The effect of continuous theta burst stimulation over premotor cortex on circuits in primary motor cortex and spinal cord.
OBJECTIVE
To understand the effect of continuous theta burst stimulation (cTBS) given to the premotor area, we studied the circuits within the primary motor cortex and spinal cord after cTBS over the dorsal premotor area (PMd).


METHODS
Three sets of parameters, including corticospinal excitability, short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) and forearm reciprocal inhibition (RI) were tested.


RESULTS
Paralleling the effects of cTBS applied directly to the primary motor cortex, cTBS over the left PMd suppressed corticospinal excitability as measured by the change in the size of MEPs evoked by single pulse TMS over primary motor cortex. Premotor cTBS appeared to have a longer lasting, but no more powerful effect on corticospinal excitability than motor cTBS, however, unlike motor cTBS it had no effect on SICI or ICF. Finally, although premotor cTBS had no effect on spinal H-reflexes, it did reduce the third phase of RI between forearm extensor and flexor muscles.


CONCLUSIONS
Premotor cTBS is a quick and useful way of modulating excitability in cortical and possibly subcortical motor circuits.


CONCLUSIONS
Premotor cTBS can be used as an alternative to regular rTMS to evaluate cortical function, motor behaviours and the response to disease therapy.
Huang
Ying-Zu
YZ
Department of Neurology, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taipei, Taiwan.
Rothwell
John C
JC
Lu
Chin-Song
CS
Wang
Jiunjie
J
Weng
Yi-Hsin
YH
Lai
Szu-Chia
SC
Chuang
Wen-Li
WL
Hung
June
J
Chen
Rou-Shayn
RS
D000328:Adult; D000704:Analysis of Variance; D001703:Biophysics; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation; D009415:Nerve Net / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012018:Reflex / Q000502:physiology; D013116:Spinal Cord / Q000502:physiology*; D013826:Theta Rhythm; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult