Event-related TMS over the right posterior parietal cortex induces ipsilateral visuo-spatial interference.
The right posterior parietal cortex (PPC) is implicated in visuo-spatial processing, as illustrated by patients with visuo-spatial neglect, but the precise time-course of its contribution is still an open question. In the present study we assessed whether single-pulse transcranial magnetic stimulation (TMS) can interfere with the performance of normal subjects in a standard visuo-spatial task. Participants had to perform a landmark task while TMS was applied over the right PPC, the homologue region in the left hemisphere or the right primary motor cortex. Stimulation was time-locked to the stimulus presentation with a stimulus onset asynchrony (SOA) varying between 50 and 200 ms. Our results indicate that TMS interfered mainly with the visuo-spatial task when applied over the right PPC at an early stage (50 ms post-stimulus). The interference effect of single-pulse TMS in the present visuo-spatial processing is revealed by a processing cost for ipsilateral targets. These results are in agreement with neuropsychological and brain imaging studies showing a right hemispheric dominance in visuo-spatial processing but add crucial information about the time-course of visuo-spatial processing within the right PPC.
Pourtois
G
G
Donders Laboratory of Cognitive and Affective Neurosciences, Department of Psychology, University of Tilburg, PO Box 90153, 5000 LE Tilburg, The Netherlands.
Vandermeeren
Y
Y
Olivier
E
E
de Gelder
B
B
D000328:Adult; D000465:Algorithms; D000704:Analysis of Variance; D004292:Dominance, Cerebral / Q000502:physiology*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D010296:Parietal Lobe / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology