Neogenomic events challenge current models of heritability, neuronal plasticity dynamics, and machine learning.

We address current needs for neogenomics-based theoretical and computational approaches for several neuroscience research fields, from investigations of heritability properties, passing by investigations of spatiotemporal dynamics in the neuromodulatory microcircuits involved in perceptual learning and attentional shifts, to the application of genetic algorithms to create robots exhibiting ongoing emergence.

Ganglion cells and displaced amacrine cells density in the retina of the collared peccary (Pecari tajacu).

In the present study, we investigated the topographical distribution of ganglion cells and displaced amacrine cells in the retina of the collared peccary (Pecari tajacu), a diurnal neotropical mammal of the suborder Suina (Order Artiodactyla) widely distributed across central and mainly South America. Retinas were prepared and processed following the Nissl staining method. The number and distribution of retinal ganglion cells and displaced amacrine cells were determined in six flat-mounted retinas from three animals. The average density of ganglion cells was 351.822 ± 31.434 GC/mm2. The peccary shows a well-developed visual streak. The average peak density was 6,767 GC/mm2 and located within the visual range and displaced temporally as an area temporalis. Displaced amacrine cells have an average density of 300 DAC/mm2, but the density was not homogeneous along the retina, closer to the center of the retina the number of cells decreases and when approaching the periphery the density increases, in addition, amacrine cells do not form retinal specialization like ganglion cells. Outside the area temporalis, amacrine cells reach up to 80% in the ganglion cell layer. However, in the region of the area temporalis, the proportion of amacrine cells drops to 32%. Thus, three retinal specializations were found in peccary's retina by ganglion cells: visual streak, area temporalis and dorsotemporal extension. The topography of the ganglion cells layer in the retina of the peccary resembles other species of Order Artiodactyla already described and is directly related to its evolutionary history and ecology of the species.

Dengue maculopathy: visual electrophysiology and optical coherence tomography.

The objective of this study was to evaluate the visual loss due to dengue fever using retinal and cortical electrophysiology and retinal imaging. The participants were three female patients with low visual acuity after dengue fever. They were evaluated by routine ophthalmological investigations, transient pattern electroretinogram (tPERG), transient pattern visual evoked cortical potential (tPVECP), and retinal optical coherence tomography (retinal OCT). tPERG and tPVECP amplitude (microV) and implicit time (ms) were the parameters evaluated using OCT retinal thickness (microm) and reflectivity. All patients presented low visual acuity and scotomata with or without changes in the oculus fundus. tPERG from two patients showed decreased amplitude or absence of the main components; it was not possible to record a reliable response in the third patient due to excessive blinking. tPVECP at 0.5 cpd was normal in all three patients, while at 2 cpd the main components were absent in one patient and normal in the other two patients. OCT image was abnormal in two patients, one of them with high reflectance areas and another with decreased retinal thickness (the third patient was not studied with this technique).The dengue fever can lead to visual impairment detectable by ophthalmological exams such as angiography, retinography, and OCT imaging, as well as retinal and cortical electrophysiology. Dengue maculopathy which could be caused by vascular alterations and/or aberrant immune response after infection may result in temporary or permanent visual losses.

Comparison of Visual Functions of Two Amazonian Populations: Possible Consequences of Different Mercury Exposure.

The present study investigated the visual perimetry and color vision of two Amazonian populations differently exposed to mercury. Ten riverines environmentally exposed to mercury by fish eating and 34 gold-miners occupationally exposed to mercury vapor. The visual perimetry was estimated using the Förster perimeter and the color vision was evaluated using a computerized version of Farnsworth-Munsell test. Riverine and gold-miners' hair mercury concentrations were quantified. Mercury hair concentration of the riverines was significantly higher than that from gold-miners. Riverines had lower perimetric area than the gold-miners. The errors in the hue ordering test of both Amazonian populations were larger than the controls (non-exposed subjects), but there was no difference between themselves. Riverines had significant multiple association between the visual function and hair mercury concentration, while the gold-miners has no significant association with the exposure. We concluded that the different ways of mercury exposure led to similar visual outcomes, with greater impairment in riverines (organic mercury exposed subjects).

Psychophysical Evaluation of Visual Functions of Ex-Alcoholic Subjects After Prolonged Abstinence.

Chronic alcohol abuse can lead to a brain damages, and the health status of alcoholics even after a long-term alcohol abstinence is a public health concern. The present study investigated the color vision and spatial luminance contrast sensitivity of a group of 17 ex-alcoholics (46.3 ± 6.7 years old) in long-term alcohol abstinence after having been previously under alcohol dependence for many years. We also investigated the association of impaired psychophysical performance in different tests we applied. The mean time of alcohol consumption was 16.9 ± 5.1 years and the mean abstinence period was 12.4 ± 8.5 years. Achromatic vision of all subjects was evaluated using spatial luminance contrast sensitivity function (CSF) test and color vision was evaluated using Mollon-Reffin color discrimination test (MR) and the Farnsworth-Munsell 100 hue arrangement test (FM100). Relative to controls, the spatial luminance contrast sensitivity was lower in 10/17 of the ex-alcoholic subjects. In the color vision tests, 11/16 ex-alcoholic subjects had impaired results compared to controls in the FM100 test and 13/14 subjects had color vision deficits measured in the MR test. Fourteen subjects performed all visual tests, three subjects had impaired results for all tests, seven subjects had impaired results in two tests, three subjects had visual deficit in one test, and one had normal results for all tests. The results showed the existence of functional deficits in achromatic and chromatic vision of subjects with history of chronic alcoholism after long abstinence. Most subjects had altered result in more than one test, especially in the color vision tests. The present investigation suggests that the damage in visual functions produced by abusive alcohol consumption is not reversed after long term alcohol abstinence.

A proposed correction in the weighted method to score the Ishihara test.

OBJECTIVE: Ishihara test is a color vision test, whose results consider that all plates of the test have the same weighting. Rodriguez-Carmona et al. (Aviat Space Environ Med 83:19-29, 2012) proposed an equation to quantify the Ishihara test results (severity index), which took an account the rate of hits from the different plates of the test considering the performance of trichromat or colorblind population. We proposed a correction in Rodiguez-Carmona's equation for the severity index. We evaluated 60 normal trichromats and 107 subjects with congenital color deficiency. We calculated three indexes to quantify the results of each subject: a non-weighted index, a weighted index similar to the Rodriguez-Carmona et al., and a weighted index modified which combined the hit frequency for each plate in a trichromat population and of the error reading frequency for each plate in color-blind populations. RESULTS: Compared to the non-weighted evaluation, the weighted index was reduced by 22.95%, 32.92%, and 35.38% from trichromats, protan and deutan groups, respectively. Receiver Operating Characteristics (ROC) analysis showed perfect performance of the classifier for all metrics to measure the Ishihara test results. The proposal correction changed significantly the value of the index, but the overall benefits were small.

Color vision impairment with low-level methylmercury exposure of an Amazonian population - Brazil.

Land exploitation that follows deforestation and mining can result in soil erosion and the release of mercury to the waters of rivers in the Amazon Basin. Inorganic mercury is methylated by bacteria that are present in the environment and it serves as a source of human contamination through fish consumption in the form of methylmercury. Long-term exposure to low-level methylmercury in the riverside populations can lead to nervous system alterations, some of which are visual impairments such as loss of luminance contrast sensitivity, restricted visual fields and color vision defects. The present study sought to examine color vision in a group of adults living in the central Brazilian Amazon who were exposed to low-levels of methylmercury. Total Hg concentrations were measured from hair collected at the time of the testing. The D15d and FM100 color vision arrangement tests were applied in a population of 36 (22 males) and 42 (25 males), respectively. Controls were healthy volunteers from the cities of São Paulo for the D15d and Belém for the FM100. There was a statistically significant difference in performance between those who were exposed and controls for both tests (p < 0.01 and p < 0.0001, respectively, Mann-Whitney U test), meaning that adults living in this region of the Amazon made more mistakes on both tests when compared to controls. A linear regression was performed using Hg concentrations and test scores. Hg concentrations accounted for 7% and 2% of color D15d and FM100 arrangement test errors, respectively. Although other studies have previously found color vision impairment in the Amazon, they tested inhabitants on the east side of the Amazon, while this study was conducted in the central Amazon region and it is the first study in a population with no direct contact with the Hg source of contamination. These results suggest that long-term exposure to low-level methylmercury in riverside populations is more widely spread in the Amazon Basin than previously reported. This information is needed to implement public health policies that will ensure a safer environment for the Amazonian population.

[Levels of mercury found in hair and fish consumption of riverine communities in the Tapajós region of the Brazilian Amazon]. / Teores de mercúrio em cabelo e consumo de pescado de comunidades ribeirinhas na Amazônia brasileira, região do Tapajós.

Riverine communities are exposed to mercury due to the high ingestion of fish in their diet. In order to evaluate the levels of exposure in the Tapajós region, also assessing the fish ingestion frequency, a study was conducted in adults living in riverine communities in the municipality of Itaituba in the State of Pará. Hair samples were collected for the determination of total mercury and the weekly frequency data of fish ingestion was recorded. The mean concentration of total mercury varied from 7.25µg/g (in 2013) to 10.80µg/g (in 2014), with no significant difference being observed (p = 0.1436). As for fish ingestion frequency, the majority of the individuals evaluated revealed high consumption both in 2013 and in 2014. High levels of total mercury were observed only in those with high consumption of fish in both years. The importance of ongoing monitoring of exposure levels in humans should be stressed, basing itself on indices of tolerance of 6µg/g recommended by the World Health Organization, and investigation about the consumption of fish such that strategies for control and prevention are improved.

Comunidades ribeirinhas estão expostas ao mercúrio devido à dieta composta por elevada ingestão de peixes. Com o objetivo de avaliar os níveis de exposição na região do Tapajós, identificando também a frequência de ingestão de pescado, realizou-se um estudo em adultos residentes nas comunidades ribeirinhas do município de Itaituba/PA. Foram coletadas amostras de cabelo para a determinação de mercúrio total e dados de frequência semanal de ingestão de peixes. A concentração média de mercúrio total variou de 7,25µg/g (em 2013) para 10,80µg/g (em 2014), não sendo observada diferença significativa (p = 0,1436). Quanto à frequência de ingestão de pescado, a maioria dos indivíduos avaliados apresentou um alto consumo, tanto em 2013 quanto em 2014. Índices elevados de mercúrio total foram observados somente naqueles com alto consumo de pescado em ambos anos. Ressalta-se a importância da continuação do monitoramento dos níveis de exposição em humanos, fundamentando-se nos índices de tolerância de 6µg/g preconizado pela Organização Mundial de Saúde, e na investigação quanto ao consumo de peixes para que as estratégias de controle e prevenção sejam melhoradas.

Voronoi analysis uncovers relationship between mosaics of normally placed and displaced amacrine cells in the thraira retina.

Although neuronal dynamics is to a high extent a function of synapse strength, the spatial distribution of neurons is also known to play an important role, which is evidenced by the topographical organization of the main stations of the visual system: retina, lateral geniculate nucleus, and cortex. The coexisting systems of normally placed and displaced amacrine cells in the vertebrate retina provide interesting examples of retinotopic spatial organization. However, it is not clear whether these two systems are spatially interrelated or not. The current work applies two mathematical-computational methods-a new method involving Voronoi diagrams for local density quantification and a more traditional approach, the Ripley K function-in order to characterize the mosaics of normally placed and displaced amacrine cells in the retina of Hoplias malabaricus and search for possible spatial relationships between these two types of mosaics. The results obtained by the Voronoi local density analysis suggest that the two systems of amacrine cells are spatially interrelated through nearly constant local density ratios.

Heart rate variability in multibacillar leprosy: Linear and nonlinear analysis.

OBJECTIVE: To evaluate the heart rate variability (HRV) in patients with multibacillary leprosy using dynamic linear and nonlinear analysis. MATERIAL AND METHODS: Twenty-one leprosy patients (mean age: 39.14 ±10.58 years) and 21 healthy subjects (mean age: 36.24 ± 12.64 years) completed the sample. Heart rate variability recording was performed by a Polar RS800 CX heart monitor during a period of 15 min in the supine position and 15 min in a sitting position. Analysis of HRV was performed by frequency domain from high frequency (HF) and low frequency (LF) spectral indexes in absolute and normalized units. The nonlinear analysis of HRV was calculated using symbolic analysis (0V%, 1V%, 2LV% and 2UV% indexes), Shannon entropy (SE) and normalized complexity index (NCI). RESULTS: Linear analysis: both groups showed higher HF values (p < 0.05) and smaller LF values (p < 0.05) in supine than in sitting position. The leprosy patients showed higher LF values (p < 0.05) and smaller HF values (p < 0.05) compared to the controls on supine position. Symbolic analysis: leprosy patients had higher 0V% values (p < 0.05), smaller 2LV% values (p < 0.05) and 2UV % values compared to healthy subjects on both positions. The 1V % had higher values (p < 0.05) for leprosy patients than for controls in the sitting position. The control subjects had smaller 0V % values (p < 0.05), and higher 2UV % values (p < 0.05) in the supine position compared to the sitting position. Leprosy patients had higher 2UV index values (p < 0.05) in the supine position compared to the sitting position. In the complexity analysis, leprosy patients had smaller SE and NCI values (p < 0.05) than the control in the supine position. There was no difference between the SE and NCI values of leprosy and the control subjects in the sitting position. The control subjects had higher SE and NCI values (p < 0.05) in the supine position than in the sitting position. CONCLUSION: Leprosy patients had higher sympathetic modulation and smaller vagal modulation than controls, indicating less HRV and cardiac modulation with lower complexity. The control group displayed significant HRV differences in response to position changes while leprosy patients had fewer HRV differences after the same postural change. An analysis of HRV with linear and non-linear dynamics proved to be a reliable method and promising for the investigation of autonomic dysfunction in patients with multibacillary leprosy.

Evidence of Asymptomatic Visual Losses after Surgical Repair of Cerebral Aneurysm.

Deficits in visual acuity, visual field, and oculomotor function are commonly detected after repair of cerebral aneurysms. However, when these deficits are absent, it does not mean that other potential visual deficits also are absent. Here, we report three cases that after complete recover from surgical repair of cerebral aneurysms presented minimal visual acuities of about 20/20 and no visual disturbances. While two of them (Cases 1 and 2) showed visual fields with no relevant central defects, two of them showed relevant impairments in spatial contrast sensitivity (Cases 2 and 3). This evidence supports that after complete recover from surgical repair of hemorrhagic cerebral aneurysms spatial contrast sensitivity can be asymptomatically impaired when visual acuity (Cases 2 and 3) and visual fields (Case 2) are not correlated with symptoms of visual disturbances. Hypothetical explanations and consequences of such evidence are discussed.

Emotional and motor symptoms in riverside dwellers exposed to mercury in the Amazon. / Manifestações emocionais e motoras de ribeirinhos expostos ao mercúrio na Amazônia.

INTRODUCTION:: The investigation of clinical and neurological impactations associated with exposure to mercury levels in exposed populations is necessary in the Amazon. OBJECTIVE:: To analyze emotional and motor symptoms of riverside dwellers exposed by diet in the municipalities of Itaituba and Acará, in Pará, Brazil. METHODS:: Hair samples were collected to assess the total mercury (HgT). Demographic data as well as emotional (depression, anxiety and insomnia) and motor (paresthesia, muscle weakness, loss of balance when walking, tremors, limb pain and dysarthria) symptomatology data were obtained. RESULTS:: Mean levels of HgT in Itaituba were significantly higher (p < 0.0001) than in Acará. Emotional symptoms were identified in 26 (26.5%) participants from Itaituba and in 24 (52.2%) from Acará. Specific motor complaints in Itaituba occurred in 63 (64.3%) volunteers; the most frequently mentioned afflictions were limb pain (36.7%), paresthesia (32.6%) and muscle weakness (27.5%). In Acará, 33 (71.7%) participants had motor symptoms, the majority of which complained of paresthesia (54.3%), limb pain (52.2%) and tremors (34.8%). Average HgT levels in Itaituba in those with emotional and motor symptoms were above the tolerable levels (6 µg/g) determined by the World Health Organization. CONCLUSION:: Results showed that mercury levels in emotional and motor symptoms in Itaituba are higher than in riverside dwellers in Acará. Further studies, including the application of specific qualitative and/or quantitative standard tests, as well as the investigation of other clinical signs are necessary.

Psychophysical Evaluation of Congenital Colour Vision Deficiency: Discrimination between Protans and Deutans Using Mollon-Reffin's Ellipses and the Farnsworth-Munsell 100-Hue Test.

We have used the Farnsworth-Munsell 100-hue (FM 100) test and Mollon-Reffin (MR) test to evaluate the colour vision of 93 subjects, 30.4 ± 9.7 years old, who had red-green congenital colour vision deficiencies. All subjects lived in Belém (State of Pará, Brazil) and were selected by the State of Pará Traffic Department. Selection criteria comprised the absence of visual dysfunctions other than Daltonism and no history of systemic diseases that could impair the visual system performance. Results from colour vision deficient were compared with those from 127 normal trichromats, 29.3 ± 10.3 years old. For the MR test, measurements were taken around five points of the CIE 1976 colour space, along 20 directions irradiating from each point, in order to determine with high-resolution the corresponding colour discrimination ellipses (MacAdam ellipses). Three parameters were used to compare results obtained from different subjects: diameter of circle with same ellipse area, ratio between ellipse's long and short axes, and ellipse long axis angle. For the FM 100 test, the parameters were: logarithm of the total number of mistakes and positions of mistakes in the FM diagram. Data were also simultaneously analysed in two or three dimensions as well as by using multidimensional cluster analysis. For the MR test, Mollon-Reffin Ellipse #3 (u' = 0.225, v' = 0.415) discriminated more efficiently than the other four ellipses between protans and deutans once it provided larger angular difference in the colour space between protan and deutan confusion lines. The MR test was more sensitive than the FM 100 test. It separated individuals by dysfunctional groups with greater precision, provided a more sophisticated quantitative analysis, and its use is appropriate for a more refined evaluation of different phenotypes of red-green colour vision deficiencies.

Spectral Sensitivity Measured with Electroretinogram Using a Constant Response Method.

A new method is presented to determine the retinal spectral sensitivity function S(λ) using the electroretinogram (ERG). S(λ)s were assessed in three different species of myomorph rodents, Gerbils (Meriones unguiculatus), Wistar rats (Ratus norvegicus), and mice (Mus musculus). The method, called AC Constant Method, is based on a computerized automatic feedback system that adjusts light intensity to maintain a constant-response amplitude to a flickering stimulus throughout the spectrum, as it is scanned from 300 to 700 nm, and back. The results are presented as the reciprocal of the intensity at each wavelength required to maintain a constant peak to peak response amplitude. The resulting S(λ) had two peaks in all three rodent species, corresponding to ultraviolet and M cones, respectively: 359 nm and 511 nm for mice, 362 nm and 493 nm for gerbils, and 362 nm and 502 nm for rats. Results for mouse and gerbil were similar to literature reports of S(λ) functions obtained with other methods, confirming that the ERG associated to the AC Constant-Response Method was effective to obtain reliable S(λ) functions. In addition, due to its fast data collection time, the AC Constant Response Method has the advantage of keeping the eye in a constant light adapted state.

The intake of fish and the mercury concentration of fishing families at the city of Imperatriz (MA), Brazil. / A ingestão de pescado e as concentrações de mercúrio em famílias de pescadores de Imperatriz (MA).

INTRODUCTION: Significant levels of mercury exposure associated with fish intake have been demonstrated in riverine populations living in areas of mineral exploration as the basin of Tapajós and Madeira. In the Tocantins region, although few studies, there is no evidence of human exposure through food. OBJECTIVE: To assess the levels of exposure to mercury in resident fishermen families in the riverside area of the middle Tocantins and to quantify the levels in fish consumed by these families. METHODS: We conducted a cross sectional study involving families of Beira Rio community fishermen, located on the Tocantins riverbanks in the city of Imperatriz, Maranhão. Brazil. Data were collected from socio demographic and food profile, as well as samples of fish and hair, which were analyzed by atomic absorption spectrophotometry. RESULTS: The socio demographic profile of families studied was common to the local population located in other basins. The food profile did not run the default rule, with the fish being the primary dietary protein source. The species of piscivorous and zooplancton habits had the highest mercury concentrations, and the mean values were 0.2775 µg/g in fish dog and 0.1360 µg/g in mapará. Among the 25 families evaluated, the lowest average concentration of family was 0.186 ± 0.043 µg/g and the higher was 5.477 ± 2.896 µg/g. CONCLUSION: Fishing families have low mercury exposure levels in the same order of magnitude, probably because of the food consumption of fish, including piscivorous species, which were found to be below the safe upper limit for human consumption established by Brazilian standards. This serves as a reference for other studies.

Peripheral variability and central constancy in mammalian visual system evolution.

Neural systems are necessarily the adaptive products of natural selection, but a neural system, dedicated to any particular function in a complex brain, may be composed of components that covary with functionally unrelated systems, owing to constraints beyond immediate functional requirements. Some studies support a modular or mosaic organization of the brain, whereas others emphasize coordination and covariation. To contrast these views, we have analysed the retina, striate cortex (V1) and extrastriate cortex (V2, V3, MT, etc.) in 30 mammals, examining the area of the neocortex and individual neocortical areas and the relative numbers of rods and cones. Controlling for brain size and species relatedness, the sizes of visual cortical areas (striate, extrastriate) within the brains of nocturnal and diurnal mammals are not statistically different from one another. The relative sizes of all cortical areas, visual, somatosensory and auditory, are best predicted by the total size of the neocortex. In the sensory periphery, the retina is clearly specialized for niche. New data on rod and cone numbers in various New World primates confirm that rod and cone complements of the retina vary substantially between nocturnal and diurnal species. Although peripheral specializations or receptor surfaces may be highly susceptible to niche-specific selection pressures, the areal divisions of the cerebral cortex are considerably more conservative.

Somatosensory Psychophysical Losses in Inhabitants of Riverside Communities of the Tapajós River Basin, Amazon, Brazil: Exposure to Methylmercury Is Possibly Involved.

The purpose of this work was to evaluate the somatosensory system of methylmercury-exposed inhabitants living in the communities of the Tapajós river basin by using psychophysical tests and to compare with measurements performed in inhabitants of the Tocantins river basin. We studied 108 subjects from Barreiras and São Luiz do Tapajós, two communities of the Tapajós river basin, State of Pará, Amazon, Brazil, aged 13-53 years old. Mercury analysis was performed in head hair samples weighting 0.1-0.2 g by using atomic absorption spectrometry. Three somatosensory psychophysical tests were performed: tactile sensation threshold, vibration sensation duration, and two-point discrimination. Semmes-Weinstein 20 monofilaments with different diameters were used to test the tactile sensation in the lower lip, right and left breasts, right and left index fingers, and right and left hallux. The threshold was the thinner monofilament perceived by the subject. Vibration sensation was investigated using a 128 Hz diapason applied to the sternum, right and left radial sides of the wrist, and right and left outer malleoli. Two trials were performed at each place. A stopwatch recorded the vibration sensation duration. The two-point discrimination test was performed using a two-point discriminator. Head hair mercury concentration was significantly higher in mercury-exposed inhabitants of Tapajós than in non-exposed inhabitants of Tocantins (p < 0.01). When all subjects were divided in two groups independently of age-mercury-exposed and non-exposed-the following results were found: tactile sensation thresholds in mercury-exposed subjects were higher than in non-exposed subjects at all body parts, except at the left chest; vibration sensation durations were shorter in mercury-exposed than in non-exposed subjects, at all locations except in the upper sternum; two-point discrimination thresholds were higher in mercury-exposed than in non-exposed subjects at all body parts. There was a weak linear correlation between tactile sensation threshold and mercury concentration in the head hair samples. No correlation was found for the other two measurements. Mercury-exposed subjects had impaired somatosensory function compared with non-exposed control subjects. Long-term mercury exposure of riverside communities in the Tapajós river basin is a possible but not a definitely proven cause for psychophysical somatosensory losses observed in their population. Additionally, the relatively simple psychophysical measures used in this work should be followed by more rigorous measures of the same population.

Joint entropy for space and spatial frequency domains estimated from psychometric functions of achromatic discrimination.

We used psychometric functions to estimate the joint entropy for space discrimination and spatial frequency discrimination. Space discrimination was taken as discrimination of spatial extent. Seven subjects were tested. Gábor functions comprising unidimensionalsinusoidal gratings (0.4, 2, and 10 cpd) and bidimensionalGaussian envelopes (1°) were used as reference stimuli. The experiment comprised the comparison between reference and test stimulithat differed in grating's spatial frequency or envelope's standard deviation. We tested 21 different envelope's standard deviations around the reference standard deviation to study spatial extent discrimination and 19 different grating's spatial frequencies around the reference spatial frequency to study spatial frequency discrimination. Two series of psychometric functions were obtained for 2%, 5%, 10%, and 100% stimulus contrast. The psychometric function data points for spatial extent discrimination or spatial frequency discrimination were fitted with Gaussian functions using the least square method, and the spatial extent and spatial frequency entropies were estimated from the standard deviation of these Gaussian functions. Then, joint entropy was obtained by multiplying the square root of space extent entropy times the spatial frequency entropy. We compared our results to the theoretical minimum for unidimensional Gábor functions, 1/4π or 0.0796. At low and intermediate spatial frequencies and high contrasts, joint entropy reached levels below the theoretical minimum, suggesting non-linear interactions between two or more visual mechanisms. We concluded that non-linear interactions of visual pathways, such as the M and P pathways, could explain joint entropy values below the theoretical minimum at low and intermediate spatial frequencies and high contrasts. These non-linear interactions might be at work at intermediate and high contrasts at all spatial frequencies once there was a substantial decrease in joint entropy for these stimulus conditions when contrast was raised.

Life quality assessment of patients after phacoemulsification or extracapsular cataract extraction.

PURPOSE: To study the quality of life, treatment outcomes, and satisfaction in patients who have undergone cataract surgery Methods: This comparative case series study was conducted at the Ophthalmology Service of the Bettina Ferro de Souza University Hospital, Belém, Pará, Brazil. Totally, 60 patients with cataract were included; 50% underwent conventional extracapsular cataract extraction (ECEE) and 50% underwent cataract extraction by phacoemulsification (PHACO). Patients were interviewed using the Visual Function 14 (VF-14) questionnaire to determine the quality of life before and 30 days after surgery. The results of ophthalmological examination were recorded in the patients' files and were available throughout this study. One-way ANOVA, Tukey's post-hoc comparison, and the sign test were used for statistical analyses. RESULTS: The mean VF-14 satisfaction index was 38.0 and 89.4 before and after surgery, respectively, for the ECEE group and 47.0 and 94.1, respectively, for the PHACO group. The improvement in patient quality of life after surgery was significant in both groups (p<0.0001), with a similar amount of improvement in both groups. CONCLUSIONS: The observed improvement in quality of life was significant (p<0.0001) and directly related to patient satisfaction with surgical outcomes, which was also significant (p<0.0001) as assessed using the VF-14. Satisfaction and quality of life are individual factors; consequently, patient responses to questions regarding improvements in the ability to perform each activity are subjective and depend uniquely on individual perception.

Ganglion cell and displaced amacrine cell density distribution in the retina of the howler monkey (Alouatta caraya).

Unlike all other New World (platyrrine) monkeys, both male and female howler monkeys (Alouatta sp.) are obligatory trichromats. In all other platyrrines, only females can be trichromats, while males are always dichromats, as determined by multiple behavioral, electrophysiological, and genetic studies. In addition to obligatory trichromacy, Alouatta has an unusual fovea, with substantially higher peak cone density in the foveal pit than every other diurnal anthropoid monkey (both platyrrhines and catarrhines) and great ape yet examined, including humans. In addition to documenting the general organization of the retinal ganglion cell layer in Alouatta, the distribution of cones is compared to retinal ganglion cells, to explore possible relationships between their atypical trichromacy and foveal specialization. The number and distribution of retinal ganglion cells and displaced amacrine cells were determined in six flat-mounted retinas from five Alouatta caraya. Ganglion cell density peaked at 0.5 mm between the fovea and optic nerve head, reaching 40,700-45,200 cells/mm2. Displaced amacrine cell density distribution peaked between 0.5-1.75 mm from the fovea, reaching mean values between 2,050-3,100 cells/mm2. The mean number of ganglion cells was 1,133,000±79,000 cells and the mean number of displaced amacrine cells was 537,000±61,800 cells, in retinas of mean area 641±62 mm2. Ganglion cell and displaced amacrine cell density distribution in the Alouatta retina was consistent with that observed among several species of diurnal Anthropoidea, both platyrrhines and catarrhines. The principal alteration in the Alouatta retina appears not to be in the number of any retinal cell class, but rather a marked gradient in cone density within the fovea, which could potentially support high chromatic acuity in a restricted central region.