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Bottom-up Visual Integration in the Medial Parietal Lobe

Pflugshaupt, Tobias ; Nösberger, Myriam ; Gutbrod, Klemens ; Weber, Konrad P. ; Linnebank, Michael ; Brugger, Peter

In: Cerebral Cortex, 2016, vol. 26, no. 3, p. 943-949

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    Title
    • Bottom-up Visual Integration in the Medial Parietal Lobe
    Author
    • Pflugshaupt, Tobias. Department of Neurology
    • Nösberger, Myriam. Department of Neurology
    • Gutbrod, Klemens. Department of Neurology, Inselspital, University Hospital Bern, Bern, Switzerland
    • Weber, Konrad P.. Department of Neurology
    • Linnebank, Michael. Department of Neurology
    • Brugger, Peter. Department of Neurology
    Document Type
    • Postprint
    Language
    • English
    Published in
    • Cerebral Cortex, 2016, vol. 26, no. 3, p. 943-949. Oxford University Press
    Other Version
    OAI-PMH Identifier
    • oai:doc.rero.ch:332815
    Summary
    Largely based on findings from functional neuroimaging studies, the medial parietal lobe is known to contribute to internally directed cognitive processes such as visual imagery or episodic memory. Here, we present 2 patients with behavioral impairments that extend this view. Both had chronic unilateral lesions of nearly the entire medial parietal lobe, but in opposite hemispheres. Routine neuropsychological examination conducted >4 years after the onset of brain damage showed little deficits of minor severity. In contrast, both patients reported persistent unusual visual impairment. A comprehensive series of tachistoscopic experiments with lateralized stimulus presentation and comparison with healthy participants revealed partial visual hemiagnosia for stimuli presented to their contralesional hemifield, applying inferential single-case statistics to evaluate deficits and dissociations. Double dissociations were found in 4 experiments during which participants had to integrate more than one visual element, either through comparison or formation of a global gestalt. Against the background of recent neuroimaging findings, we conclude that of all medial parietal structures, the precuneus is the most likely candidate for a crucial involvement in such bottom-up visual integration.