Inhibitory control of the human dorsolateral prefrontal cortex during the anti-saccade paradigm--a transcranial magnetic stimulation study.
In the anti-saccade paradigm, subjects are instructed not to make a reflexive saccade to an appearing lateral target but to make an intentional saccade to the opposite side instead. The inhibition of reflexive saccade triggering is under the control of the dorsolateral prefrontal cortex (DLPFC). The critical time interval at which this inhibition takes place during the paradigm, however, is not exactly known. In the present study, we used single-pulse transcranial magnetic stimulation (TMS) to interfere with DLPFC function in 15 healthy subjects. TMS was applied over the right DLPFC either 100 ms before the onset of the visual target (i.e. -100 ms), at target onset (i.e. 0 ms) or 100 ms after target onset (i.e. +100 ms). Stimulation 100 ms before target onset significantly increased the percentage of anti-saccade errors to both sides, while stimulation at, or after, target onset had no significant effect. All three stimulation conditions had no significant influence on saccade latency of correct or erroneous anti-saccades. These findings show that the critical time interval at which the DLPFC controls the suppression of a reflexive saccade in the anti-saccade paradigm is before target onset. In addition, the results suggest the view that the triggering of correct anti-saccades is not under direct control of the DLPFC.
Nyffeler
Thomas
T
Perception and Eye Movement Laboratory, Department of Neurology, University Hospital, University of Bern, Freiburgstrasse 10, 3010 Bern, Switzerland. thomas.nyffeler@insel.ch
Müri
René M
RM
Bucher-Ottiger
Y
Y
Pierrot-Deseilligny
Charles
C
Gaymard
Bertrand
B
Rivaud-Pechoux
Sophie
S
D000328:Adult; D000704:Analysis of Variance; D004558:Electric Stimulation / Q000379:methods; D004562:Electrocardiography / Q000379:methods; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D009433:Neural Inhibition / Q000502:physiology* / Q000528:radiation effects; D017397:Prefrontal Cortex / Q000502:physiology* / Q000528:radiation effects; D011930:Reaction Time / Q000502:physiology; D012438:Saccades / Q000502:physiology*; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation