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Cortical visual impairment

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https://www.readbyqxmd.com/read/28821647/plasticity-beyond-v1-reinforcement-of-motion-perception-upon-binocular-central-retinal-lesions-in-adulthood
#1
Kalina Burnat, Tjing-Tjing Hu, Małgorzata Kossut, Ulf T Eysel, Lutgarde Arckens
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 spatio-temporal 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...
August 16, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28819687/central-not-peripheral-vestibular-processing-impairs-gait-coordination
#2
Yoav Gimmon, Jennifer Millar, Rebecca Pak, Elizabeth Liu, Michael C Schubert
Gait coordination is generated by neuronal inter-connections between central pattern generators in the spinal cord governed by cortical areas. Malfunction of central vestibular processing areas generates vestibular symptoms in the absence of an identifiable peripheral vestibular system lesion. Walking in the dark enforces a coordinated afference primarily from the vestibular and somatosensory systems. We hypothesized that patients with aberrant central vestibular processing would demonstrate unique gait characteristics, and have impaired gait coordination compared with those patients with abnormal peripheral vestibular function and healthy controls...
August 17, 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/28813816/computational-rehabilitation-of-neglect-using-state-space-models-to-understand-the-recovery-mechanisms
#3
Giulia Sedda, Marcella Ottonello, Elena Fiabane, Caterina Pistarini, Anna Sedda, Vittorio Sanguineti
Unilateral spatial neglect is a neuropsychological syndrome often observed in right hemisphere stroke patients. The symptoms differ from subject to subject. A few rehabilitation approaches, e.g. prism adaptation, have demonstrated some effect in reducing the symptoms, but the underlying mechanisms are still largely unclear. Recently, neural models have been proposed to qualitatively describe cortical lesions, the resulting neglect symptoms and the effects of treatment. However, these predictions are qualitative and cannot be used to compare different hypotheses or to interpret symptoms at individual subjects level...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28807648/not-all-visual-symmetry-is-equal-partially-distinct-neural-bases-for-vertical-and-horizontal-symmetry
#4
Zaira Cattaneo, Silvia Bona, Juha Silvanto
Visual mirror symmetry plays an important role in visual perception in both human and animal vision; its importance is reflected in the fact that it can be extracted automatically during early stages of visual processing. However, how this extraction is implemented at the cortical level remains an open question. Given the importance of symmetry in visual perception, one possibility is that there is a network which extracts all types of symmetry irrespective of axis of orientation; alternatively, symmetry along different axes might be encoded by different brain regions, implying that that there is no single neural mechanism for symmetry processing...
August 11, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/28803382/cortical-afferent-inhibition-abnormalities-reveal-cholinergic-dysfunction-in-parkinson-s-disease-a-reappraisal
#5
REVIEW
Raffaele Nardone, Francesco Brigo, Viviana Versace, Yvonne Höller, Frediano Tezzon, Leopold Saltuari, Eugen Trinka, Luca Sebastianelli
Parkinson's disease (PD) is a multisystem neurodegenerative disorder affecting, besides the dopaminergic function, multiple neurotransmission systems, including the cholinergic system. Central cholinergic circuits of human brain can be tested non-invasively by coupling peripheral nerve stimulation with transcranial magnetic stimulation (TMS) of motor cortex; this test is named short latency afferent inhibition (SAI). SAI abnormalities have been reported in PD patients with gait disturbances and many non-motor symptoms, such as visual hallucinations (VHs), REM sleep behavior disorder (RBD), dysphagia, and olfactory impairment...
August 12, 2017: Journal of Neural Transmission
https://www.readbyqxmd.com/read/28802915/neurological-evaluation-of-the-selection-stage-of-metaphor-comprehension-in-individuals-with-and-without-autism-spectrum-disorder
#6
Brea Chouinard, Joanne Volden, Ivor Cribben, Jacqueline Cummine
Because of their difficulties with figurative language in conversation, it is commonly thought that individuals with autism spectrum disorder (ASD) do not understand figurative meaning. However, recent research indicates that individuals with and without ASD are similar in the first two stages of metaphor comprehension, up to and including successful generation of the figurative meaning. In the current study, we used a sentence decision task to evaluate the subsequent stage of metaphor comprehension, the selection stage, which requires suppression/inhibition of the unintended meaning as part of selecting the intended meaning...
August 9, 2017: Neuroscience
https://www.readbyqxmd.com/read/28797600/the-rat-retrosplenial-cortex-as-a-link-for-frontal-functions-a-lesion-analysis
#7
Anna L Powell, Andrew J D Nelson, Emma Hindley, Moira Davies, John P Aggleton, Seralynne D Vann
Cohorts of rats with excitotoxic retrosplenial cortex lesions were tested on four behavioural tasks sensitive to dysfunctions in prelimbic cortex, anterior cingulate cortex, or both. In this way the study tested whether retrosplenial cortex has nonspatial functions that reflect its anatomical interactions with these frontal cortical areas. In Experiment 1, retrosplenial cortex lesions had no apparent effect on a set-shifting digging task that taxed intradimensional and extradimensional attention, as well as reversal learning...
August 8, 2017: Behavioural Brain Research
https://www.readbyqxmd.com/read/28768527/bilateral-blindness-secondary-to-optic-nerve-ischemia-from-severe-amlodipine-overdose-a-case-report
#8
Raymond Kao, Yves Landry, Genevieve Chick, Andrew Leung
BACKGROUND: Calcium channel blockers are commonly prescribed medications; calcium channel blocker overdose is becoming increasingly prevalent. The typical presentation of a calcium channel blocker overdose is hypotension and decreased level of consciousness. We describe a case of a calcium channel blocker overdose that led to bilateral cortical blindness, a presentation that has not previously been reported. CASE PRESENTATION: A 49-year-old white woman with known bilateral early optic atrophy presented to our hospital with hypotension and obtundation following a known ingestion of 150 mg of amlodipine...
August 3, 2017: Journal of Medical Case Reports
https://www.readbyqxmd.com/read/28762086/regional-microstructural-damage-and-patterns-of-eye-movement-impairment-a-dti-and-video-oculography-study-in-neurodegenerative-parkinsonian-syndromes
#9
Martin Gorges, Melanie N Maier, Johannes Rosskopf, Olga Vintonyak, Elmar H Pinkhardt, Albert C Ludolph, Hans-Peter Müller, Jan Kassubek
Characteristic alterations of eye movement control are a common feature of neurodegenerative parkinsonism, including Parkinson's disease (PD), progressive supranuclear palsy (PSP), and multiple system atrophy (MSA). Regional microstructural alterations as assessed by diffusion tensor imaging (DTI) have been reported in PD, PSP, and MSA. Therefore, we investigated the specific association between eye movement disturbances and microstructural impairment in these diseases. Video-oculographic recordings of smooth pursuit and visually guided reactive saccades as well as fractional anisotropy (FA) maps computed from whole-brain DTI data were analyzed for 36 PD, 30 PSP, 18 MSA patients, and 23 matched healthy control subjects...
July 31, 2017: Journal of Neurology
https://www.readbyqxmd.com/read/28760867/asymmetric-dichoptic-masking-in-visual-cortex-of-amblyopic-macaque-monkeys
#10
Christopher Shooner, Luke E Hallum, Romesh D Kumbhani, Virginia García-Marín, Jenna G Kelly, Najib J Majaj, J Anthony Movshon, Lynne Kiorpes
In amblyopia, abnormal visual experience leads to an extreme form of eye dominance, in which vision through the non-dominant eye is degraded. A key aspect of this disorder is perceptual suppression: The image seen by the stronger eye often dominates during binocular viewing, blocking the weaker eye's image from reaching awareness. Interocular suppression is the focus of ongoing work aimed at understanding and treating amblyopia, yet its physiological basis remains unknown. We measured binocular interactions in visual cortex of anesthetized amblyopic monkeys (female Macaca nemestrina), using 96-channel 'Utah' arrays to record from populations of neurons in V1 and V2...
July 31, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28745642/assessing-spatial-memory-impairment-in-a-mouse-model-of-traumatic-brain-injury-using-a-radial-water-tread-maze
#11
Marcella M Cline, Megan A Ostlie, Chloe G Cross, Gregory G Garwin, Satoshi Minoshima, Donna J Cross
Despite the recent increase in use of mouse models in scientific research, researchers continue to use cognitive tasks that were originally designed and validated for rat use. The Radial Water Tread (RWT) maze test of spatial memory (designed specifically for mice and requiring no swimming) has been shown previously to successfully distinguish between controlled cortical impact-induced TBI mice and sham controls. Here, a detailed protocol for this task is presented. The RWT maze capitalizes on the natural tendency of mice to avoid open areas in favor of hugging the sides of an apparatus (thigmotaxis)...
July 17, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28741987/multimodal-characterization-of-gray-matter-alterations-in-neuromyelitis-optica
#12
Yaou Liu, Xueyan Jiang, Helmut Butzkueven, Yunyun Duan, Jing Huang, Zhuoqiong Ren, Huiqing Dong, Fu-Dong Shi, Frederik Barkhof, Kuncheng Li, Jinhui Wang
OBJECTIVE: To investigate structural and functional alterations of gray matter (GM) and examine their clinical relevance in neuromyelitis optica (NMO) using multimodal magnetic resonance imaging (MRI) techniques. METHODS: A total of 35 NMO and 36 healthy controls (HC) were recruited in this study. Cortical lesions were investigated by double inversion recovery technique. Five voxel-wise MRI measurements were obtained for each participant in the GM including gray matter volume (GMV), fractional anisotropy (FA), mean diffusivity (MD), amplitude of low-frequency fluctuation (ALFF), and weighted functional connectivity strength (wFCS)...
July 1, 2017: Multiple Sclerosis: Clinical and Laboratory Research
https://www.readbyqxmd.com/read/28719508/is-the-organisation-of-the-primary-motor-cortex-in-low-back-pain-related-to-pain-movement-and-or-sensation
#13
Edith Elgueta-Cancino, Siobhan Schabrun, Paul Hodges
Primary motor cortex (M1) organisation differs between individuals with and without chronic low back pain (CLBP), in parallel with motor and sensory impairments. This study investigated whether movement behaviour and tactile/pain sensation are related to M1 organisation in CLBP. Transcranial magnetic stimulation (TMS) was used to map the M1 representation of the erector spinae and multifidus muscles in 20 participants with and without CLBP. Cortical organisation was quantified by: map volume; center of gravity (CoG); number of peaks; and primary and secondary peak location...
July 17, 2017: Clinical Journal of Pain
https://www.readbyqxmd.com/read/28716601/changes-in-refractive-status-in-an-elderly-chinese-population-in-a-7-year-follow-up-the-shihpai-eye-study
#14
Tung-Mei Kuang, Su-Ying Tsai, Catherine Jiu-Ling Liu, Yu-Chieh Ko, Shui-Mei Lee, Pesus Chou
BACKGROUND: Refractive error is the major cause of moderate and severe visual impairment. Visual impairment limits people's ability to perform daily tasks and affects their quality of life. Longitudinal data on the refractive status of the elderly was available only for whites and Africans. The purpose of this study was to report the 7-year incidence of myopia, hyperopia and refractive error change as well as their associated risk factors in a metropolitan elderly Chinese population. METHODS: The Shihpai Eye Study 2006 included 460/824 (55...
July 14, 2017: Journal of the Chinese Medical Association: JCMA
https://www.readbyqxmd.com/read/28714429/structural-brain-correlations-of-visuospatial-and-visuoperceptual-tests-in-parkinson-s-disease
#15
Anna Isabel Garcia-Diaz, Barbara Segura, Hugo Cesar Baggio, Maria Jose Marti, Francesc Valldeoriola, Yaroslau Compta, Nuria Bargallo, Carme Uribe, Anna Campabadal, Alexandra Abos, Carme Junque
BACKGROUND: Diagnosis of mild cognitive impairment in Parkinson's disease (PD) is relevant because it is a marker for evolution to dementia. However, the selection of suitable tests to evaluate separate cognitive domains in mild cognitive impairment related to PD remains an open question. The current work aims to investigate the neuroanatomical correlates of several visuospatial/visuoperceptual tests using the same sample and a multimodal MRI approach. METHODS: The study included 36 PD patients and 20 healthy subjects matched for age, sex, and education...
July 17, 2017: Journal of the International Neuropsychological Society: JINS
https://www.readbyqxmd.com/read/28709123/subclinical-white-matter-lesions-and-medial-temporal-lobe-atrophy-are-associated-with-eeg-slowing-in-a-memory-clinic-cohort
#16
Milica G Kramberger, Katarina Giske, Lena Cavallin, Ingemar Kåreholt, Thomas Andersson, Bengt Winblad, Vesna Jelic
OBJECTIVE: The aim of the study was to describe the relationship between electroencephalographic (EEG) findings obtained by standardized visual analysis, subclinical white matter lesions (WML) and brain atrophy in a large memory clinic population. METHODS: Patients with Alzheimer's disease (AD, n=58), mild cognitive impairment (MCI, n=141), subjective cognitive impairment (SCI, n=194) had clinical, MRI based WML severity and regional atrophy assessments, and routine resting EEG recording...
September 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28708110/cognitive-changes-in-the-spinocerebellar-ataxias-due-to-expanded-polyglutamine-tracts-a-survey-of-the-literature
#17
REVIEW
Evelyn Lindsay, Elsdon Storey
The dominantly-inherited ataxias characterised by expanded polyglutamine tracts-spinocere bellar ataxias (SCAs) 1, 2, 3, 6, 7, 17, dentatorubral pallidoluysian atrophy (DRPLA) and, in part, SCA 8-have all been shown to result in various degrees of cognitive impairment. We survey the literature on the cognitive consequences of each disorder, attempting correlation with their published neuropathological, magnetic resonance imaging (MRI) and clinical features. We suggest several psychometric instruments for assessment of executive function, whose results are unlikely to be confounded by visual, articulatory or upper limb motor difficulties...
July 14, 2017: Brain Sciences
https://www.readbyqxmd.com/read/28702344/directional-information-flow-in-patients-with-alzheimer-s-disease-a-source-space-resting-state-meg-study
#18
M M A Engels, M Yu, C J Stam, A A Gouw, W M van der Flier, Ph Scheltens, E C W van Straaten, A Hillebrand
In a recent magnetoencephalography (MEG) study, we found posterior-to-anterior information flow over the cortex in higher frequency bands in healthy subjects, with a reversed pattern in the theta band. A disruption of information flow may underlie clinical symptoms in Alzheimer's disease (AD). In AD, highly connected regions (hubs) in posterior areas are mostly disrupted. We therefore hypothesized that in AD the information flow from these hub regions would be disturbed. We used resting-state MEG recordings from 27 early-onset AD patients and 26 healthy controls...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28689980/the-contribution-of-area-mt-to-visual-motion-perception-depends-on-training
#19
Liu D Liu, Christopher C Pack
Perceptual decisions require the transformation of raw sensory inputs into cortical representations suitable for stimulus discrimination. One of the best-known examples of this transformation involves the middle temporal area (MT) of the primate visual cortex. Area MT provides a robust representation of stimulus motion, and previous work has shown that it contributes causally to performance on motion discrimination tasks. Here we report that the strength of this contribution can be highly plastic: depending on the recent training history, pharmacological inactivation of MT can severely impair motion discrimination, or it can have little detectable influence...
July 19, 2017: Neuron
https://www.readbyqxmd.com/read/28677992/illusory-increases-in-font-size-improve-letter-recognition
#20
Martin Lages, Stephanie C Boyle, Rob Jenkins
Visual performance of human observers depends not only on the optics of the eye and early sensory encoding but also on subsequent cortical processing and representations. In two experiments, we demonstrated that motion adaptation can enhance as well as impair visual acuity. Observers who experienced an expanding motion aftereffect exhibited improved letter recognition, whereas observers who experienced a contracting motion aftereffect showed impaired letter recognition. We conclude that illusory enlargement and shrinkage of a visual stimulus can modulate visual acuity...
August 2017: Psychological Science
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