Visual Field Reconstruction in Hemianopia Using fMRI Based Mapping Techniques
PurposeA stroke that includes the primary visual cortex unilaterally leads to a loss of visual field (VF) representation in the hemifield contralateral to the damage. While behavioral procedures for measuring the VF, such as perimetry, may indicate that a patient cannot see in a particular area, det...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2021-08-01
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| Series: | Frontiers in Human Neuroscience |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fnhum.2021.713114/full |
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| author | Hinke N. Halbertsma Holly Bridge Joana Carvalho Frans W. Cornelissen Sara Ajina Sara Ajina |
| author_facet | Hinke N. Halbertsma Holly Bridge Joana Carvalho Frans W. Cornelissen Sara Ajina Sara Ajina |
| author_sort | Hinke N. Halbertsma |
| collection | DOAJ |
| description | PurposeA stroke that includes the primary visual cortex unilaterally leads to a loss of visual field (VF) representation in the hemifield contralateral to the damage. While behavioral procedures for measuring the VF, such as perimetry, may indicate that a patient cannot see in a particular area, detailed psychophysical testing often detects the ability to perform detection or discrimination of visual stimuli (“blindsight”). The aim of this study was to determine whether functional magnetic resonance imaging (fMRI) could be used to determine whether perimetrically blind regions of the VF were still represented in VF maps reconstructed on the basis of visually evoked neural activity.MethodsThirteen patients with hemianopia and nine control participants were scanned using 3T MRI while presented with visual stimulation. Two runs of a dynamic “wedge and ring” mapping stimulus, totaling approximately 10 min, were performed while participants fixated centrally. Two different analysis approaches were taken: the conventional population receptive field (pRF) analysis and micro-probing (MP). The latter is a variant of the former that makes fewer assumptions when modeling the visually evoked neural activity. Both methods were used to reconstruct the VF by projecting modeled activity back onto the VF. Following a normalization step, these “coverage maps” can be compared to the VF sensitivity plots obtained using perimetry.ResultsWhile both fMRI-based approaches revealed regions of neural activity within the perimetrically “blind” sections of the VF, the MP approach uncovered more voxels in the lesioned hemisphere in which a modest degree of visual sensitivity was retained. Furthermore, MP-based analysis indicated that both early (V1/V2) and extrastriate visual areas contributed equally to the retained sensitivity in both patients and controls.ConclusionIn hemianopic patients, fMRI-based approaches for reconstructing the VF can pick up activity in perimetrically blind regions of the VF. Such regions of the VF may be particularly amenable for rehabilitation to regain visual function. Compared to conventional pRF modeling, MP reveals more voxels with retained visual sensitivity, suggesting it is a more sensitive approach for VF reconstruction. |
| first_indexed | 2024-12-22T04:13:47Z |
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| institution | Directory Open Access Journal |
| issn | 1662-5161 |
| language | English |
| last_indexed | 2024-12-22T04:13:47Z |
| publishDate | 2021-08-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Human Neuroscience |
| spelling | doaj.art-3bfad8aef5764113872856f08afd1daa2022-12-21T18:39:28ZengFrontiers Media S.A.Frontiers in Human Neuroscience1662-51612021-08-011510.3389/fnhum.2021.713114713114Visual Field Reconstruction in Hemianopia Using fMRI Based Mapping TechniquesHinke N. Halbertsma0Holly Bridge1Joana Carvalho2Frans W. Cornelissen3Sara Ajina4Sara Ajina5Laboratory for Experimental Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, NetherlandsWellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United KingdomChampalimaud Centre for the Unknown, Champalimaud Foundation, Lisbon, PortugalLaboratory for Experimental Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, NetherlandsWellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United KingdomDepartment of Neurorehabilitation, National Hospital for Neurology and Neurosurgery, London, United KingdomPurposeA stroke that includes the primary visual cortex unilaterally leads to a loss of visual field (VF) representation in the hemifield contralateral to the damage. While behavioral procedures for measuring the VF, such as perimetry, may indicate that a patient cannot see in a particular area, detailed psychophysical testing often detects the ability to perform detection or discrimination of visual stimuli (“blindsight”). The aim of this study was to determine whether functional magnetic resonance imaging (fMRI) could be used to determine whether perimetrically blind regions of the VF were still represented in VF maps reconstructed on the basis of visually evoked neural activity.MethodsThirteen patients with hemianopia and nine control participants were scanned using 3T MRI while presented with visual stimulation. Two runs of a dynamic “wedge and ring” mapping stimulus, totaling approximately 10 min, were performed while participants fixated centrally. Two different analysis approaches were taken: the conventional population receptive field (pRF) analysis and micro-probing (MP). The latter is a variant of the former that makes fewer assumptions when modeling the visually evoked neural activity. Both methods were used to reconstruct the VF by projecting modeled activity back onto the VF. Following a normalization step, these “coverage maps” can be compared to the VF sensitivity plots obtained using perimetry.ResultsWhile both fMRI-based approaches revealed regions of neural activity within the perimetrically “blind” sections of the VF, the MP approach uncovered more voxels in the lesioned hemisphere in which a modest degree of visual sensitivity was retained. Furthermore, MP-based analysis indicated that both early (V1/V2) and extrastriate visual areas contributed equally to the retained sensitivity in both patients and controls.ConclusionIn hemianopic patients, fMRI-based approaches for reconstructing the VF can pick up activity in perimetrically blind regions of the VF. Such regions of the VF may be particularly amenable for rehabilitation to regain visual function. Compared to conventional pRF modeling, MP reveals more voxels with retained visual sensitivity, suggesting it is a more sensitive approach for VF reconstruction.https://www.frontiersin.org/articles/10.3389/fnhum.2021.713114/fullcortical blindnessvisual cortexresidual visionpopulation receptive fieldvisual field (VF) |
| spellingShingle | Hinke N. Halbertsma Holly Bridge Joana Carvalho Frans W. Cornelissen Sara Ajina Sara Ajina Visual Field Reconstruction in Hemianopia Using fMRI Based Mapping Techniques Frontiers in Human Neuroscience cortical blindness visual cortex residual vision population receptive field visual field (VF) |
| title | Visual Field Reconstruction in Hemianopia Using fMRI Based Mapping Techniques |
| title_full | Visual Field Reconstruction in Hemianopia Using fMRI Based Mapping Techniques |
| title_fullStr | Visual Field Reconstruction in Hemianopia Using fMRI Based Mapping Techniques |
| title_full_unstemmed | Visual Field Reconstruction in Hemianopia Using fMRI Based Mapping Techniques |
| title_short | Visual Field Reconstruction in Hemianopia Using fMRI Based Mapping Techniques |
| title_sort | visual field reconstruction in hemianopia using fmri based mapping techniques |
| topic | cortical blindness visual cortex residual vision population receptive field visual field (VF) |
| url | https://www.frontiersin.org/articles/10.3389/fnhum.2021.713114/full |
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