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https://www.readbyqxmd.com/read/29410359/modulation-of-the-zebrafish-optokinetic-reflex-by-pharmacologic-agents-targeting-gabaa-receptors
#1
Enhua Shao, Seth D Scheetz, Wenting Xie, Edward A Burton
Optokinetic reflex (OKR) responses provide a convenient means to evaluate visual, integrative and oculomotor function in larval zebrafish. We measured multiple aspects of the OKR response in zebrafish exposed systemically to compounds altering signaling at GABAA receptors in order to derive quantitative concentration-response relationships. The GABAA antagonist picrotoxin caused concentration-dependent decreases in reflex gain, saccade velocity, saccade amplitude, interocular concordance and interocular gain...
February 2, 2018: Neuroscience Letters
https://www.readbyqxmd.com/read/29391484/a-highly-efficient-murine-model-of-experimental-myopia
#2
Xiaoyan Jiang, Toshihide Kurihara, Hiromitsu Kunimi, Maki Miyauchi, Shin-Ichi Ikeda, Kiwako Mori, Kinya Tsubota, Hidemasa Torii, Kazuo Tsubota
Despite the global pandemic of myopia, the precise molecular mechanism of the onset of myopia remains largely unknown. This is partially because of the lack of efficient murine myopic models that allow genetic manipulation at low cost. Here we report a highly practical and reproducible lens-induced myopia model by specially designed frames and lenses for mice. A lens power dependent myopic induction in mice was shown until minus 30 diopter lenses. The phenotype was significantly stronger than form-deprivation myopia...
February 1, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29346495/long-term-temporal-changes-in-structure-and-function-of-rat-visual-system-after-blast-exposure
#3
Daniel F Shedd, Nikolaus A Benko, Justin Jones, Brian E Zaugg, Robert L Peiffer, Brittany Coats
Purpose: We identify long-term ocular sequelae subsequent to experimental blast exposure. Methods: Male Long-Evans rats were exposed to 230 kPa side-on primary blast overpressure using a compressed air driven shock tube. Visual system function and structure were assessed for 8 weeks after exposure using optokinetic nystagmus and optical coherence tomography. Vitreous protein expression and histology (TUNEL, H&E) were performed at 1 day and 1, 4, and 8 weeks. IOP was recorded bilaterally during blast in a subset of animals...
January 1, 2018: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29340763/the-retinal-projection-to-the-nucleus-lentiformis-mesencephali-in-zebra-finch-taeniopygia-guttata-and-anna-s-hummingbird-calypte-anna
#4
Cristian Gutierrez-Ibanez, Andrea H Gaede, Max R Dannish, Douglas L Altshuler, Douglas R Wylie
In birds, the nucleus of the basal optic root (nBOR) and the nucleus lentiformis mesencephali (LM) are retinal recipient nuclei involved in the analysis of optic flow and the generation of the optokinetic response. In both pigeons and chickens, retinal inputs to the nBOR arise from displaced ganglion cells (DGCs), which are found at the margin of the inner nuclear and inner plexiform layers. The LM receives afferents from retinal ganglion cells, but whether DGCs also project to LM is a matter of debate. Previous work in chickens had concluded that DGCs do not project to LM, but a recent study in pigeons found that both retinal ganglion cells and DGCs project to LM...
January 16, 2018: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
https://www.readbyqxmd.com/read/29332093/structure-function-correlation-in-hemianopic-vision-loss-in-children-aged-3-6-years-using-oct-and-svop-and-comparison-with-adult-eyes
#5
Wadim Bowl, Robert Knobloch, Silke Schweinfurth, Kerstin Holve, Knut Stieger, Birgit Lorenz
PURPOSE: To correlate visual field assessment with saccadic vector optokinetic perimetry (SVOP) in children with ganglion cell loss due to anterior pathway pathologies resulting in hemianopic visual field defects measured with optical coherence tomography (OCT). METHODS: 5 young (aged 3-6 years) and 5 adult patients with hemianopia, 10 healthy preschoolers (mean age 4.4 years), and 10 healthy adults (mean age 25.3 years) were tested with SVOP and OCT (focusing on the ganglion cell layer, GCL+)...
January 13, 2018: Ophthalmic Research
https://www.readbyqxmd.com/read/29313871/standing-postural-reaction-to-visual-and-proprioceptive-stimulation-in-chronic-acquired-demyelinating-polyneuropathy
#6
Clement P Provost, Sophie Tasseel-Ponche, Pierre Lozeron, Giulia Piccinini, Victorine Quintaine, Bertrand Arnulf, Nathalie Kubis, Alain P Yelnik
OBJECTIVE: To investigate the weight of visual and proprioceptive inputs, measured indirectly in standing position control, in patients with chronic acquired demyelinating polyneuropathy (CADP). DESIGN: Prospective case study. SUBJECTS: Twenty-five patients with CADP and 25 healthy controls. METHODS: Posture was recorded on a double force platform. Stimulations were optokinetic (60°/s) for visual input and vibration (50 Hz) for proprioceptive input...
January 9, 2018: Journal of Rehabilitation Medicine
https://www.readbyqxmd.com/read/29305606/xanthohumol-protects-morphology-and-function-in-a-mouse-model-of-retinal-degeneration
#7
Nathaniel F Henneman, Stephanie L Foster, Micah A Chrenek, Jana T Sellers, Charles B Wright, Robin H Schmidt, John M Nickerson, Jeffrey H Boatright
Purpose: To investigate whether treatment with xanthohumol (XN), the principal prenylated chalconoid from Humulus lupulus (hops), is protective in a mouse model of light-induced retinal degeneration (LIRD). Methods: Mice (129S2/SvPasCrl) were intraperitoneally injected with vehicle or XN prior to toxic light exposure and every 3 days thereafter. Retinal function was assessed by electroretinograms at 1, 2, and 4 weeks following toxic light exposure. Visual acuity was tested by optokinetic tracking 1 week and 4 weeks after toxic light exposure...
January 1, 2018: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29259575/visually-induced-dizziness-in-children-and-validation-of-the-pediatric-visually-induced-dizziness-questionnaire
#8
Marousa Pavlou, Susan L Whitney, Abdulaziz A Alkathiry, Marian Huett, Linda M Luxon, Ewa Raglan, Emma L Godfrey, Doris-Eva Bamiou
Aims: To develop and validate the Pediatric Visually Induced Dizziness Questionnaire (PVID) and quantify the presence and severity of visually induced dizziness (ViD), i.e., symptoms induced by visual motion stimuli including crowds and scrolling computer screens in children. Methods: 169 healthy (female n = 89; recruited from mainstream schools, London, UK) and 114 children with a primary migraine, concussion, or vestibular disorder diagnosis (female n = 62), aged 6-17 years, were included...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/29212065/development-of-the-visual-system-in-a-burrow-nesting-seabird-leach-s-storm-petrel
#9
Mindaugas Mitkus, Gabrielle A Nevitt, Almut Kelber
Little is known about the development of vision in wild birds. It is unknown, for example, whether the ability to see can be predicted by the level of prenatal growth or whether the eyes are open at hatching in a particular species. In this study, we investigated the growth of eyes, the formation of retinal ganglion cell topography, and the appearance of simple, visually guided behaviours in chicks of a small procellariiform seabird, Leach's storm petrel (Oceanodroma leucorhoa). This semi-precocial species, which has a well-developed sense of smell, nests in underground burrows where adults provision chicks for 6-8 weeks in the dark before fledging...
December 7, 2017: Brain, Behavior and Evolution
https://www.readbyqxmd.com/read/29190849/concussion-recovery-phase-affects-vestibular-and-oculomotor-symptom-provocation
#10
Kelly M Cheever, Jane McDevitt, Ryan Tierney, W Geoffrey Wright
Vestibular and oculomotor testing is emerging as a valuable assessment in sport-related concussion (SRC). However, their usefulness for tracking recovery and guiding return-to-play decisions remains unclear. Therefore the purpose of this study was to evaluate their clinical usefulness for tracking SRC recovery. Vestibular and oculomotor assessments were used to measure symptom provocation in an acute group (n=21) concussed≤10 days, prolonged symptoms group (n=10) concussed ≥16 days (median=84 days), healthy group (n=58) no concussions in >6 months...
November 30, 2017: International Journal of Sports Medicine
https://www.readbyqxmd.com/read/29179637/cone-dystrophy-and-ectopic-synaptogenesis-in-a-cacna1f-loss-of-function-model-of-congenital-stationary-night-blindness-csnb2a
#11
D M Waldner, N C Giraldo Sierra, S Bonfield, L Nguyen, I S Dimopoulos, Y Sauvé, W K Stell, N T Bech-Hansen
Congenital stationary night blindness 2A (CSNB2A) is an X-linked retinal disorder, characterized by phenotypically variable signs and symptoms of impaired vision. CSNB2A is due to mutations in CACNA1F, which codes for the pore-forming α1F subunit of a L-type voltage-gated calcium channel, Cav1.4. Mouse models of CSNB2A, used for characterizing the effects of various Cacna1f mutations, have revealed greater severity of defects than in human CSNB2A. Specifically, Cacna1f-knockout mice show an apparent lack of visual function, gradual retinal degeneration, and disruption of photoreceptor synaptic terminals...
November 28, 2017: Channels
https://www.readbyqxmd.com/read/29176570/population-scale-organization-of-cerebellar-granule-neuron-signaling-during-a-visuomotor-behavior
#12
Sherika J G Sylvester, Melanie M Lee, Alexandro D Ramirez, Sukbin Lim, Mark S Goldman, Emre R F Aksay
Granule cells at the input layer of the cerebellum comprise over half the neurons in the human brain and are thought to be critical for learning. However, little is known about granule neuron signaling at the population scale during behavior. We used calcium imaging in awake zebrafish during optokinetic behavior to record transgenically identified granule neurons throughout a cerebellar population. A significant fraction of the population was responsive at any given time. In contrast to core precerebellar populations, granule neuron responses were relatively heterogeneous, with variation in the degree of rectification and the balance of positive versus negative changes in activity...
November 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29157002/effects-of-circadian-clock-protein-per1b-on-zebrafish-visual-functions
#13
Ke Nie, Kun Wang, Deng-Feng Huang, Yu-Bin Huang, Wu Yin, Da-Long Ren, Han Wang, Bing Hu
The circadian clock is an endogenous and entrainable time-keeping mechanism with a period of approximately 24 h, operated by transcription/translation feedback loops composed of circadian clock genes and their proteins. The visual system displays robust circadian changes. Relatively little, however, is known about the mechanisms underlying visual circadian rhythmicity. Zebrafish period1b (per1b), as a canonical circadian clock gene, is involved in circadian regulation. Here, we observed that zebrafish per1b mutants exhibit visual defects including reduced behavioral contrast sensitivity and significant retinal dopaminergic deficiency...
November 20, 2017: Chronobiology International
https://www.readbyqxmd.com/read/29141881/it-s-not-all-black-and-white-visual-scene-parameters-influence-optokinetic-reflex-performance-in-xenopus-laevis-tadpoles
#14
Céline M Gravot, Alexander G Knorr, Stefan Glasauer, Hans Straka
The maintenance of visual acuity during active and passive body motion is ensured by gaze-stabilizing reflexes that aim at minimizing retinal image slip. For the optokinetic reflex (OKR), large-field visual motion of the surround forms the essential stimulus that activates eye movements. Properties of the moving visual world influence cognitive motion perception and the estimation of visual image velocity. Therefore, the performance of brainstem-mediated visuo-motor behaviors might also depend on image scene characteristics...
November 15, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/29120919/nystagmus
#15
Alexander A Tarnutzer, Dominik Straumann
PURPOSE OF REVIEW: The clinical and laboratory assessment of nystagmus in patients with neurologic disorders can provide crucial elements for a state-of-the-art differential diagnosis. An increasing number of publications in the fields of neuro-otology and neuro-ophthalmology have nystagmus in the center of interest, which makes frequent updates on the diagnostic and therapeutic relevance of these contributions indispensable. This review covers important clinical studies and studies in basic research relevant for the neurologist published from January 2016 to August 2017...
February 2018: Current Opinion in Neurology
https://www.readbyqxmd.com/read/29110135/the-effect-of-visual-contrast-on-human-vestibulo-ocular-reflex-adaptation
#16
M Muntaseer Mahfuz, Michael C Schubert, Christopher J Todd, William V C Figtree, Serajul I Khan, Americo A Migliaccio
The vestibulo-ocular reflex (VOR) is the main retinal image stabilising mechanism during rapid head movement. When the VOR does not stabilise the world or target image on the retina, retinal image slip occurs generating an error signal that drives the VOR response to increase or decrease until image slip is minimised, i.e. VOR adaptation occurs. Visual target contrast affects the human smooth pursuit and optokinetic reflex responses. We sought to determine if contrast also affected VOR adaptation. We tested 12 normal subjects, each over 16 separate sessions...
November 6, 2017: Journal of the Association for Research in Otolaryngology: JARO
https://www.readbyqxmd.com/read/29060092/analysis-of-computerized-optokinetic-nystagmus-induction-and-effect-of-contrast-on-ocular-fatigue
#17
Ji Sung Kim, Changhoon Baek, Sunyoung Yoo, Jeong-Min Hwang, Jong Mo Seo
Optokinetic nystagmus (OKN) is useful in evaluating visual function objectively, and the classical black-and-white-striped OKN drum is being replaced by video or computer monitor. However, the examinee may feel fatigue during test because of high contrast of luminous pattern from monitor. This paper suggests a plan to reduce eye fatigue of participant by decreasing contrast of patterns without reducing OKN response. Alternating black and white stripes are shown on flat-panel liquid-crystal display monitor and moved horizontally to evoke OKN of the examinee, and the OKN wasW observed through electrooculography (EOG)...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29042258/an-open-source-method-to-analyze-optokinetic-reflex-responses-in-larval-zebrafish
#18
Seth D Scheetz, Enhua Shao, Yangzhong Zhou, Clinton L Cario, Qing Bai, Edward A Burton
BACKGROUND: Optokinetic reflex (OKR) responses provide a convenient means to evaluate oculomotor, integrative and afferent visual function in larval zebrafish models, which are commonly used to elucidate molecular mechanisms underlying development, disease and repair of the vertebrate nervous system. NEW METHOD: We developed an open-source MATLAB-based solution for automated quantitative analysis of OKR responses in larval zebrafish. The package includes applications to: (i) generate sinusoidally-transformed animated grating patterns suitable for projection onto a cylindrical screen to elicit the OKR; (ii) determine and record the angular orientations of the eyes in each frame of a video recording showing the OKR response; and (iii) analyze angular orientation data from the tracking program to yield a set of parameters that quantify essential elements of the OKR...
October 14, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/29038003/hemin-supports-the-survival-of-photoreceptors-injured-by-n-methyl-n-nitrosourea-the-contributory-role-of-neuroglobin-in-photoreceptor-degeneration
#19
Ye Tao, Zhao Ma, Bei Liu, Wei Fang, Limin Qin, Yi Fei Huang, Lu Wang, Yanling Gao
Retina is a critical component of the central nerve system that is responsible for the conversion of light stimulus into electrical spikes. Retinitis pigmentosa (RP) comprises a heterogeneous group of inherited retinal dystrophies leading to blindness. We examined retinal neuroglobin (Ngb) expression in a pharmacologically induced RP animal model, the N-Methyl-N-nitrosourea (MNU) administered mice. The retinal Ngb expression in MNU administered mice attenuated following a time dependent manner, suggesting Ngb was involved in the photoreceptor degeneration...
October 13, 2017: Brain Research
https://www.readbyqxmd.com/read/28978733/head-movements-quadruple-the-range-of-speeds-encoded-by-the-insect-motion-vision-system-in-hawkmoths
#20
Shane P Windsor, Graham K Taylor
Flying insects use compensatory head movements to stabilize gaze. Like other optokinetic responses, these movements can reduce image displacement, motion and misalignment, and simplify the optic flow field. Because gaze is imperfectly stabilized in insects, we hypothesized that compensatory head movements serve to extend the range of velocities of self-motion that the visual system encodes. We tested this by measuring head movements in hawkmoths Hyles lineata responding to full-field visual stimuli of differing oscillation amplitudes, oscillation frequencies and spatial frequencies...
October 11, 2017: Proceedings. Biological Sciences
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