Base de dados : MEDLINE
Pesquisa : G14.020 [Categoria DeCS]
Referências encontradas : 4921 [refinar]
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  1 / 4921 MEDLINE  
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[PMID]:29196762
[Au] Autor:Pons C; Mazade R; Jin J; Dul MW; Zaidi Q; Alonso JM
[Ad] Endereço:Department of Biological and Visual Sciences, State University of New York College of Optometry, New York, NY, USA.
[Ti] Título:Neuronal mechanisms underlying differences in spatial resolution between darks and lights in human vision.
[So] Source:J Vis;17(14):5, 2017 Dec 01.
[Is] ISSN:1534-7362
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Artists and astronomers noticed centuries ago that humans perceive dark features in an image differently from light ones; however, the neuronal mechanisms underlying these dark/light asymmetries remained unknown. Based on computational modeling of neuronal responses, we have previously proposed that such perceptual dark/light asymmetries originate from a luminance/response saturation within the ON retinal pathway. Consistent with this prediction, here we show that stimulus conditions that increase ON luminance/response saturation (e.g., dark backgrounds) or its effect on light stimuli (e.g., optical blur) impair the perceptual discrimination and salience of light targets more than dark targets in human vision. We also show that, in cat visual cortex, the magnitude of the ON luminance/response saturation remains relatively constant under a wide range of luminance conditions that are common indoors, and only shifts away from the lowest luminance contrasts under low mesopic light. Finally, we show that the ON luminance/response saturation affects visual salience mostly when the high spatial frequencies of the image are reduced by poor illumination or optical blur. Because both low luminance and optical blur are risk factors in myopia, our results suggest a possible neuronal mechanism linking myopia progression with the function of the ON visual pathway.
[Mh] Termos MeSH primário: Adaptação Ocular/fisiologia
Retina/fisiologia
Acuidade Visual
Córtex Visual/fisiologia
Vias Visuais/fisiologia
Percepção Visual/fisiologia
[Mh] Termos MeSH secundário: Eletrorretinografia
Seres Humanos
Iluminação
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1712
[Cu] Atualização por classe:171226
[Lr] Data última revisão:
171226
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171203
[St] Status:MEDLINE
[do] DOI:10.1167/17.14.5


  2 / 4921 MEDLINE  
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[PMID]:29228141
[Au] Autor:Zeng H; Kreutzer S; Fink GR; Weidner R
[Ad] Endereço:Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Center Jülich, Jülich, Germany.
[Ti] Título:The source of visual size adaptation.
[So] Source:J Vis;17(14):8, 2017 Dec 01.
[Is] ISSN:1534-7362
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Size adaptation describes the tendency of the visual system to adjust neural responsiveness of size representations after prolonged exposure to particular stimulations. A larger (or smaller) adaptor stimulus influences the perceived size of a similar test stimulus shown subsequently. Size adaptation may emerge on various processing levels. Functional representations of the adaptor to which the upcoming stimulus is adapted may be coded early in the visual system mainly reflecting retinal size. Alternatively, size adaptation may involve higher order processes that take into account additional information such as an object's estimated distance from the observer, hence reflecting perceived size. The present study investigated whether size adaptation is based on the retinal or the perceived size of an adaptor stimulus. A stimulus' physical and perceived sizes were orthogonally varied using perceived depth via binocular disparity, employing polarized 3D glasses. Four different adaptors were used, which varied in physical size, perceived size, or both. Two pairs of adaptors which were identical in physical size did not cause significantly different adaptation effects although they elicited different perceived sizes which were sufficiently large to produce differential aftereffects when induced by stimuli that physically differed in size. In contrast, there was a significant aftereffect when adaptors differed in physical size but were matched in perceived size. Size adaptation was thus unaffected by perceived size and binocular disparity. Our data suggest that size adaptation emerges from neural stages where information from both eyes is still coded in separate channels without binocular interactions, such as the lateral geniculate nucleus.
[Mh] Termos MeSH primário: Adaptação Ocular/fisiologia
Percepção de Tamanho/fisiologia
[Mh] Termos MeSH secundário: Adolescente
Adulto
Percepção de Profundidade/fisiologia
Feminino
Seres Humanos
Masculino
Estimulação Luminosa
Retina/fisiologia
Disparidade Visual/fisiologia
Adulto Jovem
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1712
[Cu] Atualização por classe:171215
[Lr] Data última revisão:
171215
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171212
[St] Status:MEDLINE
[do] DOI:10.1167/17.14.8


  3 / 4921 MEDLINE  
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[PMID]:29052730
[Au] Autor:Meermeier A; Gremmler S; Richert K; Eckermann T; Lappe M
[Ad] Endereço:Department of Psychology & Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Muenster, Muenster, Germany.
[Ti] Título:The reward of seeing: Different types of visual reward and their ability to modify oculomotor learning.
[So] Source:J Vis;17(12):11, 2017 Oct 01.
[Is] ISSN:1534-7362
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Saccadic adaptation is an oculomotor learning process that maintains the accuracy of eye movements to ensure effective perception of the environment. Although saccadic adaptation is commonly considered an automatic and low-level motor calibration in the cerebellum, we recently found that strength of adaptation is influenced by the visual content of the target: pictures of humans produced stronger adaptation than noise stimuli. This suggests that meaningful images may be considered rewarding or valuable in oculomotor learning. Here we report three experiments that establish the boundaries of this effect. In the first, we tested whether stimuli that were associated with high and low value following long term self-administered reinforcement learning produce stronger adaptation. Twenty-eight expert gamers participated in two sessions of adaptation to game-related high- and low-reward stimuli, but revealed no difference in saccadic adaptation (Bayes Factor01 = 5.49). In the second experiment, we tested whether cognitive (literate) meaning could induce stronger adaptation by comparing targets consisting of words and nonwords. The results of twenty subjects revealed no difference in adaptation strength (Bayes Factor01 = 3.21). The third experiment compared images of human figures to noise patterns for reactive saccades. Twenty-two subjects adapted significantly more toward images of human figures in comparison to noise (p < 0.001). We conclude that only primary (human vs. noise), but not secondary, reinforcement affects saccadic adaptation (words vs. nonwords, high- vs. low-value video game images).
[Mh] Termos MeSH primário: Adaptação Ocular/fisiologia
Adaptação Fisiológica
Movimentos Oculares/fisiologia
Aprendizagem/fisiologia
Reconhecimento Visual de Modelos/fisiologia
[Mh] Termos MeSH secundário: Feminino
Seres Humanos
Masculino
Adulto Jovem
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1711
[Cu] Atualização por classe:171102
[Lr] Data última revisão:
171102
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171021
[St] Status:MEDLINE
[do] DOI:10.1167/17.12.11


  4 / 4921 MEDLINE  
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[PMID]:28912158
[Au] Autor:Joiner WM; Cavanaugh J; Wurtz RH; Cumming BG
[Ad] Endereço:Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, and wjoiner2@gmu.edu.
[Ti] Título:Visual Responses in FEF, Unlike V1, Primarily Reflect When the Visual Context Renders a Receptive Field Salient.
[So] Source:J Neurosci;37(41):9871-9879, 2017 Oct 11.
[Is] ISSN:1529-2401
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:When light falls within a neuronal visual receptive field (RF) the resulting activity is referred to as the visual response. Recent work suggests this activity is in response to both the visual stimulation and the abrupt appearance, or salience, of the presentation. Here we present a novel method for distinguishing the two, based on the timing of random and nonrandom presentations. We examined these contributions in frontal eye field (FEF; = 51) and as a comparison, an early stage in the primary visual cortex (V1; = 15) of male monkeys ( ). An array of identical stimuli was presented within and outside the neuronal RF while we manipulated salience by varying the time between stimulus presentations. We hypothesized that the rapid presentation would reduce salience (the sudden appearance within the visual field) of a stimulus at any one location, and thus decrease responses driven by salience in the RF. We found that when the interstimulus interval decreased from 500 to 16 ms there was an approximate 79% reduction in the FEF response compared with an estimated 17% decrease in V1. This reduction in FEF response for rapid presentation was evident even when the random sequence preceding a stimulus did not stimulate the RF for 500 ms. The time course of these response changes in FEF suggest that salience is represented much earlier (<100 ms following stimulus onset) than previously estimated. Our results suggest that the contribution of salience dominates at higher levels of the visual system. The neuronal responses in early visual processing [e.g., primary visual cortex (V1)] reflect primarily the retinal stimulus. Processing in higher visual areas is modulated by a combination of the visual stimulation and contextual factors, such as salience, but identifying these components separately has been difficult. Here we quantified these contributions at a late stage of visual processing [frontal eye field (FEF)] and as a comparison, an early stage in V1. Our results suggest that as visual information continues through higher levels of processing the neural responses are no longer driven primarily by the visual stimulus in the receptive field, but by the broader context that stimulus defines-very different from current views about visual signals in FEF.
[Mh] Termos MeSH primário: Visão Ocular/fisiologia
Córtex Visual/fisiologia
Campos Visuais/fisiologia
[Mh] Termos MeSH secundário: Adaptação Ocular
Animais
Macaca mulatta
Masculino
Neurônios/fisiologia
Estimulação Luminosa
Córtex Visual/citologia
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171026
[Lr] Data última revisão:
171026
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170916
[St] Status:MEDLINE
[do] DOI:10.1523/JNEUROSCI.1446-17.2017


  5 / 4921 MEDLINE  
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[PMID]:28728172
[Au] Autor:Vera-Diaz FA; Woods RL; Peli E
[Ad] Endereço:New England College of Optometry, Boston, Massachusetts, United States 2Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States 3Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States.
[Ti] Título:Blur Adaptation to Central Retinal Disease.
[So] Source:Invest Ophthalmol Vis Sci;58(9):3646-3655, 2017 Jul 01.
[Is] ISSN:1552-5783
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Purpose: The long-term, low-resolution vision experienced by individuals affected by retinal disease that causes central vision loss (CVL) may change their perception of blur through adaptation. This study used a short-term adaptation paradigm to evaluate adaptation to blur and sharpness in patients with CVL. Methods: A variation of Webster's procedure was used to measure the point of subjective neutrality (PSN). The image that appeared normal after adaptation to each of seven blur and sharpness levels (PSN) was measured in 12 patients with CVL (20/60 to 20/320) and 5 subjects with normal sight (NS). Patients with CVL used a preferred retinal locus to view the images. Small control studies investigated the effects of long-term and medium-term (1 hour) defocus and diffusive blur. Results: Adaptation was reliably measured in patients with CVL and in the peripheral vision of NS subjects. The shape of adaptation curves was similar in patients with CVL and both central and peripheral vision of NS subjects. No statistical correlations were found between adaptation and age, visual acuity, retinal eccentricity, or contrast sensitivity. Long-term blur experience by a non-CVL myopic participant caused a shift in the adaptation function. Conversely, medium-term adaptation did not cause a shift in the adaptation function. Conclusions: Blur and sharp short-term adaptation occurred in peripheral vision of normal and diseased retinas. In most patients with CVL, neither adaptation nor blur perception was affected by long-term attention to peripheral low-resolution vision. The impact of blur/sharp adaptation on the benefit of image enhancement techniques for patients with CVL is discussed.
[Mh] Termos MeSH primário: Adaptação Ocular/fisiologia
Sensibilidades de Contraste/fisiologia
Miopia/fisiopatologia
Doenças Retinianas/fisiopatologia
Transtornos da Visão/fisiopatologia
Percepção Visual/fisiologia
[Mh] Termos MeSH secundário: Adulto
Idoso
Idoso de 80 Anos ou mais
Feminino
Seres Humanos
Masculino
Meia-Idade
Refração Ocular/fisiologia
Acuidade Visual
Adulto Jovem
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1707
[Cu] Atualização por classe:170728
[Lr] Data última revisão:
170728
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170721
[St] Status:MEDLINE
[do] DOI:10.1167/iovs.16-20849


  6 / 4921 MEDLINE  
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[PMID]:28719913
[Au] Autor:Sun HC; Kingdom FAA; Baker CL
[Ad] Endereço:McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, QC, Canadahua-chun.sun@mail.mcgill.cahttps://www.researchgate.net/profile/Hua_Chun_Sun.
[Ti] Título:Texture density adaptation can be bidirectional.
[So] Source:J Vis;17(8):9, 2017 Jul 01.
[Is] ISSN:1534-7362
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Texture density has previously been thought of as a scalar attribute on the assumption that texture density adaptation only reduces, not enhances, perceived density (Durgin & Huk, 1997). This "unidirectional" property of density adaptation is in contradistinction to the finding that simultaneous density contrast (SDC) is "bidirectional"; that is, not only do denser surrounds reduce the perceived density of a lower density region, but sparser surrounds enhance it (Sun, Baker, & Kingdom, 2016). Here we reexamine the directionality of density adaptation using random dot patterns and a two-alternative forced choice task in which observers compare the perceived density of adapted test patches with unadapted match stimuli. In the first experiment, we observed a unidirectional density aftereffect when test and match were presented simultaneously as in previous studies. However, when they were presented sequentially, bidirectionality was obtained. This bidirectional aftereffect remained when the presentation order of test and match was reversed (second experiment). In the third experiment, we used sequential presentation to measure the density aftereffect for a wide range of adaptor densities (0-73 dots/deg2) and test densities (1.6, 6.4, and 25.6 dots/deg2). We found bidirectionality for all combinations of adaptor and test densities, consistent with our previous SDC results. This evidence supports the idea that there are multiple channels selective to texture density in human vision.
[Mh] Termos MeSH primário: Adaptação Ocular/fisiologia
Sensibilidades de Contraste/fisiologia
Reconhecimento Visual de Modelos/fisiologia
[Mh] Termos MeSH secundário: Comportamento de Escolha
Área de Dependência-Independência
Seres Humanos
Psicometria
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170908
[Lr] Data última revisão:
170908
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170719
[St] Status:MEDLINE
[do] DOI:10.1167/17.8.9


  7 / 4921 MEDLINE  
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[PMID]:28617929
[Au] Autor:Huang J; Gegenfurtner KR; Schütz AC; Billino J
[Ad] Endereço:Abteilung Allgemeine Psychologie, Justus-Liebig-Universität Gießen, Gießen, Germanyjing.huang@psychol.uni-giessen.dehttp://www.allpsych.uni-giessen.de/huang/.
[Ti] Título:Age effects on saccadic adaptation: Evidence from different paradigms reveals specific vulnerabilities.
[So] Source:J Vis;17(6):9, 2017 Jun 01.
[Is] ISSN:1534-7362
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Saccadic eye movements provide an opportunity to study closely interwoven perceptual, motor, and cognitive changes during aging. Here, we investigated age effects on different mechanisms of saccadic plasticity. We compared age effects in two different adaptation paradigms that tap into low- and high-level adaptation processes. A total of 27 senior adults and 25 young adults participated in our experiments. In our first experiment, we elicited adaptation by a double-step paradigm, which is designed to trigger primarily low-level, gradual motor adaptation. Age groups showed equivalent adaptation of saccadic gain. In our second experiment, adaptation was induced by a perceptual task that emphasizes high-level, fast processes. We consistently found no evidence for age-related differences in low-level adaptation; however, the fast adaptation response was significantly more pronounced in the young adult group. We conclude that low-level motor adaptation is robust during healthy aging but that high-level contributions, presumably involving executive strategies, are subject to age-related decline. Our findings emphasize the need to differentiate between specific aging processes in order to understand functional decline and stability across the adult life span.
[Mh] Termos MeSH primário: Adaptação Ocular/fisiologia
Envelhecimento/fisiologia
Movimentos Sacádicos/fisiologia
[Mh] Termos MeSH secundário: Adulto
Idoso
Feminino
Seres Humanos
Masculino
Meia-Idade
Desempenho Psicomotor/fisiologia
Adulto Jovem
[Pt] Tipo de publicação:COMPARATIVE STUDY; JOURNAL ARTICLE
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170908
[Lr] Data última revisão:
170908
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170616
[St] Status:MEDLINE
[do] DOI:10.1167/17.6.9


  8 / 4921 MEDLINE  
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[PMID]:28617928
[Au] Autor:Olkkonen M; Aguirre GK; Epstein RA
[Ad] Endereço:Department of Psychology, University of Pennsylvania, Philadelphia, PA, USAPresent address: Department of Psychology, Durham University, Durham, England; and Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finlandmaria.olkkonen@durham.ac.ukhttp://www.mv.helsinki.fi/home/molkkone/.
[Ti] Título:Expectation modulates repetition priming under high stimulus variability.
[So] Source:J Vis;17(6):10, 2017 Jun 01.
[Is] ISSN:1534-7362
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Neural responses to stimuli are often attenuated by repeated presentation. When observed in blood oxygen level-dependent signals, this attenuation is known as fMRI adaptation (fMRIa) or fMRI repetition suppression. According to a prominent account, fMRIa reflects the fulfillment of perceptual expectations during recognition of repeated items (Summerfield, Trittschuh, Monti, Mesulam, & Egner, 2008). Supporting this idea, expectation has been shown to modulate fMRIa under some circumstances; however, it is not currently known whether expectation similarly modulates recognition performance. To address this lacuna, we measured behavioral and fMRI responses to faces while varying the extent to which each stimulus was informative about its successor. Behavioral priming was greater when repetitions were more likely, suggesting that recognition was facilitated by the expectation than an item would repeat. Notably, this effect was only observed when stimuli were drawn from a broad set of faces including many ethnicities and both genders, but not when stimuli were drawn from a narrower face set, thus making repetitions less informative. Moreover, expectation did not modulate fMRIa in face-selective cortex, contrary to previous studies, although an exploratory analysis indicated that it did so in a medial frontal region. These results support the idea that expectation modulates recognition efficiency, but insofar as behavioral effects of expectation were not accompanied by fMRI effects in visual cortex, they suggest that fMRIa cannot be entirely explained in terms of fulfilled expectations.
[Mh] Termos MeSH primário: Priming de Repetição/fisiologia
Córtex Visual/fisiologia
Percepção Visual/fisiologia
[Mh] Termos MeSH secundário: Adaptação Ocular/fisiologia
Adolescente
Adulto
Feminino
Seres Humanos
Imagem por Ressonância Magnética/métodos
Masculino
Meia-Idade
Probabilidade
Desempenho Psicomotor/fisiologia
Adulto Jovem
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170908
[Lr] Data última revisão:
170908
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170616
[St] Status:MEDLINE
[do] DOI:10.1167/17.6.10


  9 / 4921 MEDLINE  
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[PMID]:28432136
[Au] Autor:Ebitz RB; Moore T
[Ad] Endereço:Department of Neurobiology and rebitz@gmail.com.
[Ti] Título:Selective Modulation of the Pupil Light Reflex by Microstimulation of Prefrontal Cortex.
[So] Source:J Neurosci;37(19):5008-5018, 2017 May 10.
[Is] ISSN:1529-2401
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The prefrontal cortex (PFC) is thought to flexibly regulate sensorimotor responses, perhaps through modulating activity in other circuits. However, the scope of that control remains unknown: it remains unclear whether the PFC can modulate basic reflexes. One canonical example of a central reflex is the pupil light reflex (PLR): the automatic constriction of the pupil in response to luminance increments. Unlike pupil size, which depends on the interaction of multiple physiological and neuromodulatory influences, the PLR reflects the action of a simple brainstem circuit. However, emerging behavioral evidence suggests that the PLR may be modulated by cognitive processes. Although the neural basis of these modulations remains unknown, one possible source is the PFC, particularly the frontal eye field (FEF), an area of the PFC implicated in the control of attention. We show that microstimulation of the rhesus macaque FEF alters the magnitude of the PLR in a spatially specific manner. FEF microstimulation enhanced the PLR to probes presented within the stimulated visual field, but suppressed the PLR to probes at nonoverlapping locations. The spatial specificity of this effect parallels the effect of FEF stimulation on attention and suggests that FEF is capable of modulating visuomotor transformations performed at a lower level than was previously known. These results provide evidence of the selective regulation of a basic brainstem reflex by the PFC. The pupil light reflex (PLR) is our brain's first and most fundamental mechanism for light adaptation. Although it is often described in textbooks as being an immutable reflex, converging evidence suggests that the magnitude of the PLR is modulated by cognitive factors. The neural bases of these modulations are unknown. Here, we report that microstimulation in the prefrontal cortex (PFC) modulates the gain of the PLR, changing how a simple reflex circuit responds to physically identical stimuli. These results suggest that control structures such as the PFC can add complexity and flexibility to even a basic brainstem circuit.
[Mh] Termos MeSH primário: Adaptação Ocular/fisiologia
Estimulação Elétrica/métodos
Rede Nervosa/fisiologia
Plasticidade Neuronal/fisiologia
Córtex Pré-Frontal/fisiologia
Reflexo Pupilar/fisiologia
[Mh] Termos MeSH secundário: Animais
Luz
Macaca mulatta
Masculino
Rede Nervosa/efeitos da radiação
Plasticidade Neuronal/efeitos da radiação
Estimulação Luminosa/métodos
Córtex Pré-Frontal/efeitos da radiação
Reflexo Pupilar/efeitos da radiação
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1708
[Cu] Atualização por classe:170818
[Lr] Data última revisão:
170818
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170423
[St] Status:MEDLINE
[do] DOI:10.1523/JNEUROSCI.2433-16.2017


  10 / 4921 MEDLINE  
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[PMID]:28403143
[Au] Autor:Howlett MH; Smith RG; Kamermans M
[Ad] Endereço:Retinal Signal Processing lab, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands.
[Ti] Título:A novel mechanism of cone photoreceptor adaptation.
[So] Source:PLoS Biol;15(4):e2001210, 2017 Apr.
[Is] ISSN:1545-7885
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:An animal's ability to survive depends on its sensory systems being able to adapt to a wide range of environmental conditions, by maximizing the information extracted and reducing the noise transmitted. The visual system does this by adapting to luminance and contrast. While luminance adaptation can begin at the retinal photoreceptors, contrast adaptation has been shown to start at later stages in the retina. Photoreceptors adapt to changes in luminance over multiple time scales ranging from tens of milliseconds to minutes, with the adaptive changes arising from processes within the phototransduction cascade. Here we show a new form of adaptation in cones that is independent of the phototransduction process. Rather, it is mediated by voltage-gated ion channels in the cone membrane and acts by changing the frequency response of cones such that their responses speed up as the membrane potential modulation depth increases and slow down as the membrane potential modulation depth decreases. This mechanism is effectively activated by high-contrast stimuli dominated by low frequencies such as natural stimuli. However, the more generally used Gaussian white noise stimuli were not effective since they did not modulate the cone membrane potential to the same extent. This new adaptive process had a time constant of less than a second. A critical component of the underlying mechanism is the hyperpolarization-activated current, Ih, as pharmacologically blocking it prevented the long- and mid- wavelength sensitive cone photoreceptors (L- and M-cones) from adapting. Consistent with this, short- wavelength sensitive cone photoreceptors (S-cones) did not show the adaptive response, and we found they also lacked a prominent Ih. The adaptive filtering mechanism identified here improves the information flow by removing higher-frequency noise during lower signal-to-noise ratio conditions, as occurs when contrast levels are low. Although this new adaptive mechanism can be driven by contrast, it is not a contrast adaptation mechanism in its strictest sense, as will be argued in the Discussion.
[Mh] Termos MeSH primário: Adaptação Ocular
Células Fotorreceptoras Retinianas Cones/fisiologia
[Mh] Termos MeSH secundário: Potenciais de Ação
Animais
Carpa Dourada
Cinética
Células Fotorreceptoras Retinianas Cones/efeitos da radiação
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1704
[Cu] Atualização por classe:170830
[Lr] Data última revisão:
170830
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170414
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pbio.2001210



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