of blindness. However, new therapeutic strategies are emerging from intensive research (gene therapy, neuroprotection, retinal prosthesis).

Relationship between slow visual processing and reading speed in people with macular degeneration

PubMed Central

Cheong, Allen MY; Legge, Gordon E; Lawrence, Mary G; Cheung, Sing-Hang; Ruff, Mary A

2007-01-01

Purpose People with macular degeneration (MD) often read slowly even with adequate magnification to compensate for acuity loss. Oculomotor deficits may affect reading in MD, but cannot fully explain the substantial reduction in reading speed. Central-field loss (CFL) is often a consequence of macular degeneration, necessitating the use of peripheral vision for reading. We hypothesized that slower temporal processing of visual patterns in peripheral vision is a factor contributing to slow reading performance in MD patients. Methods Fifteen subjects with MD, including 12 with CFL, and five age-matched control subjects were recruited. Maximum reading speed and critical print size were measured with RSVP (Rapid Serial Visual Presentation). Temporal processing speed was studied by measuring letter-recognition accuracy for strings of three randomly selected letters centered at fixation for a range of exposure times. Temporal threshold was defined as the exposure time yielding 80% recognition accuracy for the central letter. Results Temporal thresholds for the MD subjects ranged from 159 to 5881 ms, much longer than values for age-matched controls in central vision (13 ms, p<0.01). The mean temporal threshold for the 11 MD subjects who used eccentric fixation (1555.8 ± 1708.4 ms) was much longer than the mean temporal threshold (97.0 ms ± 34.2 ms, p<0.01) for the age-matched controls at 10° in the lower visual field. Individual temporal thresholds accounted for 30% of the variance in reading speed (p<0.05). Conclusion The significant association between increased temporal threshold for letter recognition and reduced reading speed is consistent with the hypothesis that slower visual processing of letter recognition is one of the factors limiting reading speed in MD subjects. PMID:17881032

Functional Architecture for Disparity in Macaque Inferior Temporal Cortex and Its Relationship to the Architecture for Faces, Color, Scenes, and Visual Field

PubMed Central

Verhoef, Bram-Ernst; Bohon, Kaitlin S.

2015-01-01

Binocular disparity is a powerful depth cue for object perception. The computations for object vision culminate in inferior temporal cortex (IT), but the functional organization for disparity in IT is unknown. Here we addressed this question by measuring fMRI responses in alert monkeys to stimuli that appeared in front of (near), behind (far), or at the fixation plane. We discovered three regions that showed preferential responses for near and far stimuli, relative to zero-disparity stimuli at the fixation plane. These “near/far” disparity-biased regions were located within dorsal IT, as predicted by microelectrode studies, and on the posterior inferotemporal gyrus. In a second analysis, we instead compared responses to near stimuli with responses to far stimuli and discovered a separate network of “near” disparity-biased regions that extended along the crest of the superior temporal sulcus. We also measured in the same animals fMRI responses to faces, scenes, color, and checkerboard annuli at different visual field eccentricities. Disparity-biased regions defined in either analysis did not show a color bias, suggesting that disparity and color contribute to different computations within IT. Scene-biased regions responded preferentially to near and far stimuli (compared with stimuli without disparity) and had a peripheral visual field bias, whereas face patches had a marked near bias and a central visual field bias. These results support the idea that IT is organized by a coarse eccentricity map, and show that disparity likely contributes to computations associated with both central (face processing) and peripheral (scene processing) visual field biases, but likely does not contribute much to computations within IT that are implicated in processing color. PMID:25926470

Retinitis pigmentosa

PubMed Central

Hamel, Christian

2006-01-01

Retinitis pigmentosa (RP) is an inherited retinal dystrophy caused by the loss of photoreceptors and characterized by retinal pigment deposits visible on fundus examination. Prevalence of non syndromic RP is approximately 1/4,000. The most common form of RP is a rod-cone dystrophy, in which the first symptom is night blindness, followed by the progressive loss in the peripheral visual field in daylight, and eventually leading to blindness after several decades. Some extreme cases may have a rapid evolution over two decades or a slow progression that never leads to blindness. In some cases, the clinical presentation is a cone-rod dystrophy, in which the decrease in visual acuity predominates over the visual field loss. RP is usually non syndromic but there are also many syndromic forms, the most frequent being Usher syndrome. To date, 45 causative genes/loci have been identified in non syndromic RP (for the autosomal dominant, autosomal recessive, X-linked, and digenic forms). Clinical diagnosis is based on the presence of night blindness and peripheral visual field defects, lesions in the fundus, hypovolted electroretinogram traces, and progressive worsening of these signs. Molecular diagnosis can be made for some genes, but is not usually performed due to the tremendous genetic heterogeneity of the disease. Genetic counseling is always advised. Currently, there is no therapy that stops the evolution of the disease or restores the vision, so the visual prognosis is poor. The therapeutic approach is restricted to slowing down the degenerative process by sunlight protection and vitaminotherapy, treating the complications (cataract and macular edema), and helping patients to cope with the social and psychological impact of blindness. However, new therapeutic strategies are emerging from intensive research (gene therapy, neuroprotection, retinal prosthesis). PMID:17032466

Catheter indwell time and phlebitis development during peripheral intravenous catheter administration.

PubMed

Pasalioglu, Kadriye Burcu; Kaya, Hatice

2014-07-01

Intravenous catheters have been indispensable tools of modern medicine. Although intravenous applications can be used for a multitude of purposes, these applications may cause complications, some of which have serious effects. Of these complications, the most commonly observed is phlebitis. This study was conducted to determine the effect of catheter indwell time on phlebitis development during peripheral intravenous catheter administration. This study determined the effect of catheter indwell time on phlebitis development during peripheral intravenous catheter administration. The study included a total of 103 individuals who were administered 439 catheters and satisfied the study enrollment criteria at one infectious diseases clinic in Istanbul/Turkey. Data were compiled from Patient Information Forms, Peripheral Intravenous Catheter and Therapy Information Forms, reported grades based on the Visual Infusion Phlebitis Assessment Scale, and Peripheral Intravenous Catheter Nurse Observation Forms. The data were analyzed using SPSS. Results : The mean patient age was 53.75±15.54 (standard deviation) years, and 59.2% of the study participants were men. Phlebitis was detected in 41.2% of peripheral intravenous catheters, and the rate decreased with increased catheter indwell time. Analyses showed that catheter indwell time, antibiotic usage, sex, and catheterization sites were significantly associated with development of phlebitis. The results of this study show that catheters can be used for longer periods of time when administered under optimal conditions and with appropriate surveillance.

Catheter indwell time and phlebitis development during peripheral intravenous catheter administration

PubMed Central

Pasalioglu, Kadriye Burcu; Kaya, Hatice

2014-01-01

Objective: Intravenous catheters have been indispensable tools of modern medicine. Although intravenous applications can be used for a multitude of purposes, these applications may cause complications, some of which have serious effects. Of these complications, the most commonly observed is phlebitis. This study was conducted to determine the effect of catheter indwell time on phlebitis development during peripheral intravenous catheter administration. Methods: This study determined the effect of catheter indwell time on phlebitis development during peripheral intravenous catheter administration. The study included a total of 103 individuals who were administered 439 catheters and satisfied the study enrollment criteria at one infectious diseases clinic in Istanbul/Turkey. Data were compiled from Patient Information Forms, Peripheral Intravenous Catheter and Therapy Information Forms, reported grades based on the Visual Infusion Phlebitis Assessment Scale, and Peripheral Intravenous Catheter Nurse Observation Forms. The data were analyzed using SPSS. Results : The mean patient age was 53.75±15.54 (standard deviation) years, and 59.2% of the study participants were men. Phlebitis was detected in 41.2% of peripheral intravenous catheters, and the rate decreased with increased catheter indwell time. Analyses showed that catheter indwell time, antibiotic usage, sex, and catheterization sites were significantly associated with development of phlebitis. Conclusion: The results of this study show that catheters can be used for longer periods of time when administered under optimal conditions and with appropriate surveillance. PMID:25097505

Aberrant Pattern of Scanning in Prosopagnosia Reflects Impaired Face Processing

ERIC Educational Resources Information Center

Stephan, Blossom Christa Maree; Caine, Diana

2009-01-01

Visual scanpath recording was used to investigate the information processing strategies used by a prosopagnosic patient, SC, when viewing faces. Compared to controls, SC showed an aberrant pattern of scanning, directing attention away from the internal configuration of facial features (eyes, nose) towards peripheral regions (hair, forehead) of the…

21 CFR 886.1605 - Perimeter.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Perimeter. 886.1605 Section 886.1605 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES... or manual device intended to determine the extent of the peripheral visual field of a patient. The...

Complications of Diabetes and Their Implications for Service Providers.

ERIC Educational Resources Information Center

Ponchillia, S. V.

1993-01-01

This article presents information on the complications of both Type I and Type II diabetes and the implications for the rehabilitation of persons with diabetes and visual impairment. Topics covered include retinopathy, cataracts, glaucoma, peripheral neuropathy, carpal tunnel syndrome, diabetic hand syndrome, neuropathy of the autonomic nervous…

An update on acquired nystagmus.

PubMed

Rucker, Janet C

2008-01-01

Proper evaluation and treatment of acquired nystagmus requires accurate characterization of nystagmus type and visual effects. This review addresses important historical and examination features of nystagmus and current concepts of pathogenesis and treatment of gaze-evoked nystagmus, nystagmus due to vision loss, acquired pendular nystagmus, peripheral and central vestibular nystagmus, and periodic alternating nystagmus.

Sounds activate visual cortex and improve visual discrimination.

PubMed

Feng, Wenfeng; Störmer, Viola S; Martinez, Antigona; McDonald, John J; Hillyard, Steven A

2014-07-16

A recent study in humans (McDonald et al., 2013) found that peripheral, task-irrelevant sounds activated contralateral visual cortex automatically as revealed by an auditory-evoked contralateral occipital positivity (ACOP) recorded from the scalp. The present study investigated the functional significance of this cross-modal activation of visual cortex, in particular whether the sound-evoked ACOP is predictive of improved perceptual processing of a subsequent visual target. A trial-by-trial analysis showed that the ACOP amplitude was markedly larger preceding correct than incorrect pattern discriminations of visual targets that were colocalized with the preceding sound. Dipole modeling of the scalp topography of the ACOP localized its neural generators to the ventrolateral extrastriate visual cortex. These results provide direct evidence that the cross-modal activation of contralateral visual cortex by a spatially nonpredictive but salient sound facilitates the discriminative processing of a subsequent visual target event at the location of the sound. Recordings of event-related potentials to the targets support the hypothesis that the ACOP is a neural consequence of the automatic orienting of visual attention to the location of the sound. Copyright © 2014 the authors 0270-6474/14/349817-08$15.00/0.

[Uveitis: diagnostic approach].

PubMed

Martínez-Berriotxoa, A; Fonollosa, A; Artaraz, J

2012-10-01

A 32 year-old woman was referred from the Ophthalmology Department to rule out a possible systemic disease. Her only past medical history of relevance was a tuberculosis contact during childhood. She complained of floaters and progressive blurring of vision in both eyes for some months, as well as arthralgia and cough. Her visual acuity was 0.3 in the right eye and 0.4 in the left eye. Biomicroscopy showed bilateral anterior granulomatous uveitis (1+ cells). Funduscopy showed bilateral vitritis 3+, snow banking and peripheral phlebitis. Fluorescein angiography did not show central vasculitis, and optical coherence tomography showed bilateral cystoid macular oedema. Fundus autofluorescence was normal. How would you initially assess this patient in order to decide which systemic examination should be performed, bearing in mind the ophthalmological manifestations? Copyright © 2011 Elsevier España, S.L. All rights reserved.

Instrument Display Visual Angles for Conventional Aircraft and the MQ-9 Ground Control Station

NASA Technical Reports Server (NTRS)

Kamine, Tovy Haber; Bendrick, Gregg A.

2008-01-01

Aircraft instrument panels should be designed such that primary displays are in optimal viewing location to minimize pilot perception and response time. Human Factors engineers define three zones (i.e. cones ) of visual location: 1) "Easy Eye Movement" (foveal vision); 2) "Maximum Eye Movement" (peripheral vision with saccades), and 3) "Head Movement (head movement required). Instrument display visual angles were measured to determine how well conventional aircraft (T-34, T-38, F- 15B, F-16XL, F/A-18A, U-2D, ER-2, King Air, G-III, B-52H, DC-10, B747-SCA) and the MQ-9 ground control station (GCS) complied with these standards, and how they compared with each other. Selected instrument parameters included: attitude, pitch, bank, power, airspeed, altitude, vertical speed, heading, turn rate, slip/skid, AOA, flight path, latitude, longitude, course, bearing, range and time. Vertical and horizontal visual angles for each component were measured from the pilot s eye position in each system. The vertical visual angles of displays in conventional aircraft lay within the cone of "Easy Eye Movement" for all but three of the parameters measured, and almost all of the horizontal visual angles fell within this range. All conventional vertical and horizontal visual angles lay within the cone of Maximum Eye Movement. However, most instrument vertical visual angles of the MQ-9 GCS lay outside the cone of Easy Eye Movement, though all were within the cone of Maximum Eye Movement. All the horizontal visual angles for the MQ-9 GCS were within the cone of "Easy Eye Movement". Most instrument displays in conventional aircraft lay within the cone of Easy Eye Movement, though mission-critical instruments sometimes displaced less important instruments outside this area. Many of the MQ-9 GCS systems lay outside this area. Specific training for MQ-9 pilots may be needed to avoid increased response time and potential error during flight. The learning objectives include: 1) Know three physiologic cones of eye/head movement; 2) Understand how instrument displays comply with these design principles in conventional aircraft and an uninhabited aerial vehicle system. Which of the following is NOT a recognized physiologic principle of instrument display design? Cone of Easy Eye Movement 2) Cone of Binocular Eye Movement 3) Cone of Maximum Eye Movement 4) Cone of Head Movement 5) None of the above. Answer: # 2) Cone of Binocular Eye Movement

75 FR 17417 - Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-06

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2010-N-0001] Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting AGENCY: Food and Drug...: Peripheral and Central Nervous System Drugs Advisory Committee. General Function of the Committee: To provide...

78 FR 63478 - Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-24

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2013-N-0001] Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting AGENCY: Food and Drug...: Peripheral and Central Nervous System Drugs Advisory Committee. General Function of the Committee: To provide...

75 FR 36428 - Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-25

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2010-N-0001] Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting AGENCY: Food and Drug...: Peripheral and Central Nervous System Drugs Advisory Committee. General Function of the Committee: To provide...

77 FR 20037 - Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-03

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2012-N-0001] Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting AGENCY: Food and Drug...: Peripheral and Central Nervous System Drugs Advisory Committee. General Function of the Committee: To provide...

78 FR 63481 - Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-24

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2013-N-0001] Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting AGENCY: Food and Drug...: Peripheral and Central Nervous System Drugs Advisory Committee. General Function of the Committee: To provide...

76 FR 3912 - Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-21

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2011-N-0002] Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting AGENCY: Food and Drug...: Peripheral and Central Nervous System Drugs Advisory Committee. General Function of the Committee: To provide...

75 FR 12768 - Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-17

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2010-N-0001] Peripheral and Central Nervous System Drugs Advisory Committee; Notice of Meeting AGENCY: Food and Drug...: Peripheral and Central Nervous System Drugs Advisory Committee. General Function of the Committee: To provide...

[Case of pediatric chronic myeloid leukemia with bilateral visual loss onset].

PubMed

Hara, Yusuke; Kamura, Yumi; Oikawa, Aki; Shichino, Hiroyuki; Mugishima, Hideo; Goto, Hiroshi

2010-05-01

Chronic myeloid leukemia (CML) during childhood is rare, and only been a few cases showed visual disturbances as an initial symptom. We report a pediatric CML case diagnosed by bilateral visual loss. An 11-year-old boy complained of visual loss in both eyes. His best corrected visual acuity was 0.5 in the right eye and 0.2 in the left. Fundus examination showed disc swelling, dilated and tortuous retinal veins and multiple elevated retinal lesions with hemorrhages of various size from one-forth to four disc diameters in both eyes. He was diagnosed as having CML by leucocytosis and systematic work-up including Philadelphia chromosome-positive, BCR-ABL kinase domain in peripheral blood and bone marrow. The ocular findings improved after treatment with hydroxyurea, leukocytaphresis and imatinib. His best corrected visual acuity improved to 0.7 in both eyes. Recent leukemia therapy including imatinib is effective not only for ocular lesions but also to induce hematological remission in childhood CML.

Modulation of auditory spatial attention by visual emotional cues: differential effects of attentional engagement and disengagement for pleasant and unpleasant cues.

PubMed

Harrison, Neil R; Woodhouse, Rob

2016-05-01

Previous research has demonstrated that threatening, compared to neutral pictures, can bias attention towards non-emotional auditory targets. Here we investigated which subcomponents of attention contributed to the influence of emotional visual stimuli on auditory spatial attention. Participants indicated the location of an auditory target, after brief (250 ms) presentation of a spatially non-predictive peripheral visual cue. Responses to targets were faster at the location of the preceding visual cue, compared to at the opposite location (cue validity effect). The cue validity effect was larger for targets following pleasant and unpleasant cues compared to neutral cues, for right-sided targets. For unpleasant cues, the crossmodal cue validity effect was driven by delayed attentional disengagement, and for pleasant cues, it was driven by enhanced engagement. We conclude that both pleasant and unpleasant visual cues influence the distribution of attention across modalities and that the associated attentional mechanisms depend on the valence of the visual cue.

Manual control of yaw motion with combined visual and vestibular cues

NASA Technical Reports Server (NTRS)

Zacharias, G. L.; Young, L. R.

1977-01-01

Measurements are made of manual control performance in the closed-loop task of nulling perceived self-rotation velocity about an earth-vertical axis. Self-velocity estimation was modelled as a function of the simultaneous presentation of vestibular and peripheral visual field motion cues. Based on measured low-frequency operator behavior in three visual field environments, a parallel channel linear model is proposed which has separate visual and vestibular pathways summing in a complementary manner. A correction to the frequency responses is provided by a separate measurement of manual control performance in an analogous visual pursuit nulling task. The resulting dual-input describing function for motion perception dependence on combined cue presentation supports the complementary model, in which vestibular cues dominate sensation at frequencies above 0.05 Hz. The describing function model is extended by the proposal of a non-linear cue conflict model, in which cue weighting depends on the level of agreement between visual and vestibular cues.

Conceptual analysis of Physiology of vision in Ayurveda.

PubMed

Balakrishnan, Praveen; Ashwini, M J

2014-07-01

The process by which the world outside is seen is termed as visual process or physiology of vision. There are three phases in this visual process: phase of refraction of light, phase of conversion of light energy into electrical impulse and finally peripheral and central neurophysiology. With the advent of modern instruments step by step biochemical changes occurring at each level of the visual process has been deciphered. Many investigations have emerged to track these changes and helping to diagnose the exact nature of the disease. Ayurveda has described this physiology of vision based on the functions of vata and pitta. Philosophical textbook of ayurveda, Tarka Sangraha, gives certain basics facts of visual process. This article discusses the second and third phase of visual process. Step by step analysis of the visual process through the spectacles of ayurveda amalgamated with the basics of philosophy from Tarka Sangraha has been analyzed critically to generate a concrete idea regarding the physiology and hence thereby interpret the pathology on the grounds of ayurveda based on the investigative reports.

Perceptual processing deficits underlying reduced FFOV efficiency in older adults.

PubMed

Power, Garry F; Conlon, Elizabeth G

2017-01-01

Older adults are known to perform more poorly on measures of the functional field of view (FFOV) than younger adults. Specific contributions by poor bottom-up and or top-down control of visual attention to the reduced FFOV of older adults were investigated. Error rates of older and younger adults were compared on a FFOV task in which a central identification task, peripheral localization task, and peripheral distractors were presented in high and low contrast. Older adults made more errors in all conditions. The effect of age was independent of the contrast of the peripheral target or distractors. The performance cost of including the central task was measured and found to be negligible for younger adults. For older adults performance costs were present in all conditions, greater with distractors than without, and greater for a low rather than high contrast central stimulus when the peripheral target was high contrast. These results are consistent with older adults compensating for reduced sensory input or bottom-up capture of attention by relying more heavily on top-down control for which they are resource limited.

Peripheral ischaemic retinopathy and neovascularisation in a patient with subacute streptococcus mitis-induced bacterial endocarditis.

PubMed

Leysen, Laura S; Kreps, Elke O; De Schryver, Ilse; Hoornaert, Kristien P; Smith, Vanessa; De Zaeytijd, Julie

2017-01-01

Objective: To describe a patient with peripheral retinal ischaemia and neovascularisation who was diagnosed with streptococcus mitis-induced bacterial endocarditis. Methods: Retrospective analysis of case report. A 57-year-old man presented with a history of a rapidly progressive, bilateral, painless visual loss. He also suffered from pain in the neck and lower back and a weight loss of 10 kg. He underwent a full ophthalmologic work-up, laboratory investigations, and imaging of the spine. Results: BCVA was reduced to 20/40 in the right eye and 20/32 in the left eye. Fundoscopy showed rare intra-retinal haemorrhages including few Roth spots and cotton wool lesions. Fluorescein angiography demonstrated large areas of peripheral retinal ischaemia and neovascularisation. Imaging of the spine showed spondylodiscitis on several levels. Further imaging and blood cultures confirmed bacterial endocarditis of the mitral valve. Streptococcus mitis was subsequently identified as the causative organism. Conclusion: Peripheral retinal ischaemia and neovascularisation were previously unrecognised as a feature of infectious endocarditis. Therefore, their presence, apart from the classic Roth spots, should prompt the consideration of infectious endocarditis in the etiologic work-up.

Loss of Peripheral Sensory Function Explains Much of the Increase in Postural Sway in Healthy Older Adults

PubMed Central

Anson, Eric; Bigelow, Robin T.; Swenor, Bonnielin; Deshpande, Nandini; Studenski, Stephanie; Jeka, John J.; Agrawal, Yuri

2017-01-01

Postural sway increases with age and peripheral sensory disease. Whether, peripheral sensory function is related to postural sway independent of age in healthy adults is unclear. Here, we investigated the relationship between tests of visual function (VISFIELD), vestibular function (CANAL or OTOLITH), proprioceptive function (PROP), and age, with center of mass sway area (COM) measured with eyes open then closed on firm and then a foam surface. A cross-sectional sample of 366 community dwelling healthy adults from the Baltimore Longitudinal Study of Aging was tested. Multiple linear regressions examined the association between COM and VISFIELD, PROP, CANAL, and OTOLITH separately and in multi-sensory models controlling for age and gender. PROP dominated sensory prediction of sway across most balance conditions (β's = 0.09–0.19, p's < 0.001), except on foam eyes closed where CANAL function loss was the only significant sensory predictor of sway (β = 2.12, p < 0.016). Age was not a consistent predictor of sway. This suggests loss of peripheral sensory function explains much of the age-associated increase in sway. PMID:28676758

Artificial ascites and pneumoperitoneum to facilitate thermal ablation of liver tumors: a pictorial essay.

PubMed

Bhagavatula, Sharath K; Chick, Jeffrey F B; Chauhan, Nikunj R; Shyn, Paul B

2017-02-01

Image-guided percutaneous thermal ablation is increasingly utilized in the treatment of hepatic malignancies. Peripherally located hepatic tumors can be difficult to access or located adjacent to critical structures that can be injured. As a result, ablation of peripheral tumors may be avoided or may be performed too cautiously, leading to inadequate ablation coverage. In these cases, separating the tumor from adjacent critical structures can increase the efficacy and safety of procedures. Artificial ascites and artificial pneumoperitoneum are techniques that utilize fluid and gas, respectively, to insulate critical structures from the thermal ablation zone. Induction of artificial ascites and artificial pneumoperitoneum can enable complete ablation of otherwise inaccessible hepatic tumors, improve tumor visualization, minimize unintended thermal injury to surrounding organs, and reduce post-procedural pain. This pictorial essay illustrates and discusses the proper technique and clinical considerations for successful artificial ascites and pneumoperitoneum creation to facilitate safe peripheral hepatic tumor ablation.

Peripheral Visual Cues Contribute to the Perception of Object Movement During Self-Movement

PubMed Central

Rogers, Cassandra; Warren, Paul A.

2017-01-01

Safe movement through the environment requires us to monitor our surroundings for moving objects or people. However, identification of moving objects in the scene is complicated by self-movement, which adds motion across the retina. To identify world-relative object movement, the brain thus has to ‘compensate for’ or ‘parse out’ the components of retinal motion that are due to self-movement. We have previously demonstrated that retinal cues arising from central vision contribute to solving this problem. Here, we investigate the contribution of peripheral vision, commonly thought to provide strong cues to self-movement. Stationary participants viewed a large field of view display, with radial flow patterns presented in the periphery, and judged the trajectory of a centrally presented probe. Across two experiments, we demonstrate and quantify the contribution of peripheral optic flow to flow parsing during forward and backward movement. PMID:29201335

[Involvement of the peripheral nervous system in systemic connective tissue diseases: report on clinical cases].

PubMed

Kujawska-Danecka, Hanna; Masiak, Anna; Smoleńska, Zaneta; Zdrojewski, Zbigniew

2011-01-01

The peripheral nervous system is usually involved in the majority of systemic connective tissue diseases, particularly in systemic lupus erythematosus, Sjögren's syndrome, vasculitis and systemic sclerosis. The pathogenesis of lesions in the peripheral nervous system associated with the autoimmune process is complex and it appears that two mechanisms, immunological and ischemic, are of greatest importance. Structures of the nervous system may be damaged by several autoantibodies (e.g. antineuronal, anti-nerve growth factor, anti-neurotrophins), by cytotoxic effects ofproinflammatory cytokines and by activated cells of the immune system. Local ischemia and hypoxia of neurons caused by inflammation of vasa nervosum represents the second significant mechanism leading to damage of nerve fibres in the peripheral nervous system. We present 3 cases with involvement of the peripheral nervous system as a dominant feature in the clinical picture of systemic connective tissue diseases. Clinical conditions in which the peripheral nervous system is involved include peripheral sensory and sensorimotor polyneuropathy, mononeuropathies, cranial neuropathies, acute inflammatory demyelinating polyneuropathy (Guillian-Barré syndrome), chronic inflammatory demyelinating polyneuropathy, plexopathy, myasthenia gravis, and dysfunctions of the autonomic nervous system. The diagnosis is based on clinical symptoms reported by the patient and disclosed during neurologic examination. The importance of electrophysiologic tests is advocated. Selection of treatment depends on the patient's clinical condition, as well as on the clinical form and type of disease. Treatment relies principally on glucocorticosteroids, intravenous immunoglobulins, cyclophosphamide, and other immunosuppressive drugs. Plasmapheresis and rituximab are administered in severe cases. Rehabilitation of the patient appears to be an important element of therapy. Cases with neurologic symptoms as the first and often the sole manifestation of systemic connective tissue disease are particularly problematic requiring a multidimensional approach; their process of diagnosis and treatment is usually long.

Animal Models of Peripheral Neuropathy Due to Environmental Toxicants

PubMed Central

Rao, Deepa B.; Jortner, Bernard S.; Sills, Robert C.

2014-01-01

Despite the progress in our understanding of pathogeneses and the identification of etiologies of peripheral neuropathy, idiopathic neuropathy remains common. Typically, attention to peripheral neuropathies resulting from exposure to environmental agents is limited relative to more commonly diagnosed causes of peripheral neuropathy (diabetes and chemotherapeutic agents). Given that there are more than 80,000 chemicals in commerce registered with the Environmental Protection Agency and that at least 1000 chemicals are known to have neurotoxic potential, very few chemicals have been established to affect the peripheral nervous system (mainly after occupational exposures). A wide spectrum of exposures, including pesticides, metals, solvents, nutritional sources, and pharmaceutical agents, has been related, both historically and recently, to environmental toxicant-induced peripheral neuropathy. A review of the literature shows that the toxicity and pathogeneses of chemicals adversely affecting the peripheral nervous system have been studied using animal models. This article includes an overview of five prototypical environmental agents known to cause peripheral neuropathy—namely, organophosphates, carbon disulfide, pyridoxine (Vitamin B6), acrylamide, and hexacarbons (mainly n-hexane, 2,5-hexanedione, methyl n-butyl ketone). Also included is a brief introduction to the structural components of the peripheral nervous system and pointers on common methodologies for histopathologic evaluation of the peripheral nerves. PMID:24615445

Ontology-based image navigation: exploring 3.0-T MR neurography of the brachial plexus using AIM and RadLex.

PubMed

Wang, Kenneth C; Salunkhe, Aditya R; Morrison, James J; Lee, Pearlene P; Mejino, José L V; Detwiler, Landon T; Brinkley, James F; Siegel, Eliot L; Rubin, Daniel L; Carrino, John A

2015-01-01

Disorders of the peripheral nervous system have traditionally been evaluated using clinical history, physical examination, and electrodiagnostic testing. In selected cases, imaging modalities such as magnetic resonance (MR) neurography may help further localize or characterize abnormalities associated with peripheral neuropathies, and the clinical importance of such techniques is increasing. However, MR image interpretation with respect to peripheral nerve anatomy and disease often presents a diagnostic challenge because the relevant knowledge base remains relatively specialized. Using the radiology knowledge resource RadLex®, a series of RadLex queries, the Annotation and Image Markup standard for image annotation, and a Web services-based software architecture, the authors developed an application that allows ontology-assisted image navigation. The application provides an image browsing interface, allowing users to visually inspect the imaging appearance of anatomic structures. By interacting directly with the images, users can access additional structure-related information that is derived from RadLex (eg, muscle innervation, muscle attachment sites). These data also serve as conceptual links to navigate from one portion of the imaging atlas to another. With 3.0-T MR neurography of the brachial plexus as the initial area of interest, the resulting application provides support to radiologists in the image interpretation process by allowing efficient exploration of the MR imaging appearance of relevant nerve segments, muscles, bone structures, vascular landmarks, anatomic spaces, and entrapment sites, and the investigation of neuromuscular relationships. RSNA, 2015

Ontology-based Image Navigation: Exploring 3.0-T MR Neurography of the Brachial Plexus Using AIM and RadLex

PubMed Central

Salunkhe, Aditya R.; Morrison, James J.; Lee, Pearlene P.; Mejino, José L. V.; Detwiler, Landon T.; Brinkley, James F.; Siegel, Eliot L.; Rubin, Daniel L.; Carrino, John A.

2015-01-01

Disorders of the peripheral nervous system have traditionally been evaluated using clinical history, physical examination, and electrodiagnostic testing. In selected cases, imaging modalities such as magnetic resonance (MR) neurography may help further localize or characterize abnormalities associated with peripheral neuropathies, and the clinical importance of such techniques is increasing. However, MR image interpretation with respect to peripheral nerve anatomy and disease often presents a diagnostic challenge because the relevant knowledge base remains relatively specialized. Using the radiology knowledge resource RadLex®, a series of RadLex queries, the Annotation and Image Markup standard for image annotation, and a Web services–based software architecture, the authors developed an application that allows ontology-assisted image navigation. The application provides an image browsing interface, allowing users to visually inspect the imaging appearance of anatomic structures. By interacting directly with the images, users can access additional structure-related information that is derived from RadLex (eg, muscle innervation, muscle attachment sites). These data also serve as conceptual links to navigate from one portion of the imaging atlas to another. With 3.0-T MR neurography of the brachial plexus as the initial area of interest, the resulting application provides support to radiologists in the image interpretation process by allowing efficient exploration of the MR imaging appearance of relevant nerve segments, muscles, bone structures, vascular landmarks, anatomic spaces, and entrapment sites, and the investigation of neuromuscular relationships. ©RSNA, 2015 PMID:25590394

Origins of strabismus and loss of binocular vision

PubMed Central

Bui Quoc, Emmanuel; Milleret, Chantal

2014-01-01

Strabismus is a frequent ocular disorder that develops early in life in humans. As a general rule, it is characterized by a misalignment of the visual axes which most often appears during the critical period of visual development. However other characteristics of strabismus may vary greatly among subjects, for example, being convergent or divergent, horizontal or vertical, with variable angles of deviation. Binocular vision may also vary greatly. Our main goal here is to develop the idea that such “polymorphy” reflects a wide variety in the possible origins of strabismus. We propose that strabismus must be considered as possibly resulting from abnormal genetic and/or acquired factors, anatomical and/or functional abnormalities, in the sensory and/or the motor systems, both peripherally and/or in the brain itself. We shall particularly develop the possible “central” origins of strabismus. Indeed, we are convinced that it is time now to open this “black box” in order to move forward. All of this will be developed on the basis of both presently available data in literature (including most recent data) and our own experience. Both data in biology and medicine will be referred to. Our conclusions will hopefully help ophthalmologists to better understand strabismus and to develop new therapeutic strategies in the future. Presently, physicians eliminate or limit the negative effects of such pathology both on the development of the visual system and visual perception through the use of optical correction and, in some cases, extraocular muscle surgery. To better circumscribe the problem of the origins of strabismus, including at a cerebral level, may improve its management, in particular with respect to binocular vision, through innovating tools by treating the pathology at the source. PMID:25309358

Memory-guided reaching in a patient with visual hemiagnosia.

PubMed

Cornelsen, Sonja; Rennig, Johannes; Himmelbach, Marc

2016-06-01

The two-visual-systems hypothesis (TVSH) postulates that memory-guided movements rely on intact functions of the ventral stream. Its particular importance for memory-guided actions was initially inferred from behavioral dissociations in the well-known patient DF. Despite of rather accurate reaching and grasping movements to visible targets, she demonstrated grossly impaired memory-guided grasping as much as impaired memory-guided reaching. These dissociations were later complemented by apparently reversed dissociations in patients with dorsal damage and optic ataxia. However, grasping studies in DF and optic ataxia patients differed with respect to the retinotopic position of target objects, questioning the interpretation of the respective findings as a double dissociation. In contrast, the findings for reaching errors in both types of patients came from similar peripheral target presentations. However, new data on brain structural changes and visuomotor deficits in DF also questioned the validity of a double dissociation in reaching. A severe visuospatial short-term memory deficit in DF further questioned the specificity of her memory-guided reaching deficit. Therefore, we compared movement accuracy in visually-guided and memory-guided reaching in a new patient who suffered a confined unilateral damage to the ventral visual system due to stroke. Our results indeed support previous descriptions of memory-guided movements' inaccuracies in DF. Furthermore, our data suggest that recently discovered optic-ataxia like misreaching in DF is most likely caused by her parieto-occipital and not by her ventral stream damage. Finally, multiple visuospatial memory measurements in HWS suggest that inaccuracies in memory-guided reaching tasks in patients with ventral damage cannot be explained by visuospatial short-term memory or perceptual deficits, but by a specific deficit in visuomotor processing. Copyright © 2016 Elsevier Ltd. All rights reserved.

Neuroactive steroids and the peripheral nervous system: An update.

PubMed

Giatti, Silvia; Romano, Simone; Pesaresi, Marzia; Cermenati, Gaia; Mitro, Nico; Caruso, Donatella; Tetel, Marc J; Garcia-Segura, Luis Miguel; Melcangi, Roberto C

2015-11-01

In the present review we summarize observations to date supporting the concept that neuroactive steroids are synthesized in the peripheral nervous system, regulate the physiology of peripheral nerves and exert notable neuroprotective actions. Indeed, neuroactive steroids have been recently proposed as therapies for different types of peripheral neuropathy, like for instance those occurring during aging, chemotherapy, physical injury and diabetes. Moreover, pharmacological tools able to increase the synthesis of neuroactive steroids might represent new interesting therapeutic strategy to be applied in case of peripheral neuropathy. Copyright © 2015 Elsevier Inc. All rights reserved.

Baseline peripheral refractive error and changes in axial refraction during one year in a young adult population.

PubMed

Hartwig, Andreas; Charman, William Neil; Radhakrishnan, Hema

2016-01-01

To determine whether the initial characteristics of individual patterns of peripheral refraction relate to subsequent changes in refraction over a one-year period. 54 myopic and emmetropic subjects (mean age: 24.9±5.1 years; median 24 years) with normal vision were recruited and underwent conventional non-cycloplegic subjective refraction. Peripheral refraction was also measured at 5° intervals over the central 60° of horizontal visual field, together with axial length. After one year, measurements of subjective refraction and axial length were repeated on the 43 subjects who were still available for examination. In agreement with earlier studies, higher myopes tended to show greater relative peripheral hyperopia. There was, however, considerable inter-subject variation in the pattern of relative peripheral refractive error (RPRE) at any level of axial refraction. Across the group, mean one-year changes in axial refraction and axial length did not differ significantly from zero. There was no correlation between changes in these parameters for individual subjects and any characteristic of their RPRE. No evidence was found to support the hypothesis that the pattern of RPRE is predictive of subsequent refractive change in this age group. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Whole-Mount Adult Ear Skin Imaging Reveals Defective Neuro-Vascular Branching Morphogenesis in Obese and Type 2 Diabetic Mouse Models.

PubMed

Yamazaki, Tomoko; Li, Wenling; Yang, Ling; Li, Ping; Cao, Haiming; Motegi, Sei-Ichiro; Udey, Mark C; Bernhard, Elise; Nakamura, Takahisa; Mukouyama, Yoh-Suke

2018-01-11

Obesity and type 2 diabetes are frequently associated with peripheral neuropathy. Though there are multiple methods for diagnosis and analysis of morphological changes of peripheral nerves and blood vessels, three-dimensional high-resolution imaging is necessary to appreciate the pathogenesis with an anatomically recognizable branching morphogenesis and patterning. Here we established a novel technique for whole-mount imaging of adult mouse ear skin to visualize branching morphogenesis and patterning of peripheral nerves and blood vessels. Whole-mount immunostaining of adult mouse ear skin showed that peripheral sensory and sympathetic nerves align with large-diameter blood vessels. Diet-induced obesity (DIO) mice exhibit defective vascular smooth muscle cells (VSMCs) coverage, while there is no significant change in the amount of peripheral nerves. The leptin receptor-deficient db/db mice, a severe obese and type 2 diabetic mouse model, exhibit defective VSMC coverage and a large increase in the amount of smaller-diameter nerve bundles with myelin sheath and unmyelinated nerve fibers. Interestingly, an increase in the amount of myeloid immune cells was observed in the DIO but not db/db mouse skin. These data suggest that our whole-mount imaging method enables us to investigate the neuro-vascular and neuro-immune phenotypes in the animal models of obesity and diabetes.

Neural Correlates of Expert Visuomotor Performance in Badminton Players.

PubMed

Hülsdünker, Thorben; Strüder, Heiko K; Mierau, Andreas

2016-11-01

Elite/skilled athletes participating in sports that require the initiation of targeted movements in response to visual cues under critical time pressure typically outperform nonathletes in a visuomotor reaction task. However, the exact physiological mechanisms of this advantage remain unclear. Therefore, this study aimed to determine the neurophysiological processes contributing to superior visuomotor performance in athletes using visual evoked potential (VEP). Central and peripheral determinants of visuomotor reaction time were investigated in 15 skilled badminton players and 28 age-matched nonathletic controls. To determine the speed of visual signal perception in the cortex, chromatic and achromatic pattern reversal stimuli were presented, and VEP values were recorded with a 64-channel EEG system. Further, a simple visuomotor reaction task was performed to investigate the transformation of the visual into a motor signal in the brain as well as the timing of muscular activation. Amplitude and latency of VEP (N75, P100, and N145) revealed that the athletes did not significantly differ from the nonathletes. However, visuomotor reaction time was significantly reduced in the athletes compared with nonathletes (athletes = 234.9 ms, nonathletes = 260.3 ms, P = 0.015). This was accompanied by an earlier activation of the premotor and supplementary motor areas (athletes = 163.9 ms, nonathletes = 199.1 ms, P = 0.015) as well as an earlier EMG onset (athletes = 167.5 ms, nonathletes = 206.5 ms, P < 0.001). The latency of premotor and supplementary motor area activation was correlated with EMG onset (r = 0.41) and visuomotor reaction time (r = 0.43). The results of this study indicate that superior visuomotor performance in athletes originates from faster visuomotor transformation in the premotor and supplementary motor cortical regions rather than from earlier perception of visual signals in the visual cortex.

Neural coding strategies in auditory cortex.

PubMed

Wang, Xiaoqin

2007-07-01

In contrast to the visual system, the auditory system has longer subcortical pathways and more spiking synapses between the peripheral receptors and the cortex. This unique organization reflects the needs of the auditory system to extract behaviorally relevant information from a complex acoustic environment using strategies different from those used by other sensory systems. The neural representations of acoustic information in auditory cortex can be characterized by three types: (1) isomorphic (faithful) representations of acoustic structures; (2) non-isomorphic transformations of acoustic features and (3) transformations from acoustical to perceptual dimensions. The challenge facing auditory neurophysiologists is to understand the nature of the latter two transformations. In this article, I will review recent studies from our laboratory regarding temporal discharge patterns in auditory cortex of awake marmosets and cortical representations of time-varying signals. Findings from these studies show that (1) firing patterns of neurons in auditory cortex are dependent on stimulus optimality and context and (2) the auditory cortex forms internal representations of sounds that are no longer faithful replicas of their acoustic structures.

Central serous retinopathy with permanent visual deficit in a commercial air transport pilot: a case report.

PubMed

Newman, David G

2002-11-01

This report describes a case of central serous retinopathy (CSR) in the right eye of a commercial air transport pilot which resulted in a permanent reduction in visual acuity and the loss of his license. The previously fit and well pilot developed sudden loss of central vision, which resolved spontaneously. He then went on to experience recurrent episodes of fluctuating visual acuity (down to 6/60) and visual dysfunction in the right eye. His left eye remained unaffected. Eventually his condition stabilized, and he was left with a permanent reduction in right visual acuity (6/36) with intact peripheral visual fields and a completely normal left eye. After a period of grounding of 12 mo, he sought to have his license reinstated. He was considered to be a functionally monocular pilot, and as such was granted a conditional Class 1 medical category. The aeromedical disposition of this pilot and the issues involved in determining the fitness to fly of pilots with permanent visual defects arising from CSR are discussed.

Presumed topiramate retinopathy: a case report.

PubMed

Yeung, Tiffany L M; Li, Patrick S H; Li, Kenneth K W

2016-08-01

We report a case of peripheral pigmentary retinopathy and visual field loss following topiramate use for uncontrolled seizures. Such side effects have not been well documented despite the increasing use of topiramate in the past 10 years. A thorough search of available English literature revealed only a small number of reports of topiramate-induced retinopathy or visual field defects in humans. One similar case has been described. We are concerned about the possible rare instances of this occurrence in future patients and hence would like to propose a presumed correlation. A 48-year-old Chinese woman developed blurred vision after 9 months of topiramate use. Her visual acuity dropped from 1.2 to 0.7 in both eyes, with bilateral diffuse pigmentary retinopathy and a constricted visual field. Despite an improvement in visual acuity after cessation of the drug, the other clinical findings remained. The temporal relationship between the initiation of topiramate and the visual disturbance suggests that topiramate could be the cause of such signs and symptoms. Topiramate potentially causes pigmentary retinopathy and constricted visual field.