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Summary: The Role of the Parietal Lobe in Visual Extinction
Studied with Transcranial Magnetic Stimulation
Lorella Battelli1,2
, George A. Alvarez2,3
, Thomas Carlson2,4
,
and Alvaro Pascual-Leone1,5
Abstract
& Interhemispheric competition between homologous areas
in the human brain is believed to be involved in a wide variety
of human behaviors from motor activity to visual perception
and particularly attention. For example, patients with lesions in
the posterior parietal cortex are unable to selectively track ob-
jects in the contralesional side of visual space when targets are
simultaneously present in the ipsilesional visual field, a form of
visual extinction. Visual extinction may arise due to an imbal-
ance in the normal interhemispheric competition. To directly
assess the issue of reciprocal inhibition, we used fMRI to local-
ize those brain regions active during attention-based visual track-
ing and then applied low-frequency repetitive transcranial
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