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Chronic pain is one of the most common symptoms of temporomandibular disorders (TMD). Although its pathophysiology is still a challenge, TMD has been associated with changes in central nervous system activity related to pain modulatory capacity. This study was conducted to examine the cortical activity of patients with temporomandibular disorders and chronic pain of myofascial origin using quantitative electroencephalography (qEEG). Individuals with TMD and chronic pain and healthy controls were evaluated using qEEG in four consecutive conditions, all with closed eyes: 1) initial resting condition; 2) non-painful motor imagery task of hand movement; 3) painful motor imagery task of clenching the teeth; 4) final resting condition. Participants with TMD and chronic pain overall presented decreased alpha power density during baseline at rest, and non-painful and painful motor imagery tasks when compared to healthy controls. Furthermore, functional brain connectivity was distinct between groups, with TMD and chronic pain showing lower small-world values for the delta (all conditions), theta (eyes closed, painful and non-painful motor imagery task), and alpha bands (painful motor imagery task), and an increase in the beta band (all conditions). These results suggest that TMD and related chronic pain is associated with maladaptive plasticity in the brain, which may correspond to a reduced ability to modify brain activity during different mental tasks, including painful and non-painful imagery. These changes can be detected by qEEG, a method which may be very important because of its characteristics of good temporal resolution and the possibility to be performed in naturalistic setups.

Introduction: There is evidence that electroacupuncture (EA) acts through the modulation of brain activity, but little is known about its influence on corticospinal excitability of the primary motor cortex (M1). Objective: To investigate the influence of EA parameters on the excitability of M1 in healthy individuals. Methods: A parallel, double blind, randomized controlled trial in healthy subjects, evaluating the influence of an EA intervention on M1 excitability. Participants had a needle inserted at LI4 in the dominant hand and received electrical stimulation of different frequencies (10 or 100 Hz) and amplitude (sensory or motor threshold) for 20 min. In the control group, only a brief (30 s) electrical stimulation was applied. Single and paired pulse transcranial magnetic stimulation coupled with electromyography was applied before and immediately after the EA intervention. Resting motor threshold, motor evoked potential, short intracortical inhibition and intracortical facilitation were measured. Results: EA increased corticospinal excitability of M1 compared to the control group only when administered with a frequency of 100 Hz at the sensory threshold ( p Conclusion: The results suggest that EA with an intensity level at the sensorial threshold and 100 Hz frequency increases the corticospinal excitability of M1. This effect may be associated with a decrease in the activity of inhibitory intracortical mechanisms. Trial registration number: U1111-1173-1946 (Registro Brasileiro de Ensaios Clínicos; http://www.ensaiosclinicos.gov.br/ )

Sentence-comprehension deficits have been described in patients with primary progressive aphasia (PPA). However, most instruments to address this domain in more detail and in a clinical context have not been adapted and translated into several languages, posing limitations to clinical practice and cross-language research.ObjectivesThe study aimed to (1) test the applicability of the Brazilian version of the Test for Reception of Grammar (TROG2-Br) to detect morphosyntactic deficits in patients with PPA; (2) investigate the association between performance in the test and sociodemographic and clinical variables (age, years of formal education, and disease duration); (3) characterize the performance of individuals presenting with the three more common variants of PPA (non-fluent, semantic, and logopenic) and mixed PPA (PPA-Mx) and analyze whether TROG-2 may assist in the distinction of these clinical profiles.MethodsA total of 74 cognitively healthy participants and 34 individuals diagnosed with PPA were assessed with TROG2-Br. Overall scores (correct items, passed blocks), types, and categories of errors were analyzed.ResultsIn controls, block scores were significantly correlated with years of formal education (Spearman's r = 0.33, p = 004) but not with age. In PPA, age, education, and disease duration were not significantly associated with performance in the test. Controls presented a significantly higher performance on TROG2-Br compared to PPA individuals and their errors pattern pointed to mild general cognitive processing difficulties (attention, working memory). PPA error types pointed to processing and morphosyntactic deficits in nonfluent or agrammatic PPA, (PPA-NF/A), logopenic PPA (PPA-L), and PPA-Mx. The semantic PPA (PPA-S) subgroup was qualitatively more similar to controls (processing difficulties and lower percentage of morphosyntactic errors). TROG2-Br presented good internal consistency and concurrent validity.DiscussionOur results corroborate findings with TROG-2 in other populations. The performance of typical older adults with heterogeneous levels of education is discussed along with recommendations for clinical use of the test and future directions of research.

On the basis of experimental data, long-range time representation has been proposed to follow a highly compressed power function, which has been hypothesized to explain the time inconsistency found in financial discount rate preferences. The aim of this study was to evaluate how well linear and power function models explain empirical data from individual participants tested in different procedural settings. The line paradigm was used in five different procedural variations with 35 adult participants. Data aggregated over the participants showed that fitted linear functions explained more than 98% of the variance in all procedures. A linear regression fit also outperformed a power model fit for the aggregated data. An individual-participant-based analysis showed better fits of a linear model to the data of 14 participants; better fits of a power function with an exponent β > 1 to the data of 12 participants; and better fits of a power function with β < 1 to the data of the remaining nine participants. Of the 35 volunteers, the null hypothesis β = 1 was rejected for 20. The dispersion of the individual β values was approximated well by a normal distribution. These results suggest that, on average, humans perceive long-range time intervals not in a highly compressed, biased manner, but rather in a linear pattern. However, individuals differ considerably in their subjective time scales. This contribution sheds new light on the average and individual psychophysical functions of long-range time representation, and suggests that any attribution of deviation from exponential discount rates in intertemporal choice to the compressed nature of subjective time must entail the characterization of subjective time on an individual-participant basis.

Foraging behavior in termites varies with the feeding habits of each species but often occurs through the formation of well-defined trails that connect the nest to food sources in species that build structured nests. We studied the formation of foraging trails and the change in caste ratio during foraging in the termite Velocitermes heteropterus. This species is widespread in Cerrado vegetation where it builds epigeal nests and forages in open-air at night. Our aim was to understand the processes involved in the formation of foraging trails, from the exploration of new unmarked areas to the recruitment of individuals to food and the stabilization of traffic on the trails, as well as the participation of the different castes during these processes. Foraging trails were videotaped in the laboratory and the videos were then analyzed both manually and automatically to assess the flow of individuals and the caste ratio on the trails as well as to examine the spatial organization of traffic over time. Foraging trails were composed of minor workers, major workers, and soldiers. The flow of individuals on the trails gradually increased from the beginning of the exploration of new areas up to the discovery of the food. The caste ratio remained constant throughout the foraging excursion: major workers, minor workers and soldiers forage in a ratio of 8:1:1, respectively. The speed of individuals was significantly different among castes, with major workers and soldiers being significantly faster than minor workers. Overall, our results show that foraging excursions in V. heteropterus may be divided in three different phases, characterized by individual speeds, differential flows and lane segregation.

Rastreamento simultâneo de muitos objetos e necessario nos casos de investigacao do comportamento de organismos vivos, principalmente insetos [1]. Os metodos atuais apresentam dificuldades em registrar com precisao este tipo de comportamento e/ou sao de alto custo monetario[2-4]. O objetivo deste trabalho foi o de desenvolver um algoritmo e uma ferramenta computacional capaz de registrar com precisao o movimento simultâneo de dezenas de insetos. Foi desenvolvido um novo metodo a partir da combinacao de tecnicas de estimacao de fundo e iluminacao, operacoes de morfologia matematica e rastreamento usando criterio de minimizacao da distância global. No inicio e estimado o fundo estatico por meio da criacao de um modelo da iluminacao do ambiente com o uso de calculo da entropia local. O fundo estimado e subtraido do valor de luminância de todos os quadros do video. Apos uma limiarizacao das imagens, e aplicada uma serie de operacoes morfologicas com o objetivo de segmentar somente os insetos, e sao registrados os componentes conectados que representam os insetos. A posicao de cada elemento e registrada e a cada um determinado intervalo de tempo, a criterio do usuario, e calculada a trajetoria dos insetos. O algoritmo de rastreamento escolhe a configuracao que minimiza a distância global, ou seja, a soma de todas as trajetorias. O sistema proposto foi testado em setup de experimentos realizados no campo da biologia comportamental de insetos, especificamente, cupins. Foram utilizados videos de cupins em condicoes experimentais de iluminacao infravermelha. O movimento dos cupins registrado pelo sistema e diversos parâmetros foram calculados, entre numero total, numero de cupins entrando e saindo da arena, velocidade, tempo na arena, distância percorrida e tamanho dos cupins. A Figura 1 apresenta algumas destas medidas: (1a) o numero de cupins que entraram ou sairam da arena ao longo do tempo; (1b) a velocidade media dos cupins em a cada trecho de 10 segundos dos videos. Em ambas figuras sao apresentados resultados para dois videos em situacoes comportamentais diferentes, inicio e meio do experimento comportamental. Os resultados foram satisfatorios, correspondendo aos valores esperados e apresentando o nivel de precisao necessario para a area. Foi desenvolvida ainda uma intuitiva interface grafica para usuarios a fim de facilitar a operacao de usuarios nao especializados na area em computacao, com controle sobre diversos parâmetros da execucao (Fig. 2). Os resultados como um todo sugerem que o novo sistema auxiliara pesquisadores no registro de comportamento animal e resultara em uma grande economia em tempo de registro manual [...]

We present a face verification system inspired by known properties of the human visual system. In the proposed algorithm the face is normalized for geometry and luminance, and Fourier‐Bessel (FB) descriptors are extracted from three locations in the eyes region (local analysis). The resulting representations are embedded in a dissimilarity space, where each image is represented by its distance to all the other images, and a Pseudo-Fisher discriminator is built. Using the FERET database, we submitted the system to a battery of tests under a wide variation of imaging conditions, including expression, age, and illumination variations. Results showed that the system outperformed previous state-of-the-art methods in most testing conditions. To deal with partial occlusions, we implemented an occluded region detector that resulted in low performance loss under up to 50% occlusion level. Finally, we automated the registration step by implementing face and eye detection algorithms. We also showed that the local-FB analysis outperforms the global-FB version of the system and an alternative polar frequency representation. In conclusion, the intermediate-scale local analysis approach used in the proposed system resulted in state-of-the-art face verification performance and high

When contrast sensitivity functions to Cartesian and angular gratings were compared in previous studies the peak sensitivity to angular stimuli was reported to be 0.21 log units higher. In experiments carried out to repeat this result, we used the same two-alternative forced-choice paradigm, but improved experimental control and precision by increasing contrast resolution from 8 to 12 bits, increasing the screen refresh rate from 30 Hz interlaced to 85 Hz non-interlaced, linearizing the voltage-luminance relation, modulating luminance in frequencies that minimize pixel aliasing, and improving control of the subject's exposure to the stimuli. The contrast sensitivity functions to Cartesian and angular gratings were similar in form and peak sensitivity (2.4 cycles per visual degree (c/deg) and 32 c/360 degrees, respectively) to those reported in a previous study (3 c/deg and 32 c/360 degrees, respectively), but peak sensitivity to angular stimuli was 0.13 log units lower than that to Cartesian stimuli. When the experiment was repeated, this time simulating the experimental control level used in the previous study, no difference between the peak sensitivity to Cartesian and angular stimuli was found. This result agrees with most current models that assume Cartesian filtering at the first visual processing stage. The discrepancy in the results is explained in part by differences in the degree of experimental control.

Recent physiological experiments support behavioral and morphological evidence for a fourth type of cone in the turtle retina, maximally sensitive in the ultraviolet (UV). This cone type has not yet been included in the models proposed for connectivity between cones and horizontal cells. In this study, we examined the inputs of UV, S, M, and L cones to horizontal cells. We used the high-resolution Dynamic Constant Response Method to measure the spectral sensitivity of horizontal cells without background light and after adaptation to UV, blue (B), green (G), and red (R) light. We concluded the following: (1) Tetrachromatic input to a Y/B horizontal cell was identified. The spectral-sensitivity curves of the cell in three of the adaptation conditions were well represented by L-, M-, and S-cone functions. Adaptation to blue light revealed a peak at 372 nm, the same wavelength location as that determined behaviorally in the turtle. A porphyropsin template could be closely fitted to the sensitivity band in that region, strong evidence for input from a UV cone. (2) The spectral-sensitivity functions of R/G horizontal cells were well represented by the L- and M-cone functions. There was no indication of UV- or S-cone inputs into these cells. (3) The spectral sensitivities of the monophasic horizontal cells were dominated by the L cone. However, the shape of the spectral-sensitivity function depended on the background wavelength, indicating secondary M-cone input. Connectivity models of the outer retina that predict input from all cone types are supported by the finding of tetrachromatic input into Y/B horizontal cells. In contrast, we did not find tetrachromatic input to R/G and monophasic horizontal cells. Chromatic adaptation revealed the spectral-sensitivity function of the turtle UV cone peaking at 372 nm.

SUMMARY We have examined the functional architecture of the turtle Pseudemys scripta elegans retina with respect to colour processing, extending spectral stimulation into the ultraviolet, which has not been studied previously in the inner retina. We addressed two questions. (i) Is it possible to deduce the ultraviolet cone spectral sensitivity function through horizontal cell responses? (ii) Is there evidence for tetrachromatic neural mechanisms, i.e. UV/S response opponency? Using a constant response methodology we have isolated the ultraviolet cone input into the S/LM horizontal cell type and described it in fine detail. Monophasic (luminosity), biphasic L/M (red-green) and triphasic S/LM (yellow-blue) horizontal cells responded strongly to ultraviolet light. The blue-adapted spectral sensitivity function of a S/LM cell peaked in the ultraviolet and could be fitted to a porphyropsin cone template with a peak at 372nm. In the inner retina eight different combinations of spectral opponency were found in the centre of the receptive field of ganglion cells. Among amacrine cells the only types found were UVSM−L+ and its reverse. One amacrine and four ganglion cells were also opponent in the receptive field surround. UV/S opponency, seen in three different types of ganglion cell, provides a neural basis for discrimination of ultraviolet colours. In conclusion, the results strongly suggest that there is an ultraviolet channel and a neural basis for tetrachromacy in the turtle retina.

Spatial frequency (SF) components encode a portion of the affective value expressed in face images. The aim of this study was to estimate the relative weight of specific frequency spectrum bandwidth on the discrimination of anger and fear facial expressions. The general paradigm was a classification of the expression of faces morphed at varying proportions between anger and fear images in which SF adaptation and SF subtraction are expected to shift classification of facial emotion. A series of three experiments was conducted. In Experiment 1 subjects classified morphed face images that were unfiltered or filtered to remove either low (32 cycles/face) SF components. In Experiment 2 subjects were adapted to unfiltered or filtered prototypical (non-morphed) fear face images and subsequently classified morphed face images. In Experiment 3 subjects were adapted to unfiltered or filtered prototypical fear face images with the phase component randomized before classifying morphed face images. Removing mid frequency components from the target images shifted classification toward fear. The same shift was observed under adaptation condition to unfiltered and low- and middle-range filtered fear images. However, when the phase spectrum of the same adaptation stimuli was randomized, no adaptation effect was observed. These results suggest that medium SF components support the perception of fear more than anger at both low and high level of processing. They also suggest that the effect at high-level processing stage is related more to high-level featural and/or configural information than to the low-level frequency spectrum.

We investigated the color vision pattern in Cebus apella monkeys by means of electroretinogram measurements (ERG) and genetic analysis. Based on ERG we could discriminate among three types of dichromatic males. Among females, this classification is more complex and requires additional genetic analysis. We found five among 10 possible different phenotypes, two trichromats and three dichromats. We also found that Cebus present a new allele with spectral peak near 552nm, with the amino acid combination SFT at positions 180, 277 and 285 of the opsin gene, in addition to the previously described SYT, AFT and AFA alleles.

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.

Motivated by a recently proposed biologically-inspired face recognition approach, psychophysical experiments have been carried out. We measured recognition performance of polar frequency filtered face images using an 8-alternatives forced-choice method. Test stimuli were generated by converting the images from the spatial to the polar frequency domain using the Fourier-Bessel transformation (FBT), filtering of the resulting coefficients with band-pass filters, and finally taking the inverse FBT of the filtered coefficients. We also evaluated an automatic FBT-based face recognition model. Contrast sensitivity functions of the human observers peaked in the 8-11.3 radial and angular frequency range, with higher peak sensitivity in the former case. The automatic face recognition algorithm presented similar behavior. These results suggest that polar frequency components could be used by the human face processing system and that human performance can be constrained by the polar frequency information content.

Recent electrophysiological studies indicate that cells in the LGN, V1, V2, and V4 areas in monkeys are specifically sensitive to Cartesian, polar and hyperbolic stimuli. We have characterized the contrast sensitivity functions (CSF) to stimuli defined in these coordinates with the two-alternatives forced-choice paradigm. CSFs to Cartesian, concentric, and hyperbolic stimuli have had similar shapes, with peak sensitivity at approximately 3 c/deg. However, the Cartesian CSF peak sensitivity has been at least 0.1 log units higher than that to stimuli in any other coordinate system. The concentric-Bessel CSF has a low-pass shape, peaking at 1.5 c/deg or below. The radial CSF has a bell shape with maximum sensitivity at 8 c/360 degrees. Only the concentric-Bessel CSF could be explained in terms of the components of maximum amplitude of the Fourier transform. Neural models, which in previous studies predicted the responses to Cartesian and polar Glass patterns, failed to account for the full CSFs data.

We present an automatic face verification system inspired by known properties of biological systems. In the proposed algorithm the whole image is converted from the spatial to polar frequency domain by a Fourier-Bessel Transform (FBT). Using the whole image is compared to the case where only face image regions (local analysis) are considered. The resulting representations are embedded in a dissimilarity space, where each image is represented by its distance to all the other images, and a Pseudo-Fisher discriminator is built. Verification test results on the FERET database showed that the local-based algorithm outperforms the global-FBT version. The local-FBT algorithm performed as state-of-the-art methods under different testing conditions, indicating that the proposed system is highly robust for expression, age, and illumination variations. We also evaluated the performance of the proposed system under strong occlusion conditions and found that it is highly robust for up to 50% of face occlusion. Finally, we automated completely the verification system by implementing face and eye detection algorithms. Under this condition, the local approach was only slightly superior to the global approach.

To study processing of UV stimuli in the retina of the turtle, Trachemys dorbignii, we recorded intracellular responses to spectral light from 89 cells: 54 horizontal (47 monophasic, five (R/G) biphasic and two (Y/B) triphasic), 14 bipolar, 12 amacrine, and nine ganglion cells. Spectral sensitivities were measured with monochromatic flashes or with the dynamic constant response method in dark or chromatic adapted states. Stray light and second-order harmonics were also measured. (1) All cells responded to UV stimuli, although none had maximum sensitivity in the UV. (2) Most horizontal, bipolar, and amacrine cells had red-peaked spectral sensitivities. (3) Red adaptation of all monophasic horizontal cells indicated a single red input, except one that had additional peaks in the blue and UV. (4) Responses of biphasic and triphasic horizontal cells to UV light were always hyperpolarizing. Opposition between hyperpolarizing and depolarizing responses at long wavelengths indicates that UV responses were not due to the beta band of red receptors. (5) An unstained spectrally opponent bipolar cell hyperpolarized in the center to green light and antagonistically depolarized in the surround to UV, blue, and green flashes, but hyperpolarized to red. (6) All dark-adapted amacrine cells were red-peaked monophasic cells, but red adaptation broadened their spectral-sensitivity curves or displaced their peaks. An A15, an A18, and an A24 wide-field amacrine cell were stained. (7) A G15 bistratified ganglion cell is shown here for the first time to be spectrally opponent. This UVB/RG cell depolarized to UV and blue and hyperpolarized to red and green. It differs from previously reported turtle ganglion cells in being color opponent in the entire field, not only in the surround, and in showing spatial opponency.

Entre os desafios que a neuroanatomia tem enfrentado desde seu início, a identificação de características que permitam distinguir diversas categorias de células neuronais do ponto de vista morfológico tem atraído atenção de pesquisadores pertencentes a diferentes áreas, os quais tentam, caracterizar quantitativamente os neurônios. Por outro lado, considerando a bem conhecida premissa de que a forma das diversas células está diretamente relacionada com sua função. A caracterização morfológica de neurônios, portanto, permite fazer análises com a finalidade de avançar em direção ao principal objetivo da neurociência: entender o funcionamento do cérebro. Os neurônios são compostos de três partes principais: corpo celular, dendritos e axônios. Os dendritos têm forma de árvore; o conjunto de dendritos de um neurônio é comumente chamado de árvore dendrítica e, de maneira análoga às árvores possuem uma hierarquia de ramos. Este trabalho tem como objetivo construir e validar novos métodos para analisar morfologicamente conjuntos de neurônios usando suas reconstruções digitais em diferentes níveis hierárquicos. Serão considerados neurônios inteiros bem como apenas as hierarquias das árvores dendríticas, com a finalidade de identificar partes morfologicamente relevantes para a classificação de reconstruções tridimensionais neurônios. Dessa maneira, seria possível otimizar a reconstrução digital de neurônios direcionando esforços para uma reconstrução mais detalhada das regiões relevantes. O método propõe diferentes estratégias de decomposição das árvores dendríticas ao longo de suas hierarquias. Um conjunto de mais de 5.000 neurônios, correspondentes a diferentes classes e provenientes de diversas espécies serão examinados com algoritmos de classificação supervisionados. Neste processo, serão consideradas 22 medidas morfológicas calculadas sobre os neurônios, principalmente, as relacionadas às árvores dendríticas. Os resultados mostram que é possível encontrar seções das árvores dendríticas morfologicamente relevantes para a classificação dos neurônios. Este resultado é relevante pois implica a possibilidade de usar apenas partes de neurônios para a classificação morfológica, o que por sua vez, ajudaria a direcionar o processo de reconstrução digital. As partes mais relevantes à classificação são os ramos mais próximos ao corpo celular, o que do ponto de vista biológico implicaria que a variabilidade causada nos ramos mais distantes do soma, gerada por estímulos externos aos indivíduos estudados, por exemplo, poderia ser desconsiderada. Em casos de neurônios similares, o método consegue identificar as hierarquias de ramos mais relevantes para a classificação, as quais não necessariamente correspondem a ramos mais próximos do soma. Neste sentido, os resultados evidenciados abrem novas possibilidades de análise parcial de neurônios, sem comprometer o resultado quando comparado à análise global além de expor possíveis implicações biológicas. Obtiveram-se acurácias de classificação similares usando-se neurônios inteiros e apenas partes deles. Among the challenges that neuroanatomy has faced since its inception, the identification of characteristics that allow to distinguish several types of neuronal cells from the morphological point of view, has attracted attention of researchers belonging to different areas, which until today try to characterize quantitatively neurons. On the other hand, considering the premise that the form is directly related to the function of several cells, the shape of the neuron can reveal many properties about its function. The morphological characterization of neurons, therefore, allows analyzes with the purpose of achieving the main objectives of neuroscience, a better understand of how the brain works. Neurons are composed of three main parts: cell body, dendrites and axons. Dendrites are tree-shaped; the set of dendrites of a neuron is commonly called dendritic tree and, similarly to trees, they have a hierarchy of branches. This work aims to construct and validate new methods to analyze morphologically sets of neurons using their digital reconstructions at different dendritic levels. This allows considering the entire neurons and only hierarchies of the dendritic trees, in order to identify parts morphologically relevant to the classification of the neuron. In this way, it would be possible to optimize the digital reconstruction of neurons by directing efforts towards a more detailed reconstruction of the relevant regions. The method proposes different strategies for the decomposition of dendritic trees throughout their hierarchies. A set of more than 5,000 neurons corresponding to different classes and coming from several species will be examined with supervised classification algorithms. In this process, we will consider 22 morphological measures calculated on the neurons and focused mainly on the dendritic trees. The results show that it is possible to find sections of the dendritic trees morphologically relevant for the classification of neurons. The relevance lies in the possibility of using only parts of neurons for the morphological classification of cells, which in turn could help direct the digital reconstruction process. The most relevant parts to the classification are the branches closest to the cell body, which biologically would imply that the variability caused in the branches but distant from the soma, generated by stimuli external to the individuals studied for example, could be disregarded. In cases of similar neurons, the method is able to identify the hierarchies of branches most relevant to classification, which do not necessarily correspond to branches closer to the soma. In this sense, the results revealed open new possibilities of partial analysis of neurons, without compromising the result when compared to the global analysis besides exposing possible biological implications. Similar classification accuracies were obtained using whole neurons and using only parts of the neurons.

Existem evidências que jogar videogames de ação (AVG) aperfeiçoa habilidades perceptuais, atentivas e cognitivas, como por exemplo, recuperação mais rápida da atenção visual e aprimoramento das dinâmicas temporais da percepção visual. Estudos correlacionais sugerem que estes aprimoramentos temporais se aplicam também ao processamento visual de baixa ordem, contudo evidências mais contundentes são necessárias. Ademais, no campo da multimídia computacional estudos apontam que a resolução temporal na qual o videogame é apresentado na tela, correspondente a taxa de quadros por segundo (QPS), afeta o desempenho e o entretenimento de jogadores. Entretanto ainda não se sabe como aspectos técnicos dos AVG, como a taxa de QPS, influenciam nos aperfeiçoamentos cognitivos citados anteriormente. Para esclarecer tais lacunas, delineou-se um estudo para verificar se AVG jogados em diferentes QPS afetam a recuperação temporal da atenção, medidos pela tarefa de Supressão Atencional (SA), e se há alterações nos limiares da resolução temporal visual, medidas através da frequência crítica de fusão e oscilação da visão (CFF). Trinta e dois (16M, 16F) participantes não jogadores de videogame voluntariaram-se para um experimento longitudinal. Inicialmente os voluntários foram separados em quatro grupos (4M, 4F) e todos eles no primeiro dia foram submetidos a uma tarefa de mensuração de CFF na região visual central e uma tarefa de SA. No dia seguinte e depois nos sete dias conseguintes dois grupos, intitulados experimentais, realizaram um treinamento com videogames de ação, sendo que cada um dos grupos treinou em diferentes resoluções temporais, um a 15 QPS e outro a 120 QPS. Simultaneamente um terceiro grupo, treinou com um videogame controle sem elementos de ação. E o quarto grupo, controle, não teve treinamento. O total de tempo de treinamento foi de 10 horas, distribuído em 8 dias, exceto para o grupo sem treino. No dia posterior ao último dia de treinamento todos os participantes foram submetidos novamente a tarefas de SA e CFF. De modo geral o CFF aumentou para todos os participantes entre pré e pós-teste, particularmente para o grupo sem treino, não houve efeito de grupo. Desempenho no SA melhorou somente no para lag2 (212ms) para participantes que treinaram AVG na taxa de QPS mais baixa. Estes resultados sugerem que treinamento com AVG não aumenta o limiar do CFF na região visual central, se não o oposto, e que o aprimoramento temporal da atenção beneficia-se com um treinamento com AVG em baixa resolução temporal, mas não de alta taxa de QPS, ao menos nas 10 horas iniciais de treino Action video game play enhances perceptual, attentional, and cognitive skills, such as leading to faster recovery of visual attention over time and improvement of temporal dynamics of visual perception. Correlational data suggest that these temporal enhancements extend to low-level vision processes, but stronger evidence is needed. Also, in the multimedia computing field it was pointed out that video game screen frame rate affects players performance and enjoyment, but it is unclear how such technical aspects of the games play a role in cognitive augmentations. To shed more light on these issues, we tested whether action video game play and the frame rate at which they are played affects flicker detection in the central visual field and performance in attentional blink task. Thirty two (16 M, 16F) non-video game players volunteered to a longitudinal experiment. They were randomly split into four groups (4M, 4F). All of the groups performed a critical flicker-fusion frequency task (by method of limits) and attentional blink task at the first day of the experiment. Two experimental groups underwent action video-game training with different screen frame-rate caps each (15 and 120 frames per second, respectively). And one control group trained with a control game and a second control group had no training. The total amount of time in video-game training was 10 hours (75 min per day for consecutive 8 days), except for the no-training group. On the 10th day, all participants performed the flicker-detection and attentional blink tasks (post-test). Generally, critical flicker-fusion thresholds increased at the post-test for all groups, particularly for the non-training group, there were no group effect. Only marginal increased were observed in lag 2 for participant trained in low-frame-rate action video games. Our data suggest that playing video games do not increase flicker sensitivity threshold, it may actually prevent increase. And lower frame rate training produce transfer effects to Attentional Blink task, but not the higher frame rate training, at least in the first 10 hours

A visãao é o sentido humano mais complexo e importante para os processos de cognição e de interação de um indivíduo com o mundo. Neurofiisiologistas buscam identificar e compreender como funcionam os mecanismos celulares envolvidos neste processo. O sistema visual recebe os sinais de imagens captadas pelos olhos e, por meio de transformações e processamento diversos, integra esses sinais em representações de objetos internos perceptuais. O projeto Olho Virtual consegue reconstruir, em três dimensões, modelos de olhos utilizando córneas reais ou simuladas em computador, reproduzindo suas propriedades ópticas captando imagens de maneira satisfatória. Este trabalho introduz, no projeto Olho Virtual, um modelo computacional de retina baseado no modelo biológico, capaz de reproduzir as propriedades das células cones e bastonetes em suas distribuições radiais e também em suas funcionalidades em particular. Além dessa, é apresentado uma modelagem para reprodução dos campos receptivos das células ganglionares presentes na retina, gerando sinais de saída nos sistemas parvo e magno. Por fim são feitas simulações de experimentos psicofísicos com propósito de verificar a validade da modelagem proposta The vision is the human sense more complex and important in cognitive processes and the interaction of an individual with the world. Neurophysiologists seek to identify and understand how the cellular mechanisms involved in this process work. The visual system receives the image signals captured by the eyes and, through several transformations and processing, integrate those signals into internal representations of perceptual objects. The project Virtual Eye can reconstruct three-dimensional models of eye corneas using real or simulated on the computer, playing their optical properties capturing images satisfactorily. This work introduces the Virtual Eye project, a computational model of retina-based biological model, able to reproduce the properties of rod and cone cells in their radial distributions and also in its functionality in particular. Besides this, a model is presented for reproduction of the receptive fields of ganglion cells present in the retina, generating output signals in the parvo and magno systems. Finally, simulations are made with psychophysical experiments in order to verify the accuracy of the proposed model