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Title

Structural white-matter connections mediating distinct behavioral components of spatial neglect in right brain-damaged patients

Authors
Vaessen, Maarten J.
Published in Cortex. 2016, vol. 77, p. 54-68
Abstract Spatial neglect is a neuropsychological syndrome in which patients fail to perceive and orient to stimuli located in the space contralateral to the lesioned hemisphere. It is characterized by a wide heterogeneity in clinical symptoms which can be grouped into distinct behavioral components correlating with different lesion sites. Moreover, damage to white-matter (WM) fiber tracts has been suggested to disconnect brain networks that mediatedifferent functions associated with spatial cognition and attention. However, it remains unclear what WM pathways are associated with functionally dissociable neglect components. In this study we examined nine patients with a focal right hemisphere stroke using a series of neuropsychological tests and diffusion tensor imaging (DTI) in order to disentangle the role of specific WM pathways in neglect symptoms. First, following previous work, the behavioral test scores of patients were factorized into three independent components reflecting perceptual, exploratory, and object-centered deficits in spatial awareness. We then examined the structural neural substrates of these components by correlating indices of WM integrity (fractional anisotropy) with the severity of deficits along each profile. Several locations in the right parietal and frontal WM correlated with neu- ropsychological scores. Fiber tracts projecting from these locations indicated that posterior parts of the superior longitudinal fasciculus (SLF), as well as nearby callosal fibers connecting ipsilateral and contralateral parietal areas, were associated with perceptual spatial deficits, whereas more anterior parts of SLF and inferior fronto-occipital fasciculus (IFOF) were predominantly associated with object-centered deficits. In addition, connections between frontal areas and superior colliculus were found to be associated with the exploratory deficits. Our results provide novel support to the view that neglect may result from disconnection lesions in distributed brain networks, but also extend these notions by highlighting the role of dissociable circuits in different functional components of the neglect syndrome. However these preliminary findings require replication with larger samples of patients.
Keywords Clinical neuroanatomyImagingNeglectDiffusion tensor imagingFiber tracking
Identifiers
PMID: 26922504
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Structures
Research group Neuropsychologie et neurologie comportementale (951)
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(ISO format)
VAESSEN, Maarten J. et al. Structural white-matter connections mediating distinct behavioral components of spatial neglect in right brain-damaged patients. In: Cortex, 2016, vol. 77, p. 54-68. https://archive-ouverte.unige.ch/unige:84659

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Deposited on : 2016-06-20

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