Interhemispheric imbalance during visuospatial attention investigated by unilateral and bilateral TMS over human parietal cortices.
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.
Dambeck
Nina
N
Department of Neurology, Technical University of Aachen, Neurologische Klinik, Universitätsklinikum, Pauwelsstr. 30, 52074 Aachen, Germany.
Sparing
Roland
R
Meister
Ingo G
IG
Wienemann
Michael
M
Weidemann
Juergen
J
Topper
Rudolf
R
Boroojerdi
Babak
B
D000328:Adult; D001288:Attention; D001931:Brain Mapping; D007839:Functional Laterality; D006801:Humans; D010296:Parietal Lobe / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D014796:Visual Perception / Q000502:physiology*