The role of the human posterior parietal cortex in memory-guided saccade execution: a double-pulse transcranial magnetic stimulation study.
The present study investigated the role of the right posterior parietal cortex (PPC) in the triggering of memory-guided saccades by means of double-pulse transcranial magnetic stimulation (dTMS). Shortly before saccade onset, dTMS with different interstimulus intervals (ISI; 35, 50, 65 or 80 ms) was applied. For contralateral saccades, dTMS significantly decreased saccadic latency with an ISI of 80 ms and increased saccadic gain with an ISI of 65 and 80 ms. Together with the findings of a previous study during frontal eye field (FEF) stimulation the present results demonstrate similarities and differences between both regions in the execution of memory-guided saccades. Firstly, dTMS facilitates saccade triggering in both regions, but the timing is different. Secondly, dTMS over the PPC provokes a hypermetria of contralateral memory-guided saccades that was not observed during FEF stimulation. The results are discussed within the context of recent neurophysiological findings in monkeys.
Nyffeler
Thomas
T
Perception and Eye Movement Laboratory, Department of Neurology, University Hospital, University of Berne, Freiburgstrasse 10, 3010 Berne, Switzerland.
Egli
Andreas
A
Pflugshaupt
Tobias
T
von Wartburg
Roman
R
Wurtz
Pascal
P
Mosimann
Urs
U
Hess
Christian W
CW
Müri
René M
RM
D000328:Adult; D004558:Electric Stimulation; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology* / Q000528:radiation effects; D010296:Parietal Lobe / Q000502:physiology / Q000528:radiation effects*; D011930:Reaction Time / Q000502:physiology / Q000528:radiation effects; D012438:Saccades / Q000502:physiology* / Q000528:radiation effects; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation