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Robert F. Hess - One of the best experts on this subject based on the ideXlab platform.
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can short term ocular Dominance plasticity provide a general index to visual plasticity to personalize treatment in amblyopia
Frontiers in Neuroscience, 2020Co-Authors: Chunwen Tao, Jiawei Zhou, Yiya Chen, Robert F. HessAbstract:Purpose: Recently, Lunghi et al showed that amblyopic Eye’s visual acuity per se after 2 months of occlusion therapy could be predicted by a homeostatic plasticity, i.e., the temporary shift of perceptual Eye Dominance observed after a 2-hour monocular deprivation, in children with anisometropic amblyopia(Lunghi et al., 2016). In this study, we assess whether the visual acuity improvement of the amblyopic Eye measured after 2 months of occlusion therapy could be predicted by this plasticity. Methods: Seven children (6.86 ± 1.46 years old; SD) with anisometropic amblyopia participated in this study. All patients were newly diagnosed and had no treatment history before participating our study. They finished 2 months of refractive adaptation and then received a 4-hour daily fellow Eye patching therapy with an opaque patch for a 2-month period. Best-corrected visual acuity of the amblyopic Eye was measured before and after the patching therapy. The homeostatic plasticity was assessed by measuring the temporary shift of perceptual Eye Dominance from 2-hour occlusion of the amblyopic Eye before treatment. A binocular phase combination paradigm was used for this study. Results: We found that there was no significant correlation between the temporary shift of perceptual Eye Dominance observed after 2-hour occlusion of the amblyopic Eye and the improvement in visual acuity in the amblyopic Eye from 2-hour of classical patching therapy. This result, although in disagreements with the conclusions of Lunghi et al involving the short-term patching of the amblyopic Eye, is in fact consistent with a reanalysis of Lunghi et al’ s data. Conclusions: The short-term changes in perceptual Eye Dominance as a result of short-term monocular deprivation do not provide an index of cortical plasticity in the general sense such that they are able to predict acuity outcomes from longer term classical patching.
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can short term ocular Dominance plasticity provide a general index to visual plasticity to personalize treatment in amblyopia
Frontiers in Neuroscience, 2020Co-Authors: Zhifen He, Yiya Chen, Jiawei Zhou, Robert F. HessAbstract:Purpose Recently, Lunghi et al. (2016) showed that amblyopic Eye's visual acuity per se after 2 months of occlusion therapy could be predicted by a homeostatic plasticity, that is, the temporary shift of perceptual Eye Dominance observed after a 2-h monocular deprivation, in children with anisometropic amblyopia. In this study, we assess whether the visual acuity improvement of the amblyopic Eye measured after 2 months of occlusion therapy could be predicted by this plasticity. Methods Seven children (6.86 ± 1.46 years old; SD) with anisometropic amblyopia participated in this study. All patients were newly diagnosed and had no treatment history before participating in our study. They finished 2 months of refractive adaptation and then received a 4-h daily fellow Eye patching therapy with an opaque patch for a 2-month period. Best-corrected visual acuity of the amblyopic Eye was measured before and after the patching therapy. The homeostatic plasticity was assessed by measuring the temporary shift of perceptual Eye Dominance from 2-h occlusion of the amblyopic Eye before treatment. A binocular phase combination paradigm was used for this study. Results We found that there was no significant correlation between the temporary shift of perceptual Eye Dominance observed after 2-h occlusion of the amblyopic Eye and the improvement in visual acuity in the amblyopic Eye from 2 months of classical patching therapy. This result, although in disagreements with the conclusions of Lunghi et al. involving the short-term patching of the amblyopic Eye, is in fact consistent with a reanalysis of Lunghi and colleagues' data. Conclusion The short-term changes in perceptual Eye Dominance as a result of short-term monocular deprivation do not provide an index of cortical plasticity in the general sense such that they are able to predict acuity outcomes from longer-term classical patching.
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cholinergic potentiation alters perceptual Eye Dominance plasticity induced by a few hours of monocular patching in adults
Frontiers in Neuroscience, 2019Co-Authors: Yasha Sheynin, Mira Chamoun, Alex S. Baldwin, Robert F. Hess, Pedro Rosaneto, Elvire VaucherAbstract:A few hours of monocular deprivation with a diffuser Eye patch temporarily strengthens the contribution of the deprived Eye to binocular vision. This shift in favour of the deprived Eye is characterized as a form of adult visual plasticity. Studies in animal and human models suggest that neuromodulators can enhance adult brain plasticity in general. Specifically, acetylcholine has been shown to improve certain aspects of visual function and plasticity in adulthood. We investigated whether a single administration of donepezil (a cholinesterase inhibitor) could further augment the temporary shift in perceptual Eye Dominance that occurs after two hours of monocular patching. Twelve healthy adults completed two experimental sessions while taking either donepezil (5 mg, oral) or a placebo (lactose) pill. We measured perceptual Eye Dominance using a binocular phase combination task before and after two hours of monocular deprivation with a diffuser Eye patch. Participants in both groups demonstrated a significant shift in favour of the patched Eye after monocular deprivation, however our results indicate that donepezil significantly reduces the magnitude and duration of the shift. We also investigated the possibility that donepezil reduces the amount of time needed to observe a shift in perceptual Eye Dominance relative to placebo control. For this experiment, seven subjects completed two sessions where we reduced the duration of deprivation to one hour. Donepezil reduces the magnitude and duration of the patching-induced shift in perceptual Eye Dominance in this experiment as well. To verify whether the effects we observed using the binocular phase combination task were also observable in a different measure of sensory Eye Dominance, six subjects completed an identical experiment using a binocular rivalry task. These results also indicate that cholinergic enhancement impedes the shift that results from short-term deprivation. In summary, our study demonstrates that enhanced cholinergic potentiation interferes with the consolidation of the perceptual Eye Dominance plasticity induced by several hours of monocular deprivation.
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Cholinergic Potentiation Alters Perceptual Eye Dominance Plasticity Induced by a Few Hours of Monocular Patching in Adults
Frontiers Media S.A., 2019Co-Authors: Yasha Sheynin, Mira Chamoun, Alex S. Baldwin, Pedro Rosa-neto, Robert F. Hess, Elvire VaucherAbstract:A few hours of monocular deprivation with a diffuser Eye patch temporarily strengthens the contribution of the deprived Eye to binocular vision. This shift in favor of the deprived Eye is characterized as a form of adult visual plasticity. Studies in animal and human models suggest that neuromodulators can enhance adult brain plasticity in general. Specifically, acetylcholine has been shown to improve certain aspects of visual function and plasticity in adulthood. We investigated whether a single administration of donepezil (a cholinesterase inhibitor) could further augment the temporary shift in perceptual Eye Dominance that occurs after 2 h of monocular patching. Twelve healthy adults completed two experimental sessions while taking either donepezil (5 mg, oral) or a placebo (lactose) pill. We measured perceptual Eye Dominance using a binocular phase combination task before and after 2 h of monocular deprivation with a diffuser Eye patch. Participants in both groups demonstrated a significant shift in favor of the patched Eye after monocular deprivation, however our results indicate that donepezil significantly reduces the magnitude and duration of the shift. We also investigated the possibility that donepezil reduces the amount of time needed to observe a shift in perceptual Eye Dominance relative to placebo control. For this experiment, seven subjects completed two sessions where we reduced the duration of deprivation to 1 h. Donepezil reduces the magnitude and duration of the patching-induced shift in perceptual Eye Dominance in this experiment as well. To verify whether the effects we observed using the binocular phase combination task were also observable in a different measure of sensory Eye Dominance, six subjects completed an identical experiment using a binocular rivalry task. These results also indicate that cholinergic enhancement impedes the shift that results from short-term deprivation. In summary, our study demonstrates that enhanced cholinergic potentiation interferes with the consolidation of the perceptual Eye Dominance plasticity induced by several hours of monocular deprivation
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on the relationship between sensory Eye Dominance and stereopsis in the normal sighted adult population normative data
Frontiers in Human Neuroscience, 2018Co-Authors: Yonghua Wang, Jiawei Zhou, Lele Cui, Wenman Lin, Robert F. HessAbstract:The extent of sensory Eye Dominance, a reflection of the interocular suppression in binocular visual processing, can be quantitatively measured using the binocular phase combination task. In this study, we aimed to provide a normative dataset for sensory Eye Dominance using this task. Based on that, we also assessed the relationship between perceptual Eye Dominance and stereopsis. One-hundred and forty-two adults (average age: 24.00 ± 1.74 years old) with normal or corrected to normal monocular visual acuity (logMAR < 0.00) participated. Observer's sensory Eye Dominance was quantified in two complementary ways: the interocular contrast ratio when the two Eyes were balanced (i.e., the balance point) and the absolute value of the binocular perceived phase when each Eye viewed maximum contrast stimuli in binocular phase combination task. Stereo acuities were measured with maximum contrast stimuli using an identical spatial frequency (0.30 cycles/degree) and stimulus arrangement to that used in the Eye Dominance assessment. The averaged balance point was 0.93 ± 0.06 (Mean ± SD), the averaged absolute value of the binocular perceived phase when both Eyes viewed maximum contrast stimuli was 7.62 ± 5.91°, and the averaged stereo acuity was 2.19 ± 0.34 log arc seconds. Neither of these two sensory Eye Dominance measures were significantly correlated with stereo acuity (Balance point: ρ = 0.14, P = 0.10; Phase: ρ = -0.13, P = 0.13). The sensory Eye Dominance, as reflected using a phase combination task, and stereopsis are not significantly correlated in the normal-sighted population at low spatial frequencies.
Jiawei Zhou - One of the best experts on this subject based on the ideXlab platform.
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can short term ocular Dominance plasticity provide a general index to visual plasticity to personalize treatment in amblyopia
Frontiers in Neuroscience, 2020Co-Authors: Chunwen Tao, Jiawei Zhou, Yiya Chen, Robert F. HessAbstract:Purpose: Recently, Lunghi et al showed that amblyopic Eye’s visual acuity per se after 2 months of occlusion therapy could be predicted by a homeostatic plasticity, i.e., the temporary shift of perceptual Eye Dominance observed after a 2-hour monocular deprivation, in children with anisometropic amblyopia(Lunghi et al., 2016). In this study, we assess whether the visual acuity improvement of the amblyopic Eye measured after 2 months of occlusion therapy could be predicted by this plasticity. Methods: Seven children (6.86 ± 1.46 years old; SD) with anisometropic amblyopia participated in this study. All patients were newly diagnosed and had no treatment history before participating our study. They finished 2 months of refractive adaptation and then received a 4-hour daily fellow Eye patching therapy with an opaque patch for a 2-month period. Best-corrected visual acuity of the amblyopic Eye was measured before and after the patching therapy. The homeostatic plasticity was assessed by measuring the temporary shift of perceptual Eye Dominance from 2-hour occlusion of the amblyopic Eye before treatment. A binocular phase combination paradigm was used for this study. Results: We found that there was no significant correlation between the temporary shift of perceptual Eye Dominance observed after 2-hour occlusion of the amblyopic Eye and the improvement in visual acuity in the amblyopic Eye from 2-hour of classical patching therapy. This result, although in disagreements with the conclusions of Lunghi et al involving the short-term patching of the amblyopic Eye, is in fact consistent with a reanalysis of Lunghi et al’ s data. Conclusions: The short-term changes in perceptual Eye Dominance as a result of short-term monocular deprivation do not provide an index of cortical plasticity in the general sense such that they are able to predict acuity outcomes from longer term classical patching.
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can short term ocular Dominance plasticity provide a general index to visual plasticity to personalize treatment in amblyopia
Frontiers in Neuroscience, 2020Co-Authors: Zhifen He, Yiya Chen, Jiawei Zhou, Robert F. HessAbstract:Purpose Recently, Lunghi et al. (2016) showed that amblyopic Eye's visual acuity per se after 2 months of occlusion therapy could be predicted by a homeostatic plasticity, that is, the temporary shift of perceptual Eye Dominance observed after a 2-h monocular deprivation, in children with anisometropic amblyopia. In this study, we assess whether the visual acuity improvement of the amblyopic Eye measured after 2 months of occlusion therapy could be predicted by this plasticity. Methods Seven children (6.86 ± 1.46 years old; SD) with anisometropic amblyopia participated in this study. All patients were newly diagnosed and had no treatment history before participating in our study. They finished 2 months of refractive adaptation and then received a 4-h daily fellow Eye patching therapy with an opaque patch for a 2-month period. Best-corrected visual acuity of the amblyopic Eye was measured before and after the patching therapy. The homeostatic plasticity was assessed by measuring the temporary shift of perceptual Eye Dominance from 2-h occlusion of the amblyopic Eye before treatment. A binocular phase combination paradigm was used for this study. Results We found that there was no significant correlation between the temporary shift of perceptual Eye Dominance observed after 2-h occlusion of the amblyopic Eye and the improvement in visual acuity in the amblyopic Eye from 2 months of classical patching therapy. This result, although in disagreements with the conclusions of Lunghi et al. involving the short-term patching of the amblyopic Eye, is in fact consistent with a reanalysis of Lunghi and colleagues' data. Conclusion The short-term changes in perceptual Eye Dominance as a result of short-term monocular deprivation do not provide an index of cortical plasticity in the general sense such that they are able to predict acuity outcomes from longer-term classical patching.
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on the relationship between sensory Eye Dominance and stereopsis in the normal sighted adult population normative data
Frontiers in Human Neuroscience, 2018Co-Authors: Yonghua Wang, Jiawei Zhou, Lele Cui, Wenman Lin, Robert F. HessAbstract:The extent of sensory Eye Dominance, a reflection of the interocular suppression in binocular visual processing, can be quantitatively measured using the binocular phase combination task. In this study, we aimed to provide a normative dataset for sensory Eye Dominance using this task. Based on that, we also assessed the relationship between perceptual Eye Dominance and stereopsis. One-hundred and forty-two adults (average age: 24.00 ± 1.74 years old) with normal or corrected to normal monocular visual acuity (logMAR < 0.00) participated. Observer's sensory Eye Dominance was quantified in two complementary ways: the interocular contrast ratio when the two Eyes were balanced (i.e., the balance point) and the absolute value of the binocular perceived phase when each Eye viewed maximum contrast stimuli in binocular phase combination task. Stereo acuities were measured with maximum contrast stimuli using an identical spatial frequency (0.30 cycles/degree) and stimulus arrangement to that used in the Eye Dominance assessment. The averaged balance point was 0.93 ± 0.06 (Mean ± SD), the averaged absolute value of the binocular perceived phase when both Eyes viewed maximum contrast stimuli was 7.62 ± 5.91°, and the averaged stereo acuity was 2.19 ± 0.34 log arc seconds. Neither of these two sensory Eye Dominance measures were significantly correlated with stereo acuity (Balance point: ρ = 0.14, P = 0.10; Phase: ρ = -0.13, P = 0.13). The sensory Eye Dominance, as reflected using a phase combination task, and stereopsis are not significantly correlated in the normal-sighted population at low spatial frequencies.
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absolute not relative interocular luminance modulates sensory Eye Dominance plasticity in adults
Neuroscience, 2017Co-Authors: Zhimo Yao, Jiawei Zhou, Yonghua Wang, Robert F. HessAbstract:Abstract If one Eye is patched for a period of 2.5 h in human adults, transient changes in sensory Eye Dominance result with the previously patched Eye’s contribution being strengthened. Similar changes result from opaque and translucent occlusion suggesting that it is the deprivation of contrast not luminance information that drives these transient shift of sensory Eye Dominance. However, this does not rule out the possibility that luminance deprivation per se cannot produce changes in sensory Eye Dominance, indeed based on what we know of the physiology, where the contrast gain of visual neurons is luminance dependent, one would expect it should. We show that if the mean luminance of one Eye is reduced 1000-fold for a period of 2.5 h, there are subsequent changes in sensory Eye Dominance. With further control experiments we show that this deprivation effect critically depends on the absolute luminance of each Eye rather than the relative interocular luminance imbalance. These results indicate that changes in contrast gain at an early, monocular stage of the pathway can result in the transient shift of sensory Eye Dominance.
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chromatic and achromatic monocular deprivation produce separable changes of Eye Dominance in adults
Proceedings of The Royal Society B: Biological Sciences, 2017Co-Authors: Jiawei Zhou, Alexandre Reynaud, Yeon Jin Kim, Kathy T Mullen, Robert F. HessAbstract:Temporarily depriving one Eye of its input, in whole or in part, results in a transient shift in Eye Dominance in human adults, with the patched Eye becoming stronger and the unpatched Eye weaker. However, little is known about the role of colour contrast in these behavioural changes. Here, we first show that the changes in Eye Dominance and contrast sensitivity induced by monocular Eye patching affect colour and achromatic contrast sensitivity equally. We next use dichoptic movies, customized and filtered to stimulate the two Eyes differentially. We show that a strong imbalance in achromatic contrast between the Eyes, with no colour content, also produces similar, unselective shifts in Eye Dominance for both colour and achromatic contrast sensitivity. Interestingly, if this achromatic imbalance is paired with similar colour contrast in both Eyes, the shift in Eye Dominance is selective, affecting achromatic but not chromatic contrast sensitivity and revealing a dissociation in Eye Dominance for colour and achromatic image content. On the other hand, a strong imbalance in chromatic contrast between the Eyes, with no achromatic content, produces small, unselective changes in Eye Dominance, but if paired with similar achromatic contrast in both Eyes, no changes occur. We conclude that perceptual changes in Eye Dominance are strongly driven by interocular imbalances in achromatic contrast, with colour contrast having a significant counter balancing effect. In the short term, Eyes can have different Dominances for achromatic and chromatic contrast, suggesting separate pathways at the site of these neuroplastic changes.
Alain Guillaume - One of the best experts on this subject based on the ideXlab platform.
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Interhemispheric Transfer Time Asymmetry of Visual Information Depends on Eye Dominance: An Electrophysiological Study.
Frontiers in neuroscience, 2018Co-Authors: Romain Chaumillon, Jean Blouin, Alain GuillaumeAbstract:The interhemispheric transfer of information is a fundamental process in the human brain. When a visual stimulus appears eccentrically in one visual-hemifield, it will first activate the contralateral hemisphere but also the ipsilateral one with a slight delay due to the interhemispheric transfer. This interhemispheric transfer of visual information is believed to be faster from the right to the left hemisphere in right-handers. Such an asymmetry is considered as a relevant fact in the context of the lateralization of the human brain. We show here using current source density (CSD) analyses of visually evoked potential (VEP) that, in right-handers and, to a lesser extent in left-handers, this asymmetry is in fact dependent on the sighting Eye Dominance, the tendency we have to prefer one Eye for monocular tasks. Indeed, in right-handers, a faster interhemispheric transfer of visual information from the right to left hemisphere was observed only in participants with a right dominant Eye (DE). Right-handers with a left DE showed the opposite pattern, with a faster transfer from the left to the right hemisphere. In left-handers, albeit a smaller number of participants has been tested and hence confirmation is required, only those with a right DE showed an asymmetrical interhemispheric transfer with a faster transfer from the right to the left hemisphere. As a whole these results demonstrate that Eye Dominance is a fundamental determinant of asymmetries in interhemispheric transfer of visual information and suggest that it is an important factor of brain lateralization.
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2018Co-Authors: Romain Chaumillon, Jean Blouin, Alain GuillaumeAbstract:The interhemispheric transfer of information is a fundamental process in the human brain. When a visual stimulus appears eccentrically in one visual-hemifield, it will first activate the contralateral hemisphere but also the ipsilateral one with a slight delay due to the interhemispheric transfer. This interhemispheric transfer of visual information is believed to be faster from the right to the left hemisphere in right-handers. Such an asymmetry is considered as a relevant fact in the context of the lateralization of the human brain. We show here using current source density (CSD) analyses of visually evoked potential (VEP) that, in right-handers and, to a lesser extent in left-handers, this asymmetry is in fact dependent on the sighting Eye Dominance, the tendency we have to prefer one Eye for monocular tasks. Indeed, in right-handers, a faster interhemispheric transfer of visual information from the right to left hemisphere was observed only in participants with a right dominant Eye (DE). Right-handers with a left DE showed the opposite pattern, with a faster transfer from the left to the right hemisphere. In left-handers, albeit a smaller number of participants has been tested and hence confirmation is required, only those with a right DE showed an asymmetrical interhemispheric transfer with a faster transfer from the right to the left hemisphere. As a whole these results demonstrate that Eye Dominance is a fundamental determinant of asymmetries in interhemispheric transfer of visual information and suggest that it is an important factor of brain lateralization.
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asymmetry in visual information processing depends on the strength of Eye Dominance
Neuropsychologia, 2017Co-Authors: Romain Chaumillon, Jean Blouin, Alain Guillaume, Nadia Alahyane, Patrice Senot, Judith Vergne, Christelle Lemoinelardennois, Karine Doremazars, Dorine VergilinoperezAbstract:Unlike handedness, sighting Eye Dominance, defined as the Eye unconsciously chosen when performing monocular tasks, is very rarely considered in studies investigating cerebral asymmetries. We previously showed that sighting Eye Dominance has an influence on visually triggered manual action with shorter reaction time (RT) when the stimulus appears in the contralateral visual hemifield with respect to the dominant Eye (Chaumillon et al. 2014). We also suggested that Eye Dominance may be more or less pronounced depending on individuals and that this Eye Dominance strength could be evaluated through saccadic peak velocity analysis in binocular recordings (Vergilino-Perez et al. 2012). Based on these two previous studies, we further examine here whether the strength of the Eye Dominance can modulate the influence of this lateralization on manual reaction time. Results revealed that participants categorized as having a strong Eye Dominance, but not those categorized as having a weak Eye Dominance, exhibited the difference in RT between the two visual hemifields. This present study reinforces that the analysis of saccade peak velocity in binocular recordings provides an effective tool to better categorize the Eye Dominance. It also shows that the influence of Eye Dominance in visuo-motor tasks depends on its strength. Our study also highlights the importance of considering the strength of Eye Dominance in future studies dealing with brain lateralization.
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Eye Dominance influences triggering action the poffenberger paradigm revisited
Cortex, 2014Co-Authors: Romain Chaumillon, Jean Blouin, Alain GuillaumeAbstract:Our dominant Eye (DE) is the one we unconsciously choose when performing a monocular task. Although it has been recognized for centuries, Eye Dominance and its behavioral consequences remain poorly understood. Here we used the simple and well-known Poffenberger paradigm (1912) in which participants press a button with the right or left index finger, in reaction to the appearance of a lateralized visual stimulus. By selecting participants according to their DE and handedness, we were able to decipher the impact of Eye Dominance on visuomotor transformation speed. We show, for the first time, that in right-handers simple reaction times (RT) in response to a lateralized visual target are shorter when it appears in the contralateral visual hemifield with respect to the DE. In left-handers, only those with a right DE exhibit a shorter RT with the left hand and they show no hemifield difference. Additionally, the Poffenberger paradigm has been used to estimate the interhemispheric transfer time (IHTT) in both directions, from the right to the left hemisphere or the reverse, by comparing hand RTs following stimulation of each visual hemifield. The present study demonstrates that this paradigm leads to biased estimations of these directionally considered IHTT and provides an explanation to the often reported IHTT negative values that otherwise appear implausible. These new findings highlight the need to consider Eye Dominance in studies investigating the neural processes underlying visually-guided actions. More generally, they demonstrate a substantial impact of Eye Dominance on the neural mechanisms involved in converting visual inputs into motor commands.
Teng Leng Ooi - One of the best experts on this subject based on the ideXlab platform.
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sensory Eye Dominance relationship between Eye and brain
Eye and Brain, 2020Co-Authors: Teng Leng OoiAbstract:Eye Dominance refers to the preference to use one Eye more than the fellow Eye to accomplish a task. However, the dominant Eye revealed can be task dependent especially when the tasks are as diverse as instructing the observer to sight a target through a ring, or to report which half-image is perceived more of during binocular rivalry stimulation. Conventionally, the former task is said to reveal motor Eye Dominance while the latter task reveals sensory Eye Dominance. While the consensus is that the motor and sensory-dominant Eye could be different in some observers, the reason for it is still unclear and has not been much researched. This review mainly focuses on advances made in recent studies of sensory Eye Dominance. It reviews studies conducted to quantify and relate sensory Eye Dominance to other visual functions, in particular to stereopsis, as well as studies conducted to explore its plasticity. It is recognized that sensory Eye Dominance in observers with clinically normal vision shares some similarity with amblyopia at least at the behavioral level, in that both exhibit an imbalance of interocular inhibition. Furthermore, sensory Eye Dominance is probably manifested at multiple sites along the visual pathway, perhaps including the level of ocular Dominance columns. But future studies with high-resolution brain imaging approaches are required to confirm this speculation in the human visual system.
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effect of interocular contrast difference on stereopsis in observers with sensory Eye Dominance
Investigative Ophthalmology & Visual Science, 2019Co-Authors: Chao Han, Teng Leng OoiAbstract:Purpose We investigated how sensory Eye Dominance (SED) affects stereopsis when the half-images of random-dot-stereo stimuli had different interocular contrast. Methods We measured crossed and uncrossed stereo disparity thresholds and reaction time to seeing random-dot-stereograms with variable interocular contrast differences (ICD), where ICD = (log10 [CLE] - log10 [CRE]) = -0.4, -0.2, 0, 0.2, or 0.4 log unit. The mean contrast of the stimuli, (log10 [CLE] + log10 [CRE])/2, remained constant at 1.2 log unit to ensure that the measured effect was solely due to ICD. We also measured SED using, respectively, dichoptic horizontal sine wave gratings with different phases (revealing SEDcombo) and dichoptic vertical and horizontal gratings (revealing SEDinhibition). Results Both measures of SEDinhibition and SEDcombo revealed the observers had the same Eye as dominant although the magnitudes differed. The observers had lower stereo thresholds and shorter stereo reaction time on stimuli with unequal interocular contrast when the non-sensory-dominant Eye viewed the higher contrast half-image, suggesting a stimulus-compensating effect. We then estimated the ICD of random-dot-stereo half-images (compensating stimuli) that would lead to minimum stereo threshold (SEDstereo-threshold) and reaction time (SEDstereo-RT) based on the stereo performance and ICD relationship, and found that they were significantly smaller than SEDinhibition and SEDcombo. Conclusions By linking SEDinhibition and SEDcombo with the effect of ICD on stereopsis, we provided further support for the notion that the stimulus-compensating effect is mediated by the interocular inhibitory and interocular gain control mechanisms. Furthermore, the interocular contrast for SEDstereo-threshold and SEDstereo-RT can be potentially applied for improving stereopsis in individuals with SED.
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on sensory Eye Dominance revealed by binocular integrative and binocular competitive stimuli
Investigative Ophthalmology & Visual Science, 2018Co-Authors: Chao Han, Teng Leng OoiAbstract:Purpose Two core processes underlie 3-D binocular vision. The first, a binocular combination/summation process, integrates similar feature signals from the two Eye channels to form a binocular representation. The second, a binocular inhibitory process, suppresses interocular conflicting signals or falsely matched binocular representations to establish single vision. Having an intrinsic interocular imbalance within one or both processes can cause sensory Eye Dominance (SED), related to imbalances of combination (SEDcombo) and/or inhibition (SEDinhibition). While much has recently been revealed about SEDcombo and SEDinhibition, the relationship between them is still unknown. Methods We measured observers' foveal SEDcombo and SEDinhibition, respectively, with a pair of dichoptic horizontal sine wave gratings with different phases and binocular rivalry stimulus with vertical and horizontal gratings. We then measured horizontal and vertical monocular contrast thresholds using sinusoidal grating stimuli, and stereo thresholds using random-dot stereograms. Results There exists a strong correlation between SEDcombo and SEDinhibition. An observer's interocular difference in contrast threshold was not always consistent with his/her SEDcombo and SEDinhihition, suggesting a partial binocular origin for the underlying imbalances. We also found stereo thresholds significantly increased with the magnitudes of SEDcombo, as well as with the magnitude of SEDinhibition. Conclusions Our findings suggest a common origin for interocular imbalance in the two different binocular processes and that both types of sensory Eye Dominance are significant factors in impeding stereopsis.
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push pull training reduces foveal sensory Eye Dominance within the early visual channels
Vision Research, 2012Co-Authors: Teng Leng OoiAbstract:A push-pull training protocol is applied to reduce sensory Eye Dominance in the foveal region. The training protocol consists of cueing the weak Eye to force it to become dominant while the strong Eye is suppressed when a pair of dichoptic orthogonal grating stimulus is subsequently presented to it (Ooi & He, 1999). We trained with four pairs of dichoptic orthogonal gratings (0°/90°, 90°/0°, 45°/135° and 135°/45° at 3cpd) to affect the interocular inhibitory interaction tuned to the four trained orientations (0°, 45°, 90° and 135°). After a 10-day training session, we found a significant learning effect (reduced sensory Eye Dominance) at the trained orientations as well as at two other untrained orientations (22.5° and 67.5°). This suggests that the four pairs of oriented training stimuli are sufficient to produce a learning effect at any other orientation. The nearly complete transfer of the learning effect across orientation is attributed to the fact that the trained and untrained orientations are close enough to fall in the same orientation tuning function of the early visual cortical neurons (∼37.5°). Applying the same notion of transfer of learning within the same feature channel, we also found a large transfer effect to an untrained spatial frequency (6cpd), which is 1 octave higher than the trained spatial frequency (3cpd). Furthermore, we found that stereopsis is improved, as is the competitive ability between the two Eyes, after the push-pull training. Our data analysis suggests that these improvements are correlated with the reduced sensory Eye Dominance after the training, i.e., due to a more balanced interocular inhibition. We also found that the learning effect (reduced SED and stereo threshold) can be retained for more than a year after the termination of the push-pull training.
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perceptual learning to reduce sensory Eye Dominance beyond the focus of top down visual attention
Vision Research, 2012Co-Authors: Teng Leng OoiAbstract:Perceptual learning is an important means for the brain to maintain its agility in a dynamic environment. Top-down focal attention, which selects task-relevant stimuli against competing ones in the background, is known to control and select what is learned in adults. Still unknown, is whether the adult brain is able to learn highly visible information beyond the focus of top-down attention. If it is, we should be able to reveal a purely stimulus-driven perceptual learning occurring in functions that are largely determined by the early cortical level, where top-down attention modulation is weak. Such an automatic, stimulus-driven learning mechanism is commonly assumed to operate only in the juvenile brain. We performed perceptual training to reduce sensory Eye Dominance (SED), a function that taps on the Eye-of-origin information represented in the early visual cortex. Two retinal locations were simultaneously stimulated with suprathreshold, dichoptic orthogonal gratings. At each location, monocular cueing triggered perception of the grating images of the weak Eye and suppression of the strong Eye. Observers attended only to one location and performed orientation discrimination of the gratings seen by the weak Eye, while ignoring the highly visible gratings at the second, unattended, location. We found SED was not only reduced at the attended location, but also at the unattended location. Furthermore, other untrained visual functions mediated by higher cortical levels improved. An automatic, stimulus-driven learning mechanism causes synaptic alterations in the early cortical level, with a far-reaching impact on the later cortical levels.
Elvire Vaucher - One of the best experts on this subject based on the ideXlab platform.
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cholinergic potentiation alters perceptual Eye Dominance plasticity induced by a few hours of monocular patching in adults
Frontiers in Neuroscience, 2019Co-Authors: Yasha Sheynin, Mira Chamoun, Alex S. Baldwin, Robert F. Hess, Pedro Rosaneto, Elvire VaucherAbstract:A few hours of monocular deprivation with a diffuser Eye patch temporarily strengthens the contribution of the deprived Eye to binocular vision. This shift in favour of the deprived Eye is characterized as a form of adult visual plasticity. Studies in animal and human models suggest that neuromodulators can enhance adult brain plasticity in general. Specifically, acetylcholine has been shown to improve certain aspects of visual function and plasticity in adulthood. We investigated whether a single administration of donepezil (a cholinesterase inhibitor) could further augment the temporary shift in perceptual Eye Dominance that occurs after two hours of monocular patching. Twelve healthy adults completed two experimental sessions while taking either donepezil (5 mg, oral) or a placebo (lactose) pill. We measured perceptual Eye Dominance using a binocular phase combination task before and after two hours of monocular deprivation with a diffuser Eye patch. Participants in both groups demonstrated a significant shift in favour of the patched Eye after monocular deprivation, however our results indicate that donepezil significantly reduces the magnitude and duration of the shift. We also investigated the possibility that donepezil reduces the amount of time needed to observe a shift in perceptual Eye Dominance relative to placebo control. For this experiment, seven subjects completed two sessions where we reduced the duration of deprivation to one hour. Donepezil reduces the magnitude and duration of the patching-induced shift in perceptual Eye Dominance in this experiment as well. To verify whether the effects we observed using the binocular phase combination task were also observable in a different measure of sensory Eye Dominance, six subjects completed an identical experiment using a binocular rivalry task. These results also indicate that cholinergic enhancement impedes the shift that results from short-term deprivation. In summary, our study demonstrates that enhanced cholinergic potentiation interferes with the consolidation of the perceptual Eye Dominance plasticity induced by several hours of monocular deprivation.
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Cholinergic Potentiation Alters Perceptual Eye Dominance Plasticity Induced by a Few Hours of Monocular Patching in Adults
Frontiers Media S.A., 2019Co-Authors: Yasha Sheynin, Mira Chamoun, Alex S. Baldwin, Pedro Rosa-neto, Robert F. Hess, Elvire VaucherAbstract:A few hours of monocular deprivation with a diffuser Eye patch temporarily strengthens the contribution of the deprived Eye to binocular vision. This shift in favor of the deprived Eye is characterized as a form of adult visual plasticity. Studies in animal and human models suggest that neuromodulators can enhance adult brain plasticity in general. Specifically, acetylcholine has been shown to improve certain aspects of visual function and plasticity in adulthood. We investigated whether a single administration of donepezil (a cholinesterase inhibitor) could further augment the temporary shift in perceptual Eye Dominance that occurs after 2 h of monocular patching. Twelve healthy adults completed two experimental sessions while taking either donepezil (5 mg, oral) or a placebo (lactose) pill. We measured perceptual Eye Dominance using a binocular phase combination task before and after 2 h of monocular deprivation with a diffuser Eye patch. Participants in both groups demonstrated a significant shift in favor of the patched Eye after monocular deprivation, however our results indicate that donepezil significantly reduces the magnitude and duration of the shift. We also investigated the possibility that donepezil reduces the amount of time needed to observe a shift in perceptual Eye Dominance relative to placebo control. For this experiment, seven subjects completed two sessions where we reduced the duration of deprivation to 1 h. Donepezil reduces the magnitude and duration of the patching-induced shift in perceptual Eye Dominance in this experiment as well. To verify whether the effects we observed using the binocular phase combination task were also observable in a different measure of sensory Eye Dominance, six subjects completed an identical experiment using a binocular rivalry task. These results also indicate that cholinergic enhancement impedes the shift that results from short-term deprivation. In summary, our study demonstrates that enhanced cholinergic potentiation interferes with the consolidation of the perceptual Eye Dominance plasticity induced by several hours of monocular deprivation
