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https://www.readbyqxmd.com/read/29155078/radial-asymmetries-in-population-receptive-field-size-and-cortical-magnification-factor-in-early-visual-cortex
#1
Maria Fatima Silva, Jan W Brascamp, Sónia Ferreira, Miguel Castelo-Branco, Serge O Dumoulin, Ben M Harvey
Human visual cortex does not represent the whole visual field with the same detail. Changes in receptive field size, population receptive field (pRF) size and cortical magnification factor (CMF) with eccentricity are well established, and associated with changes in visual acuity with eccentricity. Visual acuity also changes across polar angle. However, it remains unclear how RF size, pRF size and CMF change across polar angle. Here, we examine differences in pRF size and CMF across polar angle in V1, V2 and V3 using pRF modeling of human fMRI data...
November 14, 2017: NeuroImage
https://www.readbyqxmd.com/read/29152467/an-unruptured-anterior-communicating-artery-aneurysm-presenting-with-left-homonymous-hemianopsia-a-case-report
#2
Jae Wook Kim, Taek Kyun Nam, Ki Su Park, Yong Sook Park, Jeong Taik Kwon
Unruptured cerebral aneurysms sometimes present with visual symptomsdue to compression of the visual pathways. However, until now, unruptured anterior communicating artery (ACoA) aneurysms presenting visual field defects have been extremely rare. The authors report the case of a 51-year-old woman who presented with left homonymous hemianopsia. Radiological findings demonstrated an ACoA aneurysm filled with thrombus, that was compressing the optic chiasm and post-chiasmal tract. The patient underwent clipping of the aneurysm, which resolved the visual field defect...
June 2017: Journal of Cerebrovascular and Endovascular Neurosurgery
https://www.readbyqxmd.com/read/29146465/more-than-blindsight-case-report-of-a-child-with-extraordinary-visual-capacity-following-perinatal-bilateral-occipital-lobe-injury
#3
Inaki-Carril Mundinano, Juan Chen, Mitchell de Souza, Marc G Sarossy, Marc F Joanisse, Melvyn A Goodale, James A Bourne
Injury to the primary visual cortex (V1, striate cortex) and the geniculostriate pathway in adults results in cortical blindness, abolishing conscious visual perception. Early studies by Larry Weiskrantz and colleagues demonstrated that some patients with an occipital-lobe injury exhibited a degree of unconscious vision and visually-guided behaviour within the blind field. A more recent focus has been the observed phenomenon whereby early-life injury to V1 often results in the preservation of visual perception in both monkeys and humans...
November 13, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/29141494/influence-of-script-direction-on-word-processing-modes-in-left-and-right-visual-fields
#4
Eric Siéroff, Yael Slama
Word processing in left (LVF) and right (RVF) visual fields may be affected by left hemisphere activation during reading and by script direction. We evaluated the effect of script direction by presenting words in left-to-right (French) and right-to-left (Hebrew) scripts to bilingual French participants. Words of different lengths were presented in the LVF and the RVF in a naming task. Results showed (1) a stronger word length effect in the LVF than in the RVF in French, and no difference of word length effect between LVF and RVF in Hebrew; (2) a first-letter advantage only in the LVF in French and in the RVF in Hebrew, showing an effect of script direction on letter processing; and (3) a stronger advantage of external over internal letters in words presented in the LVF than in the RVF for both languages, showing a left hemisphere influence on letter activation...
November 15, 2017: Laterality
https://www.readbyqxmd.com/read/29138476/visuospatial-attention-in-the-lateralised-brain-of-pigeons-a-matter-of-ontogenetic-light-experiences
#5
Sara Letzner, Onur Güntürkün, Stephanie Lor, Robert Jan Pawlik, Martina Manns
The ontogenetic mechanisms leading to complementary hemispheric specialisations of the two brain halves are poorly understood. In pigeons, asymmetrical light stimulation during development triggers the left-hemispheric dominance for visuomotor control but light effects on right-hemispheric specialisations are largely unknown. We therefore tested adult pigeons with and without embryonic light experience in a visual search task in which the birds pecked peas regularly scattered on an area in front of them. Comparing the pecking pattern of both groups indicates that the embryonic light conditions differentially influence biased visuospatial attention under mono- and binocular seeing conditions...
November 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29133438/normal-topography-and-binocularity-of-the-superior-colliculus-in-strabismus
#6
John R Economides, Brittany C Rapone, Daniel L Adams, Jonathan C Horton
In subjects with alternating strabismus either eye can be used to saccade to visual targets. The brain must calculate the correct vector for each saccade, which will depend on the eye chosen to make it. The superior colliculus, a major midbrain center for saccade generation, was examined to determine if the maps serving each eye were shifted to compensate for strabismus.Alternating exotropia was induced in two male macaques at age one month by sectioning the tendons of the medial recti. Once the animals grew to maturity, they were trained to fixate targets with either eye...
November 13, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29131903/slow-reading-in-glaucoma-is-it-due-to-the-shrinking-visual-span-in-central-vision
#7
MiYoung Kwon, Rong Liu, Bhavika N Patel, Christopher Girkin
Purpose: Glaucoma is a leading cause of blindness worldwide, characterized by progressive loss of retinal ganglion cells. Patients with bilateral glaucoma read slower than normal cohorts. Here we examined the factors that may underlie slow reading in glaucoma and determined the best predictor of reading speed in glaucoma. Methods: A total of 38 subjects participated in this study: 17 patients with primary open-angle glaucoma (mean age = 64.71 years) and 21 age-similar normal controls (58...
November 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29126774/fixating-at-far-distance-shortens-reaction-time-to-peripheral-visual-stimuli-at-specific-locations
#8
Masahiro Kokubu, Soichi Ando, Shingo Oda
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...
November 7, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/29117252/preclinical-4d-flow-magnetic-resonance-phase-contrast-imaging-of-the-murine-aortic-arch
#9
Moritz Braig, Jochen Leupold, Marius Menza, Maximilian Russe, Cheng-Wen Ko, Juergen Hennig, Dominik von Elverfeldt
PURPOSE: Cardiovascular diseases remain the number one death cause worldwide. Preclinical 4D flow phase contrast magnetic resonance imaging can provide substantial insights in the analysis of aortic pathophysiologies in various animal models. These insights may allow a better understanding of pathophysiologies, therapy monitoring, and can possibly be translated to humans. This study provides a framework to acquire the velocity field within the aortic arch. It analyses important flow values at different locations within the aortic arch...
2017: PloS One
https://www.readbyqxmd.com/read/29110092/tracking-posttraumatic-hemianopia
#10
Thomas Decramer, Karel Van Keer, Peter Stalmans, Patrick Dupont, Stefan Sunaert, Tom Theys
Hemianopia after traumatic brain injury is not infrequent and results from retro-chiasmatic lesions. Differentiating optic pathway lesions can be challenging with classic imaging. Advanced imaging techniques as an investigational tool for posttraumatic hemianopia are discussed and their pitfalls highlighted through an illustrative case study. In a patient with posttraumatic hemianopia, MRI at 8 weeks and 2 years after trauma were analyzed. Diffusion tensor imaging (DTI) and morphometric analysis of the primary visual cortex (V1) were performed...
November 6, 2017: Journal of Neurology
https://www.readbyqxmd.com/read/29100949/plasticity-of-the-human-visual-brain-after-early-cortical-lesion
#11
K Mikellidou, R Arrighi, G Aghakhanyan, F Tinelli, F Frijia, S Crespi, F De Masi, D Montanaro, M C Morrone
In adults, partial damage to V1 or optic radiations abolishes perception in the corresponding part of the visual field, causing a scotoma. However, it is widely accepted that the developing cortex has superior capacities to reorganize following an early lesion to endorse adaptive plasticity. Here we report a single patient case (G.S.) with near normal central field vision despite a massive unilateral lesion to the optic radiations acquired early in life. The patient underwent surgical removal of a right hemisphere parieto-temporal-occipital atypical choroid plexus papilloma of the right lateral ventricle at four months of age, which presumably altered the visual pathways during in utero development...
October 31, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/29096198/face-inversion-reveals-holistic-processing-of-peripheral-faces
#12
Petra Kovács, Balázs Knakker, Petra Hermann, Gyula Kovács, Zoltán Vidnyánszky
Face perception is accomplished by face-selective neural processes, involving holistic processing that enables highly efficient integration of facial features into a whole-face representation. It has been shown that in face-selective regions of the ventral temporal cortex (VTC), neural resources involved in holistic processing are primarily dedicated to the central portion of the visual field. These findings raise the intriguing possibility that holistic processing might be the privilege of centrally presented faces and could be strongly diminished in the case of peripheral faces...
October 6, 2017: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/29084330/characterizing-the-natural-history-of-visual-function-in-choroideremia-using-microperimetry-and-multimodal-retinal-imaging
#13
RANDOMIZED CONTROLLED TRIAL
Jasleen K Jolly, Kanmin Xue, Thomas L Edwards, Markus Groppe, Robert E MacLaren
Purpose: Centripetal retinal degeneration in choroideremia (CHM) leads to early visual field restriction and late central vision loss. The latter marks an acute decline in quality of life but visual prognostication remains challenging. We investigated visual function in CHM by correlating best-corrected visual acuity (BCVA), microperimetry and multimodal imaging. Methods: Fifty-six consecutive CHM patients attending Oxford Eye Hospital were examined with BCVA, 10-2 microperimetry, optical coherence tomography, and fundus autofluorescence (AF)...
October 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29073920/homeostatic-modulation-on-unconscious-hedonic-responses-to-food
#14
Wataru Sato, Reiko Sawada, Yasutaka Kubota, Motomi Toichi, Tohru Fushiki
OBJECTIVE: Hedonic/affective responses to food play a critical role in eating behavior. Previous behavioral studies have shown that hedonic responses to food are elicited consciously and unconsciously. Although the studies also showed that hunger and satiation have a modulatory effect on conscious hedonic responses to food, the effect of these homeostatic states on unconscious hedonic responses to food remains unknown. RESULTS: We investigated unconscious hedonic responses to food in hungry and satiated participants using the subliminal affective priming paradigm...
October 26, 2017: BMC Research Notes
https://www.readbyqxmd.com/read/29067576/a-new-fluorescence-imaging-technique-for-visualizing-hepatobiliary-structures-using-sodium-fluorescein-result-of-a-preclinical-study-in-a-rat-model
#15
Sam-Youl Yoon, Chang Min Lee, Tae-Jin Song, Hyung Joon Han, Seonghan Kim
BACKGROUND: Near-infrared fluorescence imaging has been recently applied in the field of hepatobiliary surgery. Our objective was to apply blue light fluorescence imaging to cholangiography and liver mapping during laparoscopic surgery. Therefore, we designed a preclinical study to evaluate the feasibility of using blue light fluorescence for cholangiography and liver mapping in a rat model. METHODS: Sodium fluorescein solution (1 mL to each individual) were administered intravenously to 20 male Sprague-Dawley rats (6 weeks old, 200-250 g), after laparotomy...
October 24, 2017: Surgical Endoscopy
https://www.readbyqxmd.com/read/29065012/preferred-retinal-locus-locations-in-age-related-macular-degeneration
#16
Murat Erbezci, Taylan Ozturk
PURPOSE: An evaluation of the preferred retinal locus (PRL) in patients with age-related macular degeneration and a central scotoma is becoming a standard of care in the practice of low-vision rehabilitation. This is a retrospective study of PRL specifications and whether they have a correlation with the best-corrected visual acuities of patients with age-related macular degeneration. METHODS: Seventy-two patients with macular degeneration (144 eyes) were included in the study...
October 23, 2017: Retina
https://www.readbyqxmd.com/read/29061290/beyond-time-and-space-the-effect-of-a-lateralized-sustained-attention-task-and-brain-stimulation-on-spatial-and-selective-attention
#17
Nir Shalev, Linde De Wandel, Paul Dockree, Nele Demeyere, Magdalena Chechlacz
The Theory of Visual Attention (TVA) provides a mathematical formalisation of the "biased competition" account of visual attention. Applying this model to individual performance in a free recall task allows the estimation of 5 independent attentional parameters: visual short-term memory (VSTM) capacity, speed of information processing, perceptual threshold of visual detection; attentional weights representing spatial distribution of attention (spatial bias), and the top-down selectivity index. While the TVA focuses on selection in space, complementary accounts of attention describe how attention is maintained over time, and how temporal processes interact with selection...
October 3, 2017: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/29051833/anatomical-and-functional-correlation-in-susac-syndrome-multimodal-imaging-assessment
#18
Alexandre G B Azevedo, Luiz H Lima, Léo Müller, Flávio Rezende Filho, Cláudio Zett, André Maia, Luiz Roisman
BACKGROUND: Susac's syndrome (SuS) is an uncommon disease characterized by retinal microangiopathy that may be assessed more accurately with optical coherence tomography angiography (OCTA), a new imaging technique which provides a retinal microvasculature map. The purpose of this case report is to describe the multimodal imaging findings of SuS correlating OCTA with functional tests. CASE PRESENTATION: Retrospective review of one case with clinical and imaging evidence of SuS...
2017: International Journal of Retina and Vitreous
https://www.readbyqxmd.com/read/29051329/safety-profile-and-efficacy-of-tacrolimus-in-the-treatment-of-birdshot-retinochoroiditis-a-retrospective-case-series-review
#19
Farrah Islam, Mark Westcott, Angela Rees, Anthony George Robson, Bharat Kapoor, Graham Holder, Carlos Pavesio
AIM: Evaluation of the use of tacrolimus in the treatment of birdshot retinochoroiditis (BRC) at a tertiary referral centre with the aim to describe its safety and efficacy. METHODS: The medical records of 25 patients diagnosed with BRC at uveitis service, Moorfields Eye Hospital, and who had received tacrolimus treatment were retrospectively reviewed. The main outcome measures of the study were (1) safety of tacrolimus in terms of side effects and (2) efficacy, as measured both by control of inflammation and visual function assessed by Humphrey visual fields and electrophysiological testing over at least 6 months and then 1 year...
October 19, 2017: British Journal of Ophthalmology
https://www.readbyqxmd.com/read/29044872/transcranial-magnetic-stimulation-of-right-inferior-parietal-cortex-causally-influences-prefrontal-activation-for-visual-detection
#20
Joana Leitão, Axel Thielscher, Hwee Ling Lee, Johannes Tuennerhoff, Uta Noppeney
For effective interactions with the environment the brain needs to form perceptual decisions based on noisy sensory evidence. Accumulating evidence suggests that perceptual decisions are formed by widespread interactions amongst sensory areas representing the noisy sensory evidence and fronto-parietal areas integrating the evidence into a decision variable that is compared to a decisional threshold. This concurrent transcranial magnetic stimulation (TMS)-fMRI study applied 10 Hz bursts of four TMS (or Sham) pulses to the intraparietal sulcus (IPS) to investigate the causal influence of IPS on the neural systems involved in perceptual decision making...
October 17, 2017: European Journal of Neuroscience
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