Slow frequency repetitive transcranial magnetic stimulation affects reaction times, but not priming effects, in a masked prime task.
OBJECTIVE
Slow frequency repetitive transcranial magnetic stimulation (rTMS) reduces motor cortex excitability, but it is unclear whether this has behavioural consequences in healthy subjects.


METHODS
We examined the effects of 1 Hz rTMS (train of 20 min; stimulus intensity 80% of active motor threshold) over left motor or left premotor cortex on performance in a visually cued choice reaction time task, using a 'masked prime' paradigm to assess whether rTMS might affect more automatic motor processes. Twelve healthy volunteers participated.


RESULTS
Motor cortex rTMS and, to a lesser extent, premotor cortex rTMS resulted in a slowing of right (stimulated) hand responses, but not of left (unstimulated) hand responses. In a control experiment, rTMS of the left somatosensory cortex did not lead to slower right hand responses.


CONCLUSIONS
We conclude that long trains of low intensity 1 Hz rTMS over the motor or premotor cortex can have subtle behavioural consequences outlasting the stimulation. rTMS did not affect the modulation of reaction times by subliminal primes, suggesting that priming effects triggered by subliminal primes are not generated at the level of motor or pre-motor cortex.
Schlaghecken
F
F
Department of Psychology, University of Warwick, Coventry CV4 7AL, UK. f.schlaghecken@warwick.ac.uk
Münchau
A
A
Bloem
B R
BR
Rothwell
J
J
Eimer
M
M
D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D002755:Choice Behavior / Q000502:physiology / Q000528:radiation effects; D004056:Differential Threshold; D004558:Electric Stimulation / Q000379:methods*; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006225:Hand / Q000294:innervation / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology* / Q000528:radiation effects; D009132:Muscles / Q000294:innervation / Q000502:physiology; D011597:Psychomotor Performance; D011930:Reaction Time / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation