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René M. Müri - One of the best experts on this subject based on the ideXlab platform.
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Visual Exploration area in neglect a new analysis method for video oculography data based on foveal vision
Frontiers in Neuroscience, 2020Co-Authors: Brigitte C Kaufmann, René M. Müri, Dario Cazzoli, Samuel E J Knobel, Thomas NyffelerAbstract:Video-oculography during Free Visual Exploration (FVE) is a valuable tool to evaluate Visual attention spatial allocation in neglect patients after right-hemispheric stroke. In conventional FVE analyses, the position of a Visual fixation is conceived as a single point in space. Here, we describe a new, complementary method to analyse FVE data, based on foveal vision, leading to an accurate estimate of the portion of the picture that was effectively explored. In 15 neglect patients and 20 healthy controls, Visual Exploration areas (i.e., considering 1°Visual angle around every single fixation) were computed. Furthermore, the proportion of single and overlapping fixations was analysed. Overlapping fixations were further categorized into capture fixations (successive overlapping fixation, putatively reflecting problem of disengagement) and re-capture fixations (temporally distant overlapping fixations, putatively reflecting spatial working memory deficits). The results of this new analysis approach were compared to the ones of conventional approaches. Conventional analyses showed the typical Visual attention deficits in neglect patients versus healthy controls: significantly less fixations and time spent within the left, and significantly more fixations and time spent within the right screen half. According the results of our new approach, patients showed a significantly smaller Visual Exploration area within the left screen half. However, the right Visual Exploration area did not differ between groups. Furthermore, in neglect patients, the proportion of overlapping fixations within the right screen half was significantly higher than within the left screen half, as well as significantly higher than in healthy controls within either screen halves. Whereas neglect patients showed significantly more capture fixations than healthy controls, the number of re-capture fixations did not differ between groups. These results suggest that, in neglect patients, the efficiency of Visual Exploration is also reduced within the right screen half and that impaired disengagement might be an important mechanism leading to overlapping fixations. Our new analysis of the Visual Exploration area, based on foveal vision, may be a promising, additional approach in Visual attention research. It allows to accurately measure the portion of the picture that was effectively explored, disentangle single from overlapping fixations, and distinguish between capture and re-capture fixations.
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Further to the right: Viewing distance modulates attentional asymmetries ('pseudoneglect') during Visual Exploration.
Brain and Cognition, 2018Co-Authors: Matthias Hartmann, René M. Müri, Nils R. Sommer, Lorenzo Diana, Aleksandra K. Eberhard-moscickaAbstract:Abstract Previous studies showed that the small leftward bias found in healthy humans’ spatial judgments of lines (“pseudoneglect”) shifts to the right with increasing distance between stimuli and observer. In this study, we investigated whether such a modulation of attentional asymmetry can also be observed in free Visual Exploration. Participants freely explored photographs of naturalistic scenes for 7 s in near (60 cm) and far (140 cm) space. After an initial leftward bias, followed by a compensatory rightward bias, gaze positions were significantly more leftward in near compared to far space (around 4 s from scene onset). Our results show that the modulation of attentional asymmetries by viewing distance previously reported for spatial judgments generalizes to free Visual Exploration, and we revealed the temporal dynamics of these asymmetries by fine-grained eye movement analysis. In contrast, an effect of viewing distance was reduced or absent when eye movements are under strong top-down control, as in systematic serial Visual search (Sensitive Negelct Test). Finally, there was no effect of viewing distance in the landmark task (as also reported in a minority of other studies), suggesting that this effect may depend on specific, yet unidentified task characteristics.
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Age-dependent Visual Exploration during simulated day- and night driving on a motorway: a cross-sectional study
BMC Geriatrics, 2015Co-Authors: Prabitha Urwyler, René M. Müri, Nicole Gruber, Michael Jäger, Rahel Bieri, Thomas Nyffeler, Urs Peter MosimannAbstract:Background Central and peripheral vision is needed for object detection. Previous research has shown that Visual target detection is affected by age. In addition, light conditions also influence Visual Exploration. The aim of the study was to investigate the effects of age and different light conditions on Visual Exploration behavior and on driving performance during simulated driving.
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Development and evaluation of a new instrument to measure Visual Exploration behavior
Medical Engineering & Physics, 2013Co-Authors: Nicole Gruber, René M. Müri, Thomas Nyffeler, Giuseppe Angelo Zito, Urs Peter MosimannAbstract:Effective Visual Exploration is required for many activities of daily living and instruments to assess Visual Exploration are important for the evaluation of the Visual and the oculomotor system. In this article, the development of a new instrument to measure central and peripheral target recognition is described. The measurement setup consists of a hemispherical projection which allows presenting images over a large area of ±90° horizontal and vertical angle. In a feasibility study with 14 younger (21–49 years) and 12 older (50–78 years) test persons, 132 targets and 24 distractors were presented within naturalistic color photographs of everyday scenes at 10°, 30°, and 50° eccentricity. After the experiment, both younger and older participants reported in a questionnaire that the task is easy to understand, fun and that it measures a competence that is relevant for activities of daily living. A main result of the pilot study was that younger participants recognized more targets with smaller reaction times than older participants. The group differences were most pronounced for peripheral target detection. This test is feasible and appropriate to assess the functional field of view in younger and older adults.
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neglect like Visual Exploration behaviour after theta burst transcranial magnetic stimulation of the right posterior parietal cortex
European Journal of Neuroscience, 2008Co-Authors: Thomas Nyffeler, Dario Cazzoli, Pascal Wurtz, Mathias Luthi, Roman Von Wartburg, Silvia Chaves, Anouk Deruaz, Christian W Hess, René M. MüriAbstract:The right posterior parietal cortex (PPC) is critically involved in Visual Exploration behaviour, and damage to this area may lead to neglect of the left hemispace. We investigated whether neglect-like Visual Exploration behaviour could be induced in healthy subjects using theta burst repetitive transcranial magnetic stimulation (rTMS). To this end, one continuous train of theta burst rTMS was applied over the right PPC in 12 healthy subjects prior to a Visual Exploration task where colour photographs of real-life scenes were presented on a computer screen. In a control experiment, stimulation was also applied over the vertex. Eye movements were measured, and the distribution of Visual fixations in the left and right halves of the screen was analysed. In comparison to the performance of 28 control subjects without stimulation, theta burst rTMS over the right PPC, but not the vertex, significantly decreased cumulative fixation duration in the left screen-half and significantly increased cumulative fixation duration in the right screen-half for a time period of 30 min. These results suggest that theta burst rTMS is a reliable method of inducing transient neglect-like Visual Exploration behaviour.
Thomas Nyffeler - One of the best experts on this subject based on the ideXlab platform.
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Visual Exploration area in neglect a new analysis method for video oculography data based on foveal vision
Frontiers in Neuroscience, 2020Co-Authors: Brigitte C Kaufmann, René M. Müri, Dario Cazzoli, Samuel E J Knobel, Thomas NyffelerAbstract:Video-oculography during Free Visual Exploration (FVE) is a valuable tool to evaluate Visual attention spatial allocation in neglect patients after right-hemispheric stroke. In conventional FVE analyses, the position of a Visual fixation is conceived as a single point in space. Here, we describe a new, complementary method to analyse FVE data, based on foveal vision, leading to an accurate estimate of the portion of the picture that was effectively explored. In 15 neglect patients and 20 healthy controls, Visual Exploration areas (i.e., considering 1°Visual angle around every single fixation) were computed. Furthermore, the proportion of single and overlapping fixations was analysed. Overlapping fixations were further categorized into capture fixations (successive overlapping fixation, putatively reflecting problem of disengagement) and re-capture fixations (temporally distant overlapping fixations, putatively reflecting spatial working memory deficits). The results of this new analysis approach were compared to the ones of conventional approaches. Conventional analyses showed the typical Visual attention deficits in neglect patients versus healthy controls: significantly less fixations and time spent within the left, and significantly more fixations and time spent within the right screen half. According the results of our new approach, patients showed a significantly smaller Visual Exploration area within the left screen half. However, the right Visual Exploration area did not differ between groups. Furthermore, in neglect patients, the proportion of overlapping fixations within the right screen half was significantly higher than within the left screen half, as well as significantly higher than in healthy controls within either screen halves. Whereas neglect patients showed significantly more capture fixations than healthy controls, the number of re-capture fixations did not differ between groups. These results suggest that, in neglect patients, the efficiency of Visual Exploration is also reduced within the right screen half and that impaired disengagement might be an important mechanism leading to overlapping fixations. Our new analysis of the Visual Exploration area, based on foveal vision, may be a promising, additional approach in Visual attention research. It allows to accurately measure the portion of the picture that was effectively explored, disentangle single from overlapping fixations, and distinguish between capture and re-capture fixations.
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Different Visual Exploration of tool-related gestures in left hemisphere brain damaged patients is associated with poor gestural imitation
Neuropsychologia, 2015Co-Authors: Tim Vanbellingen, Thomas Nyffeler, Rahel Schumacher, Noëmi Eggenberger, Simone Hopfner, Dario Cazzoli, Basil Preisig, Manuel Bertschi, Klemens Gutbrod, Claudio L. BassettiAbstract:According to the direct matching hypothesis, perceived movements automatically activate existing motor components through matching of the perceived gesture and its execution. The aim of the present study was to test the direct matching hypothesis by assessing whether Visual Exploration behavior correlate with deficits in gestural imitation in left hemisphere damaged (LHD) patients. Eighteen LHD patients and twenty healthy control subjects took part in the study. Gesture imitation performance was measured by the test for upper limb apraxia (TULIA). Visual Exploration behavior was measured by an infrared eye-tracking system. Short videos including forty gestures (20 meaningless and 20 communicative gestures) were presented. Cumulative fixation duration was measured in different regions of interest (ROIs), namely the face, the gesturing hand, the body, and the surrounding environment. Compared to healthy subjects, patients fixated significantly less the ROIs comprising the face and the gesturing hand during the Exploration of emblematic and tool-related gestures. Moreover, Visual Exploration of tool-related gestures significantly correlated with tool-related imitation as measured by TULIA in LHD patients. Patients and controls did not differ in the Visual Exploration of meaningless gestures, and no significant relationships were found between Visual Exploration behavior and the imitation of emblematic and meaningless gestures in TULIA. The present study thus suggests that altered Visual Exploration may lead to disturbed imitation of tool related gestures, however not of emblematic and meaningless gestures. Consequently, our findings partially support the direct matching hypothesis.
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Age-dependent Visual Exploration during simulated day- and night driving on a motorway: a cross-sectional study
BMC Geriatrics, 2015Co-Authors: Prabitha Urwyler, René M. Müri, Nicole Gruber, Michael Jäger, Rahel Bieri, Thomas Nyffeler, Urs Peter MosimannAbstract:Background Central and peripheral vision is needed for object detection. Previous research has shown that Visual target detection is affected by age. In addition, light conditions also influence Visual Exploration. The aim of the study was to investigate the effects of age and different light conditions on Visual Exploration behavior and on driving performance during simulated driving.
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Development and evaluation of a new instrument to measure Visual Exploration behavior
Medical Engineering & Physics, 2013Co-Authors: Nicole Gruber, René M. Müri, Thomas Nyffeler, Giuseppe Angelo Zito, Urs Peter MosimannAbstract:Effective Visual Exploration is required for many activities of daily living and instruments to assess Visual Exploration are important for the evaluation of the Visual and the oculomotor system. In this article, the development of a new instrument to measure central and peripheral target recognition is described. The measurement setup consists of a hemispherical projection which allows presenting images over a large area of ±90° horizontal and vertical angle. In a feasibility study with 14 younger (21–49 years) and 12 older (50–78 years) test persons, 132 targets and 24 distractors were presented within naturalistic color photographs of everyday scenes at 10°, 30°, and 50° eccentricity. After the experiment, both younger and older participants reported in a questionnaire that the task is easy to understand, fun and that it measures a competence that is relevant for activities of daily living. A main result of the pilot study was that younger participants recognized more targets with smaller reaction times than older participants. The group differences were most pronounced for peripheral target detection. This test is feasible and appropriate to assess the functional field of view in younger and older adults.
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The link between Visual Exploration and neuronal activity: a multi-modal study combining eye tracking, functional magnetic resonance imaging and transcranial magnetic stimulation.
NeuroImage, 2011Co-Authors: Silvia Chaves, Thomas Nyffeler, Pascal Wurtz, Patrizia Vannini, Kay Jann, Andrea Federspiel, Mathias Luethi, Daniela Hubl, Roland Wiest, Thomas DierksAbstract:In the present multi-modal study we aimed to investigate the role of Visual Exploration in relation to the neuronal activity and performance during visuospatial processing. To this end, event related functional magnetic resonance imaging er-fMRI was combined with simultaneous eye tracking recording and transcranial magnetic stimulation (TMS). Two groups of twenty healthy subjects each performed an angle discrimination task with different levels of difficulty during er-fMRI. The number of fixations as a measure of Visual Exploration effort was chosen to predict blood oxygen level-dependent (BOLD) signal changes using the general linear model (GLM). Without TMS, a positive linear relationship between the Visual Exploration effort and the BOLD signal was found in a bilateral fronto-parietal cortical network, indicating that these regions reflect the increased number of fixations and the higher brain activity due to higher task demands. Furthermore, the relationship found between the number of fixations and the performance demonstrates the relevance of Visual Exploration for visuospatial task solving. In the TMS group, offline theta bursts TMS (TBS) was applied over the right posterior parietal cortex (PPC) before the fMRI experiment started. Compared to controls, TBS led to a reduced correlation between Visual Exploration and BOLD signal change in regions of the fronto-parietal network of the right hemisphere, indicating a disruption of the network. In contrast, an increased correlation was found in regions of the left hemisphere, suggesting an intent to compensate functionality of the disturbed areas. TBS led to fewer fixations and faster response time while keeping accuracy at the same level, indicating that subjects explored more than actually needed.
Susanne Schuett - One of the best experts on this subject based on the ideXlab platform.
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rehabilitation of reading and Visual Exploration in Visual field disorders transfer or specificity
Brain, 2012Co-Authors: Susanne Schuett, Charles A Heywood, Robert W Kentridge, Ruth Dauner, Josef ZihlAbstract:Reading and Visual Exploration impairments in unilateral homonymous Visual field disorders are frequent and disabling consequences of acquired brain injury. Compensatory therapies have been developed, which allow patients to regain sufficient reading and Visual Exploration performance through systematic oculomotor training. However, it is still unclear whether the reading and Visual Exploration impairments require specific compensatory training for their improvement. We present the first cross-over rehabilitation study to determine whether the training-related performance improvements are task-specific, or whether there is a transfer of training-related improvements between reading and Visual Exploration. We compared the therapeutic effects of compensatory oculomotor reading and Visual Exploration training in 36 patients with unilateral homonymous Visual field loss in a cross-over design. In addition, we explored whether the training sequence determines the overall treatment outcome. Our findings demonstrate that the training-related improvements in reading and Visual Exploration are highly specific and task-dependent, and there was no effect of training sequence. * Abbreviations : HVFD : homonymous Visual field disorders
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Rehabilitation of reading and Visual Exploration in Visual field disorders: transfer or specificity?
Brain : a journal of neurology, 2012Co-Authors: Susanne Schuett, Charles A Heywood, Robert W Kentridge, Ruth Dauner, Josef ZihlAbstract:Reading and Visual Exploration impairments in unilateral homonymous Visual field disorders are frequent and disabling consequences of acquired brain injury. Compensatory therapies have been developed, which allow patients to regain sufficient reading and Visual Exploration performance through systematic oculomotor training. However, it is still unclear whether the reading and Visual Exploration impairments require specific compensatory training for their improvement. We present the first cross-over rehabilitation study to determine whether the training-related performance improvements are task-specific, or whether there is a transfer of training-related improvements between reading and Visual Exploration. We compared the therapeutic effects of compensatory oculomotor reading and Visual Exploration training in 36 patients with unilateral homonymous Visual field loss in a cross-over design. In addition, we explored whether the training sequence determines the overall treatment outcome. Our findings demonstrate that the training-related improvements in reading and Visual Exploration are highly specific and task-dependent, and there was no effect of training sequence.
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Adaptation of eye-movements to simulated hemianopia in reading and Visual Exploration: Transfer or specificity?
Neuropsychologia, 2009Co-Authors: Susanne Schuett, Robert W Kentridge, Josef Zihl, Charles A HeywoodAbstract:Reading and Visual Exploration impairments in unilateral homonymous hemianopia are well-established clinical phenomena. Spontaneous adaptation of eye-movements to the Visual field defect leads to improved reading and Visual Exploration performance. Yet, it is still unclear whether oculomotor adaptation to Visual field loss is task-specific or whether there is a transfer of adaptation-related improvements between reading and Visual Exploration. We therefore simulated unilateral homonymous hemianopia in healthy participants and explored the specificity with which oculomotor adaptation to this pure Visual-sensory dysfunction during uninstructed reading or Visual Exploration practice leads to improvements in both abilities. Our findings demonstrate that there is no transfer of adaptation-related changes of eye-movements and performance improvements between reading and Visual Exploration. Efficient oculomotor adaptation to Visual field loss is highly specific and task-dependent.
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Are Hemianopic Reading and Visual Exploration Impairments Visually Elicited? New Insights from Eye Movements in Simulated Hemianopia.
Neuropsychologia, 2008Co-Authors: Susanne Schuett, Robert W Kentridge, Josef Zihl, Charles A HeywoodAbstract:Hemianopic reading and Visual Exploration impairments are well-known clinical phenomena. Yet, it is unclear whether they are primarily caused by the hemianopic Visual field defect itself or by additional brain injury preventing efficient spontaneous oculomotor adaptation. To establish the extent to which these impairments are Visually elicited we simulated unilateral homonymous hemianopia in healthy participants, using a gaze-contingent display paradigm, and investigated its effect on reading and Visual Exploration. We demonstrate that simulated hemianopia induces the reading and Visual Exploration impairments of hemianopic patients. Over time, however, all participants showed efficient spontaneous oculomotor adaptation to the Visual-sensory loss which improved their reading and Visual Exploration performance. Our results suggest that the hemianopic Visual field defect is a major component of the chronic impairments of reading and Visual and Exploration found in hemianopic patients although it may not be their sole cause.
Kristen Grauman - One of the best experts on this subject based on the ideXlab platform.
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An Exploration of Embodied Visual Exploration
arXiv: Computer Vision and Pattern Recognition, 2020Co-Authors: Santhosh K. Ramakrishnan, Dinesh Jayaraman, Kristen GraumanAbstract:Embodied computer vision considers perception for robots in general, unstructured environments. Of particular importance is the embodied Visual Exploration problem: how might a robot equipped with a camera scope out a new environment? Despite the progress thus far, many basic questions pertinent to this problem remain unanswered: (i) What does it mean for an agent to explore its environment well? (ii) Which methods work well, and under which assumptions and environmental settings? (iii) Where do current approaches fall short, and where might future work seek to improve? Seeking answers to these questions, we perform a thorough empirical study of four state-of-the-art paradigms on two photorealistic simulated 3D environments. We present a taxonomy of key Exploration methods and a standard framework for benchmarking Visual Exploration algorithms. Our experimental results offer insights, and suggest new performance metrics and baselines for future work in Visual Exploration.
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ECCV (12) - Sidekick Policy Learning for Active Visual Exploration
Computer Vision – ECCV 2018, 2018Co-Authors: Santhosh K. Ramakrishnan, Kristen GraumanAbstract:We consider an active Visual Exploration scenario, where an agent must intelligently select its camera motions to efficiently reconstruct the full environment from only a limited set of narrow field-of-view glimpses. While the agent has full observability of the environment during training, it has only partial observability once deployed, being constrained by what portions it has seen and what camera motions are permissible. We introduce sidekick policy learning to capitalize on this imbalance of observability. The main idea is a preparatory learning phase that attempts simplified versions of the eventual Exploration task, then guides the agent via reward shaping or initial policy supervision. To support interpretation of the resulting policies, we also develop a novel policy Visualization technique. Results on active Visual Exploration tasks with \(360^{\circ }\) scenes and 3D objects show that sidekicks consistently improve performance and convergence rates over existing methods. Code, data and demos are available (Project website: http://vision.cs.utexas.edu/projects/sidekicks/).
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sidekick policy learning for active Visual Exploration
European Conference on Computer Vision, 2018Co-Authors: Santhosh K. Ramakrishnan, Kristen GraumanAbstract:We consider an active Visual Exploration scenario, where an agent must intelligently select its camera motions to efficiently reconstruct the full environment from only a limited set of narrow field-of-view glimpses. While the agent has full observability of the environment during training, it has only partial observability once deployed, being constrained by what portions it has seen and what camera motions are permissible. We introduce sidekick policy learning to capitalize on this imbalance of observability. The main idea is a preparatory learning phase that attempts simplified versions of the eventual Exploration task, then guides the agent via reward shaping or initial policy supervision. To support interpretation of the resulting policies, we also develop a novel policy Visualization technique. Results on active Visual Exploration tasks with \(360^{\circ }\) scenes and 3D objects show that sidekicks consistently improve performance and convergence rates over existing methods. Code, data and demos are available (Project website: http://vision.cs.utexas.edu/projects/sidekicks/).
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sidekick policy learning for active Visual Exploration
arXiv: Computer Vision and Pattern Recognition, 2018Co-Authors: Santhosh K. Ramakrishnan, Kristen GraumanAbstract:We consider an active Visual Exploration scenario, where an agent must intelligently select its camera motions to efficiently reconstruct the full environment from only a limited set of narrow field-of-view glimpses. While the agent has full observability of the environment during training, it has only partial observability once deployed, being constrained by what portions it has seen and what camera motions are permissible. We introduce sidekick policy learning to capitalize on this imbalance of observability. The main idea is a preparatory learning phase that attempts simplified versions of the eventual Exploration task, then guides the agent via reward shaping or initial policy supervision. To support interpretation of the resulting policies, we also develop a novel policy Visualization technique. Results on active Visual Exploration tasks with 360 scenes and 3D objects show that sidekicks consistently improve performance and convergence rates over existing methods. Code, data and demos are available.
Josef Zihl - One of the best experts on this subject based on the ideXlab platform.
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rehabilitation of reading and Visual Exploration in Visual field disorders transfer or specificity
Brain, 2012Co-Authors: Susanne Schuett, Charles A Heywood, Robert W Kentridge, Ruth Dauner, Josef ZihlAbstract:Reading and Visual Exploration impairments in unilateral homonymous Visual field disorders are frequent and disabling consequences of acquired brain injury. Compensatory therapies have been developed, which allow patients to regain sufficient reading and Visual Exploration performance through systematic oculomotor training. However, it is still unclear whether the reading and Visual Exploration impairments require specific compensatory training for their improvement. We present the first cross-over rehabilitation study to determine whether the training-related performance improvements are task-specific, or whether there is a transfer of training-related improvements between reading and Visual Exploration. We compared the therapeutic effects of compensatory oculomotor reading and Visual Exploration training in 36 patients with unilateral homonymous Visual field loss in a cross-over design. In addition, we explored whether the training sequence determines the overall treatment outcome. Our findings demonstrate that the training-related improvements in reading and Visual Exploration are highly specific and task-dependent, and there was no effect of training sequence. * Abbreviations : HVFD : homonymous Visual field disorders
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Rehabilitation of reading and Visual Exploration in Visual field disorders: transfer or specificity?
Brain : a journal of neurology, 2012Co-Authors: Susanne Schuett, Charles A Heywood, Robert W Kentridge, Ruth Dauner, Josef ZihlAbstract:Reading and Visual Exploration impairments in unilateral homonymous Visual field disorders are frequent and disabling consequences of acquired brain injury. Compensatory therapies have been developed, which allow patients to regain sufficient reading and Visual Exploration performance through systematic oculomotor training. However, it is still unclear whether the reading and Visual Exploration impairments require specific compensatory training for their improvement. We present the first cross-over rehabilitation study to determine whether the training-related performance improvements are task-specific, or whether there is a transfer of training-related improvements between reading and Visual Exploration. We compared the therapeutic effects of compensatory oculomotor reading and Visual Exploration training in 36 patients with unilateral homonymous Visual field loss in a cross-over design. In addition, we explored whether the training sequence determines the overall treatment outcome. Our findings demonstrate that the training-related improvements in reading and Visual Exploration are highly specific and task-dependent, and there was no effect of training sequence.
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Adaptation of eye-movements to simulated hemianopia in reading and Visual Exploration: Transfer or specificity?
Neuropsychologia, 2009Co-Authors: Susanne Schuett, Robert W Kentridge, Josef Zihl, Charles A HeywoodAbstract:Reading and Visual Exploration impairments in unilateral homonymous hemianopia are well-established clinical phenomena. Spontaneous adaptation of eye-movements to the Visual field defect leads to improved reading and Visual Exploration performance. Yet, it is still unclear whether oculomotor adaptation to Visual field loss is task-specific or whether there is a transfer of adaptation-related improvements between reading and Visual Exploration. We therefore simulated unilateral homonymous hemianopia in healthy participants and explored the specificity with which oculomotor adaptation to this pure Visual-sensory dysfunction during uninstructed reading or Visual Exploration practice leads to improvements in both abilities. Our findings demonstrate that there is no transfer of adaptation-related changes of eye-movements and performance improvements between reading and Visual Exploration. Efficient oculomotor adaptation to Visual field loss is highly specific and task-dependent.
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Are Hemianopic Reading and Visual Exploration Impairments Visually Elicited? New Insights from Eye Movements in Simulated Hemianopia.
Neuropsychologia, 2008Co-Authors: Susanne Schuett, Robert W Kentridge, Josef Zihl, Charles A HeywoodAbstract:Hemianopic reading and Visual Exploration impairments are well-known clinical phenomena. Yet, it is unclear whether they are primarily caused by the hemianopic Visual field defect itself or by additional brain injury preventing efficient spontaneous oculomotor adaptation. To establish the extent to which these impairments are Visually elicited we simulated unilateral homonymous hemianopia in healthy participants, using a gaze-contingent display paradigm, and investigated its effect on reading and Visual Exploration. We demonstrate that simulated hemianopia induces the reading and Visual Exploration impairments of hemianopic patients. Over time, however, all participants showed efficient spontaneous oculomotor adaptation to the Visual-sensory loss which improved their reading and Visual Exploration performance. Our results suggest that the hemianopic Visual field defect is a major component of the chronic impairments of reading and Visual and Exploration found in hemianopic patients although it may not be their sole cause.
