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https://www.readbyqxmd.com/read/28424655/sustained-and-transient-vestibular-systems-a-physiological-basis-for-interpreting-vestibular-function
#1
REVIEW
Ian S Curthoys, Hamish G MacDougall, Pierre-Paul Vidal, Catherine de Waele
Otolithic afferents with regular resting discharge respond to gravity or low-frequency linear accelerations, and we term these the static or sustained otolithic system. However, in the otolithic sense organs, there is anatomical differentiation across the maculae and corresponding physiological differentiation. A specialized band of receptors called the striola consists of mainly type I receptors whose hair bundles are weakly tethered to the overlying otolithic membrane. The afferent neurons, which form calyx synapses on type I striolar receptors, have irregular resting discharge and have low thresholds to high frequency (e...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28418222/modified-loop-myopexy-technique-for-severe-high-myopic-strabismus-fixus
#2
Leilei Zou, Shuai Liu, Rui Liu, Yao Jing, Yan Liu, Jing Lin, Hong Liu
IMPORTANCE: This study introduces a modified loop myopexy technique for severe high myopic strabismus fixus (MSF). BACKGROUND: To evaluate the surgical results of loop myopexy with or without medial rectus (MR) recession for the treatment of patients with MSF. DESIGN: A retrospective study in a Chinese teaching hospital. PARTICIPANTS: Data was collected from 25 MSF patients (33 eyes) with restriction in both abduction and sursumduction...
April 18, 2017: Clinical & Experimental Ophthalmology
https://www.readbyqxmd.com/read/28414059/a-mouse-ocular-explant-model-that-enables-the-study-of-living-optic-nerve-head-events-after-acute-and-chronic-intraocular-pressure-elevation-focusing-on-retinal-ganglion-cell-axons-and-mitochondria
#3
Elizabeth C Kimball, Mary E Pease, Matthew R Steinhart, Ericka N Oglesby, Ian Pitha, Cathy Nguyen, Harry A Quigley
We developed an explant model of the mouse eye and optic nerve that facilitates the study of retinal ganglion cell axons and mitochondria in the living optic nerve head (ONH) in an ex vivo environment. Two transgenic mouse strains were used, one expressing yellow fluorescent protein in selected axons and a second strain expressing cyan fluorescent protein in all mitochondria. We viewed an explanted mouse eye and optic nerve by laser scanning microscopy at and behind the ONH, the site of glaucoma injury. Explants from previously untreated mice were studied with the intraocular pressure (IOP) set artificially at normal or elevated levels for several hours...
April 14, 2017: Experimental Eye Research
https://www.readbyqxmd.com/read/28410563/wernicke-s-encephalopathy-following-reduced-food-intake-due-to-depressive-disorders
#4
Donato Melchionda, Tommaso Martino, Elena Carapelle, Alessandra Lalla, Daniela Cologno, Carlo Avolio
Wernicke's encephalopathy (WE) is an unexpected common neurological disorder caused by thiamine deficiency often due to alcohol abuse, but WE-not alcohol related is also frequent. A prolonged reduction of food intake can cause WE. This condition can arise in depression disorders, especially in the early stages of these psychiatric syndromes. WE is characterized by the triad of signs: ataxia, ocular dysfunctions and confusional state. However, they rarely appear together and this makes the diagnosis particularly difficult, especially when there is not a history of alcohol abuse...
April 14, 2017: Nutritional Neuroscience
https://www.readbyqxmd.com/read/28409282/motor-neuron-vulnerability-and-resistance-in-amyotrophic-lateral-sclerosis
#5
REVIEW
Jik Nijssen, Laura H Comley, Eva Hedlund
In the fatal disease-amyotrophic lateral sclerosis (ALS)-upper (corticospinal) motor neurons (MNs) and lower somatic MNs, which innervate voluntary muscles, degenerate. Importantly, certain lower MN subgroups are relatively resistant to degeneration, even though pathogenic proteins are typically ubiquitously expressed. Ocular MNs (OMNs), including the oculomotor, trochlear and abducens nuclei (CNIII, IV and VI), which regulate eye movement, persist throughout the disease. Consequently, eye-tracking devices are used to enable paralysed ALS patients (who can no longer speak) to communicate...
April 13, 2017: Acta Neuropathologica
https://www.readbyqxmd.com/read/28404827/new-insights-into-vestibular-saccade-interaction-based-on-covert-corrective-saccades-in-patients-with-unilateral-vestibular-deficits
#6
Paolo Colagiorgio, Maurizio Versino, Silvia Colnaghi, Silvia Quaglieri, Marco Manfrin, Ewa Zamaro, Georgios Mantokoudis, David S Zee, Stefano Ramat
In response to passive high-acceleration head impulses patients with low vestibulo-ocular reflex (VOR) gains often produce covert (executed while the head is still moving) corrective saccades in the direction of deficient slow phases. Here we examined 23 patients using passive, and nine also active, head impulses with acute (< 10 days from onset) unilateral vestibular neuritis and low VOR gains. We found that when corrective saccades are larger than 10°, the slow-phase component of the VOR is inhibited, even though inhibition increases further the time to reacquire the fixation target...
April 12, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28397316/proposed-expansion-margins-for-planning-organ-at-risk-volume-for-lenses-during-radiation-therapy-of-the-nasal-cavity-in-dogs-and-cats
#7
Zaki Jafry, Arnon Gal, Andre Fleck, Johnson Darko, Valerie J Poirier
Radiation therapy protocols for the feline or canine nasal cavity can damage epithelial cells of the posterior pole of the lens and lead to the development of cataracts. Aims of this retrospective, descriptive study were to calculate movements of the lens during radiation therapy of the nasal cavity in a sample of cats and dogs, and to propose species-specific expansion margins for planning organ at risk volume (PRV) to minimize radiation doses to the lens. All included patients were immobilized with an indexed bite block and positioned in a vacuum positioning cushion for head irradiation...
April 11, 2017: Veterinary Radiology & Ultrasound
https://www.readbyqxmd.com/read/28393118/postural-compensation-strategy-depends-on-the-severity-of-vestibular-damage
#8
Lara A Thompson, Csilla Haburcakova, Richard F Lewis
The purpose of this study was to investigate the effects of various levels of vestibular function on balance in two, free-standing rhesus monkeys. We hypothesized that postural control strategy depended on the severity of vestibular damage. More specifically, that increased muscle stiffness (via short-latency mechanisms) was adequate to compensate for mild damage, but long-latency mechanisms must be utilized for more severe vestibular damage. One animal was studied for pre-ablated and mild vestibular dysfunction states, while a second animal was studied in a pre-ablated and severe vestibular dysfunction state...
March 2017: Heliyon
https://www.readbyqxmd.com/read/28387687/vibro-tactile-and-auditory-balance-biofeedback-changes-muscle-activity-patterns-possible-implications-for-vestibular%C3%A2-implants
#9
John H J Allum, Flurin Honegger
BACKGROUND: The two different types of balance prostheses being developed, implants and vibro-tactile/auditory feedback prostheses, rely on different measures to prove efficacy (those based on vestibular ocular reflexes versus balance control, respectively). Here we provide evidence that examining muscle activity might provide a useful alternative for both. METHODS: The muscle activity of 6 bilateral vestibular loss (BVL) and 7 age-matched healthy controls (HC) was examined while standing eyes closed on a foam support surface...
2017: Journal of Vestibular Research: Equilibrium & Orientation
https://www.readbyqxmd.com/read/28387548/review-of-vestibular-and-oculomotor-screening-and-concussion-rehabilitation
#10
Anthony P Kontos, Jamie McAllister Deitrick, Michael W Collins, Anne Mucha
Vestibular and oculomotor impairment and symptoms may be associated with worse outcomes after sport-related concussion (SRC), including prolonged recovery. In this review, we evaluate current findings on vestibular and oculomotor impairments as well as treatment approaches after SRC, and we highlight areas in which investigation is needed. Clinical researchers have intimated that recovery from SRC may follow certain clinical profiles that affect the vestibular and oculomotor pathways. Identifying clinical profiles may help to inform better treatment and earlier intervention to reduce recovery time after SRC...
March 2017: Journal of Athletic Training
https://www.readbyqxmd.com/read/28385301/marshall-m-parks-memorial-lecture-ocular-motor-misbehavior-in-children-where-neuro-ophthalmology-meets-strabismus
#11
REVIEW
Michael C Brodsky
Clinical diagnosis has been supplemented by neuroimaging advances, genetic discoveries, and molecular research to generate new neurobiological discoveries pertaining to early maldevelopment of ocular motor control systems. In this focused review, I examine recent paradigm shifts that have transformed our understanding of pediatric ocular motor disease at the prenuclear and infranuclear levels. The pathogenesis of complex ocular motor disorders, such as paradoxical pupillary constriction to darkness, benign tonic upgaze of infancy, congenital fibrosis syndrome, and the constellation of unique eye movements that accompany Joubert syndrome, are elucidated...
April 3, 2017: Ophthalmology
https://www.readbyqxmd.com/read/28380076/strength-of-baseline-inter-trial-correlations-forecasts-adaptive-capacity-in-the-vestibulo-ocular-reflex
#12
Kara H Beaton, Aaron L Wong, Steven B Lowen, Mark Shelhamer
Individual differences in sensorimotor adaptability may permit customized training protocols for optimum learning. Here, we sought to forecast individual adaptive capabilities in the vestibulo-ocular reflex (VOR). Subjects performed 400 head-rotation steps (400 trials) during a baseline test, followed by 20 min of VOR gain adaptation. All subjects exhibited mean baseline VOR gain of approximately 1.0, variable from trial to trial, and showed desired reductions in gain following adaptation with variation in extent across individuals...
2017: PloS One
https://www.readbyqxmd.com/read/28360792/orbital-myositis-evaluating-five-new-cases-regarding-clinical-and-radiological-features
#13
Özlem Önder, Rıfat Reha Bilgin, Aslı Köşkderelioğlu, Muhteşem Gedizlioğlu
Orbital myositis (OM) is an inflammatory disorder of the extraocular muscles. The signs and symptoms of OM are periorbital pain, eyelid swelling and redness, restricted ocular motility, and strabismus. There are at least two major forms, described by Benedikt GH Schoser, a limited oligosymptomatic ocular myositis (LOOM), which is associated with conjunctival injection only, and severe exophthalmic ocular myositis (SEOM), which presents with additional ptosis, chemosis, and proptosis. We report the clinical and radiological features of five patients with OM who were recently followed in our clinic...
June 2016: Noro Psikiyatri Arsivi
https://www.readbyqxmd.com/read/28356369/the-independence-of-eye-movements-in-a-stomatopod-crustacean-is-task-dependent
#14
Ilse M Daly, Martin J How, Julian C Partridge, Nicholas W Roberts
Stomatopods have an extraordinary visual system, incorporating independent movement of their eyes in all three degrees of rotational freedom. In this work, we demonstrate that in the peacock mantis shrimp, Odontodactylus scyllarus, the level of ocular independence is task dependent. During gaze stabilization in the context of optokinesis, there is weak but significant correlation between the left and right eyes in the yaw degree of rotational freedom, but not in pitch and torsion. When one eye is completely occluded, the uncovered eye does not drive the covered eye during gaze stabilization...
April 1, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28340582/optimisation-of-an-exemplar-oculomotor-model-using-multi-objective-genetic-algorithms-executed-on-a-gpu-cpu-combination
#15
Eleftherios Avramidis, Ozgur E Akman
BACKGROUND: Parameter optimisation is a critical step in the construction of computational biology models. In eye movement research, computational models are increasingly important to understanding the mechanistic basis of normal and abnormal behaviour. In this study, we considered an existing neurobiological model of fast eye movements (saccades), capable of generating realistic simulations of: (i) normal horizontal saccades; and (ii) infantile nystagmus - pathological ocular oscillations that can be subdivided into different waveform classes...
March 24, 2017: BMC Systems Biology
https://www.readbyqxmd.com/read/28336357/assessment-of-vestibulo-ocular-function-without-measuring-eye-movements
#16
Kara H Beaton, Michael Schubert, Mark Shelhamer
BACKGROUND: The vestibulo-ocular reflex (VOR) maintains stable gaze during head motion. Deficiencies lead to apparent world motion due to incomplete stabilization of eyes in space. VOR measurement requires specialized apparatus, trained operators, and significant setup time. NEW METHOD: We present a system (VON: vestibulo-ocular nulling) for rapid vestibulo-ocular assessment without measuring eye movements per se. VON uses a head-mounted motion sensor, laptop computer with user input control, and laser target whose position is controlled by the computer...
March 20, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28330041/retinal-tractography-influence-of-diffusion-acquisition-ocular-laterality-and-ocular-dominance-in-healthy-subjects
#17
Clément Jean, Arnaud Attyé, Sylvie Grand, Augustin Lecler, Christophe Chiquet, Florent Aptel, Laurent Lamalle, Alexandre Krainik
PURPOSE: Exploration of the human retina has never been described with MRI tractography, supposedly because of ocular movement-related artifacts and imaging distortions with EPI diffusion acquisition. In this work, we used track-weighting imaging to assess retinal fascicles. Diffusion acquisition parameters influence was studied and the relationship between variability and ocular laterality and ocular dominance was explored. MATERIALS AND METHODS: Twenty healthy subjects underwent MRI, with retinal tractography calculated with the constrained spherical deconvolution model...
March 2017: Journal of Neuroradiology. Journal de Neuroradiologie
https://www.readbyqxmd.com/read/28323487/pathological-eye-movements-influence-on-the-recordings-of-ocular-vestibular-evoked-myogenic-potential
#18
Ting-Hua Yang, Hsin-Lin Chen, Yi-Ho Young
OBJECTIVE: This study investigated the influence of pathological eye movements on the recordings of ocular vestibulo-evoked myogenic potential (oVEMP). METHODS: Ten patients with pathological eye movements of non-vestibular origin (nine congenital nystagmus and one opsoclonus) who had negative MRI result were assigned to Group A. Another 20 vestibular neuritis (VN) patients with spontaneous nystagmus were assigned to Group B. Both groups underwent audiometry, and caloric, oVEMP and cervical VEMP (cVEMP) tests...
March 21, 2017: Acta Oto-laryngologica
https://www.readbyqxmd.com/read/28303385/after-effects-of-cerebellar-continuous-theta-burst-stimulation-on-reflexive-saccades-and-smooth-pursuit-in-humans
#19
Silvia Colnaghi, P Colagiorgio, S Ramat, E D'Angelo, G Koch, M Versino
The use of cerebellar repetitive transcranial magnetic stimulation has been attempted for perturbing reflexive and voluntary eye movements, but discrepancies are seen between the results of distinct studies possibly due to the different stimulation sites, intensities, and paradigms. We describe the after effects of 20 and 40 s continuous Theta Burst Stimulation (cTBS) as compared to sham stimulation, applied over the lateral cerebellar vermis and paravermis on Reflexive Saccades (RS) and Smooth Pursuit (SP) eye movements, recorded in the 30 min following stimulation...
March 16, 2017: Cerebellum
https://www.readbyqxmd.com/read/28300605/a-rapid-quantification-of-binocular-misalignment-without-recording-eye-movements-vertical-and-torsional-alignment-nulling
#20
Kara H Beaton, Mark J Shelhamer, Dale C Roberts, Michael C Schubert
BACKGROUND: Small, innate asymmetries between the left and right otolith organs can cause ocular misalignment with symptoms that include double vision and motion sickness. Additionally, ocular misalignment affects nearly 5% of the US population. We have developed a portable, non-invasive technology that uses subjective perception of binocular visual signals to estimate relative binocular alignment. NEW METHOD AND RESULTS: The Vertical Alignment Nulling (VAN) and Torsional Alignment Nulling (TAN) tests ask subjects to view one red and one blue line on a tablet computer while looking through color-matched red and blue filters so that each eye sees only one of the lines...
March 12, 2017: Journal of Neuroscience Methods
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