The role of the parietal lobe in visual extinction studied with transcranial magnetic stimulation

Lorella Battelli*, George A. Alvarez, Thomas Carlson, Alvaro Pascual-Leone

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)


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 objects 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 imbalance in the normal interhemispheric competition. To directly assess the issue of reciprocal inhibition, we used fMRI to localize those brain regions active during attention-based visual tracking and then applied low-frequency repetitive transcranial magnetic stimulation over identified areas in the left and right intraparietal sulcus to asses the behavioral effects on visual tracking. We induced a severe impairment in visual tracking that was selective for conditions of simultaneous tracking in both visual fields. Our data show that the parietal lobe is essential for visual tracking and that the two hemispheres compete for attentional resources during tracking. Our results provide a neuronal basis for visual extinction in patients with parietal lobe damage.

Original languageEnglish
Pages (from-to)1946-1955
Number of pages10
JournalJournal of cognitive neuroscience
Issue number10
Publication statusPublished - Oct 2009
Externally publishedYes


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