Central and parietal event-related lateralizations in a flanker task.
Recently Wascher et al. (1999) reported that in a flanker task with arrow stimuli not only the known lateralized readiness potential (LRP) that reflects lateralized response activation was induced, but also a parietal lateralized activation (direction encoding lateralization; DEL) that was interpreted as reflecting an earlier coding of a response side. However, the Wascher study did not exclude that the DEL could have also been due to lateralized stimulus- or attention-related factors. In the present study we used vertically directed arrow stimuli, and had our subjects perform responses in the vertical dimension. To separate flanker-induced from target-induced lateralizations the delay between the presentations of irrelevant and relevant stimuli (stimulus onset asynchrony; SOA) was manipulated. Apart from the usual LRPs we obtained clear DELs that varied in a similar way with the experimental variables, but peaked earlier and had a more posterior topography than the LRP. These results indicate that the DEL reflects premotor response representation.
Willemssen
Rita
R
Leibniz Research Center for Working Environment and Human Factors, Dortmund, Germany.
Hoormann
Jöorg
J
Hohnsbein
Joachim
J
Falkenstein
Michael
M
D000328:Adult; D001288:Attention / Q000502:physiology; D002490:Central Nervous System / Q000502:physiology*; D004569:Electroencephalography; D004585:Electrooculography; D005260:Female; D005556:Form Perception / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D010296:Parietal Lobe / Q000502:physiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology*