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Cortical visual impairment

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https://www.readbyqxmd.com/read/29677338/evidence-of-a-retinotopic-organization-of-early-visual-cortex-but-impaired-extrastriate-processing-in-sight-recovery-individuals
#1
Suddha Sourav, Davide Bottari, Ramesh Kekunnaya, Brigitte Röder
Numerous studies in visually deprived nonhuman animals have demonstrated sensitive periods for the functional development of the early visual cortex. However, in humans it is yet unknown which visual areas are shaped to which degree based on visual experience. The present study investigated the functional organization and processing capacities of early visual cortex in sight recovery individuals with either a history of congenital cataracts (CC) or late onset cataracts (developmental cataracts, DC). Visual event-related potentials (VERPs) were recorded to grating stimuli which were flashed in one of the four quadrants of the visual field...
March 1, 2018: Journal of Vision
https://www.readbyqxmd.com/read/29674416/altered-white-matter-microstructure-in-the-corpus-callosum-and-its-cerebral-interhemispheric-tracts-in-adolescent-idiopathic-scoliosis-diffusion-tensor-imaging-analysis
#2
C Xue, L Shi, S C N Hui, D Wang, T P Lam, C-B Ip, B K W Ng, J C Y Cheng, W C W Chu
BACKGROUND AND PURPOSE: Neural system was one of the important contributors to the etiopathogenesis of adolescent idiopathic scoliosis; additionally, the morphology of corpus callosum interconnecting both hemispheres of the brain was found to be altered morphologically. Our aim was to evaluate and compare the microstructural changes of the corpus callosum and its interhemispheric white matter fiber tracts interconnecting both cerebral hemispheres in patients with adolescent idiopathic scoliosis and matched controls using diffusion tensor imaging...
April 19, 2018: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/29672930/clinical-and-imaging-correlates-of-amyloid-deposition-in-dementia-with-lewy-bodies
#3
Paul C Donaghy, Michael J Firbank, Alan J Thomas, Jim Lloyd, George Petrides, Nicola Barnett, Kirsty Olsen, John T O'Brien
BACKGROUND: Amyloid deposition is common in dementia with Lewy bodies, but its pathophysiological significance is unclear. OBJECTIVE: The objective of this study was to investigate the relationship between amyloid deposition and clinical profile, gray matter volume, and brain perfusion in dementia with Lewy bodies. METHODS: Dementia with Lewy bodies (n = 37), Alzheimer's disease (n = 20), and controls (n = 20) underwent a thorough clinical assessment, 3T MRI, and early- and late-phase 18 F-Florbetapir PET-CT to assess cortical perfusion and amyloid deposition, respectively...
April 19, 2018: Movement Disorders: Official Journal of the Movement Disorder Society
https://www.readbyqxmd.com/read/29668848/adult-onset-hearing-impairment-induces-layer-specific-cortical-reorganization-evidence-of-crossmodal-plasticity-and-central-gain-enhancement
#4
Ashley L Schormans, Marei Typlt, Brian L Allman
Adult-onset hearing impairment can lead to hyperactivity in the auditory pathway (i.e., central gain enhancement) as well as increased cortical responsiveness to nonauditory stimuli (i.e., crossmodal plasticity). However, it remained unclear to what extent hearing loss-induced hyperactivity is relayed beyond the auditory cortex, and thus, whether central gain enhancement competes or coexists with crossmodal plasticity throughout the distinct layers of the audiovisual cortex. To that end, we investigated the effects of partial hearing loss on laminar processing in the auditory, visual and audiovisual cortices of adult rats using extracellular electrophysiological recordings performed 2 weeks after loud noise exposure...
April 13, 2018: Cerebral Cortex
https://www.readbyqxmd.com/read/29660939/aberrant-cortical-event-related-potentials-during-associative-learning-in-rat-models-for-presymptomatic-stages-of-alzheimer-s-disease
#5
Bardia Nouriziabari, Susmita Sarkar, Stephanie E Tanninen, Robert D Dayton, Ronald L Klein, Kaori Takehara-Nishiuchi
Trace eyeblink conditioning is a hippocampus-dependent associative learning paradigm which is impaired in patients with Alzheimer's disease (AD) and animal AD models. Learning in this paradigm accompanies changes in oscillatory activity in forebrain regions, some of which are loci of pathogenic changes in prodromal AD stages. These observations motivated us to examine how cortical event-related potentials (ERPs) during this paradigm are affected by two features of the asymptomatic, AD-related brain abnormality, entorhinal tau accumulation and mild cholinergic deficit...
April 11, 2018: Journal of Alzheimer's Disease: JAD
https://www.readbyqxmd.com/read/29626609/homozygous-lamc3-mutation-links-to-structural-and-functional-changes-in-visual-attention-networks
#6
REVIEW
Buse M Urgen, Yasemin Topac, F Seyhun Ustun, Pinar Demirayak, Kader K Oguz, Tulay Kansu, Serap Saygi, Tayfun Ozcelik, Huseyin Boyaci, Katja Doerschner
The occipital lobe contains a substantial part of the neural machinery involved in visual perception. Mutations in the LAMC3 gene have recently been shown to cause complex bilateral occipital cortical gyration abnormalities. However, to what extent these structural changes impact visual behavior is not known. We recorded responses for two screening test batteries targeting visual function (Leuven - Perceptual Organization Screening Test, Cortical Vision Screening Test) and measured eye fixation performance in a visual attention experiment from a patient with homozygous LAMC3 gene mutation...
April 4, 2018: NeuroImage
https://www.readbyqxmd.com/read/29615923/mental-fatigue-alters-cortical-activation-and-psychological-responses-impairing-performance-in-a-distance-based-cycling-trial
#7
Flávio O Pires, Fernando L Silva-Júnior, Cayque Brietzke, Paulo E Franco-Alvarenga, Fabiano A Pinheiro, Nanci M de França, Silmar Teixeira, Tony Meireles Santos
Purpose: We sought to verify if alterations in prefrontal cortex (PFC) activation and psychological responses would play along with impairments in pacing and performance of mentally fatigued cyclists. Materials and Methods: Eight recreational cyclists performed two preliminary sessions to familiarize them with the rapid visual information processing (RVP) test, psychological scales and 20 km cycling time trial (TT20km ) (session 1), as well as to perform a VO2MAX test (session 2). Thereafter, they performed a TT20km either after a RVP test (30 min) or a time-matched rest control session (session 3 and 4 in counterbalanced order)...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29614297/eeg-based-neglect-assessment-a-feasibility-study
#8
Aya Khalaf, Jessica Kersey, Safaa Eldeeb, Gazihan Alankus, Emily Grattan, Laura Waterstram, Elizabeth Skidmore, Murat Akcakaya
BACKGROUND: Spatial neglect (SN) is a neuropsychological syndrome that impairs automatic attention orienting to stimuli in the contralesional visual space of stroke patients. SN is commonly assessed using paper and pencil tests. Recently, computerized tests have been proposed to provide a dynamic assessment of SN. However, both paper- and computer-based methods have limitations. NEW METHOD: Electroencephalography (EEG) shows promise for overcoming the limitations of current assessment methods The aim of this work is to introduce an objective passive BCI system that records EEG signals in response to visual stimuli appearing in random locations on a screen with a dynamically changing background...
March 31, 2018: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/29611142/combined-transcranial-direct-current-stimulation-and-virtual-reality-based-paradigm-for-upper-limb-rehabilitation-in-individuals-with-restricted-movements-a-feasibility-study-with-a-chronic-stroke-survivor-with-severe-hemiparesis
#9
María Antonia Fuentes, Adrián Borrego, Jorge Latorre, Carolina Colomer, Mariano Alcañiz, María José Sánchez-Ledesma, Enrique Noé, Roberto Llorens
Impairments of the upper limb function are a major cause of disability and rehabilitation. Most of the available therapeutic options are based on active exercises and on motor and attentional inclusion of the affected arm in task oriented movements. However, active movements may not be possible after severe impairment of the upper limbs. Different techniques, such as mirror therapy, motor imagery, and non-invasive brain stimulation have been shown to elicit cortical activity in absence of movements, which could be used to preserve the available neural circuits and promote motor learning...
April 2, 2018: Journal of Medical Systems
https://www.readbyqxmd.com/read/29573378/why-do-herpes-simplex-encephalitis-and-semantic-dementia-show-a-different-pattern-of-semantic-impairment-in-spite-of-their-main-common-involvement-within-the-anterior-temporal-lobes
#10
Guido Gainotti
A very challenging problem in the domain of the cognitive neurosciences is to explain why herpes simplex encephalitis and semantic dementia show, respectively, a category-specific semantic disorder for biological entities and an across-categories semantic disruption, despite highly overlapping areas of anterior temporal lobe damage. The aim of the present review consisted in trying to make a separate survey of anatomo-clinical investigations (single-case studies and group studies) and of activation studies, in order to analyse the factors that could explain these different patterns of semantic disruption...
March 24, 2018: Reviews in the Neurosciences
https://www.readbyqxmd.com/read/29563063/early-postnatal-development-of-the-visual-cortex-in-mice-with-retinal-degeneration
#11
D Himmelhan, O Rawashdeh, H H A Oelschläger
This study characterizes the early postnatal development of the visual neocortex in C3H/HeNRj mice. These mice are homozygous for the Pde6brd1 mutation, which causes retinal degeneration starting from postnatal day 7 (P7). To monitor the development of the visual cortex between P3 and P28 we used eight antigens known to be expressed at different developmental stages (Nestin, tau3, β3- Tubulin, Calbindin, Doublecortin, MAP2, Parvalbumin and NeuN). Using semiquantitative analysis we traced the expression and localization of different developmental markers throughout the layers of the visual cortex...
March 18, 2018: Mechanisms of Development
https://www.readbyqxmd.com/read/29562536/update-on-vascular-cognitive-impairment-associated-with-subcortical-small-vessel-disease
#12
Anders Wallin, Gustavo C Román, Margaret Esiri, Petronella Kettunen, Johan Svensson, George P Paraskevas, Elisabeth Kapaki
Subcortical small-vessel disease (SSVD) is a disorder well characterized from the clinical, imaging, and neuropathological viewpoints. SSVD is considered the most prevalent ischemic brain disorder, increasing in frequency with age. Vascular risk factors include hypertension, diabetes, hyperlipidemia, elevated homocysteine, and obstructive sleep apnea. Ischemic white matter lesions are the hallmark of SSVD; other pathological lesions include arteriolosclerosis, dilatation of perivascular spaces, venous collagenosis, cerebral amyloid angiopathy, microbleeds, microinfarcts, lacunes, and large infarcts...
2018: Journal of Alzheimer's Disease: JAD
https://www.readbyqxmd.com/read/29556734/neural-correlates-of-binocular-depth-inversion-illusion-in-antipsychotic-na%C3%A3-ve-first-episode-schizophrenia-patients
#13
Cathrin Rohleder, Dagmar Koethe, Stefan Fritze, Cristina E Topor, F Markus Leweke, Dusan Hirjak
OBJECTIVES: Binocular depth inversion illusion (BDII), a visual, 'top-down'-driven information process, is impaired in schizophrenia and particularly in its early stages. BDII is a sensitive measure of impaired visual information processing and represents a valid diagnostic tool for schizophrenia and other psychotic disorders. However, neurobiological underpinnings of aberrant BDII in first-episode schizophrenia are largely unknown at present. METHODS: In this study, 22 right-handed, first-episode, antipsychotic-naïve schizophrenia patients underwent BDII assessment and MRI scanning at 1...
March 19, 2018: European Archives of Psychiatry and Clinical Neuroscience
https://www.readbyqxmd.com/read/29540554/major-vault-protein-a-candidate-gene-in-16p11-2-microdeletion-syndrome-is-required-for-the-homeostatic-regulation-of-visual-cortical-plasticity
#14
Jacque P K Ip, Ikue Nagakura, Jeremy Petravicz, Keji Li, Erik A C Wiemer, Mriganka Sur
Microdeletion of a region in chromosome 16p11.2 increases susceptibility to autism. Although this region contains exons of 29 genes, disrupting only a small segment of the region, which spans 5 genes, is sufficient to cause autistic traits. One candidate gene in this critical segment is MVP , which encodes for the major vault protein (MVP) that has been implicated in regulation of cellular transport mechanisms. MVP expression levels in MVP +/- mice closely phenocopy those of 16p11.2 mutant mice, suggesting that MVP +/- mice may serve as a model of MVP function in 16p11...
March 14, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29528296/effects-of-acute-ketamine-infusion-on-visual-working-memory-event-related-potentials
#15
Ivan Koychev, John Francis William Deakin, Wael El-Deredy, Corinna Haenschel
BACKGROUND: Working memory (WM) deficits are a core feature of schizophrenia. Electrophysiological studies suggest that impaired early visual processing may contribute to impaired WM in the visual domain. Abnormal N-methyl-D-aspartate (NMDA) receptor function has been implicated both in WM and in early visual processing deficits in schizophrenia. We investigated whether ketamine, a noncompetitive NMDA antagonist, would replicate in healthy volunteers the WM performance and early visual processing abnormalities we and others have reported in patients with schizophrenia...
April 2017: Biological Psychiatry: Cognitive Neuroscience and Neuroimaging
https://www.readbyqxmd.com/read/29522759/dorsal-and-ventral-stream-contribution-to-the-paired-object-affordance-effect
#16
Alexia Roux-Sibilon, Solène Kalénine, Cédric Pichat, Carole Peyrin
Visual extinction, a parietal syndrome in which patients exhibit perceptual impairments when two objects are simultaneously presented in the visual field, is reduced when objects are correctly positioned for action, indicating that action helps patients' visual attention. Similarly, healthy individuals make faster action decisions on object pairs that appear in left/right standard co-location for actions in comparison to object pairs that appear in a mirror location, a phenomenon called the paired-object affordance effect...
March 6, 2018: Neuropsychologia
https://www.readbyqxmd.com/read/29518257/reduced-contrast-sensitivity-among-older-women-is-associated-with-increased-risk-of-cognitive-impairment
#17
Michael E Ward, Jeffrey M Gelfand, Li-Yung Lui, Yvonne Ou, Ari J Green, Katie Stone, Kathryn L Pedula, Steven R Cummings, Kristine Yaffe
OBJECTIVE: Several cross-sectional studies have reported an association between visual contrast sensitivity (a functional measure of low contrast vision) and poor cognitive performance or dementia, but no studies have investigated this association prospectively in a population-based cohort with final adjudication of mild cognitive impairment (MCI)/dementia. METHODS: In a prospective, community-based study of aging women (Study of Osteoporotic Fractures), we analyzed whether visual contrast sensitivity was associated with increased risk of MCI or dementia and/or worse performance on various cognitive tests assessed 10 years later...
March 8, 2018: Annals of Neurology
https://www.readbyqxmd.com/read/29515618/verbal-or-visual-memory-score-and-regional-cerebral-blood-flow-in-alzheimer-disease
#18
Satoshi Hayashi, Seishi Terada, Etsuko Oshima, Shuhei Sato, Kairi Kurisu, Shintaro Takenoshita, Osamu Yokota, Norihito Yamada
Objective: Among many cognitive function deficits, memory impairment is an initial and cardinal symptom in Alzheimer disease (AD). In most cases, verbal and visual memory scores correlate highly, but in some cases the deficit of verbal or visual memory is very different from that of the other memory. In this study, we examined the neural substrates of verbal and visual memory in patients with AD. Methods: One hundred eighty-eight consecutive patients with AD were recruited from outpatient units...
January 2018: Dementia and Geriatric Cognitive Disorders Extra
https://www.readbyqxmd.com/read/29510692/are-dementia-with-lewy-bodies-and-parkinson-s-disease-dementia-the-same-disease
#19
Kurt A Jellinger, Amos D Korczyn
BACKGROUND: Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD), which share many clinical, neurochemical, and morphological features, have been incorporated into DSM-5 as two separate entities of major neurocognitive disorders with Lewy bodies. Despite clinical overlap, their diagnosis is based on an arbitrary distinction concerning the time of onset of motor and cognitive symptoms, namely as early cognitive impairment in DLB and later onset following that of motor symptoms in PDD...
March 6, 2018: BMC Medicine
https://www.readbyqxmd.com/read/29501387/emotional-context-restores-cortical-prediction-error-responses-in-schizophrenia
#20
Bob O Vogel, Joanna Stasch, Henrik Walter, Andres H Neuhaus
The mismatch negativity (MMN) deficit in schizophrenia is a consistently replicated finding and is considered a potential biomarker. From the cognitive neuroscience perspective, MMN represents a cortical correlate of the prediction error, a fundamental computational operator that may be at the core of various cognitive and clinical deficits observed in schizophrenia. The impact of emotion on cognitive processes in schizophrenia is insufficiently understood, and its impact on basic operators of cortical computation is largely unknown...
February 28, 2018: Schizophrenia Research
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