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Abnormal attentional modulation of retinotopic cortex in parietal patients with spatial neglect

Maravita, Angelo
Hutton, Chloe
Husain, Masud
Driver, Jon
Published in Current Biology. 2008, vol. 18, no. 19, p. 1525-9
Abstract Brain regions beyond visual cortex are thought to be responsible for attention-related modulation of visual processing [1, 2], but most evidence is indirect. Here, we applied functional magnetic resonance imaging (fMRI), including retinotopic mapping of visual areas, to patients with focal right-parietal lesions and left spatial neglect [3, 4]. When attentional load at fixation was minimal, retinotopic areas in right visual cortex showed preserved responses to task-irrelevant checkerboards in the contralateral left hemifield, analogously to left visual cortex for right-hemifield checkerboards, indicating a "symmetric" pattern in both hemispheres with respect to contralateral stimulation under these conditions. But when attentional load at fixation was increased, a functional asymmetry emerged for visual cortex, with contralateral responses in right visual areas being pathologically reduced (even eliminated for right V4/TEO), whereas left visual areas showed no such reduction in their contralateral response. These results reveal attention-dependent abnormalities in visual cortex after lesions in distant (parietal) regions. This may explain otherwise puzzling aspects of neglect [5, 6], as confirmed here by additional behavioral testing.
Keywords Attention/physiologyHumansMagnetic Resonance ImagingParietal Lobe/injuriesPerceptual Disorders/physiopathologyVisual Cortex/physiopathology
PMID: 18848444
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Research groups Mécanismes cérébraux du comportement et des fonctions cognitives (701)
Neuroimagerie du Sommeil et de la Cognition (832)
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VUILLEUMIER, Patrik et al. Abnormal attentional modulation of retinotopic cortex in parietal patients with spatial neglect. In: Current Biology, 2008, vol. 18, n° 19, p. 1525-9. doi: 10.1016/j.cub.2008.08.072 https://archive-ouverte.unige.ch/unige:1419

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Deposited on : 2009-04-28

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