Eye-movement training-induced plasticity in patients with post-stroke hemianopia

Nelles, Gereon; Pscherer, Anja; Greiff, Armin de; Forsting, Michael; Gerhard, H.; Esser, Joachim; Hc, Diener

doi:10.1007/s00415-009-5005-x

Cited by 38 publications

(25 citation statements)

References 28 publications

(28 reference statements)

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“…Thus these training programs require patients to search for a number of targets over an extended time period and have explicitly instructed patients to make large initial saccades into the hemianopic hemifield, and to search in a rigid systematic manner [5, 24, 28, 31, 32, 35, 36] or through extended visual search training [37]. By contrast we trained [30] subjects to search for a single target for 3 s or less, and did not suggest any particular oculomotor behaviour.…”

Section: Discussionmentioning

confidence: 99%

“…Secondly, as repeated visual search practise leads to perceptual learning can the reductions in response times associated with visual search training be explained by neuronal changes in response to the learnt stimulus features, rather than changes in eye movement strategies? Several recent studies have attempted to answer these questions by evaluating oculomotor behaviour in patients with HH following oculomotor training [35, 36] or training on extended visual search containing multiple targets [37]. By contrast, Pambakian et al [30] trained 29 patients with homonymous visual field defects to perform visual search without prescribing any particular oculomotor strategy to patients, reasoning that repeated visual search practise with search durations of 3 s or less would allow patients to develop their own adaptive scanpaths [38].…”

Section: Introductionmentioning

confidence: 99%

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Compensatory strategies following visual search training in patients with homonymous hemianopia: an eye movement study

2010

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A total of 29 patients with homonymous visual field defects without neglect practised visual search in 20 daily sessions, over a period of 4 weeks. Patients searched for a single randomly positioned target amongst distractors displayed for 3 s. After training patients demonstrated significantly shorter reaction times for search stimuli (Pambakian et al. in J Neurol Neurosurg Psychiatry 75:1443–1448, 2004). In this study, patients achieved improved search efficiency after training by altering their oculomotor behaviour in the following ways: (1) patients directed a higher proportion of fixations into the hemispace containing the target, (2) patients were quicker to saccade into the hemifield containing the target if the initial saccade had been made into the opposite hemifield, (3) patients made fewer transitions from one hemifield to another before locating the target, (4) patients made a larger initial saccade, although the direction of the initial saccade did not change as a result of training, (5) patients acquired a larger visual lobe in their blind hemifield after training. Patients also required fewer saccades to locate the target after training reflecting improved search efficiency. All these changes were confined to the training period and maintained at follow-up. Taken together these results suggest that visual training facilitates the development of specific compensatory eye movement strategies in patients with homonymous visual field defects.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Compensatory strategies following visual search training in patients with homonymous hemianopia: an eye movement study

2010

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“…However, such modulatory effects on the delay period activity in naive monkeys were observed only in a small fraction of the neurons with saccadic bursts, while the majority of the neurons in the ipsi SC showed sustained activities during the delay period regardless of the presence or absence of saccadic bursts. Therefore, it seems likely that a kind of plastic changes in response to the V1 lesion (Leh et al, 2006;Bridge et al, 2008;Nelles et al, 2009) underlies the sustained activity in the ipsi SC. Given that a previous study reported that visually driven activity was absent in the deeper layer of the SC after lesion and during inactivation of the V1 in anesthetized, untrained monkeys (Schiller et al, 1974), the visual response observed in this study seems to emerge as a result of the recovery processes and the behavioral training.…”

Section: Discussionmentioning

confidence: 99%

Neural Substrate of Spatial Memory in the Superior Colliculus after Damage to the Primary Visual Cortex

Takaura¹,

Yoshida²,

Isa³

2011

J. Neurosci.

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In the primate brain, the primary visual cortex (V1) is a major source of visual information processing in the cerebral cortex, although some patients and monkeys with damage to the V1 show visually guided behaviors in the visual field affected by the damage. Until now, behaviors of the surviving brain regions after damage to V1 and their contribution to the residual visual functions remain unclear. Here, we report that the monkeys with a unilateral lesion of V1 can make not only visually guided saccades but also memory-guided saccades (MGS) into the affected visual field. Furthermore, while the monkeys were performing the MGS task, sustained activity was observed in a large fraction of the neurons in the superior colliculus ipsilateral to the lesion, which has been supposed as a key node for recovery after damage to V1. These neurons maintained the spatial information throughout the delay period regardless of whether they exhibited saccadic bursts or not, which was not the case on the intact side. Error analysis revealed that the sustained activity was correlated with monkeys' behavioral outcome. These results suggest that the ipsilesional SC might function as a neural substrate for spatial memory in the affected visual field. Our findings provide new insight into the understanding of the compensatory mechanisms after damage to V1.

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“…This concept also underlies rehabilitation strategies that use visuospatial cues to direct attention to locations in or at the edge of the blind field (e.g. [39]). We assume that an endogenous spatial attention bias develops gradually as a result of repetitive, spatially biased eye movement training.…”

Section: Methodsmentioning

confidence: 99%

Visual Search and Line Bisection in Hemianopia: Computational Modelling of Cortical Compensatory Mechanisms and Comparison with Hemineglect

Lanyon

Barton

2013

PLoS ONE

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Hemianopia patients have lost vision from the contralateral hemifield, but make behavioural adjustments to compensate for this field loss. As a result, their visual performance and behaviour contrast with those of hemineglect patients who fail to attend to objects contralateral to their lesion. These conditions differ in their ocular fixations and perceptual judgments. During visual search, hemianopic patients make more fixations in contralesional space while hemineglect patients make fewer. During line bisection, hemianopic patients fixate the contralesional line segment more and make a small contralesional bisection error, while hemineglect patients make few contralesional fixations and a larger ipsilesional bisection error. Hence, there is an attentional failure for contralesional space in hemineglect but a compensatory adaptation to attend more to the blind side in hemianopia. A challenge for models of visual attentional processes is to show how compensation is achieved in hemianopia, and why such processes are hindered or inaccessible in hemineglect. We used a neurophysiology-derived computational model to examine possible cortical compensatory processes in simulated hemianopia from a V1 lesion and compared results with those obtained with the same processes under conditions of simulated hemineglect from a parietal lesion. A spatial compensatory bias to increase attention contralesionally replicated hemianopic scanning patterns during visual search but not during line bisection. To reproduce the latter required a second process, an extrastriate lateral connectivity facilitating form completion into the blind field: this allowed accurate placement of fixations on contralesional stimuli and reproduced fixation patterns and the contralesional bisection error of hemianopia. Neither of these two cortical compensatory processes was effective in ameliorating the ipsilesional bias in the hemineglect model. Our results replicate normal and pathological patterns of visual scanning, line bisection, and differences between hemianopia and hemineglect, and may explain why compensatory processes that counter the effects of hemianopia are ineffective in hemineglect.

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Eye-movement training-induced plasticity in patients with post-stroke hemianopia

Cited by 38 publications

References 28 publications

Compensatory strategies following visual search training in patients with homonymous hemianopia: an eye movement study

Compensatory strategies following visual search training in patients with homonymous hemianopia: an eye movement study

Neural Substrate of Spatial Memory in the Superior Colliculus after Damage to the Primary Visual Cortex

Visual Search and Line Bisection in Hemianopia: Computational Modelling of Cortical Compensatory Mechanisms and Comparison with Hemineglect

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