Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 16.981
Filtrar
1.
J Int Med Res ; 50(1): 3000605211039571, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34994217

RESUMO

This case report describes the detailed electrophysiological features and the corresponding relationship with the structural changes in a case of X-linked juvenile retinoschisis (XLRS). A 25-year-old male presented with a history of several years of decreased visual acuity in both eyes. The best corrected visual acuity was 20/200 in oculus dexter (OD) and 20/80 in oculus sinister. Retinoschisis was found in the macula by optical coherence tomography, which was more severe in OD. Electroretinogram revealed a similar electronegative waveform in both eyes. Visual evoked potential detected a reduced amplitude and delayed phase in P100-wave, which was worse in OD. The patient was diagnosed as XLRS and advised to undergo continuous medical observation. He was followed up for the next year, with no significant change in retinal function and structure being observed. These current findings suggest that electrophysiology permits the detailed analysis of the clinical picture of XLRS and helps to gain a deeper understanding of the pathogenesis.


Assuntos
Retinosquise , Adulto , Eletrorretinografia , Potenciais Evocados Visuais , Humanos , Masculino , Retinosquise/diagnóstico por imagem , Retinosquise/genética , Tomografia de Coerência Óptica , Acuidade Visual
2.
Indian J Ophthalmol ; 70(1): 201-209, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34937239

RESUMO

Purpose: There are no effective treatments currently available for optic nerve transection injuries. Stem cell therapy represents a feasible future treatment option. This study investigated the therapeutic potential of human umbilical cord-derived mesenchymal stem cell (hUC-MSC) transplantation in rats with optic nerve injury. Methods: Sprague-Dawley (SD) rats were divided into three groups: a no-treatment control group (n = 6), balanced salt solution (BSS) treatment group (n = 6), and hUC-MSCs treatment group (n = 6). Visual functions were assessed by flash visual evoked potential (fVEP) at baseline, Week 3, and Week 6 after optic nerve crush injury. Right eyes were enucleated after 6 weeks for histology. Results: The fVEP showed shortened latency delay and increased amplitude in the hUC-MSCs treated group compared with control and BSS groups. Higher cellular density was detected in the hUC-MSC treated group compared with the BSS and control groups. Co-localized expression of STEM 121 and anti-S100B antibody was observed in areas of higher nuclear density, both in the central and peripheral regions. Conclusion: Peribulbar transplantation of hUC-MSCs demonstrated cellular integration that can potentially preserve the optic nerve function with a significant shorter latency delay in fVEP and higher nuclear density on histology, and immunohistochemical studies observed cell migration particularly to the peripheral regions of the optic nerve.


Assuntos
Células-Tronco Mesenquimais , Traumatismos do Nervo Óptico , Animais , Potenciais Evocados Visuais , Humanos , Traumatismos do Nervo Óptico/terapia , Ratos , Ratos Sprague-Dawley , Cordão Umbilical
3.
Nutrients ; 13(12)2021 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-34959793

RESUMO

Fish oil is rich in omega-3 fatty acids and essential for neuronal myelination and maturation. The aim of this study was to investigate whether the use of a mixed-lipid emulsion composed of soybean oil, medium-chain triglycerides, olive oil, and fish oil (SMOF-LE) compared to a pure soybean oil-based lipid emulsion (S-LE) for parenteral nutrition had an impact on neuronal conduction in preterm infants. This study is a retrospective matched cohort study comparing preterm infants <1000 g who received SMOF-LE in comparison to S-LE for parenteral nutrition. Visual evoked potentials (VEPs) were assessed longitudinally from birth until discharge. The latencies of the evoked peaks N2 and P2 were analyzed. The analysis included 76 infants (SMOF-LE: n = 41 and S-LE: n = 35) with 344 VEP measurements (SMOF-LE: n= 191 and S-LE n = 153). Values of N2 and P2 were not significantly different between the SMOF-LE and S-LE groups. A possible better treatment effect in the SMOF-LE group was seen as a trend toward a shorter latency, indicating faster neural conduction at around term-equivalent age. Prospective trials and follow-up studies are necessary in order to evaluate the potential positive effect of SMOF-LE on neuronal conduction and visual pathway maturation.


Assuntos
Potenciais Evocados Visuais/efeitos dos fármacos , Emulsões Gordurosas Intravenosas/administração & dosagem , Emulsões Gordurosas Intravenosas/química , Óleos de Peixe/administração & dosagem , Condução Nervosa/efeitos dos fármacos , Feminino , Humanos , Recém-Nascido , Recém-Nascido Prematuro/fisiologia , Masculino , Azeite de Oliva/administração & dosagem , Nutrição Parenteral , Estudos Retrospectivos , Óleo de Soja/administração & dosagem , Triglicerídeos/administração & dosagem
4.
Neurol India ; 69(5): 1247-1258, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34747792

RESUMO

Background: Huntington's disease (HD) is a progressive neurodegenerative disorder characterized by motor, cognitive, and psychiatric abnormalities. Currently, matched analyses of structural and functional differences in the brain from the same study cohort and, specifically, in HD patients from an ethnically diverse Indian population are lacking. Such findings aid in identifying noninvasive and sensitive imaging biomarkers. Objective: The aim of the study was to understand the structural and functional differences between HD and control brain, and presymptomatic and symptomatic HD brain in the Indian population. Materials and Methods: Seventeen HD (11 symptomatic HD [S-HD] and six presymptomatic HD [P-HD], with comparable CAG repeats), and 12 healthy controls were examined. Macrostructural (volume), microstructural (diffusivity), and functional (neurochemical levels and glucose metabolism) imaging of the brain was done along with the determination of visual latencies. Results: HD brain showed increased intercaudate distance; significant subcortical volumetric loss; reduced fractional anisotropy; increased mean, axial, and radial diffusivity; lower levels of total N-acetyl aspartate; elevated total choline levels; and reduced glucose metabolism compared with control brain. Interestingly, compared with P-HD, S-HD patients demonstrated a strong inverse correlation between age at onset and CAG repeat length, and prolonged P100 latency. In addition, caudate and putamen in S-HD brain showed significant volumetric loss and increased diffusivity compared with P-HD brain. Conclusions: HD brain showed distinct macrostructural, microstructural, and functional differences compared with control brain in the Indian population. Interestingly, patients with S-HD had a significant volumetric loss, increased diffusivity, altered neurochemical profile, and delayed P100 latency compared with P-HD patients. Examining these alterations clinically could aid in monitoring the progression of HD.


Assuntos
Potenciais Evocados Visuais , Doença de Huntington , Encéfalo/diagnóstico por imagem , Imagem de Difusão por Ressonância Magnética , Humanos , Doença de Huntington/diagnóstico por imagem , Doença de Huntington/genética , Imageamento por Ressonância Magnética , Imagem Multimodal
5.
Neurol India ; 69(5): 1349-1353, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34747810

RESUMO

Background: Central nervous system (CNS) involvement in leprosy is sparsely documented. Neurophysiological tests and magnetic resonance imaging (MRI) helps in demonstrating CNS involvement in the patient of pure neuritic leprosy. Objectives: To demonstrate CNS involvement in pure neuritic leprosy. Methods: Detailed clinical presentation and skin lesions were evaluated. Sural nerve biopsy, MRI diffusion tensor imaging of spinal cord and optic nerve were performed. Visual evoked potential and tibial somatosensory evoked potential were done. Their clinical, electrophysiological, and MRI were done at follow-up visits. Results: We report three patients of pure neuritic leprosy with bilateral foot drop as the initial presentation. MRI T2W sequence of cervico dorsal cord showed dorsal column hyperintensity in two patients. Diffusion-weighted MR revealed decrease fractional anisotropy and an increase in the apparent diffusion coefficient. Similar findings were also noted in the optic nerves. The patients were managed with multidrug therapy multibacillary regimen and steroid in tapering dose. At follow-up, they showed clinical improvement in vision and power of ankle dorsiflexor. Conclusions: Patients of pure neuritic leprosy may manifest with bilateral foot drop with the involvement of posterior column and cranial nerves.


Assuntos
Hanseníase , Neuropatias Fibulares , Imagem de Tensor de Difusão , Quimioterapia Combinada , Potenciais Evocados Visuais , Humanos , Hansenostáticos/uso terapêutico , Hanseníase/complicações , Hanseníase/diagnóstico por imagem , Hanseníase/tratamento farmacológico , Imageamento por Ressonância Magnética , Neuropatias Fibulares/tratamento farmacológico
6.
Sensors (Basel) ; 21(21)2021 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-34770482

RESUMO

This paper introduces a cognitive psychological experiment that was conducted to analyze how traditional film editing methods and the application of cognitive event segmentation theory perform in virtual reality (VR). Thirty volunteers were recruited and asked to watch a series of short VR videos designed in three dimensions: time, action (characters), and space. Electroencephalograms (EEG) were recorded simultaneously during their participation. Subjective results show that any of the editing methods used would lead to an increased load and reduced immersion. Furthermore, the cognition of event segmentation theory also plays an instructive role in VR editing, with differences mainly focusing on frontal, parietal, and central regions. On this basis, visual evoked potential (VEP) analysis was performed, and the standardized low-resolution brain electromagnetic tomography algorithm (sLORETA) traceability method was used to analyze the data. The results of the VEP analysis suggest that shearing usually elicits a late event-related potential component, while the sources of VEP are mainly the frontal and parietal lobes. The insights derived from this work can be used as guidance for VR content creation, allowing VR image editing to reveal greater richness and unique beauty.


Assuntos
Realidade Virtual , Cognição , Eletroencefalografia , Potenciais Evocados , Potenciais Evocados Visuais , Humanos
7.
Sensors (Basel) ; 21(21)2021 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-34770554

RESUMO

Research focused on signals derived from the human organism is becoming increasingly popular. In this field, a special role is played by brain-computer interfaces based on brainwaves. They are becoming increasingly popular due to the downsizing of EEG signal recording devices and ever-lower set prices. Unfortunately, such systems are substantially limited in terms of the number of generated commands. This especially applies to sets that are not medical devices. This article proposes a hybrid brain-computer system based on the Steady-State Visual Evoked Potential (SSVEP), EOG, eye tracking, and force feedback system. Such an expanded system eliminates many of the particular system shortcomings and provides much better results. The first part of the paper presents information on the methods applied in the hybrid brain-computer system. The presented system was tested in terms of the ability of the operator to place the robot's tip to a designated position. A virtual model of an industrial robot was proposed, which was used in the testing. The tests were repeated on a real-life industrial robot. Positioning accuracy of system was verified with the feedback system both enabled and disabled. The results of tests conducted both on the model and on the real object clearly demonstrate that force feedback improves the positioning accuracy of the robot's tip when controlled by the operator. In addition, the results for the model and the real-life industrial model are very similar. In the next stage, research was carried out on the possibility of sorting items using the BCI system. The research was carried out on a model and a real robot. The results show that it is possible to sort using bio signals from the human body.


Assuntos
Interfaces Cérebro-Computador , Eletroencefalografia , Eletroculografia , Potenciais Evocados Visuais , Tecnologia de Rastreamento Ocular , Retroalimentação , Humanos , Estimulação Luminosa
8.
BMC Ophthalmol ; 21(1): 394, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34781927

RESUMO

PURPOSE: The present study compared the expression of early growth responsive gene-1 (Egr-1) in visual cortex between amblyopia kittens and normal kittens, and to explore the role of Egr-1 in the pathogenesis of amblyopia. METHODS: A total of 20 healthy kittens were randomly divided into deprivation group and control group with 10 kittens in each group. Raised in natural light, and covered the right eye of the deprived kittens with a black opaque covering cloth. Pattern visual evoked potentials (PVEP) were measured before and at the 1st, 3rd and 5th week after covering in all kittens. After the last PVEP test, all kittens were killed. The expression of Egr-1 in the visual cortex of the two groups was compared by immunohistochemistry and in situ hybridization. RESULTS: PVEP detection showed that at the age of 6 and 8 weeks, the P100 wave latency in the right eye of deprivation group was higher than that in the left eye of deprivation group (P < 0.05) and the right eye of control group (P < 0.05), while the amplitude decreased (P < 0.05). The number of positive cells (P < 0.05) and mean optical density (P < 0.05) of Egr-1 protein expression in visual cortex of 8-week-old deprivation group were lower than those of normal group, as well as the number (P < 0.05) and mean optical density of Egr-1 mRNA-positive cells (P < 0.05). CONCLUSIONS: Monocular form deprivation amblyopia can lead to the decrease of Egr-1 protein and mRNA expression in visual cortex, and then promote the occurrence and development of amblyopia.


Assuntos
Ambliopia , Córtex Visual , Animais , Gatos , Potenciais Evocados Visuais , Olho , Feminino , Privação Sensorial
9.
Transl Vis Sci Technol ; 10(12): 3, 2021 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-34605876

RESUMO

Purpose: The purpose of this study was to present normative data of optical coherence tomography (OCT), electrophysiological, and ocular biometry parameters and their correlation in minipigs. Methods: Eighty-eight eyes of 44 minipigs underwent full-field electroretinogram (ERG) recording and ocular biometry. However, 10 eyes of 6 minipigs were excluded because of poor OCT image quality. The thickness of the retinal sublayers was measured on a vertical line at 5 locations with a 1 mm interval from the disc margin to the dorsal periphery and at 10 locations on the visual streak. Visual evoked potentials (VEPs) were measured in 15 eyes of 8 minipigs. Results: All minipigs were female with a mean age and axial length of 13.83 ± 10.56 months and 20.33 ± 0.88 mm, respectively. The implicit time of the a-wave and b-wave in scotopic 3.0 ERGs was longer than that in photopic 3.0 ERG. The implicit time of the n2-wave and p2-wave in VEP was 25.67 ± 7.41 ms and 52.96 ± 10.38 ms, respectively. The total retinal layer (TRL) and nerve fiber layer (NFL) became thinner near the periphery. The inner retinal sublayers near the visual streak were thicker than those at other locations. Central TRL and NFL thickness on visual streak was 223.06 ± 23.19 µm and 74.03 ± 13.93 µm, respectively. The temporal TRL and NFL on the visual streak were thicker than those on the nasal side. Conclusions: The normative electrophysiological and OCT parameters used in our study can be used as reference data in further pig studies. Translational Relevance: This study presents normative data of minipigs, which are adequate animal models for preclinical studies.


Assuntos
Eletrorretinografia , Potenciais Evocados Visuais , Animais , Feminino , Humanos , Fibras Nervosas , Retina/diagnóstico por imagem , Suínos , Porco Miniatura
10.
J Neural Eng ; 18(5)2021 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-34607320

RESUMO

Objective.Brain-machine interfaces (BMIs) interpret human intent into machine reactions, and the visual stimulation (VS) paradigm is one of the most widely used of these approaches. Although VS-based BMIs have a relatively high information transfer rate (ITR), it is still difficult for BMIs to control machines in dynamic environments (for example, grabbing a dynamic object or targeting a walking person).Approach.In this study, we utilized a BMI based on augmented reality (AR) VS (AR-VS). The proposed VS was dynamically generated based on machine vision, and human intent was interpreted by a dynamic decision time interval approach. A robot based on the coordination of a task and self-motion system was controlled by the proposed paradigm in a fast and flexible state.Methods.Objects in scenes were first recognized by machine vision and tracked by optical flow. AR-VS was generated based on the objects' parameters. The number and distribution of VS was confirmed by the recognized objects. Electroencephalogram (EEG) features corresponding to VS and human intent were collected by a dry-electrode EEG cap and determined by the filter bank canonical correlation analysis method. Key parameters in the AR-VS, including the effect of VS size, frequency, dynamic object moving speed, ITR and the performance of the BMI-controlled robot, were analyzed.Conclusion and significance.The ITR of the proposed AR-VS paradigm for nine healthy subjects was 36.3 ± 20.1 bits min-1. In the online robot control experiment, brain-controlled hybrid tasks including self-moving and grabbing objects were 64% faster than when using the traditional steady-state visual evoked potential paradigm. The proposed paradigm based on AR-VS could be optimized and adopted in other kinds of VS-based BMIs, such as P300, omitted stimulus potential, and miniature event-related potential paradigms, for better results in dynamic environments.


Assuntos
Realidade Aumentada , Interfaces Cérebro-Computador , Eletroencefalografia , Potenciais Evocados Visuais , Humanos , Estimulação Luminosa
11.
J Neurodev Disord ; 13(1): 43, 2021 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-34592931

RESUMO

BACKGROUND: Autism spectrum disorders (ASD) are associated with altered sensory processing and perception. Scalp recordings of electrical brain activity time-locked to sensory events (event-related potentials; ERPs) provide precise information on the time-course of related altered neural activity, and can be used to model the cortical loci of the underlying neural networks. Establishing the test-retest reliability of these sensory brain responses in ASD is critical to their use as biomarkers of neural dysfunction in this population. METHODS: EEG and behavioral data were acquired from 33 children diagnosed with ASD aged 6-9.4 years old, while they performed a child-friendly task at two different time-points, separated by an average of 5.2 months. In two blocked conditions, participants responded to the occurrence of an auditory target that was either preceded or not by repeating visual stimuli. Intraclass correlation coefficients (ICCs) were used to assess test-retest reliability of measures of sensory (auditory and visual) ERPs and performance, for the two experimental conditions. To assess the degree of reliability of the variability of responses within individuals, this analysis was performed on the variance of the measurements, in addition to their means. This yielded a total of 24 measures for which ICCs were calculated. RESULTS: The data yielded significant good ICC values for 10 of the 24 measurements. These spanned across behavioral and ERPs data, experimental conditions, and mean as well as variance measures. Measures of the visual evoked responses accounted for a disproportionately large number of the significant ICCs; follow-up analyses suggested that the contribution of a greater number of trials to the visual compared to the auditory ERP partially accounted for this. CONCLUSIONS: This analysis reveals that sensory ERPs and related behavior can be highly reliable across multiple measurement time-points in ASD. The data further suggest that the inter-trial and inter-participant variability reported in the ASD literature likely represents replicable individual participant neural processing differences. The stability of these neuronal readouts supports their use as biomarkers in clinical and translational studies on ASD. Given the minimum interval between test/retest sessions across our cohort, we also conclude that for the tested age-range of ~ 6 to 9.4 years, these reliability measures are valid for at least a 3-month interval. Limitations related to EEG task demands and study length in the context of a clinical trial are considered.


Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Transtorno do Espectro Autista/diagnóstico , Criança , Potenciais Evocados , Potenciais Evocados Visuais , Humanos , Lactente , Reprodutibilidade dos Testes
12.
Eur J Neurosci ; 54(10): 7575-7598, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34661322

RESUMO

It has been suggested that aesthetically pleasing stimuli are processed efficiently by the visual system, whereas uncomfortable stimuli are processed inefficiently. This study consists of a series of three experiments investigating this idea using a range of images of abstract artworks, photographs of natural scenes, and computer-generated stimuli previously shown to be uncomfortable. Subjective judgements and neural correlates were measured using electroencephalogram (EEG) (steady-state visual evoked potentials, SSVEPs). In addition, global image statistics (contrast, Fourier amplitude spectral slope and fractal dimension) were taken into account. When effects of physical image contrast were controlled, fractal dimension predicted discomfort judgements, suggesting the SSVEP response is more likely to be influenced by distribution of edges than the spectral slope. Importantly, when effects of physical contrast and fractal dimension were accounted for using linear mixed effects modelling, SSVEP responses predicted subjective judgements of images. Specifically, when stimuli were not matched for perceived contrast, there was a positive relationship between SSVEP responses and how pleasing a stimulus was judged to be, and conversely a negative relationship between discomfort and SSVEP response. This is significant as it shows that the neural responses in early visual areas contribute to the subjective (un)pleasantness of images, although the results of this study do not provide clear support for the theory of efficient coding as the cause of perceived pleasantness or discomfort of images, and so other explanations need to be considered.


Assuntos
Eletroencefalografia , Potenciais Evocados Visuais , Exame Neurológico , Estimulação Luminosa
13.
Ecotoxicol Environ Saf ; 227: 112866, 2021 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-34634599

RESUMO

OBJECTIVES: To investigate how PM2.5 exposure affects the microstructure, metabolites or functions of the visual system. METHODS: C57BL/6J mice were randomly assigned to groups exposed to the filtered air (the control group) or the concentrated ambient PM2.5 (the PM2.5 group). Visual evoked potentials (VEP), electroretinograms (ERG), diffusion tensor imaging (DTI), proton magnetic resonance spectroscopy (1H-MRS) and resting-state functional MRI (rsfMRI) were performed. Parameters were obtained and compared between the two groups, including latencies and amplitudes of the P1 wave, N1 wave and P2 wave from VEP, latencies and amplitudes of the a wave and b wave from ERG, fractional anisotropy (FA), mean diffusion (MD), axial diffusivity (AD) and radial diffusivity (RD) from DTI, visual cortex (VC) metabolites from 1H-MRS, and regional homogeneity (ReHo) from rsfMRI. RESULTS: Compared with the values of the control group, the PM2.5 group showed a prolonged N1 latency (43.11 ±â€¯7.94 ms vs. 38.75 ±â€¯4.60 ms) and lowered P1 amplitude (5.62 ±â€¯4.38 µV vs. 8.56 ±â€¯5.92 µV) on VEP (all p < 0.05). On ERG, the amplitude of the a wave was lowered (- 91.39 ±â€¯56.29 µV vs. - 138.68 ±â€¯89.05 µV), the amplitude of the b wave was lowered (194.38 ±â€¯126.27 µV vs. 284.72 ±â€¯170.99 µV), and the latency of the b wave was prolonged (37.78 ±â€¯10.72 ms vs. 33.01 ±â€¯4.34 ms) than the values of the control group (all p < 0.05). DTI indicated FA increase in the bilateral piriform cortex (Pir), FA decrease in the bilateral somatosensory cortex (S) and the bilateral striatum (Stri), AD decrease in the bilateral VC, the right S and the bilateral Pir, MD decrease in the bilateral Pir, and RD decrease in the bilateral Pir in the PM2.5 mice (all p < 0.05, Alphasim corrected). 1H-MRS showed Glutamate (Glu) increase and Phosphocholine (PCh) increase in the VC of the PM2.5 group than those of the control group (PCh 1.63 ±â€¯0.25 vs. 1.50 ±â€¯0.25; PCh/total creatine(tCr) 0.19 ±â€¯0.03 vs. 0.18 ±â€¯0.03; Glu 10.46 ±â€¯1.50 vs. 9.60 ±â€¯1.19; Glu/tcr 1.23 ±â€¯0.11 vs. 1.12 ±â€¯0.11) (all p < 0.05). rsfMRI showed higher ReHo in the PM2.5 mice in the left superior colliculus, the left motor cortex, the hippocampus, the periaqueductal gray and the right mesencephalic reticular formation (all p < 0.01, AlphaSim corrected). CONCLUSIONS: This study revealed that PM2.5 exposure triggered visual dysfunction, and altered microstructure, metabolite and function in the retina and visual brain areas along the visual system.


Assuntos
Imagem de Tensor de Difusão , Potenciais Evocados Visuais , Animais , Imageamento por Ressonância Magnética , Camundongos , Camundongos Endogâmicos C57BL , Material Particulado/toxicidade
14.
PLoS One ; 16(10): e0258667, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34673791

RESUMO

Current theories about visual perception assume that our perceptual system weights the a priori incomplete, noisy and ambiguous sensory information with previous, memorized perceptual experiences in order to construct stable and reliable percepts. These theories are supported by numerous experimental findings. Theories about precognition have an opposite point of view. They assume that information from the future can have influence on perception, thoughts, and behavior. Several experimental studies provide evidence for precognition effects, other studies found no such effects. One problem may be that the vast majority of precognition paradigms did not systematically control for potential effects from the perceptual history. In the present study, we presented ambiguous Necker cube stimuli and disambiguated cube variants and systematically tested in two separate experiments whether perception of a currently observed ambiguous Necker cube stimulus can be influenced by a disambiguated cube variant, presented in the immediate perceptual past (perceptual history effects) and/or in the immediate perceptual future (precognition effects). We found perceptual history effects, which partly depended on the length of the perceptual history trace but were independent of the perceptual future. Results from some individual participants suggest on the first glance a precognition pattern, but results from our second experiment make a perceptual history explanation more probable. On the group level, no precognition effects were statistically indicated. The perceptual history effects found in the present study are in confirmation with related studies from the literature. The precognition analysis revealed some interesting individual patterns, which however did not allow for general conclusions. Overall, the present study demonstrates that any future experiment about sensory or extrasensory perception urgently needs to control for potential perceptual history effects and that temporal aspects of stimulus presentation are of high relevance.


Assuntos
Percepção de Profundidade/fisiologia , Potenciais Evocados Visuais , Julgamento , Reconhecimento Visual de Modelos , Estimulação Luminosa , Acuidade Visual/fisiologia , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
15.
Sci Rep ; 11(1): 17940, 2021 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-34504129

RESUMO

Functional connectivity networks (FCN) are the physiological basis of brain synchronization to integrating neural activity. They are not rigid but can reorganize under pathological conditions or during mental or behavioral states. However, because mental acts can be very fast, like the blink of an eye, we now used the visual system as a model to explore rapid FCN reorganization and its functional impact in normal, abnormal and post treatment vision. EEG-recordings were time-locked to visual stimulus presentation; graph analysis of neurophysiological oscillations were used to characterize millisecond FCN dynamics in healthy subjects and in patients with optic nerve damage before and after neuromodulation with alternating currents stimulation and were correlated with visual performance. We showed that rapid and transient FCN synchronization patterns in humans can evolve and dissolve in millisecond speed during visual processing. This rapid FCN reorganization is functionally relevant because disruption and recovery after treatment in optic nerve patients correlated with impaired and recovered visual performance, respectively. Because FCN hub and node interactions can evolve and dissolve in millisecond speed to manage spatial and temporal neural synchronization during visual processing and recovery, we propose "Brain Spacetime" as a fundamental principle of the human mind not only in visual cognition but also in vision restoration.


Assuntos
Encéfalo/fisiopatologia , Terapia por Estimulação Elétrica/métodos , Rede Nervosa/fisiopatologia , Doenças do Nervo Óptico/fisiopatologia , Doenças do Nervo Óptico/terapia , Recuperação de Função Fisiológica , Percepção Visual , Adulto , Cognição , Método Duplo-Cego , Eletroencefalografia/métodos , Sincronização de Fases em Eletroencefalografia , Potenciais Evocados Visuais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento , Testes de Campo Visual/métodos , Campos Visuais
16.
Curr Opin Ophthalmol ; 32(6): 515-520, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34494975

RESUMO

PURPOSE OF REVIEW: Dementia is a term for loss of memory, language, problem-solving, and other thinking abilities, which significantly interferes with daily life. Certain dementing conditions may also affect visual function. The eye is an accessible window to the brain that can provide valuable information for the early diagnosis of people who suffer from Alzheimer's disease, Parkinson's disease, dementia with Lewy bodies as well as from more rare causes of dementias, such as Creutzfeldt-Jacob and Huntington's diseases. Herein, we present the ocular manifestations of neurocognitive disorders focusing on the neuro-ophthalmic ones and further discuss potential ocular biomarkers that could help in early detection of these disorders. RECENT FINDINGS: Ophthalmic examination along with the recent developments in in-vivo testing have provided a strong foundation of useful knowledge about brain disorder in neurodegenerative diseases without the need for invasive studies. Currently, a number of visual measures, such as visual acuity, contrast sensitivity, pupil response, and saccades in addition to various ophthalmic tests, such as electroretinogram, visual evoked potential, optical coherence tomography (OCT), and OCT-angiography have been widely used and evaluated as potential biomarkers for different stages of dementia. SUMMARY: Ophthalmologic and neuro-ophthalmic evaluation is evolving as an important part of the early diagnosis and management of people with dementia. A particular focus on ocular biomarkers in dementing illnesses has arisen over the past few years and there are several promising measures and imaging tools that have been proposed as potential biomarkers for these diseases.


Assuntos
Doença de Alzheimer , Doença de Huntington , Doença de Parkinson , Encéfalo , Potenciais Evocados Visuais , Humanos
17.
Comput Methods Programs Biomed ; 211: 106410, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34587563

RESUMO

PURPOSE: The characteristics of children's reading interest, stimulated by the visual evoked potentials of colour graphics in children's picture books, were tested to explore their normal reference value. The characteristics of chromatic pattern visual evoked potential (CP-VEP) can be harnessed by our methodology and may be applied to the visual screening of children in clinical ophthalmology. METHODS: The PR-650 spectral colour metre can strictly control factors, such as brightness and colour retention, based on colour contrast. This is performed in order to reduce the brightness contrast method. In our paper, we set up three kinds of visual stimulation conditions and performed CP-VEP inspections of the eye, based on 64 cases (128 eyes) of normal children (32 males and 32 females). Using CP-VEP detection, the latency and amplitude of the P100 wave were recorded and the waveforms of each group, under different spectral modes were compared. Art therapy combined with children's colour physiology and psychology will be more skilfully practiced in clinical practice. RESULTS: There was no significant difference in the amplitude and peak time of visual evoked potential (VEP) waveforms between the left and right eyes of the children using the three stimuli, indicating that the visual function and visual conduction pathway of children can vary. There was no significant difference in the latency and amplitude of the NPN complex wave. Note that the P1 wave of the right and left eyes of normal children is not statistically different (P > 0.05). We also found that there is insignificant difference in the visual impact of the colours for both male and female children in terms of reading interest, and red is a more stimulating colour for both sexes. CONCLUSION: Our study can provide normal reference value and methodological reference for clinical visual acuity detection in children. Combined with the visual characteristics of children, this paper selects the visual impact created by the colour of picture books and combines it with medical treatment. Make the whole test cover the scope of ophthalmology clinical more comprehensive.


Assuntos
Potenciais Evocados Visuais , Leitura , Biometria , Criança , Feminino , Humanos , Masculino , Estimulação Luminosa , Vias Visuais
18.
J Neural Eng ; 18(5)2021 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-34592716

RESUMO

Objective. The steady-state visual evoked potential (SSVEP) is one of the most commonly used control signals for brain-computer interfaces (BCIs) due to its excellent interactive potential, such as high tolerance to noises and robust performance across users. In addition, it has a stable cycle, obvious characteristics and minimal training requirements. However, the SSVEP is extremely weak and companied with strong and multi-scale noise, resulting in a poor signal-to-noise ratio in practice. Common algorithms for classification are based on the principle of template matching and spatial filtering, which cannot obtain satisfied performance of SSVEP detection under the multi-scale noise. Therefore, using linear methods to extract SSVEP with obvious nonlinear and non-stationary characteristics, the useful signal will be attenuated or lost.Approach.To address this issue, two novel frameworks based on a two-dimensional nonlinear FitzHugh-Nagumo (FHN) neuron system are proposed to extract feature frequency of SSVEP.Results.In order to evaluate the effectiveness of the proposed methods, this research recruit 22 subjects to participate the experiment. Experimental results show that nonlinear FHN neuron model can force the energy of noise to be transferred into SSVEP and hence amplifying the amplitude of the target frequency. Compared with the traditional methods, the FHN and FHNCCA methods can achieve higher classification accuracy and faster processing speed, which effectively improves the information transmission rate of SSVEP-based BCI.


Assuntos
Interfaces Cérebro-Computador , Potenciais Evocados Visuais , Eletroencefalografia , Humanos , Neurônios , Estimulação Luminosa
19.
Mult Scler ; 27(11): 1717-1726, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34558326

RESUMO

BACKGROUND: While damage to the optic nerve following optic neuritis (ON) is readily quantifiable, the evaluation of prognosis for visual function and neuroaxonal loss in the acute ON is challenging. OBJECTIVE: The objective of this study is to investigate the value of multifocal visual evoked potential (mfVEP) in acute ON, diagnostically for acute ON and prognostically for visual outcome and subsequent ganglion cell/inner plexiform layer thickness (GCLIPLt). METHODS: A prospective cohort study of mfVEP and full-field visual evoked potential (ffVEP) in acute, unilateral ON (onset < 31 days) was conducted. Comparisons with healthy controls (n = 30) and association analysis with follow-up optical coherence tomography (OCT) measurements (of the GCLIPLt) and visual function (Sloan low-contrast visual acuity (LCVA)) were conducted. RESULTS: Seventy-nine ON patients were included (mean: 17 days from onset). Excluding measurements with conduction block, ffVEP (n = 54) and mfVEP (n = 44) showed sensitivities of 89% and 84% to a specificity of 97%. 65/79 patients were re-examined (mean: 200 days follow-up). mfVEP amplitude and latency inter-eye asymmetry in acute ON correlated with GCLIPLt (r = 0.587 and Spearman's ρ = 0.597, for both, p < 0.001). mfVEP amplitude correlated with LCVA inter-eye asymmetry at follow-up (r = 0.421, p < 0.001), mfVEP latency did not. CONCLUSION: mfVEP may support the prognostic evaluation of acute ON patients and prove valuable in future neuroprotective and remyelinating trials. In acute ON, the increase in diagnostic value of mfVEP to ffVEP may be limited due to widespread conduction block.


Assuntos
Potenciais Evocados Visuais , Neurite Óptica , Humanos , Neurite Óptica/diagnóstico , Estudos Prospectivos , Retina , Tomografia de Coerência Óptica
20.
Stem Cell Res Ther ; 12(1): 518, 2021 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-34579767

RESUMO

PURPOSE: To investigate the effect of the combination of Wharton's jelly derived mesenchymal stem cells (WJ-MSC) and high frequency repetitive electromagnetic stimulation (rEMS) in the therapy of toxic optic neuropathies with severe symptoms after the available current therapy modalities which were unsucessful. MATERIAL AND METHODS: This prospective, open-label clinical phase-3 study was conducted at Ankara University Faculty of Medicine, Department of Ophthalmology between April 2019 and April 2021. Thirty-six eyes of 18 patients with toxic optic neuropathy (TON) were included in the study. Within 1-3 months after the emergency interventions, patients with various degrees of sequela visual disturbances were studied in this clinical trial. The cases were divided into three groups according to similar demographic characteristics. Group 1: Consists of 12 eyes of 12 patients treated with the WJ-MSC and rEMS combination in one eye. Group 2: Consists of 12 eyes of 12 patients treated with only rEMS in one eye. Group 3: Consists of 12 eyes of six patients treated with only WJ-MSC in both eyes. The course was evaluated by comparing the quantitive functional and structural assessment parameters measured before and at the fourth month of applications in each group. RESULTS: The mean best corrected visual acuity (BCVA) delta change percentages of the groups can be ranked as: Group 1 (47%) > Group 3 (32%) > Group 2 (21%). The mean fundus perimetry deviation index (FPDI) delta change percentages of the groups can be ranked as: Group 1 (95%) > Group 2 (33%) > Group 3 (27%). The mean ganglion cell complex (GCC) thickness delta change (decrease in thickness) percentages can be ranked as: Group 1 (- 21%) > Group 3 (- 15%) > Group 2 (- 13%). The visual evoked potential (VEP) P100 latency delta change percentages of the groups can be ranked as: Group 1 (- 18%) > Group 3 (- 10%) > Group 2 (- 8%). The P100 amplitude delta change percentages of the groups can be ranked as: Group 1 (105%) > Group 3 (83%) > Group 2 (24%). CONCLUSION: Toxic optic neuropathies are emergent pathologies that can result in acute and permanent blindness. After poisoning with toxic substances, progressive apoptosis continues in optic nerve axons and ganglion cells. After the proper first systemic intervention in intensive care clinic, the WJ-MSC and rEMS combination seems very effective in the short-term period in cases with TON. To prevent permanent blindness, a combination of WJ-MSC and rEMS application as soon as possible may increase the chance of success in currently untreatable cases. Trial Registration ClinicalTrials.gov ID: NCT04877067.


Assuntos
Células-Tronco Mesenquimais , Geleia de Wharton , Diferenciação Celular , Fenômenos Eletromagnéticos , Potenciais Evocados Visuais , Humanos , Estudos Prospectivos , Neuropatia Óptica Tóxica
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...