Is second-order spatial loss in amblyopia explained by the loss of first-order spatial input?

Wong, Erwin; Levi, Dennis M.; McGraw, Paul V.

doi:10.1016/s0042-6989(01)00189-4

Cited by 56 publications

(64 citation statements)

References 48 publications

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“…The RFs of individual V2 neurons are much larger than those of V1 neurons and consist of multiple subfields that are thought to reflect V1 inputs. Therefore, V2 neurons are capable of encoding the spatial relationship between local stimulus features such as orientation and spatial frequency as an initial processing of complex visual images (Ito and Komatsu, 2004;Anzai et al, 2007;Willmore et al, 2010;El-Shamayleh and Movshon, 2011;Tao et al, 2012). In this study, we show that the spatial maps of RF subfields of multiple nearby V2 neurons are severely disorganized in amblyopic monkeys, and as a result, the ability of these neurons to accurately encode geometric relationships among neighboring local stimulus features over space is compromised.…”

Section: Introductionmentioning

confidence: 61%

“…The term "subfields" refers to the subunits of the RFs that were experimentally revealed by the LSRC method (Nishimoto et al, 2006;Tao et al, 2012;Zhang et al, 2013). Previously some heterogeneity in the subfield maps of normal V2 neurons has been observed and these neurons are thought to be capable of encoding nonlinear contours (Ito and Komatsu, 2004;Anzai et al, 2007;Willmore et al, 2010;El-Shamayleh and Movshon, 2011;Tao et al, 2012). The extent to which heterogeneity is higher in amblyopic monkeys provides a measure of their abnormality.…”

Section: Disorganized Spatial Maps Of Rf Subfieldsmentioning

confidence: 99%

“…Suppressive profiles can interact with facilitatory profiles and make the spiking output of subfield maps more complex compared with maps without suppressive profiles (Nishimoto et al, 2006;Anzai et al, 2007;Willmore et al, 2010;Tao et al, 2012;Zhang et al, 2013). Some subfields showed suppression that resembles cross orientation suppression in V1 neurons (Fig.…”

Section: Subfield Maps With Suppressive Profilesmentioning

confidence: 99%

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Early Monocular Defocus Disrupts the Normal Development of Receptive-Field Structure in V2 Neurons of Macaque Monkeys

et al. 2014

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Experiencing different quality images in the two eyes soon after birth can cause amblyopia, a developmental vision disorder. Amblyopic humans show the reduced capacity for judging the relative position of a visual target in reference to nearby stimulus elements (position uncertainty) and often experience visual image distortion. Although abnormal pooling of local stimulus information by neurons beyond striate cortex (V1) is often suggested as a neural basis of these deficits, extrastriate neurons in the amblyopic brain have rarely been studied using microelectrode recording methods. The receptive field (RF) of neurons in visual area V2 in normal monkeys is made up of multiple subfields that are thought to reflect V1 inputs and are capable of encoding the spatial relationship between local stimulus features. We created primate models of anisometropic amblyopia and analyzed the RF subfield maps for multiple nearby V2 neurons of anesthetized monkeys by using dynamic two-dimensional noise stimuli and reverse correlation methods. Unlike in normal monkeys, the subfield maps of V2 neurons in amblyopic monkeys were severely disorganized: subfield maps showed higher heterogeneity within each neuron as well as across nearby neurons. Amblyopic V2 neurons exhibited robust binocular suppression and the strength of the suppression was positively correlated with the degree of hereogeneity and the severity of amblyopia in individual monkeys. Our results suggest that the disorganized subfield maps and robust binocular suppression of amblyopic V2 neurons are likely to adversely affect the higher stages of cortical processing resulting in position uncertainty and image distortion.

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Section: Introductionmentioning

confidence: 61%

Section: Disorganized Spatial Maps Of Rf Subfieldsmentioning

confidence: 99%

Section: Subfield Maps With Suppressive Profilesmentioning

confidence: 99%

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Early Monocular Defocus Disrupts the Normal Development of Receptive-Field Structure in V2 Neurons of Macaque Monkeys

et al. 2014

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“…and argue for a primary deficit in ventral as well as dorsal extrastriate function. Wong, Levi, and McGraw (2001) also show that the deficit for contrast-defined form is not simply due to reduced visibility of the carrier, suggesting extra-striate involvement. Similarly, Husk, Farivar, and Hess (2012) argue that deficits for motiondefined form remain even after correcting for low-level differences in contrast sensitivity.…”

Section: Introductionmentioning

confidence: 68%

The amblyopic deficit for 2nd order processing: Generality and laterality

et al. 2015

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A number of previous reports have suggested that the processing of second-order stimuli by the amblyopic eye (AE) is defective and that the fellow non-amblyopic eye (NAE) also exhibits an anomaly. Second-order stimuli involve extra-striate as well as striate processing and provide a means of exploring the extent of the cortical anomaly in amblyopia using psychophysics. We use a range of different second-order stimuli to investigate how general the deficit is for detecting second-order stimuli in adult amblyopes. We compare these results to our previously published adult normative database using the same stimuli and approach to determine the extent to which the detection of these stimuli is defective for both amblyopic and non-amblyopic eye stimulation. The results suggest that the second-order deficit affects a wide range of second-order stimuli, and by implication a large area of extra-striate cortex, both dorsally and ventrally. The NAE is affected only in motion-defined form judgments, suggesting a difference in the degree to which ocular dominance is disrupted in dorsal and ventral extra-striate regions.

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“…30 Although the amblyopic deficit was once thought to be limited to the striate cortex, 31 there is now growing evidence that the amblyopic deficit may also involve the extrastriate cortex, as there are deficits for detecting second-order stimuli that cannot be fully accounted for by the known first-order deficit. [32][33][34] Here we address two questions: Does a sensory imbalance also exist in the binocular combination of second-order stimuli, and if so, is it more severe than that expected on the basis of iovs.arvojournals.org j ISSN: 1552-5783 the imbalance for first order? We do this using a binocular phase combination paradigm 35 that we recently modified to investigate the pattern of binocular combination of secondorder phase (contrast-modulated) in normal adults.…”

mentioning

confidence: 99%

Deficient Binocular Combination of Second-Order Stimuli in Amblyopia

Zhou

Liu

Feng

et al. 2016

Invest. Ophthalmol. Vis. Sci.

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Citation: Zhou J, Liu R, Feng L, Zhou Y, Hess RF. Deficient binocular combination of second-order stimuli in amblyopia. Invest Ophthalmol Vis Sci. 2016;57:163557: -164257: . DOI:10.1167 PURPOSE. Sensory imbalances in humans with amblyopia have been well documented using luminance-modulated (first-order) stimuli. However, little is known regarding whether there is a deficient binocular combination in amblyopes for stimuli defined by modulations in contrast (second-order stimuli). To address this, we asked two questions: Does a sensory imbalance also exist in the binocular combination of second-order stimuli, and if so, is it more severe than that expected on the basis of the imbalance for first-order stimuli?METHODS. The sensory imbalances of 14 adult amblyopes (mean age: 30.5 6 11.5 years; 5 with strabismus and 9 without) were measured using a dichoptic phase combination task. Three types of second-order dichoptic stimulus pairs were used in the study, where the carriers in the two eyes were either correlated, anticorrelated, or uncorrelated. Results were compared with those obtained using first-order stimuli in all observers. RESULTS.We found that second-order binocular combination in amblyopes was not affected by the interocular carrier correlations. The amblyopic eye's contribution to the binocularly fused percept was much less than that of the nonamblyopic eye. The resulting sensory imbalance in binocular combination for second-order images was comparable to that for first-order images in 8 of the observers but was more severe in the other 6 amblyopes.CONCLUSIONS. These results indicate that amblyopia does not disrupt the normal architecture of binocular combination for second-order signals; however, there is an additional deficit in binocular combination of second-order image in some amblyopes that cannot be fully accounted for by the known first-order sensory imbalance.Keywords: amblyopia, suppression, second-order, contrast-gain control, sensory imbalance A mblyopia is a common disorder caused by abnormal visual development during childhood. [1][2][3] This makes amblyopia a unique model for investigating what factors are critical in early development. Normally, people with amblyopia have reduced visual function when viewing stimuli with their amblyopic eye, even when the appropriate optical correction is used. These deficits can include reduced visual acuity, reduced contrast sensitivity function, and spatiotemporal distortions. 3-8 Recently, imbalances in binocular function have been put forward as a possible primary factor in the disorder. [9][10][11] This has led to new binocular training therapies. 12-16 Such a sensory imbalance has been demonstrated in several paradigms, for example, local phase combination, 9,17 global motion coherence, 18 and global orientation coherence. 19 Even at low spatial frequencies where the two eyes have equivalent monocular visual thresholds, the amblyopic eye still makes less of a contribution to the binocularly fused percept than the nonamblyopic eye. 9,11,[17][18][19]...

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Is second-order spatial loss in amblyopia explained by the loss of first-order spatial input?

Cited by 56 publications

References 48 publications

Early Monocular Defocus Disrupts the Normal Development of Receptive-Field Structure in V2 Neurons of Macaque Monkeys

Early Monocular Defocus Disrupts the Normal Development of Receptive-Field Structure in V2 Neurons of Macaque Monkeys

The amblyopic deficit for 2nd order processing: Generality and laterality

Deficient Binocular Combination of Second-Order Stimuli in Amblyopia

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