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Spatial neglect

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https://www.readbyqxmd.com/read/28429801/the-dizzy-patient-don-t-forget-disorders-of-the-central-vestibular-system
#1
REVIEW
Thomas Brandt, Marianne Dieterich
Vertigo and dizziness are among the most common complaints in neurology clinics, and they account for about 13% of the patients entering emergency units. In this Review, we focus on central vestibular disorders, which are mostly attributable to acute unilateral lesions of the bilateral vestibular circuitry in the brain. In a tertiary interdisciplinary outpatient dizziness unit, central vestibular disorders, including vestibular migraine, comprise about 25% of the established diagnoses. The signs and symptoms of these disorders can mimic those of peripheral vestibular disorders with sustained rotational vertigo...
April 21, 2017: Nature Reviews. Neurology
https://www.readbyqxmd.com/read/28413340/history-dependence-and-the-continuum-approximation-breakdown-the-impact-of-domain-growth-on-turing-s-instability
#2
Václav Klika, Eamonn A Gaffney
A diffusively driven instability has been hypothesized as a mechanism to drive spatial self-organization in biological systems since the seminal work of Turing. Such systems are often considered on a growing domain, but traditional theoretical studies have only treated the domain size as a bifurcation parameter, neglecting the system non-autonomy. More recently, the conditions for a diffusively driven instability on a growing domain have been determined under stringent conditions, including slow growth, a restriction on the temporal interval over which the prospect of an instability can be considered and a neglect of the impact that time evolution has on the stability properties of the homogeneous reference state from which heterogeneity emerges...
March 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28392004/-paradox-of-slow-frequencies-are-slow-frequencies-in-upper-cortical-layers-a-neural-predisposition-of-the-level-state-of-consciousness-npc
#3
Georg Northoff
Consciousness research has much focused on faster frequencies like alpha or gamma while neglecting the slower ones in the infraslow (0.001-0.1Hz) and slow (0.1-1Hz) frequency range. These slower frequency ranges have a "bad reputation" though; their increase in power can observed during the loss of consciousness as in sleep, anesthesia, and vegetative state. However, at the same time, slower frequencies have been conceived instrumental for consciousness. The present paper aims to resolve this paradox which I describe as "paradox of slow frequencies"...
April 5, 2017: Consciousness and Cognition
https://www.readbyqxmd.com/read/28387593/a-case-of-posterior-cortical-atrophy-with-vertical-neglect
#4
Hilary Glazer, Leila Saadatpour, Leilani Doty, Kenneth M Heilman
Posterior cortical atrophy (PCA) is a syndrome caused by a neurodegenerative disease that often presents with visuospatial deficits, and can be debilitating. PCA is often characterized by elements of Balint's syndrome and dyslexia. The most common underlying pathology has been found to be Alzheimer's disease. Signs of horizontal neglect are frequently associated with PCA, but the presence of vertical (or altitudinal) neglect has not yet been reported in a patient with PCA or other forms of neurodegenerative dementia...
April 7, 2017: Neurocase
https://www.readbyqxmd.com/read/28385053/using-real-time-fmri-neurofeedback-to-restore-right-occipital-cortex-activity-in-patients-with-left-visuo-spatial-neglect-proof-of-principle-and-preliminary-results
#5
Fabien Robineau, Arnaud Saj, Rémi Neveu, Dimitri Van De Ville, Frank Scharnowski, Patrik Vuilleumier
Hemineglect is common after right parietal stroke, characterised by impaired awareness for stimuli in left visual space, with suppressed neural activity in the right visual cortex due to losses in top-down attention signals. Here we sought to assess whether hemineglect patients are able to up-regulate their right visual cortex activity using auditory real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback. We also examined any effect of this training procedure on neglect severity. Two different neurofeedback methods were used...
April 6, 2017: Neuropsychological Rehabilitation
https://www.readbyqxmd.com/read/28382579/a-neuroanatomical-model-of-space-based-and-object-centered-processing-in-spatial-neglect
#6
Elena Pedrazzini, Armin Schnider, Radek Ptak
Visual attention can be deployed in space-based or object-centered reference frames. Right-hemisphere damage may lead to distinct deficits of space- or object-based processing, and such dissociations are thought to underlie the heterogeneous nature of spatial neglect. Previous studies have suggested that object-centered processing deficits (such as in copying, reading or line bisection) result from damage to retro-rolandic regions while impaired spatial exploration reflects damage to more anterior regions. However, this evidence is based on small samples and heterogeneous tasks...
April 5, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/28382548/study-of-persistent-toxic-pollutants-in-a-river-basin-ecotoxicological-risk-assessment
#7
Evangelia Terzopoulou, Dimitra Voutsa
This study presents a complementary approach for the evaluation of water quality in a river basin by employing active and passive sampling. Persistent toxic pollutants representing three classes: organochlorinated pesticides (OCPs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), were studied in grab water samples, in passive samplers/SemiPermeable Membrane Devices (SPMDs) and in fish tissues collected along the Strymonas River, northern Greece at three sampling campaigns during the year 2013...
April 5, 2017: Ecotoxicology
https://www.readbyqxmd.com/read/28378709/hybrid-system-calibration-for-multidimensional-magnetic-particle-imaging
#8
A von Gladiss, M Graeser, P Szwargulski, T Knopp, T M Buzug
Magnetic particle imaging visualizes the spatial distribution of superparamagnetic nanoparticles. Because of its key features of excellent sensitivity, high temporal and spatial resolution and biocompatibility of the tracer material it can be used in multiple medical imaging applications. The common reconstruction technique for Lissajous-type trajectories uses a system matrix that has to be previously acquired in a time-consuming calibration scan, leading to long downtimes of the scanning device. In this work, the system matrix is determined by a hybrid approach...
April 5, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28358553/shifts-of-spatial-attention-underlie-numerical-comparison-and-mental-arithmetic-evidence-from-a-patient-with-right-unilateral-neglect
#9
Nicolas Masson, Mauro Pesenti, Françoise Coyette, Michael Andres, Valérie Dormal
OBJECTIVES: Recent findings suggest that mental arithmetic involves shifting attention on a mental continuum in which numbers would be ordered from left to right, from small to large numbers, with addition and subtraction causing rightward or leftward shifts, respectively. Neuropsychological data showing that brain-damaged patients with left neglect experience difficulties in solving subtraction but not addition problems support this hypothesis. However, the reverse dissociation is needed to establish the causal role of spatial attention in mental arithmetic...
March 30, 2017: Neuropsychology
https://www.readbyqxmd.com/read/28353204/large-scale-carbon-stock-assessment-of-woody-vegetation-in-tropical-dry-deciduous-forest-of-sathanur-reserve-forest-eastern-ghats-india
#10
Durai Sanjay Gandhi, Somaiah Sundarapandian
Tropical dry forests are one of the most widely distributed ecosystems in tropics, which remain neglected in research, especially in the Eastern Ghats. Therefore, the present study was aimed to quantify the carbon storage in woody vegetation (trees and lianas) on large scale (30, 1 ha plots) in the dry deciduous forest of Sathanur reserve forest of Eastern Ghats. Biomass of adult (≥10 cm DBH) trees was estimated by species-specific allometric equations using diameter and wood density of species whereas in juvenile tree population and lianas, their respective general allometric equations were used to estimate the biomass...
April 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/28345171/spatio-angular-consistent-construction-of-neonatal-diffusion-mri-atlases
#11
Behrouz Saghafi, Jaeil Kim, Geng Chen, Feng Shi, Weili Lin, Pew-Thian Yap, Dinggang Shen
Atlases constructed using diffusion-weighted imaging are important tools for studying human brain development. Atlas construction is in general a two-step process involving spatial registration and fusion of individual images. The focus of most studies so far has been on improving the accuracy of registration while image fusion is commonly performed using simple averaging, often resulting in fuzzy atlases. In this article, we propose a patch-based method for diffusion-weighted (DW) atlas construction. Unlike other atlases that are based on the diffusion tensor model, our atlas is model-free and generated directly from the diffusion-weighted images...
March 27, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28340375/repetitive-tms-in-right-sensorimotor-areas-affects-the-selection-and-completion-of-contralateral-movements
#12
Maria Gutierrez-Herrera, Styrmir Saevarsson, Thomas Huber, Joachim Hermsdörfer, Waltraud Stadler
Although the existence of directional motor deficits (DMD) associated with movement planning and/or execution seems to be widely recognized, neglect and single cell studies examining their neuroanatomical foundation have produced contradictory and inconclusive findings. The present study assessed the occurrence of DMD following the application of repetitive transcranial magnetic stimulation (rTMS) over two regions, as commonly reported in the neglect literature, namely the right middle frontal gyrus (rMFG) and the right angular gyrus (rAG)...
February 24, 2017: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/28330962/distinct-white-matter-alterations-following-severe-stroke-longitudinal-dti-study-in-neglect
#13
Roza M Umarova, Lena Beume, Marco Reisert, Christoph P Kaller, Stefan Klöppel, Irina Mader, Volkmar Glauche, Valerij G Kiselev, Marco Catani, Cornelius Weiller
OBJECTIVE: To distinguish white matter remodeling directly induced by stroke lesion from that evoked by remote network dysfunction, using spatial neglect as a model. METHODS: We examined 24 visual neglect/extinction patients and 17 control patients combining comprehensive analyses of diffusion tensor metrics and global fiber tracking with neuropsychological testing in the acute (6.3 ± 0.5 days poststroke) and chronic (134 ± 7 days poststroke) stroke phases. RESULTS: Compared to stroke controls, patients with spatial neglect/extinction displayed longitudinal white matter alterations with 2 defining signatures: (1) perilesional degenerative changes characterized by congruently reduced fractional anisotropy and increased radial diffusivity (RD), axial diffusivity, and mean diffusivity, all suggestive of direct axonal damage by lesion and therefore nonspecific for impaired attention network and (2) transneuronal changes characterized by an increased RD in contralesional frontoparietal and bilateral occipital connections, suggestive of primary periaxonal involvement; these changes were distinctly related to the degree of unrecovered neglect symptoms in chronic stroke, hence emerging as network-specific alterations...
March 22, 2017: Neurology
https://www.readbyqxmd.com/read/28327791/a-tale-of-two-neglected-tropical-infections-using-gis-to-assess-the-spatial-and-temporal-overlap-of-schistosomiasis-and-leprosy-in-a-region-of-minas-gerais-brazil
#14
David Alexander Phillips, José Antonio Ferreira, Deidra Ansah, Herica Sa Teixeira, Uriel Kitron, Thelma de Filippis, Marcelo H de Alcântara, Jessica K Fairley
BACKGROUND: Despite public health efforts to reduce the global burden of leprosy, gaps remain in the knowledge surrounding transmission of infection. Helminth co-infections have been associated with a shift towards the lepromatous end of the disease spectrum, potentially increasing transmission in co-endemic areas. OBJECTIVES: Using this biologically plausible association, we conducted a geographic information systems (GIS) study to investigate the spatial associations of schistosomiasis and leprosy in an endemic area of Minas Gerais (MG), Brazil...
April 2017: Memórias do Instituto Oswaldo Cruz
https://www.readbyqxmd.com/read/28325371/the-role-of-spatial-statistics-in-the-control-and-elimination-of-neglected-tropical-diseases-in-sub-saharan-africa-a-focus-on-human-african-trypanosomiasis-schistosomiasis-and-lymphatic-filariasis
#15
M C Stanton
Disease control and elimination programmes can benefit greatly from accurate information on the spatial variability of disease risk, particularly when risk is highly spatially heterogeneous. Due to advances in statistical methodology, coupled with the increased availability of geospatial technology, this information is becoming increasingly accessible. In this chapter we describe recent advancements in spatial methods associated with the analysis of disease data measured at the point-level and demonstrate their application to the control and elimination of neglected tropical diseases (NTDs)...
2017: Advances in Parasitology
https://www.readbyqxmd.com/read/28323684/shifting-spatial-neglect-with-repeated-line-bisections-possible-role-of-lateralized-attentional-fatigue
#16
Mary Woods, John B Williamson, Keith D White, Charles G Maitland, Kenneth M Heilman
BACKGROUND AND OBJECTIVE: Many patients who have signs of neglect immediately after a right hemisphere stroke remain disabled even when they improve on tests of neglect. Few patients are tested for attentional persistence and fatigue despite their importance in many instrumental activities. To investigate whether stimulus repetition might alter the allocation of attention, we repeatedly tested a patient 16 weeks after she developed hemispatial neglect from a right hemisphere stroke. METHODS: During each of three testing sessions given in 1 day, we asked the patient to bisect 90 lines of two lengths, presented in 30-trial blocks in three locations: left, center, and right of her midsagittal plane, partially counterbalanced across sessions...
March 2017: Cognitive and Behavioral Neurology: Official Journal of the Society for Behavioral and Cognitive Neurology
https://www.readbyqxmd.com/read/28315613/parietomotor-connectivity-in-the-contralesional-hemisphere-after-stroke-a-paired-pulse-tms-study
#17
Etienne Allart, Arnaud Delval, Alexandre Caux-Dedeystere, Julien Labreuche, Romain Viard, Renaud Lopes, Hervé Devanne
OBJECTIVES: To assess the contralesional connectivity between the posterior parietal cortex (PPC) and the motor cortex (M1) in stroke patients, and to probe putative relationships with spatial neglect and motor impairment. METHODS: In 12 right-side stroke patients and 12 age-matched healthy controls, we used paired-pulse transcranial magnetic stimulation to assess the contralesional connectivity between three left-side PPC sites (the anterior intraparietal sulcus (aIPS), the posterior intraparietal sulcus and the superior parieto-occipital cortex (SPOC)) and M1...
May 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28314918/oculomotor-prismatic-training-is-effective-in-ameliorating-spatial-neglect-a-pilot-study
#18
I Ronga, M Franza, P Sarasso, M Neppi-Modona
Visuomotor prismatic training has been demonstrated to be among the most effective rehabilitative techniques of spatial neglect, a neurological syndrome manifested by a number of right brain-damaged patients characterized by unawareness of the egocentric left half of the world. In the present study, we demonstrate that a novel oculomotor prismatic training procedure only consisting in a sequence of gaze shifts to visual targets, can reduce spatial neglect symptoms. Following oculomotor prismatic training, patients show a significant decrease in neglect severity in straight ahead and paper and pencil tasks...
March 17, 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/28298004/driven-optical-matter-dynamics-of-electrodynamically-coupled-nanoparticles-in-an-optical-ring-vortex
#19
Patrick Figliozzi, Nishant Sule, Zijie Yan, Ying Bao, Stanislav Burov, Stephen K Gray, Stuart A Rice, Suriyanarayanan Vaikuntanathan, Norbert F Scherer
To date investigations of the dynamics of driven colloidal systems have focused on hydrodynamic interactions and often employ optical (laser) tweezers for manipulation. However, the optical fields that provide confinement and drive also result in electrodynamic interactions that are generally neglected. We address this issue with a detailed study of interparticle dynamics in an optical ring vortex trap using 150-nm diameter Ag nanoparticles. We term the resultant electrodynamically interacting nanoparticles a driven optical matter system...
February 2017: Physical Review. E
https://www.readbyqxmd.com/read/28290071/structural-connectivity-in-spatial-attention-network-reconstruction-from-left-hemispatial-neglect
#20
Takaaki Hattori, Kenji Ito, Chika Nakazawa, Yoshiyuki Numasawa, Mayumi Watanabe, Shigeki Aoki, Hidehiro Mizusawa, Sumio Ishiai, Takanori Yokota
Left hemispatial neglect (neglect) is an impaired state of spatial attention. We aimed to reconstruct structural connectivity in the spatial attention network and to identify disconnection patterns underlying neglect. We enrolled 59 right-handed patients who had their first-ever infarction in the right hemisphere and classified them into neglect group (34 patients with neglect) and control group (25 patients without neglect). The neglect group was further subcategorized into 6 subgroups based on infarcted vascular territories...
March 13, 2017: Brain Imaging and Behavior
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