Division of labor between M and P visual pathways: different visual pathways minimize joint entropy differently

Visual perception and action are strongly linked with parallel processing channels connecting the retina, the lateral geniculate nucleus, and the input layers of the primary visual cortex. Achromatic vision is provided by at least two of such channels formed by the M and P neurons. These cell pathways are similarly organized in primates having different lifestyles, including species that are diurnal, nocturnal, and which exhibit a variety of color vision phenotypes. We describe the M and P cell properties by 3D Gábor functions and their 3D Fourier transform. The M and P cells occupy different loci in the Gábor information diagram or Fourier Space. This separation allows the M and P pathways to transmit visual signals with distinct 6D joint entropy for space, spatial frequency, time, and temporal frequency. By combining the M and P impacts on the cortical neurons beyond V1 input layers, the cortical pathways are able to process aspects of visual stimuli with a better precision than it would be possible using the M or P pathway alone. This performance fulfils the requirements of different behavioral tasks.

Estimativa da sensibilidade ao contraste espacial de luminância e discriminação de cores por meio do potencial provocado visual transiente

O potencial provocado visual (VEP) é uma resposta cortical registrável na superfície do couro cabeludo, que reflete a atividade dos neurônios de V1. É classificado, a partir da freqüência temporal de estimulação, em transiente ou de estado estacionário. Outras propriedades do estímulo parecem provocar uma atividade seletiva dos diversos grupos de neurônios existentes em V1. Desse modo, o VEP vem sendo usado para estudar a visão humana acromática e cromática. Diversos trabalhos usaram o VEP para estimar a sensibilidade ao contraste de luminância no domínio das freqüências espaciais. Mais recentemente, há estudos que empregaram o VEP para medir os limiares de discriminação de cores. O VEP transiente pode complementar as medidas psicofísicas de sensibilidade ao contraste espacial de luminância e de discriminação cromática, e constitui um método não invasivo para estudar a visão de indivíduos com dificuldades de realizar testes psicofísicos.

Avaliação visual de sujeitos expostos de forma ocupacional a solventes orgânicos através de métodos psicofísicos

Os solventes orgânicos são substâncias neurotóxicas que podem causar efeitos danosos sobre as funções visuais. É comum a exposição ocupacional a esses tipos de substâncias, pois elas apresentam grande aplicabilidade em inúmeras atividades. Os efeitos podem ser quantificados por testes psicofísicos. Os testes mais usados nesse tipo de avaliação são de ordenamento de matizes, como o Teste D15 Dessaturado de Lanthony e o Teste dos 100 Matizes de Farnsworth-Munsell, e avaliação de sensibilidade ao contraste espacial de luminância, como MCT 8000 Vistech, VCTS 6500 Vistech e FACT 101. Em geral esses testes descrevem perda de discriminação de cores, afetando tanto o eixo azul-amarelo quanto o eixo verde-vermelho, e diminuição da sensibilidade ao contraste de luminância principalmente para as frequências espaciais mais baixas. Existe correlação positiva entre os resultados da avaliação psicofísica e vários marcadores biológicos e ambientais, mas essa correlação depende do marcador e do tipo de solvente ao qual os indivíduos são expostos. Fatores como alcoolismo crônico e tabagismo inveterado podem interferir no processo de correlacionar esses resultados.

Comparative neurophysiology of spatial luminance contrast sensitivity

The luminance contrast sensitivity function has been investigated using behavioral and electrophysiological methods in many vertebrate species. Some features are conserved across species as a shape of the function, but other features, such as the contrast sensitivity peak value, spatial frequency contrast sensitivity peak, and visual acuity have changed. Here, we review contrast sensitivity across different classes of vertebrates, with an emphasis on the frequency contrast sensitivity peak and visual acuity. We also correlate the data obtained from the literature to test the power of the association between visual acuity and the spatial frequency of the contrast sensitivity function peak.

Percepção viso-motora de escolares com Transtorno do Déficit de Atenção com Hiperatividade

PURPOSE: The aim of this study was to characterize and to compare the visual-motor perception of students with Attention Deficit with Hyperactivity Disorder (ADHD) with students with good academic performance. METHODS: Forty students from 2nd to 5th grades of an elementary public school, male gender (100%), aged between 7 and 10 years and 8 months old participated, divided into: GI (20 students with ADHD) and GII (20 students with good academic performance), paired according to age, schooling and gender with GI. The students were submitted to Developmental Test of Visual Perception (DTVP-2). RESULTS: The students of GI presented low performance in spatial position and visual closure (reduced motor) and inferior age equivalent in reduced motor perception, when compared to GII. CONCLUSION: The difficulties in visual-motor perception presented by students of GI cannot be attributed to a primary deficit, but to a secondary phenomenon of inattention that interferes directly in their visual-motor performance.

Learning strategies evaluation in students with attention deficit hyperactivity disorder

This study aim to verify the use of learning strategies in students of the elementary level presenting interdisciplinary diagnosis of attention dei cit hyperactivity disorder (ADHD). Nine students, male gender, attending 3rd to 9th grade level of the elementary level, average age 10 years and 7 months, presenting interdisciplinary diagnosis of attention dei cit hyperactivity disorder (ADHD). h e students were submitted to the application of the Evaluation of Learning Strategies from elementary level – EAVAP-EF – scale, which aimed to evaluate the strategies reported and used by students in situation of study and learning, as follows: cognitive strategies, metacognitive strategies and absence of dysfunctional metacognitive strategies. h e general result at EAVAP-EF scale, showed that students with ADHD reached the percentile 25%, considered as low performance in the use of the learning strategies. For the variable absence of dysfunctional metacognitive strategies, the students presented percentile 30%, percentile 25% for cognitive strategies and 55% for metacognitive strategies. h e results showed that ADHD students do not use ef ectively the learning cognitive and metacognitive strategies and present the use of dysfunctional metacognitive strategies. h ese alterations match with the framework of ADHD because the entry of information, either visual or auditory, showed alterations, derived from inattention, which af ected the learning in classroom situation.

Characterizing background heterogeneity in visual communication

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Visual cues and gait improvement in Parkinson's disease: which piece of information is really important?

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Beta Diversity of Plant-Pollinator Networks and the Spatial Turnover of Pairwise Interactions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The phonological and visual basis of developmental dyslexia in Brazilian Portuguese reading children

Evidence from opaque languages suggests that visual attention processing abilities in addition to phonological skills may act as cognitive underpinnings of developmental dyslexia. We explored the role of these two cognitive abilities on reading fluency in Brazilian Portuguese, a more transparent orthography than French or English. Sixty-six children with developmental dyslexia and normal Brazilian Portuguese children participated. They were administered three tasks of phonological skills (phoneme identification, phoneme, and syllable blending) and three visual tasks (a letter global report task and two non-verbal tasks of visual closure and visual constancy). Results show that Brazilian Portuguese children with developmental dyslexia are impaired not only in phonological processing but further in visual processing. The phonological and visual processing abilities significantly and independently contribute to reading fluency in the whole population. Last, different cognitively homogeneous subtypes can be identified in the Brazilian Portuguese population of children with developmental dyslexia. Two subsets of children with developmental dyslexia were identified as having a single cognitive disorder, phonological or visual; another group exhibited a double deficit and a few children showed no visual or phonological disorder. Thus the current findings extend previous data from more opaque orthographies as French and English, in showing the importance of investigating visual processing skills in addition to phonological skills in children with developmental dyslexia whatever their language orthography transparency.

Automatic visual dictionary generation through optimum-path forest clusteringautomatic visual dictionary generation through optimum-path forest clustering

Image categorization by means of bag of visual words has received increasing attention by the image processing and vision communities in the last years. In these approaches, each image is represented by invariant points of interest which are mapped to a Hilbert Space representing a visual dictionary which aims at comprising the most discriminative features in a set of images. Notwithstanding, the main problem of such approaches is to find a compact and representative dictionary. Finding such representative dictionary automatically with no user intervention is an even more difficult task. In this paper, we propose a method to automatically find such dictionary by employing a recent developed graph-based clustering algorithm called Optimum-Path Forest, which does not make any assumption about the visual dictionary's size and is more efficient and effective than the state-of-the-art techniques used for dictionary generation.

Orientação espacial em pessoas com deficiência visual: um estudo de triangulação por meio de monitoramento remoto

This study was conducted to investigate how visually impaired people perform distance estimation tasks by movement and navigation during deprivation of effective perceptual and proprioceptive information. For that they performed the task of walking three distances, being the first and second of 100 meters and the third of 140 meters (triangulation) from a point of origin in open field on a inverted L shaped trajectory and then returning to the origin. The first and second tasks were driven by means of a guide with GPS adapted to the study coordinates, and the third one was freeform with three sessions, the first without perceptual and proprioceptive restrictions, the second without auditory perception, and the third in a wheelchair, without proprioception. The objective of this study was to indicate the differences in distance reproduction in relation to accuracy and investigate the spatial representation of participants in a navigation task, in which there is active movement, but no effective perceptual and proprioceptive information. Results showed that the average participants underestimated distances producing average angles close to the value of 45°. And by means of the "t" students test no significant differences between subjects can be pointed out. To achieve these results we used remote monitoring by GPS and software TrackMaker.

Ergonomia de tablets em uso ocupacional: atividade visual e biomecânica postural sob a influência de ofuscamentos reflexivos causados pela iluminação

Pós-graduação em Design - FAAC

A contribuição do projeto de identidade corporativa na redução da poluição visual nas cidades

One of the actual biggest problems in big towns is the visual pollution. The advertising has become a necessity for any type of business, resulting in the use of as urban spaces as possible like fronts structures, lights, with too many colors and details to keep the attention of sight, thus becoming an important problem for the social and cultural coexistence. The work of graphic designer can reduce this problem through the concepts of visual identity applied on the enterprise building front, giving harmony in the colors and spaces where they can apply the advertising without to attack the urban beauty and esthetics.

The Perception of Natural, Cell Phone, and Computer-Synthesized Speech During The Performance Of Simultaneous Visual-Motor Tasks

This study investigated the influence of top-down and bottom-up information on speech perception in complex listening environments. Specifically, the effects of listening to different types of processed speech were examined on intelligibility and on simultaneous visual-motor performance. The goal was to extend the generalizability of results in speech perception to environments outside of the laboratory. The effect of bottom-up information was evaluated with natural, cell phone and synthetic speech. The effect of simultaneous tasks was evaluated with concurrent visual-motor and memory tasks. Earlier works on the perception of speech during simultaneous visual-motor tasks have shown inconsistent results (Choi, 2004; Strayer & Johnston, 2001). In the present experiments, two dual-task paradigms were constructed in order to mimic non-laboratory listening environments. In the first two experiments, an auditory word repetition task was the primary task and a visual-motor task was the secondary task. Participants were presented with different kinds of speech in a background of multi-speaker babble and were asked to repeat the last word of every sentence while doing the simultaneous tracking task. Word accuracy and visual-motor task performance were measured. Taken together, the results of Experiments 1 and 2 showed that the intelligibility of natural speech was better than synthetic speech and that synthetic speech was better perceived than cell phone speech. The visual-motor methodology was found to demonstrate independent and supplemental information and provided a better understanding of the entire speech perception process. Experiment 3 was conducted to determine whether the automaticity of the tasks (Schneider & Shiffrin, 1977) helped to explain the results of the first two experiments. It was found that cell phone speech allowed better simultaneous pursuit rotor performance only at low intelligibility levels when participants ignored the listening task. Also, simultaneous task performance improved dramatically for natural speech when intelligibility was good. Overall, it could be concluded that knowledge of intelligibility alone is insufficient to characterize processing of different speech sources. Additional measures such as attentional demands and performance of simultaneous tasks were also important in characterizing the perception of different kinds of speech in complex listening environments.