Hyper-vision in a patient with central and paracentral vision loss reflects cortical reorganization

Casco, Clara; Campana, Gianluca; Grieco, Alba; Musetti, Silvana; Perrone, Salvatore

doi:10.1017/s0952523803205046

Cited by 11 publications

(20 citation statements)

References 39 publications

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“…In explaining the lack of the crowding effect for MD patients it should be noted that for MD2 and MD3 critical spacing was already very low before PL, confirming the evidence of a major use-dependent responsiveness of eccentric vision in MD patients (Casco et al, 2003;De Stefani, Pinello, Campana, Mazzarolo, Lo Giudice, & Casco, 2011) and an overall reduced crowding effect for the PRL location in MD patients without previous training (Chung, 2011).…”

Section: Fig 7 About Here]mentioning

confidence: 49%

“…This aspect should be taken into account when planning a training protocol for MD patients who often have non-localized PRL or more than one PRL (Timberlake et al, 1987). However, since it is unpractical to use eye movements recording during PL, it should be considered whether it is more appropriate to present randomly the stimuli either in the right or in the left visual hemi-field for very short durations, a procedure that reduces eye movements (Casco et al, 2003) or simply train the PRL.…”

Section: Discussionmentioning

confidence: 99%

“…PL results (pooled for retinal location) are shown in The effect of PL on retinal location suggesting that MD patients can maximize the effect of PL even if the stimulus location is not optimal for fixation (Casco, Campana, Grieco, Musetti, & Perrone, 2003).…”

Section: The Effect Of Pl On Sensitivity (D')mentioning

confidence: 99%

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Perceptual learning leads to long lasting visual improvement in patients with central vision loss

Maniglia

Pavan

Sato³

et al. 2016

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2 AbstractPurpose: The study investigated whether perceptual learning (PL) of a task consisting in detecting a low contrast Gabor patch flanked above and below by high contrast Gabor patches presented monocularly in the preferred retinal locus (PRL) of patients with macular degeneration (MD), improved their residual visual functions. Method:We measured contrast detection thresholds using both a Yes/No task (three MD patients and three controls) and a temporal two-alternative forced-choice task (2AFC; four MD patients and three controls).Results: Both tasks produced a significant improvement in contrast sensitivity for the trained target.However, only in the case of the temporal-2AFC this improvement depended on the target-toflankers distance. Furthermore, in both tasks PL improved visual acuity but with the temporal-2AFC task we found a higher degree of generalization of the training to untrained stimuli and tasks.In fact, we found a reduction of the crowding effect and an improvement of the contrast sensitivity for untrained spatial frequencies.Although PL is more effective with a temporal-2AFC task, it is also present with a Yes/No task, suggesting that PL reflects sensory enhancement, rather than improvement in decision mechanisms.Most importantly, follow-up tests on MD patients showed that PL effects were retained between four and eight months, suggesting PL induced long-term neural plasticity in the visual cortex. Conclusion:The results show for the first time that PL with a collinear configuration has strong, non-invasive and long lasting rehabilitative potential to improve vision in the PRL of patients with central vision loss.3

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confidence: 49%

Section: Discussionmentioning

confidence: 99%

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Perceptual learning leads to long lasting visual improvement in patients with central vision loss

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Pavan

Sato³

et al. 2016

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“…Casco et al (2003) recently reported on a comparison in parafoveal and peripheral visual function between a 21-year-old JMD patient and a group of normally sighted control participants. Casco et al found comparable or even better performance from the JMD patient in some of the parafoveal and peripheral visual tasks including lexical decision, recognition of crowded letters and visual search.…”

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confidence: 99%

Functional and cortical adaptations to central vision loss

2005

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Age-related macular degeneration (AMD), affecting the retina, afflicts one out of ten people aged 80 years or older in the United States. AMD often results in vision loss to the central 15-20 deg of the visual field (i.e. central scotoma), and frequently afflicts both eyes. In most cases, when the central scotoma includes the fovea, patients will adopt an eccentric preferred retinal locus (PRL) for fixation. The onset of a central scotoma results in the absence of retinal inputs to corresponding regions of retinotopically mapped visual cortex. Animal studies have shown evidence for reorganization in adult mammals for such cortical areas following experimentally induced central scotomata. However, it is still unknown whether reorganization occurs in primary visual cortex (V1) of AMD patients. Nor is it known whether the adoption of a PRL corresponds to changes to the retinotopic mapping of V1. Two recent advances hold out the promise for addressing these issues and for contributing to the rehabilitation of AMD patients: improved methods for assessing visual function across the fields of AMD patients using the scanning laser ophthalmoscope, and the advent of brain-imaging methods for studying retinotopic mapping in humans. For the most part, specialists in these two areas come from different disciplines and communities, with few opportunities to interact. The purpose of this review is to summarize key findings on both the clinical and neuroscience issues related to questions about visual adaptation in AMD patients.

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“…The success of some patients with macular degeneration in the successful negotiation of activities of daily life indicates that the brain is capable of compensation for this disruption. [8][9][10] If we can understand this natural process, we may be able to enhance this process for other patients during visual rehabilitation.…”

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Reproducibility of Activation Maps for Longitudinal Studies of Visual Function by Functional Magnetic Resonance Imaging

Ming

Thulborn

Szlyk

2012

Invest. Ophthalmol. Vis. Sci.

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PURPOSE.To test the intra-and intersubject reproducibility of brain activation patterns that underlie visually guided saccades and word recognition in normally sighted subjects and patients with macular degeneration using functional magnetic resonance imaging (fMRI). METHODS.Ten normally sighted subjects and five patients with macular degeneration were asked to perform two visually guided saccade tasks and two word-recognition tasks during fMRI with behavioral monitoring. The fMRI measurements were repeated three times at intervals of at least 4 weeks between sessions. The intrasubject reproducibility of the brain activation patterns was examined in a model-independent manner by comparing the distributions of activation across the frontal, parietal, temporal, and occipital brain lobes using Intraclass Correlation Coefficients (ICCs). Intersubject reproducibility was examined by repeated-measure ANOVA.RESULTS. Control subjects showed overall higher intrasubject reproducibility of brain activation patterns (75% ICCs > 0.5) than that of patients with macular degeneration (56% ICCs > 0.5). The intrasubject reproducibility for the patients improved when the target location was fixed, as in the word-recognition tasks (75% ICCs > 0.5), compared with the visually saccade tasks (37% ICCs > 0.5). Intersubject variability of brain activation patterns was strikingly high for both the control and patient groups.CONCLUSIONS. The fMRI method can serve as a reliable withinsubjects measure of brain activation that has potential for measuring longitudinal changes in brain networks associated with rehabilitation training. Striking intersubject variability reflected at the level of lobes of the brain among control subjects with similar behavioral performance, suggests individual analysis is necessary when implementing longitudinal brain activation studies. (Invest Ophthalmol Vis Sci.

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Hyper-vision in a patient with central and paracentral vision loss reflects cortical reorganization

Cited by 11 publications

References 39 publications

Perceptual learning leads to long lasting visual improvement in patients with central vision loss

Perceptual learning leads to long lasting visual improvement in patients with central vision loss

Functional and cortical adaptations to central vision loss

Reproducibility of Activation Maps for Longitudinal Studies of Visual Function by Functional Magnetic Resonance Imaging

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