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Ptak R, Bourgeois A, Cavelti S, Doganci N, Schnider A, Iannotti GR. Discrete Patterns of Cross-Hemispheric Functional Connectivity Underlie Impairments of Spatial Cognition after Stroke. J Neurosci 2020; 40:6638-6648. [PMID: 32709694 PMCID: PMC7486659 DOI: 10.1523/jneurosci.0625-20.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 06/06/2020] [Accepted: 07/04/2020] [Indexed: 12/17/2022] Open
Abstract
Despite intense research, the neural correlates of stroke-induced deficits of spatial cognition remain controversial. For example, several cortical regions and white-matter tracts have been designated as possible anatomic predictors of spatial neglect. However, many studies focused on local anatomy, an approach that does not harmonize with the notion that brain-behavior relationships are flexible and may involve interactions among distant regions. We studied in humans of either sex resting-state fMRI connectivity associated with performance in line bisection, reading and visual search, tasks commonly used for he clinical diagnosis of neglect. We defined left and right frontal, parietal, and temporal areas as seeds (or regions of interest, ROIs), and measured whole-brain seed-based functional connectivity (FC) and ROI-to-ROI connectivity in subacute right-hemisphere stroke patients. Performance on the line bisection task was associated with decreased FC between the right fusiform gyrus and left superior occipital cortex. Complementary increases and decreases of connectivity between both temporal and occipital lobes predicted reading errors. In addition, visual search deficits were associated with modifications of FC between left and right inferior parietal lobes and right insular cortex. These distinct connectivity patterns were substantiated by analyses of FC between left- and right-hemispheric ROIs, which revealed that decreased interhemispheric and right intrahemispheric FC was associated with higher levels of impairment. Together, these findings indicate that intrahemispheric and interhemispheric cooperation between brain regions lying outside the damaged area contributes to spatial deficits in a way that depends on the different cognitive components recruited during reading, spatial judgments, and visual exploration.SIGNIFICANCE STATEMENT Focal damage to the right cerebral hemisphere may result in a variety of deficits, often affecting the domain of spatial cognition. The neural correlates of these disorders have traditionally been studied with lesion-symptom mapping, but this method fails to capture the network dynamics that underlie cognitive performance. We studied functional connectivity in patients with right-hemisphere stroke and found a pattern of correlations between the left and right temporo-occipital, inferior parietal, and right insular cortex that were distinctively predictive of deficits in reading, spatial judgment, and visual exploration. This finding reveals the importance of interhemispheric interactions and network adaptations for the manifestation of spatial deficits after damage to the right hemisphere.
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Affiliation(s)
- Radek Ptak
- Laboratory of Cognitive Neurorehabilitation, Department of Clinical Neurosciences, Faculty of Medicine, University of Geneva, Geneva, 1206, Switzerland
- Division of Neurorehabilitation, University Hospitals of Geneva, Geneva, 1206, Switzerland
- Faculty of Psychology and Educational Sciences, University of Geneva, Geneva, 1205, Switzerland
| | - Alexia Bourgeois
- Laboratory of Cognitive Neurorehabilitation, Department of Clinical Neurosciences, Faculty of Medicine, University of Geneva, Geneva, 1206, Switzerland
| | - Silvia Cavelti
- Laboratory of Cognitive Neurorehabilitation, Department of Clinical Neurosciences, Faculty of Medicine, University of Geneva, Geneva, 1206, Switzerland
| | - Naz Doganci
- Laboratory of Cognitive Neurorehabilitation, Department of Clinical Neurosciences, Faculty of Medicine, University of Geneva, Geneva, 1206, Switzerland
| | - Armin Schnider
- Laboratory of Cognitive Neurorehabilitation, Department of Clinical Neurosciences, Faculty of Medicine, University of Geneva, Geneva, 1206, Switzerland
- Division of Neurorehabilitation, University Hospitals of Geneva, Geneva, 1206, Switzerland
| | - Giannina Rita Iannotti
- Laboratory of Cognitive Neurorehabilitation, Department of Clinical Neurosciences, Faculty of Medicine, University of Geneva, Geneva, 1206, Switzerland
- Swiss Foundation for Innovation and Training in Surgery, University Hospitals of Geneva, Geneva, 1206, Switzerland
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Ptak R, Lazeyras F. Functional connectivity and the failure to retrieve meaning from shape in visual object agnosia. Brain Cogn 2019; 131:94-101. [DOI: 10.1016/j.bandc.2018.12.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 12/18/2018] [Accepted: 12/18/2018] [Indexed: 10/27/2022]
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Welcome SE, Pasquarella A, Chen X, Olson DR, Joanisse MF. Preserved mid-fusiform activation for visual words in a patient with a visual word recognition impairment. Neuropsychologia 2014; 65:113-24. [PMID: 25447068 DOI: 10.1016/j.neuropsychologia.2014.10.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 10/08/2014] [Accepted: 10/13/2014] [Indexed: 11/25/2022]
Abstract
Previous functional imaging studies have highlighted the role of left ventral temporal cortex in processing written word forms. We explored activation and anatomical connectivity of this region in HE, a professional writer with alexia as a result of stroke affecting primarily white matter in the left inferior temporal lobe. We used a one-back visual recognition task and functional Magnetic Resonance Imaging to elicit automatic activation to various orthographic and non-orthographic stimuli. Surprisingly, HE showed cortical activation in the left mid-fusiform area during the presentation of words and word-like stimuli, suggesting that this region׳s role in processing visual words is intact despite his severely impaired reading. Diffusion Tensor Imaging data further suggest that HE shows an anatomical disconnection between the ventral temporal cortex and posterior middle temporal cortex. Together, these findings suggest that activation of word-specific regions of mid-fusiform gyrus is not sufficient to yield the conscious experience of reading in the absence of activity in downstream regions of the classical reading network.
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Affiliation(s)
- Suzanne E Welcome
- Department of Psychology, University of Missouri - St. Louis, One University Boulevard, 325 Stadler Hall, St. Louis, MO 63121-4499, USA.
| | | | - Xi Chen
- Department of Applied Psychology and Human Development, Ontario Institute for Studies in Education of the University of Toronto, Toronto, ON, Canada
| | - David R Olson
- Department of Applied Psychology and Human Development, Ontario Institute for Studies in Education of the University of Toronto, Toronto, ON, Canada
| | - Marc F Joanisse
- Department of Psychology and The Brain and Mind Institute, The University of Western Ontario, London, ON, Canada
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Ptak R, Lazeyras F, Di Pietro M, Schnider A, Simon SR. Visual object agnosia is associated with a breakdown of object-selective responses in the lateral occipital cortex. Neuropsychologia 2014; 60:10-20. [PMID: 24863251 DOI: 10.1016/j.neuropsychologia.2014.05.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2014] [Revised: 04/26/2014] [Accepted: 05/13/2014] [Indexed: 10/25/2022]
Abstract
Patients with visual object agnosia fail to recognize the identity of visually presented objects despite preserved semantic knowledge. Object agnosia may result from damage to visual cortex lying close to or overlapping with the lateral occipital complex (LOC), a brain region that exhibits selectivity to the shape of visually presented objects. Despite this anatomical overlap the relationship between shape processing in the LOC and shape representations in object agnosia is unknown. We studied a patient with object agnosia following isolated damage to the left occipito-temporal cortex overlapping with the LOC. The patient showed intact processing of object structure, yet often made identification errors that were mainly based on the global visual similarity between objects. Using functional Magnetic Resonance Imaging (fMRI) we found that the damaged as well as the contralateral, structurally intact right LOC failed to show any object-selective fMRI activity, though the latter retained selectivity for faces. Thus, unilateral damage to the left LOC led to a bilateral breakdown of neural responses to a specific stimulus class (objects and artefacts) while preserving the response to a different stimulus class (faces). These findings indicate that representations of structure necessary for the identification of objects crucially rely on bilateral, distributed coding of shape features.
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Affiliation(s)
- Radek Ptak
- Division of Neurorehabilitation, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland; Laboratory of Cognitive Neurorehabilitation, Department of Clinical Neurosciences, Medical School, University of Geneva, Geneva, Switzerland; Faculty of Psychology and Educational Sciences, University of Geneva, Geneva, Switzerland.
| | - François Lazeyras
- Department of Radiology and Medical Informatics, University of Geneva, Geneva, Switzerland
| | - Marie Di Pietro
- Division of Neurorehabilitation, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland; Laboratory of Cognitive Neurorehabilitation, Department of Clinical Neurosciences, Medical School, University of Geneva, Geneva, Switzerland
| | - Armin Schnider
- Division of Neurorehabilitation, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland; Laboratory of Cognitive Neurorehabilitation, Department of Clinical Neurosciences, Medical School, University of Geneva, Geneva, Switzerland
| | - Stéphane R Simon
- Department of Radiology and Medical Informatics, University of Geneva, Geneva, Switzerland
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