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1.
Article in English | WPRIM | ID: wpr-765114

ABSTRACT

BACKGROUND: It has been frequently reported that non-negligible numbers of individuals have steady-state visual evoked potential (SSVEP) responses of low signal-to-noise-ratio (SNR) to specific stimulation frequencies, which makes detection of the SSVEP difficult especially in brain–computer interface applications. We investigated whether SSVEP can be modulated by anodal transcranial direct-current stimulation (tDCS) of the visual cortex. METHODS: Each participant participated in two 20-min experiments—an actual tDCS experiment and a sham tDCS experiment—that were conducted on different days. Two representative electroencephalogram (EEG) features used for the SSVEP detection, SNR and amplitude, were tested for pre- and post-tDCS conditions to observe the effect of the anodal tDCS. RESULTS: The EEG features were significantly enhanced by the anodal tDCS for the electrodes with low pre-tDCS SNR values, whereas the effect was not significant for electrodes with relatively higher SNR values. CONCLUSION: Anodal tDCS of the visual cortex may be effective in enhancing the SNR and amplitude of the SSVEP response especially for individuals with low-SNR SSVEP.


Subject(s)
Electrodes , Electroencephalography , Evoked Potentials, Visual , Transcranial Direct Current Stimulation , Visual Cortex
2.
Acta Physiologica Sinica ; (6): 33-44, 2019.
Article in Chinese | WPRIM | ID: wpr-777212

ABSTRACT

Integrating different visual features into a coherent object is a central challenge for the visual system, which is referred as the binding problem. Firstly, this review introduces the conception of the binding problem and the theoretical and empirical controversies regarding whether and how the binding processes are implemented in visual system. Although many neurons throughout the visual hierarchy are known to code multiple features, feature binding is recruited by visual system. Feature misbinding (or illusory conjunction) is probably the most striking evidence for the existence of the binding mechanism. Next, this review summarizes some critical issues in feature binding literature, including early binding theories, late binding theories, neural synchrony theory, the feature integration theory and re-entry processing theory. Feature binding is not a fully automatic or bottom-up processing. Reentrant connection from higher visual areas to early visual cortex (top-down processes) plays a critical role in feature binding, especially in active feature binding (i.e. feature misbinding). In addition, with electrophysiology, electroencephalography (EEG), magnetoencephalography (MEG) and transcranial electric stimulation (tEs) approaches, recent studies explored both correlational and causal relations between brain oscillations and feature binding, suggesting that brain oscillations are of great importance for feature binding. Finally, this review discusses some potential problems and open questions associated with visual feature binding mechanisms which need to be addressed in future studies.


Subject(s)
Brain , Physiology , Electroencephalography , Humans , Magnetoencephalography , Neurons , Physiology , Transcranial Direct Current Stimulation , Visual Cortex , Physiology , Visual Perception
3.
Acta Physiologica Sinica ; (6): 45-52, 2019.
Article in Chinese | WPRIM | ID: wpr-777211

ABSTRACT

The human visual system efficiently extracts local elements from cluttered backgrounds and integrates these elements into meaningful contour perception. This process is a critical step before object recognition, in which contours often play an important role in defining the shapes and borders of the to-be-recognized objects. However, the neural mechanism of the contour integration is still under debate. The investigation of the neural mechanism underlying contour integration could deepen our understanding of perceptual grouping in the human visual system and advance the development of the algorithms for image grouping and segmentation in computer vision. Here, we review two theoretical frameworks that were proposed over the past decades. The first framework is based on hardwired horizontal connection in primary visual cortex, while the second one emphasizes the role of recurrent connections within intra- and inter-areas. At the end of review, we also raise the unsolved issues that need to be addressed in future studies.


Subject(s)
Form Perception , Humans , Models, Neurological , Pattern Recognition, Visual , Visual Cortex , Physiology , Visual Perception
4.
Acta Physiologica Sinica ; (6): 53-61, 2019.
Article in Chinese | WPRIM | ID: wpr-777210

ABSTRACT

The core of visual processing is the identification and recognition of the objects relevant to cognitive behaviors. In natural environment, visual input is often comprised of highly complex 3-dimensional signals involving multiple visual objects. One critical determinant of object recognition is visual contour. Despite substantial insights on visual contour processing gained from previous findings, these studies have focused on limited aspects or particular stages of contour processing. So far, a systematic perspective of contour processing that comprehensively incorporates previous evidence is still missing. We therefore propose an integrated framework of the cognitive and neural mechanisms of contour processing, which involves three mutually interacting cognitive stages: contour detection, border ownership assignment and contour integration. For each stage, we provide an elaborated discussion of the neural properties, processing mechanism, and its functional interaction with the other stages by summarizing the relevant electrophysiological and human cognitive neuroscience evidence. Finally, we present the major challenges for further unraveling the mechanisms of visual contour processing.


Subject(s)
Cognition , Form Perception , Humans , Visual Cortex , Physiology , Visual Perception
5.
Acta Physiologica Sinica ; (6): 62-72, 2019.
Article in Chinese | WPRIM | ID: wpr-777209

ABSTRACT

Visual memory, mainly composed of visual long-term memory (VLTM) and visual working memory (VWM), is an important mechanism of human information storage. Since Baddeley proposed the multicomponent working memory model, the idea that VWM is independent of the VLTM system has been widely accepted. However, the new theoretical evidence suggested a close connection between VLTM and VWM. For instance, the three embedded components model describes the VLTM and VWM in the same framework, which suggests that VWM is only a distinct state of VLTM. On the one hand, the operating function of VWM is supported by the persistence of VLTM. On the other hand, the evidence from neuroimaging studies shows that VWM and VLTM tasks activate some same brain areas. In addition, the whole visual memory system shows a trend of processing from early visual cortex to prefrontal cortex. The present article not only reviews the current studies about the relationship between VLTM and VWM but also gives some forecasts for future studies.


Subject(s)
Brain , Physiology , Humans , Memory, Long-Term , Memory, Short-Term , Visual Cortex , Physiology , Visual Perception
6.
Journal of Stroke ; : 207-216, 2019.
Article in English | WPRIM | ID: wpr-766245

ABSTRACT

BACKGROUND AND PURPOSE: We aimed to assess whether early resting-state functional connectivity (RSFC) changes measured via functional magnetic resonance imaging (fMRI) could predict recovery from visual field defect (VFD) in acute stroke patients. METHODS: Patients with VFD due to acute ischemic stroke in the visual cortex and age-matched healthy controls were prospectively enrolled. Serial resting-state (RS)-fMRI and Humphrey visual field (VF) tests were performed within 1 week and at 1 and 3 months (additional VF test at 6 months) after stroke onset in the patient group. The control group also underwent RS-fMRI and a Humphrey VF test. The changes in RSFCs and VF scores (VFSs) over time and their correlations were investigated. RESULTS: In 32 patients (65±10 years, 25 men), the VFSs were lower and the interhemispheric RSFC in the visual cortices was decreased compared to the control group (n=15, 62±6 years, seven men). The VFSs and interhemispheric RSFC in the visual cortex increased mainly within the first month after stroke onset. The interhemispheric RSFC and VFSs were positively correlated at 1 month after stroke onset. Moreover, the interhemispheric RSFCs in the visual cortex within 1 week were positively correlated with the follow-up VFSs. CONCLUSIONS: Interhemispheric RSFCs in the visual cortices within 1 week after stroke onset may be a useful biomarker to predict long-term VFD recovery.


Subject(s)
Follow-Up Studies , Humans , Infarction, Posterior Cerebral Artery , Magnetic Resonance Imaging , Prospective Studies , Recovery of Function , Stroke , Visual Cortex , Visual Fields
7.
Article in English | WPRIM | ID: wpr-761804

ABSTRACT

It is known that top-down associative inputs terminate on distal apical dendrites in layer 1 while bottom-up sensory inputs terminate on perisomatic dendrites of layer 2/3 pyramidal neurons (L2/3 PyNs) in primary sensory cortex. Since studies on synaptic transmission in layer 1 are sparse, we investigated the basic properties and cholinergic modulation of synaptic transmission in layer 1 and compared them to those in perisomatic dendrites of L2/3 PyNs of rat primary visual cortex. Using extracellular stimulations of layer 1 and layer 4, we evoked excitatory postsynaptic current/potential in synapses in distal apical dendrites (L1-EPSC/L1-EPSP) and those in perisomatic dendrites (L4-EPSC/L4-EPSP), respectively. Kinetics of L1-EPSC was slower than that of L4-EPSC. L1-EPSC showed presynaptic depression while L4-EPSC was facilitating. In contrast, inhibitory postsynaptic currents showed similar paired-pulse ratio between layer 1 and layer 4 stimulations with depression only at 100 Hz. Cholinergic stimulation induced presynaptic depression by activating muscarinic receptors in excitatory and inhibitory synapses to similar extents in both inputs. However, nicotinic stimulation enhanced excitatory synaptic transmission by ~20% in L4-EPSC. Rectification index of AMPA receptors and AMPA/NMDA ratio were similar between synapses in distal apical and perisomatic dendrites. These results provide basic properties and cholinergic modulation of synaptic transmission between distal apical and perisomatic dendrites in L2/3 PyNs of the visual cortex, which might be important for controlling information processing balance depending on attentional state.


Subject(s)
Animals , Electronic Data Processing , Dendrites , Depression , Inhibitory Postsynaptic Potentials , Kinetics , Pyramidal Cells , Rats , Receptors, AMPA , Receptors, Muscarinic , Synapses , Synaptic Transmission , Visual Cortex
8.
Protein & Cell ; (12): 909-929, 2018.
Article in English | WPRIM | ID: wpr-758007

ABSTRACT

70%-80% of our sensory input comes from vision. Light hit the retina at the back of our eyes and the visual information is relayed into the dorsal lateral geniculate nuclei (dLGN) and primary visual cortex (V1) thereafter, constituting the image-forming visual circuit. Molecular cues are one of the key factors to guide the wiring and refinement of the image-forming visual circuit during pre- and post-embryonic stages. Distinct molecular cues are involved in different developmental stages and nucleus, suggesting diverse guidance mechanisms. In this review, we summarize molecular guidance cues throughout the image-forming visual circuit, including chiasm determination, eye-specific segregation and refinement in the dLGN, and at last the reciprocal connections between the dLGN and V1.


Subject(s)
Animals , Geniculate Bodies , Metabolism , Humans , Visual Cortex , Metabolism , Visual Pathways , Metabolism
9.
Neuroscience Bulletin ; (6): 438-448, 2018.
Article in English | WPRIM | ID: wpr-777052

ABSTRACT

Diffusion-weighted magnetic resonance imaging (dMRI) is widely used to study white and gray matter (GM) micro-organization and structural connectivity in the brain. Super-resolution track-density imaging (TDI) is an image reconstruction method for dMRI data, which is capable of providing spatial resolution beyond the acquired data, as well as novel and meaningful anatomical contrast that cannot be obtained with conventional reconstruction methods. TDI has been used to reveal anatomical features in human and animal brains. In this study, we used short track TDI (stTDI), a variation of TDI with enhanced contrast for GM structures, to reconstruct direction-encoded color maps of fixed tree shrew brain. The results were compared with those obtained with the traditional diffusion tensor imaging (DTI) method. We demonstrated that fine microstructures in the tree shrew brain, such as Baillarger bands in the primary visual cortex and the longitudinal component of the mossy fibers within the hippocampal CA3 subfield, were observable with stTDI, but not with DTI reconstructions from the same dMRI data. The possible mechanisms underlying the enhanced GM contrast are discussed.


Subject(s)
Animals , Brain Mapping , Diffusion Tensor Imaging , Methods , Hippocampus , Diagnostic Imaging , Image Processing, Computer-Assisted , Methods , Male , Neural Pathways , Diagnostic Imaging , Tupaiidae , Visual Cortex , Diagnostic Imaging
10.
Neuroscience Bulletin ; (6): 465-475, 2018.
Article in English | WPRIM | ID: wpr-777041

ABSTRACT

The visual system plays an important role in our daily life. In this study, we found that loss of dendritic cell factor 1 (DCF1) in the primary visual cortex (V1) caused a sight deficit in mice and induced an abnormal increase in glutamic acid decarboxylase 67, an enzyme that catalyzes the decarboxylation of glutamate to gamma aminobutyric acid and CO, particularly in layer 5. In vivo electrophysiological recordings confirmed a decrease in delta, theta, and beta oscillation power in DCF1-knockout mice. This study presents a previously unknown function of DCF1 in V1, suggests an unknown contact between DCF1 and GABA systems, and provides insight into the mechanism and treatment of visual deficits.


Subject(s)
Animals , Brain Waves , Genetics , Disease Models, Animal , Electroencephalography , Gene Expression Regulation , Genetics , Geniculate Bodies , Metabolism , Ginkgolides , Therapeutic Uses , Glutamate Decarboxylase , Metabolism , Lactones , Therapeutic Uses , Membrane Proteins , Genetics , Mice , Mice, Inbred C57BL , Mice, Knockout , Nerve Tissue Proteins , Genetics , Photic Stimulation , Proto-Oncogene Proteins c-fos , Metabolism , Vision Disorders , Drug Therapy , Genetics , Pathology , Visual Cortex , Metabolism , Pathology , gamma-Aminobutyric Acid , Metabolism
11.
Einstein (Säo Paulo) ; 15(1): 17-23, Jan.-Mar. 2017. tab, graf
Article in English | LILACS | ID: biblio-840293

ABSTRACT

ABSTRACT Objective To assess changes in blood-oxygen-level-dependent activity after light deprivation compared to regular light exposure in subjects with migraine in the interictal state and in controls. Methods Ten subjects with migraine and ten controls participated in two sessions of functional magnetic resonance imaging. In each session, they performed a finger-tapping task with the right hand, cued by visual stimuli. They were scanned before and after 30 minutes of light deprivation or light exposure. In subjects with migraine, functional magnetic resonance imaging was performed interictally. Analysis of variance was made with the factors time (before or after), session (light deprivation or exposure), and group (migraine or control). Results There were significant “group” effects in a cluster in the bilateral cuneus encompassing the superior border of the calcarine sulcus and extrastriate cortex. There were no significant effects of “time”, “session”, or interactions between these factors. Conclusion The main result of this study is consistent with aberrant interictal processing of visual information in migraine. Light deprivation did not modulate functional magnetic resonance imaging activity in subjects with or without migraine.


RESUMO Objetivo Avaliar mudanças na atividade cerebral por meio de ressonância magnética funcional após privação luminosa comparada à exposição à luz, em indivíduos com enxaqueca no estado interictal e em controles. Métodos Dez indivíduos com enxaqueca e dez controles participaram de duas sessões de ressonância magnética funcional. Em cada sessão, realizaram uma tarefa motora com a mão direita guiada por estímulos visuais. Foram colhidas imagens antes e após 30 minutos de privação luminosa ou exposição à luz. Em indivíduos com enxaqueca, a ressonância funcional foi realizada no período interictal. Foi feita a análise de variância com fatores tempo (antes ou depois), sessão (privação ou exposição à luz) e grupo (enxaqueca ou controle). Resultados Houve efeitos significativos de “grupo” em uma área no cúneo bilateral, incluindo a borda superior do sulco calcarino e o córtex extraestriado. Não houve efeitos significativos de “tempo”, “sessão” ou interações entre estes fatores. Conclusão O principal resultado deste estudo sugere um processamento interictal anormal das informações visuais em indivíduos com enxaqueca. A privação luminosa não modulou a atividade na ressonância magnética funcional em indivíduos com ou sem enxaqueca.


Subject(s)
Humans , Female , Adult , Middle Aged , Young Adult , Photic Stimulation , Visual Cortex/physiopathology , Magnetic Resonance Imaging/methods , Migraine Disorders/physiopathology , Motor Activity/physiology , Reference Values , Sensory Deprivation/physiology , Time Factors , Visual Cortex/diagnostic imaging , Case-Control Studies , Analysis of Variance , Disability Evaluation , Functional Neuroimaging , Hemodynamics , Light , Migraine Disorders/blood , Migraine Disorders/diagnostic imaging
12.
Article in English | WPRIM | ID: wpr-626995

ABSTRACT

The purpose of this study was to characterize, differentiate and correlate visual field and brain activation in visual cortex for normal, glaucoma suspect (GS) and primary open angle glaucoma (POAG) participants using Standard Automated Perimetry (SAP) and functional Magnetic Resonance Imaging (fMRI) respectively. The fMRI scans and SAP test were both carried out in Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM). Two types of black-and-white checkerboard pattern were displayed to the participants during the fMRI scans. The fMRI data were analyzed using WFU pickatlas toolbox targeting visual cortex area. The results showed that there was no significant difference in number of activated voxel between the three groups in visual cortex (BA 17, 18 and 19) while viewing all the given stimuli (p > 0.05). The pattern standard deviation (PSD) of SAP for visual field also revealed no significant differences (p > 0.05) in all groups of participants. However, negative correlation between PSD and fMRI activation was observed. The PSD values increased with a decrease in fMRI activation. With reference to visual field analysis, the results suggest that glaucomatous neuropathy of POAG patients has led to a gradual decrease in visual cortex activation and a gradual increase in PSD.


Subject(s)
Visual Cortex , Magnetic Resonance Imaging , Magnetic Resonance Spectroscopy
13.
Article in English | WPRIM | ID: wpr-34200

ABSTRACT

In neurosurgical procedures that may cause visual impairment in the intraoperative period, the monitoring of flash visual evoked potential (VEP) is clinically used to evaluate visual function. Patients are unconscious during surgery under general anesthesia, making flash VEP monitoring useful as it can objectively evaluate visual function. The flash stimulus input to the retina is transmitted to the optic nerve, optic chiasm, optic tract, lateral geniculate body, optic radiation (geniculocalcarine tract), and visual cortical area, and the VEP waveform is recorded from the occipital region. Intraoperative flash VEP monitoring allows detection of dysfunction arising anywhere in the optic pathway, from the retina to the visual cortex. Particularly important steps to obtain reproducible intraoperative flash VEP waveforms under general anesthesia are total intravenous anesthesia with propofol, use of retinal flash stimulation devices using high-intensity light-emitting diodes, and a combination of electroretinography to confirm that the flash stimulus has reached the retina. Relatively major postoperative visual impairment can be detected by intraoperative decreases in the flash VEP amplitude.


Subject(s)
Anesthesia, General , Anesthesia, Intravenous , Electroretinography , Evoked Potentials, Visual , Geniculate Bodies , Humans , Intraoperative Period , Monitoring, Intraoperative , Neurosurgical Procedures , Occipital Lobe , Optic Chiasm , Optic Nerve , Optic Tract , Propofol , Retina , Retinaldehyde , Vision Disorders , Visual Cortex
14.
Article in English | WPRIM | ID: wpr-152978

ABSTRACT

OBJECTIVE: Perspective-taking ability is an essential spatial faculty that is of much interest in both health and neuropsychiatric disorders. There is limited data on the neural correlates of perspective taking in the context of a realistic three-dimensional environment. We report the results of a pilot study exploring the same in eight healthy volunteers. METHODS: Subjects underwent two runs of an experiment in a 3 Tesla magnetic resonance imaging (MRI) involving alternate blocks of a first-person perspective based allocentric object location memory task (OLMT), a third-person perspective based egocentric visual perspective taking task (VPRT), and a table task (TT) that served as a control. Difference in blood oxygen level dependant response during task performance was analyzed using Statistical Parametric Mapping software, version 12. Activations were considered significant if they survived family-wise error correction at the cluster level using a height threshold of p<0.001, uncorrected at the voxel level. RESULTS: A significant difference in accuracy and reaction time based on task type was found. Subjects had significantly lower accuracy in VPRT compared to TT. Accuracy in the two active tasks was not significantly different. Subjects took significantly longer in the VPRT in comparison to TT. Reaction time in the two active tasks was not significantly different. Functional MRI revealed significantly higher activation in the bilateral visual cortex and left temporoparietal junction (TPJ) in VPRT compared to OLMT. CONCLUSION: The results underscore the importance of TPJ in egocentric manipulation in healthy controls in the context of reality-based spatial tasks.


Subject(s)
Healthy Volunteers , Magnetic Resonance Imaging , Memory , Oxygen , Pilot Projects , Reaction Time , Task Performance and Analysis , Visual Cortex
15.
Rev. bras. enferm ; 68(2): 244-252, Mar-Apr/2015. tab
Article in Portuguese | LILACS, BDENF | ID: lil-752512

ABSTRACT

RESUMO Objetivo: estudo descritivo, exploratório, de corte transversal, cujo objetivo foi identificar a vulnerabilidade de famílias de idosos assistidos pela Estratégia Saúde da Família (ESF). Método: foi desenvolvido por meio de entrevistas domiciliárias realizadas com uma amostra de 500 famílias de idosos assistidas por 32 equipes da ESF da cidade de Dourados, MS. O Índice de Desenvolvimento da Família (IDF) foi adaptado para classificá-las em função da situação de vulnerabilidade. Resultados: os resultados revelaram a presença de famílias multigeracionais, com baixa escolaridade entre os indivíduos com idade superior a 20 anos e alta taxa de analfabetismo entre os idosos. Identificaram-se 403 famílias em situação de vulnerabilidade aceitável, 95 em vulnerabilidade grave e duas famílias em situação de vulnerabilidade muito grave. As dimensões mais críticas do IDF foram os acessos ao conhecimento e ao trabalho. Conclusão: conclui-se que há necessidade de mais investimentos no cuidado a esses idosos e suas famílias na Atenção Básica. .


RESUMEN Objetivo: estudio descriptivo, exploratorio, transversal, con el objetivo de identificar la vulnerabilidad de familias adultos mayores asistidas por la Estrategia Salud de la Familia (ESF). Método: fue desarrollado mediante entrevistas a una muestra de 500 familias de adultos mayores bajo la responsabilidad de 32 equipos de ESF en la ciudad de Dourados, MS, Brasil. El Índice de Desarrollo de la Familia (IDF) fue adaptado para clasificar las familias de acuerdo a la situación de vulnerabilidad. Resultados: los resultados revelaron la presencia de familias multigeneracionales con bajo nivel de educación entre las personas mayores de 20 años y las altas tasas de analfabetismo entre los adultos mayores. Se identificaron 403 familias en situación de vulnerabilidad aceptable, 95 con vulnerabilidad grave y dos familias en situación de vulnerabilidad muy grave. Las dimensiones más críticas en el IDF fueron el acceso al conocimiento y al trabajo. Conclusión: se concluye que existe la necesidad de una mayor inversión, con un enfoque en la atención primaria, con el fin de atender a las personas mayores y sus familias. .


ABSTRACT Objective: the present descriptive, exploratory, cross-sectional study aimed to identify the vulnerability of families of elderly citizens cared for by the Family Health Strategy (FHS). Method: the research employed home interviews and was developed with a sample of 500 families of aged people cared for by 32 FHS teams in the city of Dourados, MS, Brazil. The Family Development Index (FDI) was adapted in order to classify the families according to their degree of vulnerability. Results: the results revealed the presence of multigenerational families with low educational levels among individuals over the age of 20 and high illiteracy rates among elderly citizens. There were 403 families whose vulnerability was acceptable, 95 in severe vulnerability, and two families in a condition of very severe vulnerability. The most critical dimensions of the FDI were the access to knowledge and to work. Conclusion: the study identifi ed that there is still a need for further investments that can assist these aged people and their families in the Primary Health Care. .


Subject(s)
Animals , Male , Contrast Sensitivity/physiology , Form Perception/physiology , Macaca mulatta/physiology , Visual Cortex/physiology , Visual Perception/physiology , Brain Mapping , Cues , Lighting , Neurons/cytology , Neurons/physiology , Optical Imaging , Photic Stimulation , Visual Cortex/anatomy & histology
16.
Cad. saúde pública ; 31(3): 531-542, 03/2015. tab
Article in Portuguese | LILACS | ID: lil-744834

ABSTRACT

Foram avaliados as concentrações séricas de vitaminas A e D e os fatores associados em crianças beneficiárias de programa de distribuição de leite fortificado, sendo utilizados modelos de regressão linear múltiplos com seleção hierárquica de variáveis independentes (condição sociodemográfica, de saúde, alimentação, amamentação, consumo do leite fortificado, exposição solar, antropometria, retinol e calcidiol séricos). Foram consideradas insuficiência e deficiência de vitamina A e de vitamina D as concentrações séricas < 1,05µmol/L, 0,70µmo/L, 30ng/mL e 20ng/mL, respectivamente. Houve inadequação do consumo alimentar de vitaminas A e D. As prevalências de insuficiência e deficiência de vitamina A e de vitamina D foram 19%, 6%, 82% e 58%, respectivamente. Os fatores associados às menores concentrações séricas de vitamina A foram: amamentação materna exclusiva < 120 dias, ausência de trabalho materno combinada com menor escolaridade materna, maior número de pessoas que consomem leite fortificado no domicílio e menor vitamina D sérica. Para a vitamina D, foram: menor exposição ao sol e menor vitamina A sérica. Ações de educação nutricional são necessárias para melhorar a situação nutricional dessas crianças.


Vitamin A and D serum concentrations and risk factors for their deficiencies were investigated in children participating in a government-sponsored fortified milk program. The study used multivariate linear regression analysis with hierarchical selection of independent variables: socio-demographic conditions, children's health, food consumption, breastfeeding, fortified milk, exposure to sunlight, anthropometric measurements, and serum concentration of retinol and 25(OH)D. Vitamin A and vitamin D insufficiency and deficiency values were defined as < 1.05µmol/L, < 0.7µmol/L, < 30ng/mL, and < 20ng/mL, respectively. Vitamin A and D intake was inadequate. Prevalence rates for vitamin A and vitamin D insufficiency and deficiency were 19%, 6%, 82%, and 58%, respectively. Factors associated with low serum vitamin A were exclusive breastfeeding for less than 120 days, low maternal schooling, maternal unemployment, more consumers of fortified milk in the family, and low serum vitamin D. Factors associated with vitamin D deficiency were low exposure to sunlight and low serum vitamin A. Nutritional education is needed to improve children's nutritional status.


Se evaluaron las concentraciones séricas de vitaminas A y D y factores asociados en niños que se benefician del programa de distribución de leche fortificada. Se utilizaron múltiples modelos de regresión lineal, con una selección jerárquica de las variables independientes (estatus sociodemográfico, salud, alimentación, lactancia materna, consumo de leche fortificada, exposición al sol, medidas antropométricas, retinol y calcidiol séricos). Para la insuficiencia y deficiencia de vitamina A y vitamina D, se adoptaron concentraciones séricas < 1,05µmol/L, < 0,70µmol/L, < 30ng/mL, < 20ng/mL, respectivamente. La inadecuación del consumo de alimentos para vitamina A y vitamina D fue de un 40% y 100%, respectivamente. La prevalencia de insuficiencia y la deficiencia de vitamina A y vitamina D fue de un 19%, 6%, 82% y 58%, respectivamente. Los factores asociados más pequeños de vitamina A sérica fueron: lactancia exclusiva < 120 días, ausencia de empleo de la madre, combinada con una baja educación materna y menor vitamina D sérica. Para la vitamina D fueron: menor exposición al sol y menor vitamina A sérica. Las acciones de educación nutricional son necesarias para mejorar la situación nutricional de estos niños.


Subject(s)
Humans , Attention/physiology , Visual Cortex/physiology , Brain Mapping/methods , Field Dependence-Independence , Magnetic Resonance Imaging/methods , Neurons/physiology , Psychophysics , Photic Stimulation/methods
17.
Article in English | WPRIM | ID: wpr-728004

ABSTRACT

Serotonin [5-hydroxytryptamine (5-HT)] regulates synaptic plasticity in the visual cortex. Although the effects of 5-HT on plasticity showed huge diversity depending on the ages of animals and species, it has been unclear how 5-HT can show such diverse effects. In the rat visual cortex, 5-HT suppressed long-term potentiation (LTP) at 5 weeks but enhanced LTP at 8 weeks. We speculated that this difference may originate from differential regulation of neurotransmission by 5-HT between the age groups. Thus, we investigated the effects of 5-HT on apha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-, gamma-aminobutyric acid receptor type A (GABA(A)R)-, and N-methyl-D-aspartic acid receptor (NMDAR)-mediated neurotransmissions and their involvement in the differential regulation of plasticity between 5 and 8 weeks. AMPAR-mediated currents were not affected by 5-HT at both 5 and 8 weeks. GABA(A)R-mediated currents were enhanced by 5-HT at both age groups. However, 5-HT enhanced NMDAR-mediated currents only at 8 weeks. The enhancement of NMDAR-mediated currents appeared to be mediated by the enhanced function of GluN2B subunit-containing NMDAR. The enhanced GABA(A)R- and NMDAR-mediated neurotransmissions were responsible for the suppression of LTP at 5 weeks and the facilitation of LTP at 8 weeks, respectively. These results indicate that the effects of 5-HT on neurotransmission change with development, and the changes may underlie the differential regulation of synaptic plasticity between different age groups. Thus, the developmental changes in 5-HT function should be carefully considered while investigating the 5-HT-mediated metaplastic control of the cortical network.


Subject(s)
Animals , Critical Period, Psychological , Humans , Long-Term Potentiation , N-Methylaspartate , Plastics , Rats , Receptors, AMPA , Receptors, GABA , Receptors, GABA-A , Serotonin , Synaptic Transmission , Visual Cortex
18.
Article in English | WPRIM | ID: wpr-99843

ABSTRACT

Previous fMRI studies of sensorimotor activation in schizophrenia have found in some cases hypoactivity, no difference, or hyperactivity when comparing patients with controls; similar disagreement exists in studies of motor laterality. In this multi-site fMRI study of a sensorimotor task in individuals with chronic schizophrenia and matched healthy controls, subjects responded with a right-handed finger press to an irregularly flashing visual checker board. The analysis includes eighty-five subjects with schizophrenia diagnosed according to the DSM-IV criteria and eighty-six healthy volunteer subjects. Voxel-wise statistical parametric maps were generated for each subject and analyzed for group differences; the percent Blood Oxygenation Level Dependent (BOLD) signal changes were also calculated over predefined anatomical regions of the primary sensory, motor, and visual cortex. Both healthy controls and subjects with schizophrenia showed strongly lateralized activation in the precentral gyrus, inferior frontal gyrus, and inferior parietal lobule, and strong activations in the visual cortex. There were no significant differences between subjects with schizophrenia and controls in this multi-site fMRI study. Furthermore, there was no significant difference in laterality found between healthy controls and schizophrenic subjects. This study can serve as a baseline measurement of schizophrenic dysfunction in other cognitive processes.


Subject(s)
Adult , Aged , Brain Mapping , Case-Control Studies , Female , Healthy Volunteers , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Motor Cortex/anatomy & histology , Schizophrenia/diagnosis , Visual Cortex/anatomy & histology , Young Adult
19.
Int. j. morphol ; 32(4): 1144-1151, Dec. 2014. ilus
Article in English | LILACS | ID: lil-734650

ABSTRACT

Monocular deprivation results in anatomical changes in the visual cortex in favor of the non-deprived eye. Although the retina forms part of the visual pathway, there is scarcity of data on the effect of monocular deprivation on its structure. The objective of this study was to describe the effects of monocular deprivation on the retinal ganglion cell dendritic features. The study design was quasi-experimental. 30 rabbits (18 experimental, 12 controls) were examined. Monocular deprivation was achieved through unilateral lid suture in the experimental animals. The rabbits were observed for three weeks. Each week, 6 experimental and 3 control animals were euthanized, their retina harvested and processed for light microscopy. Photomicrographs of the retina were taken using a digital camera then entered into FIJI software for analysis. The number of primary branches, terminal branches and dendritic field area among the non-deprived eyes increased by 66.7%(p=0.385), 400%(p=0.002), and 88.4%(p=0.523) respectively. Non-deprived eyes had 114.3% more terminal dendrites (p=0.002) compared to controls. Among deprived eyes, all variables measured had a gradual rise in the first two weeks followed by decline with further deprivation. There were no statistically significant differences noted between the deprived and control eyes. Monocular deprivation results in increase in synaptic contacts in the non-deprived eye, with reciprocal changes occurring in the deprived eye.


La privación monocular de la visión resulta en cambios anatómicos en la corteza visual en favor del ojo no privado. Aunque la retina forma parte de la vía visual, hay escasez de datos sobre el efecto de la privación monocular en su estructura. El objetivo de esta investigación fue describir los efectos de la privación monocular en las características de las dendritas de las células ganglionares de la retina. Se diseñó un estudio cuasi-experimental. Se examinaron 30 conejos (18 experimentales, 12 controles). La privación monocular se logró a través de la sutura unilateral del párpado en los animales de experimentación. Los conejos fueron observados durante tres semanas. Cada semana, 6 animales experimentales y 3 control fueron eutanasiados, donde se obtuvo la retina y fue procesada para realizar microscopía óptica. Las microfotografías de la retina fueron tomadas con una cámara digital y luego se utilizó el software FIJI para su análisis. El número de dendritas primarias, terminales y el área del campo de dendritas en los ojos no privados aumentó un 66,7% (p=0,385), 400% (p=0,002), y 88,4% (p=0,523), respectivamente. Los ojos no privados, tenían 114,3% más dendritas terminales (p=0,002) en comparación con los controles. Entre los ojos privados, todas las variables medidas tuvieron un aumento gradual en las dos primeras semanas, seguido de descenso con mayor privación. No se observaron diferencias estadísticamente significativas entre los ojos privados y el grupo control. En conclusion, la privación monocular produce un aumento de los contactos sinápticos en los ojos no privados, con cambios recíprocos que se manifiestan en los ojos privados de la visión.


Subject(s)
Animals , Rabbits , Retina/cytology , Retinal Ganglion Cells/cytology , Vision, Monocular , Dendrites/ultrastructure , Sensory Deprivation , Visual Cortex/cytology
20.
Arq. bras. oftalmol ; 77(5): 275-279, Sep-Oct/2014. tab, graf
Article in English | LILACS | ID: lil-730373

ABSTRACT

The practical advantages of quantifying an angle by a ratio of linear lengths instead of arcs of circles has led to the definition of the prism-diopter, a conventional unity for numbering prisms and measuring strabismic deviations. However, a major inconvenience of using prism-diopter unities to express angular measurements is the non-linearity of the scale, which reaches an infinite value for the angle of 90º, then becomes negative, with decreasing magnitudes for increasing angles between 90º and 180º. As a consequence, arithmetical operations and comparisons of angles measured by such unities present errors of very great magnitudes. In order to retain the advantages of defining an angle by straight line dimensions but to diminish the severe inconveniences of this method, a new definition of the prism-diopter is proposed. Here, instead of defining the prism-diopter by the asymmetrical condition, the conception of this new unity is based on a geometrically symmetrical condition; that of the relationship of an isosceles triangle (where the leg is perpendicular to the bisector of the angle and the bisector itself ). The condition of symmetry for the definition of the new unity represents a conceptual advance because it reproduces the already well accepted, conventional criteria for quantifying the value of a prism, that of its minimum deviation. Furthermore, it corresponds to the most commonly observed clinical conditions of binocular balance. The absolute differences between the unitary values of the prism-diopter and that of the new unity are negligible (0.0025%), but the scale of values expressed by the new unity is closer to the ideal scale of angular measurements. (With the new unity, the infinite value is only reached for an angle of 180º and the errors due to arithmetical operations are much smaller.) Numerical examples showing the advantages of using the new unity of angular measurements instead of the prism-diopter are presented. A mathematical generalization of the modifying concept (partition of an angle) with which the new unity is based is also provided.


As vantagens práticas de quantificação de um ângulo pela relação de comprimentos lineares em lugar dos de arcos de círculos propiciaram a definição da dioptria- prismática, uma unidade convencional de numeração dos prismas e de medições do estrabismo. Entretanto, um grande inconveniente do uso das dioptrias- -prismáticas para exprimir medidas angulares é a não-linearidade da escala, que alcança um valor infinito para o ângulo de 90º e passa a valores negativos e com magnitudes decrescentes para ângulos crescentes entre 90º e 180º. Como consequência, operações aritméticas e comparações de ângulos com medidas angulares expressas com tais unidades apresentam erros de magnitude muito grande. Para manutenção das vantagens de definição de um ângulo pela dimensão de distâncias retas, mas reduzindo os graves inconvenientes dessa escolha, propõe-se uma nova definição para a dioptria-prismática. Ao invés da condição assimétrica pela qual a dioptria-prismática é definida, a concepção dessa nova unidade é baseada em uma condição geometricamente simétrica, a das relações de um triângulo isósceles (o cateto perpendicular à bissetriz do ângulo e essa própria bissetriz). Essa condição de simetria para a definição da nova unidade corresponde a um avanço conceitual, por reproduzir o critério convencional, já bem aceito, de quantificação do valor do prisma, o de seu desvio mínimo, além de corresponder às condições clínicas de exame do equilíbrio binocular comumente usadas. A diferença absoluta entre os valores unitários da dioptria-prismática e o da nova unidade é negligenciável (0,0025%) mas a escala dos valores expressos pela nova unidade é mais próxima da escala ideal de medidas angulares. (Com a nova unidade, o valor infinito é apenas alcançado para um ângulo de 180º e os erros devidos às operações aritméticas são muito menores.) Dão-se exemplos numéricos mostrando as vantagens de uso da nova unidade de medidas angulares em lugar da dioptria-prismática. Apresenta-se, também, uma generalização matemática do conceito de modificação (partição de um ângulo) pelo qual a nova unidade é baseada.


Subject(s)
Visual Cortex , Weights and Measures , Strabismus , Convergence, Ocular
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