Modulation of motor cortical excitability following rapid-rate transcranial magnetic stimulation.
OBJECTIVE
To investigate the effect of high frequency rTMS (25 Hz at 90-100% of resting motor threshold) on the excitability of the motor cortex of healthy human subjects.


METHODS
Resting and active motor threshold, MEP recruitment curve (I/O curve), short interval intracortical inhibition (SICI) and facilitation (ICF), and the duration of the silent period (SP) were tested in the right first dorsal interosseous muscle (FDI) before and twice after the end of 1500 pulses in 16 normal young adult male volunteers.


RESULTS
Twenty-five Hertz rTMS decreased motor thresholds, reduced the duration of the silent period and had a tendency to increase the slope of the I/O curve. Most of these effects lasted for the duration of the two post-testing sessions (at least 30 min) and had returned to normal by 2h. There were no significant effects on SICI/ICF.


CONCLUSIONS
Twenty-five Hertz rTMS can produce a long lasting increase in cortical excitability in healthy subjects.


CONCLUSIONS
This method may prove useful for the study of normal human physiology and for therapeutic manipulation of brain plasticity.
Khedr
Eman M
EM
Department of Neurology, Assiut University Hospital, Assiut, Egypt. emankhedr99@yahoo.com
Rothwell
John C
JC
Ahmed
Mohamed A
MA
Shawky
Ola A
OA
Farouk
Mona
M
D000328:Adult; D000704:Analysis of Variance; D004056:Differential Threshold / Q000528:radiation effects; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000528:radiation effects*; D007839:Functional Laterality; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000528:radiation effects*; D009433:Neural Inhibition / Q000502:physiology / Q000528:radiation effects; D011930:Reaction Time; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation