Laminar, columnar and topographic aspects of ocular dominance in the primary visual cortex ofCebus monkeys

Rosa, Marcello G. P.; Gattass, Ricardo; Fiorani, Mário; Soares, José Agnelo

doi:10.1007/bf02259100

Cited by 36 publications

(48 citation statements)

References 47 publications

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“…However, the likelihood of finding monocularity in orientation-specific learning is even lower because most monocular cells have been shown to be nonselective for stimulus orientation. Indeed, evidence from electrophysiology as well as 2-deoxyglucose (2-DG) and optical imaging studies argues for a correlation between orientation selectivity and binocular input: (a) in layers 4A and 4Cb, cells are probably exclusively monocular and nonoriented (26)(27)(28), while in layer 4Ca, more binocular as well as oriented cells (26,29,30) and orientation columns (30) are found; (b) in the cytochrome oxidase blobs in layer 3, nonoriented cells tended to be more monocular (30); and (c) as for the uppermost layers studied with optical imaging methods, Blasdel (31) demonstrated that orientation selectivity is highly correlated with binocularity, and that regions strongly dominated by one eye and regions strongly selective for orientation are partially segregated.…”

Section: Discussionmentioning

confidence: 99%

Interocular transfer in perceptual learning of a pop-out discrimination task.

Schoups

Orban

1996

Proc. Natl. Acad. Sci. U.S.A.

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The specificity of the improvement in perceptual learning is often used to localize the neuronal changes underlying this type of adult plasticity. We investigated a visual texture discrimination task previously reported to be accomplished preattentively and for which learning-related changes were inferred to occur at a very early level of the visual processing stream. The stimulus was a matrix of lines from which a target popped out, due to an orientation difference between the three target lines and the background lines. The task was to report the global orientation of the target and was performed monocularly. The subjects' performance improved dramatically with training over the course of 2-3 weeks, after which we tested the specificity of the improvement for the eye trained. In all subjects tested, there was complete interocular transfer of the learning effect. The neuronal correlates of this learning are therefore most likely localized in a visual area where input from the two eyes has come together.The specificity of improvement in performance with perceptual training is widely regarded as the key to the neurological localization of the learning effect. For simple tasks, the learning effect is specific for some particular stimulus attributes, such as orientation (1-3) and spatial frequency (4). Moreover, the improvement in performance observed in these simple tasks remains restricted to stimulus position in the subject's visual field (3-8). By contrast, for more complex tasks, the learned improvement transferred to different stimulus attributes as well as to other positions in the visual field (9).Specificity of the learning effect to particular stimulus attributes and to stimulus position implies that the improvement in performance is due to changes in populations of neurons at early stages of the visual pathway, where neurons are highly specialized for simple stimulus attributes and for stimulus position and size, in contrast to neurons in higher visual areas, which generalize over these stimulus variables.

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Section: Discussionmentioning

confidence: 99%

Interocular transfer in perceptual learning of a pop-out discrimination task.

Schoups

Orban

1996

Proc. Natl. Acad. Sci. U.S.A.

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“…A detailed description of the animal preparation and recording procedures has been published (22). Briefly, at least 1 week before the first recording session the animal was anesthetized with ketamine (30 mg/kg) and Saffan and surgically implanted with a cranial prosthesis capable of holding the head in a modified stereotaxic holder without further pressure points.…”

Section: Methodsmentioning

confidence: 99%

“…A survival time of 18 days was allowed before perfusion. All monkeys were perfused with 3% (wt/vol) paraformaldehyde/ phosphate-buffered saline, and every section was treated for cytochrome oxidase (23) to reveal the limits of the cortical optic disk representation (22), the electrode tracks, and the electrolytic lesions (4 AuA, 5 sec) used as markers.…”

Section: Methodsmentioning

confidence: 99%

Dynamic surrounds of receptive fields in primate striate cortex: a physiological basis for perceptual completion?

Júnior

Rosa

Gattass

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

145

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Visual receptive fields (RFs) were mapped inside and outside the cortical representation of the optic disk in the striate cortex (area V1) of anesthetized and paralyzed Cebus monkeys. Unexpectedly, most cells were found to be binocularly driven, and the RFs mapped with contralateral-eye stimulation progressed in a topographically appropriate fashion as the optic disk sector was crossed. Activation of these neurons by the contralateral eye was shown to depend on stimulation of the parts of the retina around the optic disk. Outside the optic disk representation, a similar effect was demonstrated by obstructing the "classical" RF with masks 5-10 times larger in size. In all cases, visual stimuli presented around the mask could be used to accurately interpolate the position of the hidden RF. These properties reflect, at a cellular level, the process of "filling in" that allows for completion of the visual image across natural and artificially induced scotomas.In the past decade, the notion that receptive fields (RFs) in adult sensory cortex have stable boundaries was challenged by a series of experiments that demonstrated changes in RF size and location after chronic (1-3) or acute (4) deafferentation. In the visual cortex, similar modifications have been seen after retinal lesions (5-7). In addition, even in the normal animal the portion of the visual field capable of modifying cellular activity has been shown to be far more extensive than the "classical" RF. Specifically, responses to stimulation within RFs of neurons in primate visual areas V1, V2, V3A, V4, and MT are modifiable by stimulation of normally silent RF peripheries with patterns differing in texture, wavelength, spatial frequency, direction of motion, and speed of motion from the pattern presented to the RF itself (6,(8)(9)(10)(11)(12)(13). Responses in area V2 can be induced by illusory contours formed by visual patterns presented outside the classical RF (14) and the boundaries of excitatory RFs in area V4 vary depending on spatial attention (15). Except for the modulation of responses by stimulation of silent peripheries with patterns differing in speed of motion (6), most of these effects seemed to be absent in the primary visual area (V1), thus contributing to the hypothesis that RFs of neurons in V1 have stable boundaries and responses.The retinal blind spot, corresponding to the optic disk, is devoid of photoreceptors. Thus, although most parts of the central visual field are usually viewed binocularly, the parts corresponding to the optic disk of one eye are viewed only through the opposite eye. Nonetheless, unless specific tests are applied, no gap in the visual field is noticed under monocular viewing. The blind spot is imperceptibly "filled in" to match the color, texture, and brightness of the regions of the visual field immediately surrounding the optic disk (16). This process of filling in is usually referred to as the completion phenomenon (16,17). This phenomenon may also account for the unawareness of other "blind" regions of ...

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“…Estes incluem outros tipos de padrões visuais, por exemplo: grades, padrões xadrez, "olho de touro", radial, angular, textura, padrões em coordenadas polares e cartesianas formados por pontos aleatórios, estímulos do tipo "glass", dentre outros (Carlson, Cohen & Gorog, 1977;Cavanagh, 1978;Cavanagh, 1982;Dodwell, 1983;Gallant, Brau & van Essen, 1993;Gallant, Connor, Rakshit, Lewis & van Essen, 1996;Hess, Wang, Demanins, Wilkinson & Wilson, 1999;Hess & Wilcox, 1994;Rosa, Gattass, Fiorani Jr & Soares, 1992;Schwartz, 1983;Verrall & Kakarala, 1998;Weisstein, Harris, Berbaum, Tangney & Williams, 1977;Wilkinson, Wilson & Habak, 1998;.…”

Section: Estímulo Espacial De Freqüência Radial/angular Acopladaunclassified

Função de Sensibilidade ao Contraste: Indicador da Percepção Visual da Forma e da Resolução Espacial

Santos¹,

Simas²

2001

Psicol. Reflex. Crit.

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Função de Sensibilidade ao ContrasteA sensibilidade ao contraste é definida na literatura como a recíproca da quantidade mínima de contraste necessária para detectar uma grade de uma freqüência espacial específica (Cornsweet, 1970). Em outras palavras, a FSC é, por definição, o inverso da curva de limiar de contraste (1/FSC). Logo, a sensibilidade ao contraste está relacionada à diferença existente entre picos e depressões das ondas. Essa diferença traduz o valor de contraste requerido pelo sistema visual humano, SVH, para distinguir um estímulo de freqüência espacial daquele com um campo uniforme de luminância média. Assim, o sistema visual, SV, possui alta sensibilidade quando um padrão precisa de pouco contraste para ser detectado ResumoEste trabalho discute a função de sensibilidade ao contraste, FSC, em três seções. A primeira descreve alguns aspectos teóricos e experimentais da FSC relacionados à pesquisa básica e aplicada. A segunda discute alguns estímulos espaciais utilizados para caracterizar a FSC ou a resposta do sistema visual humano. A terceira apresenta algumas considerações finais sobre a FSC e estímulos espaciais elementares. Um dos objetivos deste trabalho é discutir a FSC que junto com a acuidade visual parecem formar os principais indicadores dos aspectos críticos da percepção visual da forma e da resolução espacial. A FSC geralmente estima a percepção de qualquer padrão em função de sua freqüência espacial. Palavras-chaves: Percepção visual da forma; acuidade visual; função de sensibilidade ao contraste; resolução espacial; freqüência espacial. Contrast Sensitivity Function: Indicator of the Visual Perception of Form and of the Spatial Resolution AbstractThis work discusses the contrast sensitivity function (CSF) in three sections. The first describes some theoretical and experimental questions of the CSF related to basic and hard-working research. The second section discusses some elementary spatial stimuli used to characterize the CSF or the response of the human visual system. The third section shows some final considerations about CSF and spatial elementary stimuli. One of the goals of this paper is to discuss the CSF that together with visual acuity appear to form important indicators of the critical aspects of the visual perception of form and of the spatial resolution. The CSF normally is an estimate of the visibility of any pattern in function of the spatial frequency. Keywords: Visual perception of form; visual acuity; contrast sensitivity function; spatial resolution; spatial frequency. contraste de grades (ou qualquer padrão) como uma função de sua freqüência espacial. Modelo de Canais Múltiplos e a Função de Sensibilidade ao ContrasteDesde que foi proposto por Campbell e Robson (1968), a abordagem de canais múltiplos tem sido utilizada para caracterizar o processamento visual da forma. Esta abordagem assume que o SVH responde seletivamente a freqüências espaciais, ou seja, o SVH processa simultaneamente diferentes faixas estreitas de freqüências espaciais (Blakemore & Campbell, ...

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Laminar, columnar and topographic aspects of ocular dominance in the primary visual cortex ofCebus monkeys

Cited by 36 publications

References 47 publications

Interocular transfer in perceptual learning of a pop-out discrimination task.

Interocular transfer in perceptual learning of a pop-out discrimination task.

Dynamic surrounds of receptive fields in primate striate cortex: a physiological basis for perceptual completion?

Função de Sensibilidade ao Contraste: Indicador da Percepção Visual da Forma e da Resolução Espacial

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