Human detection and motion recovery based on monocular vision / Detecção humana e recuperação de movimento com base na visão monocular / Detección humana y recuperación de movimiento basada en visión monocular

ABSTRACT Objective: Provides interactive games and human animation real motion data and technical options. Therefore, how to complete the position, attitude detection, and motion recovery under monocular vision has become an important research direction. Methods: This paper improves the part-based human detection algorithm and uses the AdaBoost multi-instance learning algorithm to train the part detector. Results: The results show that obtaining blood pressure waveform based on monocular vision pulse wave is feasible and has generalization. Conclusions: The results show the feasibility and accuracy of the gait motion detection, motion recovery and analysis system for human lower limbs based on monocular vision. Level of evidence II; Therapeutic studies - investigation of treatment results.

RESUMO Objetivo: Fornece jogos interativos e dados de movimento real de animação humana e opções técnicas. Portanto, como completar a posição, detecção de atitude e recuperação de movimento sob visão monocular tornou-se uma importante direção de pesquisa. Métodos: este artigo aprimora o algoritmo de detecção humana baseado em partes e usa o algoritmo de aprendizado de múltiplas instâncias AdaBoost para treinar o detector de partes. Resultados: Os resultados mostram que o método de obtenção da forma de onda da pressão arterial com base na onda de pulso de visão monocular é viável e se pode generalizar. Conclusões: Os resultados mostram a viabilidade e precisão do sistema de detecção, recuperação e análise do movimento da marcha para membros inferiores humanos com base na visão monocular. Nível de evidência II; Estudos terapêuticos- investigação dos resultados do tratamento.

RESUMEN Objetivo: Proporciona juegos interactivos y animación humana, datos de movimiento real y opciones técnicas. Por lo tanto, cómo completar la posición, la detección de actitud y la recuperación de movimiento bajo visión monocular se ha convertido en una importante dirección de investigación. Métodos: este documento mejora el algoritmo de detección humana basado en piezas y utiliza el algoritmo de aprendizaje de instancias múltiples AdaBoost para entrenar el detector de piezas. Resultados: Los resultados muestran que el método de obtención de la forma de onda de la presión arterial basado en la onda de pulso de visión monocular es factible y se puede generalizar. Conclusiones: Los resultados muestran la viabilidad y precisión del sistema de detección, recuperación y análisis del movimiento de la marcha para miembros inferiores humanos basado en visión monocular. Nivel de evidencia II; Estudios terapéuticos- investigación de los resultados del tratamiento.

Intragroup differences and similarities in performance on rapid automatized naming tasks in children with ADHD symptoms, children with reading disabilities, and controls

Abstract Introduction Rapid automatized naming (RAN) is the ability to name, as fast as possible, symbols such as letters, digits and figures. The present study aimed to investigate intragroup performance patterns on RAN tasks in children with attention deficit hyperactivity disorder (ADHD) symptoms alone, children with reading disability (RD) alone and controls with typical development. Methods A total of 216 Brazilian children between 8 to 11 years old were selected from public schools located in two Brazilian capitals, namely Porto Alegre and Belo Horizonte, to participate in the study. Mixed 3 (participant group: ADHD symptoms, RD or control group) × 3 (type of stimulus: letters, numbers or figures) ANOVAs were performed using response time and number of errors as dependent variables. Only intragroup comparisons are described in this paper. Results The groups with ADHD symptoms and RD showed similar performance results on naming speed. There were no differences between letters and numbers within each group, but we found slower responses in figure naming compared to the other tasks for both groups. Concerning accuracy, children with ADHD symptoms showed a similar number of errors in all three tasks. These patterns were distinct from the performance of the control group. Conclusion Results suggest a shared deficit in naming speed of alphanumeric stimuli in children with ADHD symptoms and those with RD, and impairments in naming digits correctly in children with ADHD symptoms.

Elaboração de lista de homônimos do Português Brasileiro para tarefas de processamento linguístico / Creation of a list of homonyms in Brazilian Portuguese for linguistic processing tasks

RESUMO Objetivo Apresentar procedimentos e etapas de elaboração de uma lista de homônimos, de seus significados e de imagens que os representam. Método Levantaram-se, por meio de pesquisa em livros escolares e dicionários, 103 homônimos do Português Brasileiro e seus significados. Os homônimos foram selecionados por critérios: serem substantivos; não eliciar mais que dois significados; representáveis por imagens. Selecionaram-se 26 homônimos e foram encontradas 2 imagens para cada significado. Para testar o instrumento participaram 20 crianças do 4º (N=10) e 5º anos (N=10) do Ensino Fundamental de escola particular do município de São Paulo. Para identificar os significados de maior e menor ocorrência, os escolares referiram o significado de cada palavra que lhes foi apresentada oralmente. Para verificar o reconhecimento das 52 imagens (uma imagem para cada um dos dois significados do homônimo), as 20 crianças foram instruídas a nomeá-las na apresentação em PowerPoint. As porcentagens de acertos foram calculadas. Resultados Dos 26 homônimos, dois foram excluídos, pois não houve nomeação para os significados. Duas imagens pouco reconhecidas foram substituídas por outras que melhor representaram os homônimos. Conclusão A lista de homônimos resultante apresenta 24 homônimos e 48 imagens (uma para o significado de maior e outra para o de menor ocorrência). A apresentação dos itens a escolares de 4o. e 5o. anos do EF indicou adequação da lista. O material mostrou-se reconhecível e apropriado para tarefas de priming semântico ou outras de processamento linguístico com homônimos em Português Brasileiro.

ABSTRACT Purpose This paper presents procedures and steps to create a list of homonyms, their meanings and representative images. Methods One hundred and three homonyms in Brazilian Portuguese were secluded through searches in text books and dictionaries and the meanings were verified. The homonyms were analyzed and selected according pre-established criteria. Twenty-six homonyms with two meanings were selected and one image was used to represent each meaning. To test the instrument, twenty elementary school children in 4th (n = 10) and 5ht (n = 10) grades were selected from a private school in São Paulo. To identify the meanings of major and minor occurrence, the students gave their understanding of the words presented to them orally. The students were also asked to name the fifty-two images to determine the degree of recognition. Percentages of accuracy were calculated. Results Among the 26 homonyms, two were excluded because the students were unable to name them. Two images were little recognized and, therefore, replaced with others that better represented the homonyms. Conclusion A list of 24 homonyms and 48 images (one for each meaning) was developed. The results of the presentation of these items to elementary school children in the 4th and 5th grades proved the adequacy of the list. The material is seen as efficient for use in recognition tasks and can be applied in semantic priming tasks.

Contrast Visual Evoked Potentials under Pattern Stimulus in Ocular Trauma / 法医学杂志

OBJECTIVES@#To study the characteristic of contrast visual evoked potentials （CVEP） in patients with ocular trauma.@*METHODS@#Sixty patients defined as ocular trauma by forensic clinical examination in our center were selected, and split into 0.2-0.3 （Group A）, 0.3-0.5 （Group B） and ≥0.5 （Group C） according to the best corrected visual acuity. The variation characteristics of wave amplitude and latency of CVEP under 100%, 25% and 10% contrast were observed and analyzed statistically.@*RESULTS@#（1） Under the same contrast, the wave amplitude of P₁₀₀ decreased with the decrease of stimulus perspective. （2） Under the same stimulus perspective, the wave amplitude of P₁₀₀ decreased with the decrease of contrast （P<0.05）. （3） Under the contrast of 100% and 25% with the same stimulus perspective （except 100% 7' perspective stimulus）, the difference between group A and group B had no statistical significance （P>0.05）. Between group A and group C, group B and group C, the wave amplitude of P₁₀₀ gradually increased with the increase of vision （P<0.05）. Under the contrast of 10% with 15' stimulus perspective, the wave amplitude of P₁₀₀ increased with the increase of vision （P<0.05）. （4） Under the same contrast with the same stimulation perspective, the latency of P₁₀₀ wave shortened with the increase of vision, while the difference had no statistical significance （P>0.05）. Under the same stimulus perspective, the latency of P₁₀₀ wave was prolonged with the decrease of contrast （P>0.05）.@*CONCLUSIONS@#CVEP may become one of the possible methods for the evaluation of contrast visual acuity.

Differential effects of aging on spatial contrast sensitivity to linear and polar sine-wave gratings

Changes in visual function beyond high-contrast acuity are known to take place during normal aging. We determined whether sensitivity to linear sine-wave gratings and to an elementary stimulus preferentially processed in extrastriate areas could be distinctively affected by aging. We measured spatial contrast sensitivity twice for concentric polar (Bessel) and vertical linear gratings of 0.6, 2.5, 5, and 20 cycles per degree (cpd) in two age groups (20-30 and 60-70 years). All participants were free of identifiable ocular disease and had normal or corrected-to-normal visual acuity. Participants were more sensitive to Cartesian than to polar gratings in all frequencies tested, and the younger adult group was more sensitive to all stimuli tested. Significant differences between sensitivities of the two groups were found for linear (only 20 cpd; P<0.01) and polar gratings (all frequencies tested; P<0.01). The young adult group was significantly more sensitive to linear than to circular gratings in the 20 cpd frequency. The older adult group was significantly more sensitive to linear than to circular gratings in all spatial frequencies, except in the 20 cpd frequency. The results suggest that sensitivity to the two kinds of stimuli is affected differently by aging. We suggest that neural changes in the aging brain are important determinants of this difference and discuss the results according to current models of human aging.

Chromatic spatial contrast sensitivity estimated by visual evoked cortical potential and psychophysics

The purpose of the present study was to measure contrast sensitivity to equiluminant gratings using steady-state visual evoked cortical potential (ssVECP) and psychophysics. Six healthy volunteers were evaluated with ssVECPs and psychophysics. The visual stimuli were red-green or blue-yellow horizontal sinusoidal gratings, 5° × 5°, 34.3 cd/m2 mean luminance, presented at 6 Hz. Eight spatial frequencies from 0.2 to 8 cpd were used, each presented at 8 contrast levels. Contrast threshold was obtained by extrapolating second harmonic amplitude values to zero. Psychophysical contrast thresholds were measured using stimuli at 6 Hz and static presentation. Contrast sensitivity was calculated as the inverse function of the pooled cone contrast threshold. ssVECP and both psychophysical contrast sensitivity functions (CSFs) were low-pass functions for red-green gratings. For electrophysiology, the highest contrast sensitivity values were found at 0.4 cpd (1.95 ± 0.15). ssVECP CSF was similar to dynamic psychophysical CSF, while static CSF had higher values ranging from 0.4 to 6 cpd (P < 0.05, ANOVA). Blue-yellow chromatic functions showed no specific tuning shape; however, at high spatial frequencies the evoked potentials showed higher contrast sensitivity than the psychophysical methods (P < 0.05, ANOVA). Evoked potentials can be used reliably to evaluate chromatic red-green CSFs in agreement with psychophysical thresholds, mainly if the same temporal properties are applied to the stimulus. For blue-yellow CSF, correlation between electrophysiology and psychophysics was poor at high spatial frequency, possibly due to a greater effect of chromatic aberration on this kind of stimulus.

Facilitatory effects of an auditory warning stimulus in a visual location identification task and a visual shape identification task

The occurrence of a weak auditory warning stimulus increases the speed of the response to a subsequent visual target stimulus that must be identified. This facilitatory effect has been attributed to the temporal expectancy automatically induced by the warning stimulus. It has not been determined whether this results from a modulation of the stimulus identification process, the response selection process or both. The present study examined these possibilities. A group of 12 young adults performed a reaction time location identification task and another group of 12 young adults performed a reaction time shape identification task. A visual target stimulus was presented 1850 to 2350 ms plus a fixed interval (50, 100, 200, 400, 800, or 1600 ms, depending on the block) after the appearance of a fixation point, on its left or right side, above or below a virtual horizontal line passing through it. In half of the trials, a weak auditory warning stimulus (S1) appeared 50, 100, 200, 400, 800, or 1600 ms (according to the block) before the target stimulus (S2). Twelve trials were run for each condition. The S1 produced a facilitatory effect for the 200, 400, 800, and 1600 ms stimulus onset asynchronies (SOA) in the case of the side stimulus-response (S-R) corresponding condition, and for the 100 and 400 ms SOA in the case of the side S-R non-corresponding condition. Since these two conditions differ mainly by their response selection requirements, it is reasonable to conclude that automatic temporal expectancy influences the response selection process.

Comparison of the reliability of multifocal visual evoked cortical potentials generated by pattern reversal and pattern pulse stimulation

This study compared the effectiveness of the multifocal visual evoked cortical potentials (mfVEP) elicited by pattern pulse stimulation with that of pattern reversal in producing reliable responses (signal-to-noise ratio >1.359). Participants were 14 healthy subjects. Visual stimulation was obtained using a 60-sector dartboard display consisting of 6 concentric rings presented in either pulse or reversal mode. Each sector, consisting of 16 checks at 99% Michelson contrast and 80 cd/m² mean luminance, was controlled by a binary m-sequence in the time domain. The signal-to-noise ratio was generally larger in the pattern reversal than in the pattern pulse mode. The number of reliable responses was similar in the central sectors for the two stimulation modes. At the periphery, pattern reversal showed a larger number of reliable responses. Pattern pulse stimuli performed similarly to pattern reversal stimuli to generate reliable waveforms in R1 and R2. The advantage of using both protocols to study mfVEP responses is their complementarity: in some patients, reliable waveforms in specific sectors may be obtained with only one of the two methods. The joint analysis of pattern reversal and pattern pulse stimuli increased the rate of reliability for central sectors by 7.14% in R1, 5.35% in R2, 4.76% in R3, 3.57% in R4, 2.97% in R5, and 1.78% in R6. From R1 to R4 the reliability to generate mfVEPs was above 70% when using both protocols. Thus, for a very high reliability and thorough examination of visual performance, it is recommended to use both stimulation protocols.

Lexical-semantic processing in the semantic priming paradigm in aphasic patients / Processamento léxico-semântico no paradigma de priming semântico em pacientes afásicos

There is evidence that the explicit lexical-semantic processing deficits which characterize aphasia may be observed in the absence of implicit semantic impairment. The aim of this article was to critically review the international literature on lexical-semantic processing in aphasia, as tested through the semantic priming paradigm. Specifically, this review focused on aphasia and lexical-semantic processing, the methodological strengths and weaknesses of the semantic paradigms used, and recent evidence from neuroimaging studies on lexical-semantic processing. Furthermore, evidence on dissociations between implicit and explicit lexical-semantic processing reported in the literature will be discussed and interpreted by referring to functional neuroimaging evidence from healthy populations. There is evidence that semantic priming effects can be found both in fluent and in non-fluent aphasias, and that these effects are related to an extensive network which includes the temporal lobe, the pre-frontal cortex, the left frontal gyrus, the left temporal gyrus and the cingulated cortex.

Há evidências de que os déficits de processamento léxico-semântico explícitos que caracterizam a afasia podem ser observados na ausência de déficits semânticos implícitos. O objetivo deste artigo foi analisar criticamente a literatura internacional sobre processamento léxico-semântico na afasia, avaliado por meio do paradigma de priming semântico. Especificamente, esta revisão teve seu foco na afasia e processamento léxico-semântico, pontos fortes e fracos da metodologia dos paradigmas léxico-semânticos usados, e evidências recentes de estudos de neuroimagem sobre o processamento léxico-semântico. Além disso, evidências de dissociações entre processamento léxico-semântico implícito e explícito relatadas na literatura serão discutidas e interpretadas, relacionando-se aos dados de neuroimagem funcional de amostras saudáveis. Há indícios de que os efeitos de priming semântico podem ser encontrados tanto em afasias fluentes como em não fluentes, e que esses efeitos são relacionados a uma extensa rede que inclui o lobo temporal, o córtex pré-frontal, o giro frontal esquerdo, o giro temporal esquerdo e o córtex cingulado.

International affective picture system (IAPS) in Chile: a cross-cultural adaptation and validation study / El sistema internacional de imágenes afectivas (International Affective Picture System-IAPS) en Chile: estudio de adaptación y validación transcultural

The International Affective Picture System (IAPS) (Lang, Ohman, & Vaitl, 1988) is a standardized set of photographs to induce emotions in the context of experimental investigations. The aim of this study was determine the psychometric behavior of the IAPS for the preparation of standards in the Chilean population and the subsequent validation of the instrument for its use in Chile. 208 university students participated (40 percent men) and had an affective experience induced using the presentation of visual stimuli extracted from sets 7 and 14 of the IAPS. In order to evaluate valence, arousal and dominance, the self-assessment manikin (SAM) was used, made up of pictographic scales for each dimension and a scale of continuous variation of emotional reactions. The IAPS showed psychometric behavior comparable to the original, with the same boomerang-shaped distribution of scores being found in the valence/arousal relationship. The IAPS is a reliable tool for inducing emotions in studies related to affectivity.

El Sistema Internacional de Imágenes Afectivas (International Affective Picture System-IAPS) (Lang, Ohman, & Vaitl, 1988) es un conjunto estandarizado de fotografías para la inducción de emociones en el contexto de investigaciones experimentales. El objetivo de este estudio fue conocer el comportamiento psicométrico del IAPS para la confección de normas en la población chilena y la validación consiguiente del instrumento para su uso en Chile. Participaron 208 estudiantes universitarios (40 por ciento hombres) a quienes se les indujo una experiencia afectiva mediante la presentación de estímulos visuales extraídos del set 1 y 14 del IAPS. Para evaluar valencia, arousal y dominancia, se utilizo el maniquí de auto-evaluación o SAM (Self - Assessment Manikin), compuesto por escalas pictográficas para cada dimensión y una escala de variación continua de reacciones emocionales. El IAPS muestran un comportamiento psicométrico comparable al original, encontrándose la dispersión de puntajes de boomerang en la relación Valencia/Arousal. El IAPS es una herramienta confiable para la inducción de emociones en estudios ligados a la afectividad.

The paradox of age: an analysis of responses by aging Brazilians to International Affective Picture System (IAPS) / Paradoxo etário: uma análise feita por idosos brasileiros sobre o International Affective Picture System(IAPS)

OBJECTIVE: To explore the possible differences in subjective analysis of the emotional stimuli from the International Affective Picture System between elderly and young samples. METHOD: 187 elderly subjects ranked the International Affective Picture System images according to the directions from the Manual of Affective Ratings. Their scores were compared to those obtained from International Affective Picture System studies with young people. RESULT: There is an age-related difference in arousal and valence in the International Affective Picture System rating. The correlation between affective valence and arousal is strong, and negative for the elderly. The expected versus the observed frequency of International Affective Picture System images between elderly and young samples show a statistical difference. CONCLUSION: This study shows an inter-age statistical dichotomy in how elderly and young people subjectively evaluate International Affective Picture System images.

OBJETIVO: Explorar as possíveis diferenças nas avaliações subjetivas dos estímulos emocionais do International Affective Picture System entre idosos e jovens. MÉTODO: 187 indivíduos idosos avaliaram as imagens do International Affective Picture System de acordo com o Manual de Aplicação do Teste. Os escores obtidos pelos idosos foram então comparados com os escores obtidos da normatização do International Affective Picture System para jovens. RESULTADOS: Há diferença nos níveis de alerta e valência afetiva entre idosos e jovens. Há uma forte e negativa correlação entre valência afetiva e nível de alerta na amostra estudada. As frequências esperadas versus observadas das imagens do International Affective Picture System entre idosos e jovens mostram diferenças estatísticas. CONCLUSÃO: Este estudo mostra uma diferença interetária na avaliação de imagens do International Affective Picture System.

Correlation of pattern reversal visual evoked potentials P100 with visual acuity / 法医学杂志

OBJECTIVE@#To explore pattern reversal visual evoked potential (PRVEP) P100 components in the patients with different visual acuity and the correlation of P100 components with visual acuity using different visual simulation angles.@*METHODS@#PRVEPs were recorded at Oz point in the patients (100 eyes) with different visual acuity including 0.2, 0.4, 0.6, 0.8 and 1.0 and induced by pattern reversal visual simulation with the different spatial frequencies(check sizes: 8 degrees-7.5'). The latency and amplitude of components P100 were analyzed and statistical analysis was performed using SPSS 13.0 software.@*RESULTS@#The latency and amplitude of P100 wave showed a curvilinear relationship with check sizes. With check size 10 simulation in 0.2 visual acuity group, the P100 latency reached to the minimum and the P100 amplitude showed peak value. Other groups displayed the best value with check size 30'. The P100 latency and amplitude showed a linear correlation with visual acuity. With the increase of visual acuity, the P100 wave latency decreased and the amplitude increased gradually. Regression models between visual acuity and the Pic wave latency and amplitude were also established.@*CONCLUSION@#The regression functions can be an objective and accurate method to evaluate the visual acuity based on the better simulation angles using PRVEP examination.

Modelos de células interativos: facilitadores na compreensão das estruturas celulares e no processo de inclusão de indivíduos com necessidades educacionais especiais visuais / Interactive cell models: facilitating the understanding of cell structures and in the process of inclusion of individuals with special educational needs visual

As políticas públicas educacionais atuais enfatizam a necessidade de práticaspedagógicas inclusivas para alunos com necessidades educacionais especiais. Entende-se por educação especial, a modalidade de educação escolar, oferecida preferencialmente na rede regular de ensino, para educandos com necessidades especiais, uma prática de política social que também chamamos de inclusão. Falar em inclusão é deparar-se com uma situação de conflito, pois ao mesmo tempo em que esses alunos têm amparo legal para freqüentar o ambiente deensino regular, enfrentam também diversas dificuldades, incluindo: a) falta depreparo dos professores, b) preconceito dos pais de crianças sem necessidades especiais, ou/e c) inobservância do cumprimento de todas as exigências que demandam o adequado atendimento dessa clientela. Com base nas dificuldades encontradas para incluir alunos com necessidades especiais, nosso projeto temcomo objetivo produzir modelos bidimensionais e tridimensional interativos relacionados ao tema Célula do tópico Biologia Celular/Citologia da área de Biologia que sejam ao mesmo tempo facilitadores e estimuladores do processo ensino-aprendizagem e que sejam inclusivos para todas as crianças, com ou sem necessidades educacionais especiais. O tema Célula apresenta complexidade contextual exigindo alto grau de abstração e com descrição nos livros didáticos que não atende, por exemplo, ao modo de aprendizagem, eminentemente tátil dos alunos com necessidades especiais visuais. A partir de um levantamento em livros didáticos, produzimos um modelo celular tridimensional e um atlas contendo organelas bidimensionais e explicações escritas e em braile. Esses materiais foram testados junto a alunos videntes e com necessidades especiais, e com professores da rede pública de ensino, sendo bem aceito pelos alunos queo consideraram muito bom e com capacidade de facilitar a compreensão do tema. De forma similar, os professores avaliaram também consideraram o material como um facilitador do processo de ensino aprendizagem, já que os aspectos visual e tátil, segundo esses profissionais, podem ajudar ao aluno a memorizar eaprender. Com base nos resultados obtidos, acreditamos que os modelos produzidos poderão atuar de forma positiva, não só no processo de inclusão dealunos com deficiência visual, como na compreensão da estrutura celular e seus componentes para todos os alunos envolvidos no processo de ensino aprendizagem.

Tipologia de erros de leitura de escolares brasileiros considerados bons leitores / Reading errors typology of Brazilian students considered good readers

BACKGROUND: assessment of oral reading. AIM: to characterize, according to the variables of public or private school and literacy, the types of errors in word reading presented by typical elementary/middle school students considered competent readers by their teachers. METHOD: participants of this study were 151 students with ages ranging between 8 and 12 years, from the 4th to the 7th grade of public and private schools. The students read a list of 38 words. The oral readings were transcribed and the errors analyzed according to their frequency. The frequency of errors was calculated based on the possibilities of errors presented by the used word list. RESULTS: the obtained results gave evidence to the errors presented by typical students of both public and private schools from all of the tested grades. There was a statistically significant progressive reduction in errors of orthographic decoding according to literacy (p<0.0001). Considering the groups, students from private schools presented fewer errors of global orthographic decoding when compared to students from public schools (p < 0.0001). CONCLUSION: the results suggest that reading errors are part of the learning process of orthographic decoding rules. These errors are progressively overcome with literacy. The domain of orthographic decoding independent of the context occurred more prematurely than that which is dependent of the grapheme context.

TEMA: avaliação da leitura oral. OBJETIVO: caracterizar, segundo as variáveis rede de ensino e escolaridade, os tipos de erro na leitura de palavras isoladas, apresentados por escolares típicos do ensino fundamental, considerados competentes por seus professores. MÉTODO: participaram da pesquisa 151 escolares com idade entre oito e doze anos, matriculados do quarto ao sétimo ano do ensino fundamental das redes pública e particular. Os escolares leram uma lista com 38 palavras. As leituras orais foram transcritas e os erros analisados, segundo a freqüência de erros cometidos calculada com base na possibilidade de erros oferecida pela lista apresentada. RESULTADOS: os resultados encontrados evidenciaram a presença de erros quando analisadas as leituras dos escolares típicos de ambas as redes de ensino e de todas as séries estudadas. Houve redução progressiva e estatisticamente significante dos erros de decodificação ortográfica em função da progressão da escolaridade (p < 0,0001). Considerando a rede de ensino, os escolares da rede particular apresentaram menor número de erros que os de escola pública quando comparado o desempenho na decodificação ortográfica global na prova de leitura de palavras (p < 0,0001). CONCLUSÃO: os resultados demonstraram que os erros de leitura fazem parte do aprendizado das regras de decodificação ortográfica e são superados, progressivamente, com o aumento da escolaridade. O domínio da decodificação da ortografia independente do contexto ocorreu mais precocemente que o da dependente do contexto grafêmico.

A novel polar-based human face recognition computational model

Motivated by a recently proposed biologically inspired face recognition approach, we investigated the relation between human behavior and a computational model based on Fourier-Bessel (FB) spatial patterns. We measured human recognition performance of FB filtered face images using an 8-alternative forced-choice method. Test stimuli were generated by converting the images from the spatial to the FB domain, filtering the resulting coefficients with a band-pass filter, and finally taking the inverse FB transformation of the filtered coefficients. The performance of the computational models was tested using a simulation of the psychophysical experiment. In the FB model, face images were first filtered by simulated V1- type neurons and later analyzed globally for their content of FB components. In general, there was a higher human contrast sensitivity to radially than to angularly filtered images, but both functions peaked at the 11.3-16 frequency interval. The FB-based model presented similar behavior with regard to peak position and relative sensitivity, but had a wider frequency band width and a narrower response range. The response pattern of two alternative models, based on local FB analysis and on raw luminance, strongly diverged from the human behavior patterns. These results suggest that human performance can be constrained by the type of information conveyed by polar patterns, and consequently that humans might use FB-like spatial patterns in face processing.

Voluntary modulations of attention in a semantic auditory-visual matching Task: an ERP study

The present study explores the neural correlates of voluntary modulations of attention in an auditory-visual matching task. Visual stimuli (a female or a male face) were preceded in close temporal proximity by auditory stimuli consisting of the Spanish word for "man" and "woman" ("hombre" or "mujer"). In 80 percent of the trials the gender of the two stimuli coincided. Participants were asked to mentally count the specific instances in which a female face appeared after hearing the word "man" (10 percent of the trials). Our results show attention-related amplitude modulation of the early visual ERP components NI and anterior P2, but also amplitude modulations of (i) the N270 potential usually associated with conflict detection, (ii) a P300 wave related to infrequency, and (iii) an N400 potential related to semantic incongruence. The elicitation of these latter components varied according to task manipulations, evidencing the role of voluntary allocation of attention in fine-tuning cognitive processing, which includes basic processes like detection of infrequency or semantic incongruity often considered to be volition-independent.

Age norms for monocular grating acuity measured by sweep-VEP in the first three years of age / Estudo normativo de acuidade visual de resolução de grades medido pelo PVE de varredura nos três primeiros anos de vida

PURPOSE: To determine age norms for grating visual acuity and interocular acuity differences measured by the sweep-visually evoked potentials (VEP) technique in the first three years of life. METHODS: Monocular grating visual acuity was measured using the sweep-VEP in 67 healthy normal infants and children in the first 36 months of life. RESULTS: Sweep-VEP grating acuity ranged from 0.80 logMAR (20/125 Snellen equivalent) in the first month of life to 0.06 logMAR (20/20 Snellen equivalent) at 36 months of age. Lower normal limits (95th percentile limit) ranged from 0.95 logMAR (20/180) to 0.12 logMAR (20/25) with a progression of approximately 3 octaves in the first 36 months of age. The largest acceptable interocular acuity difference for clinical purposes was 0.10 logMAR. CONCLUSIONS: Age norms for grating acuity along with interocular acuity differences were determined using the sweep-VEP technique. These norms should be incorporated in clinical practice for precise diagnosis of visual status in infants and preverbal children.

OBJETIVOS: Propor valores normativos de acuidade visual de grades e sua respectiva diferença interocular medidas pelo potencial visual evocado de varredura nos primeiros três anos de vida. MÉTODOS: Foram avaliadas 67 crianças sadias, sem doenças oculares, que tiveram a acuidade visual medida pelos potenciais evocados visuais de varredura. RESULTADOS: A acuidade visual média variou de 0,80 logMAR (equivalente de Snellen de 20/125) no primeiro mês de vida a 0,06 logMAR (equivalente de Snellen de 20/20) aos 36 meses. Os limites normais inferiores (percentil 95 por cento) variaram de 0,95 logMAR (20/180) a 0,12 logMAR (20/25) com progressão de aproximadamente 3 oitavas nos primeiros 36 meses de vida. A diferença interocular máxima aceitável foi de 0,10 logMAR. CONCLUSÕES: Os valores normativos de acuidade visual e de diferença interocular de acuidade foram obtidos pela técnica do potencial visual evocado de varredura. Propõe-se sua adoção na prática clínica para diagnóstico preciso do estado visual de bebês e de crianças pré-verbais.

Alterações encontradas no potencial visual evocado por padrão reverso em pacientes com esclerose múltipla definida / Pattern-reversal visual evoked potential abnormalities in patients with defined multiple sclerosis

INTRODUÇÃO: Esclerose múltipla é uma doença desmielinizante idiopática, podendo acometer o nervo óptico com perda visual unilateral aguda que pode ser observada através do potencial visual evocado (PVE), definindo tal exame como de grande validade para o estudo pré-quiasmático das vias visuais na esclerose múltipla. OBJETIVO: Analisar os achados dos potenciais visuais evocados por reversão de padrões em pacientes com diagnóstico prévio de esclerose múltipla e sua comparação com a acuidade visual. MÉTODOS: Vinte e quatro pacientes com diagnóstico definido de esclerose múltipla foram submetidos ao PVE por reversão de padrões no período de outubro de 2001 a março de 2007. RESULTADOS: Na resposta do componente P100, nos estímulos de 15' e 1º, se observou que 19 olhos apresentaram resposta de latência até 115 ms em ambas as estimulações, coincidindo também em 6 olhos que apresentaram resposta de latência entre 116 a 135 ms, em 11 olhos que apresentaram resposta de latências superiores a 135 ms, e em 4 olhos que não apresentaram respostas às estimulações. Correlacionando a acuidade visual com a latência de P100 para 15', obtemos na correlação de Pearson r= 0,85 com p= 0,000000123, e para 1º, r= 0,87 com p= 0,0000000338. CONCLUSÃO: Aproximadamente 60,4 por cento dos pacientes apresentaram anormalidades no PVE por padrões reversos. Contudo, a correlação entre a latência de P100 (15' e 1º) e a acuidade visual foi estatisticamente significativa, assim sendo, quanto melhor a acuidade visual, melhor será sua resposta aos estímulos do PVE por reversão de padrões.

INTRODUCTION: Multiple sclerosis is an idiopathic demyelinating disease that may affect the optic nerve leading to acute unilateral visual loss, which could be observed by means of evoked visual potential (VEP). This exam is much valued for studying prechiasmatic visual paths in multiple sclerosis. PURPOSE: To analyze the findings of pattern reversal VEP in patients with prior diagnosis of multiple sclerosis and to compare them to visual acuity. METHODS: Twenty-four patients with a definite diagnosis of multiple sclerosis were submitted to pattern reversal VEP from October 2001 to March 2007. RESULTS: In P100 component response, at 15' and 1º stimuli, 19 eyes presented latency response up to 115 ms in both stimuli, which coincided in 6 eyes with latency response between 116 and 135 ms; 11 eyes had a latency response higher than 135 ms, and four eyes did not respond to stimuli. Correlating visual acuity with P100 latency for 15', in Pearson r correlation, r=0.85 with p=0.000000123, and for 1º, r = 0.87 with p=0.0000000338. CONCLUSION: Approximately 60.4 percent of patients presented abnormalities. However, the correlation between the P100 latency (15' and 1º) and visual acuity was statistically significant; therefore the better the visual acuity, the better the response to stimuli of the pattern-reversal VEP.

Desempenho de adultos brasileiros normais na prova semântica: efeito da escolaridade / Performance of normal Brazilian adults in a semantic test: effect of literacy

TEMA: nas modernas visões sobre as bases neuropsicobiológicas da linguagem, aceita-se seu funcionamento em estreita relação com sistemas de suporte, como atenção e memória. A memória semântica constitui a base do conhecimento, comunicação e aprendizado. O conhecimento semântico se consolida com a exposição a informações e a possibilidade de integração dessas informações. Assim sendo, a idade e a escolaridade podem estar associadas ao conhecimento semântico. OBJETIVO: analisar a interferência do nível de escolaridade no desempenho, de adultos brasileiros normais, na prova semântica. MÉTODO: cinqüenta e seis brasileiros normais, vinte do sexo masculino, trinta e seis do feminino, com faixa etária variando entre vinte e sessenta e cinco anos, e escolaridade entre um e vinte anos, foram divididos em dois grupos, de acordo com o nível de escolaridade. O Grupo 1 (N = 31) com um a oito anos de escolaridade; e o Grupo 2 (N = 25) com escolaridade acima de oito anos. A prova semântica consistiu em apresentar questões, em relação a dez figuras, sobre categoria, traço físico, e função, e após as questões solicitar a nomeação dessas figuras. Resultados: o nível de escolaridade influenciou o desempenho dos sujeitos. Houve diferença entre os Grupos em julgamento de traços semânticos e na nomeação, onde o Grupo 2 obteve os melhores escores na maioria das provas. As questões negativas foram as que apresentaram o maior número de erros. A partir da análise qualitativa das respostas na nomeação observou-se que as figuras de seres animados foram as que mais apresentaram respostas desviantes, com maior ocorrência de substituições por itens coordenados. CONCLUSÃO: foi possível observar que o menor nível de escolaridade influenciou o desempenho negativamente, em tarefas de conhecimento semântico, em ambos julgamento de traços e nomeação, particularmente na categoria animados.

BACKGROUND: modern concepts on the neuropsychological bases of language consider that its network has a direct relation with the support systems such as attention and memory. Semantic memory constitutes the basis of knowledge, communication and learning. Semantic knowledge is consolidated with the exposure to information and the possibility to integrate information. Thus, aging and literacy can be associated to semantic knowledge. AIM: to analyze in normal Brazilian adults the interference of literacy through the performance in a semantic test. Method: 56 normal Brazilian adults, 20 males and 36 females, with ages between 20 and 56 years and literacy between 1 and 20 years. Participants were divided in two groups according to years of literacy: Group 1 (n = 31) with 1 to 8 years and Group 2 (n=25) with more than 8 years. The semantic test consisted on the presentation of questions related to 10 pictures. These questions involved: category, physical traces and function. After the questions, the naming of the pictures was requested. RESULTS: the level of literacy had an influence on the performance of the participants. There were differences between the groups regarding the judgment of the semantic traces and in the naming task: Group 2 presented better scores in most of the tasks. Negative questions presented a higher number o errors. The qualitative analyses of the answers obtained in the naming task indicate that the animated figures presented a higher number of deviant answers, with a higher occurrence of substitutions by a coordinated answer. CONCLUSION: it was possible to observe that low literacy levels had a negative influence on the performance presented in tasks involving semantic knowledge, judgment of traces and naming, particularly when involving animated pictures.

Classification methods for ongoing EEG and MEG signals

Classification algorithms help predict the qualitative properties of a subject's mental state by extracting useful information from the highly multivariate non-invasive recordings of his brain activity. In particular, applying them to Magneto-encephalography (MEG) and electro-encephalography (EEG) is a challenging and promising task with prominent practical applications to e.g. Brain Computer Interface (BCI). In this paper, we first review the principles of the major classification techniques and discuss their application to MEG and EEG data classification. Next, we investigate the behavior of classification methods using real data recorded during a MEG visuomotor experiment. In particular, we study the influence of the classification algorithm, of the quantitative functional variables used in this classifier, and of the validation method. In addition, our findings suggest that by investigating the distribution of classifier coefficients, it is possible to infer knowledge and construct functional interpretations of the underlying neural mechanisms of the performed tasks. Finally, the promising results reported here (up to 97 percent classification accuracy on 1-second time windows) reflect the considerable potential of MEG for the continuous classification of mental states.