Elsevier

Brain Research

Volume 1072, Issue 1, 9 February 2006, Pages 194-199
Brain Research

Short Communication
Interhemispheric imbalance during visuospatial attention investigated by unilateral and bilateral TMS over human parietal cortices

https://doi.org/10.1016/j.brainres.2005.05.075Get rights and content

Abstract

We used single-pulse transcranial magnetic stimulation (TMS) to study visuospatial attention. TMS was applied over one hemisphere, or simultaneously over both the right and left posterior parietal cortex (PPC), at two different interstimulus intervals (ISI) during a visual detection task. Unilateral TMS over the right and left PPC, respectively, impaired detection of contralateral presented visual stimuli at an ISI of 150 ms. By contrast, simultaneous biparietal TMS induced no significant changes in correct stimulus detection. TMS at an ISI of 250 ms evoked no changes for magnetic stimulation over either the right or the left parietal cortex. These results suggest that both PPC play a crucial role at a relatively early stage in the widely distributed brain network of visuospatial attention. The abolition of behavioral deficits during simultaneous biparietal TMS underlines the common hypothesis that an interhemispheric imbalance might underlie the disorders of neglect and extinction seen following unilateral brain damage.

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Acknowledgments

This study was supported by Deutsche Forschungsgemeinschaft (DFG) (KFo 112/1), the IZKF “BIOMAT,” “Interdisciplinary Center for Clinical Research (BMBF project No. 01 KS 9503/9)”, and START program of the University of Aachen. The authors thank Dr. S. Fellows for skillful editing of the manuscript.

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