Continuous theta-burst stimulation over primary somatosensory cortex modulates short-latency afferent inhibition.
OBJECTIVE
The present study investigated the effects of continuous theta-burst stimulation (cTBS) over primary somatosensory (SI) and motor (M1) cortices on motor-evoked potentials (MEPs) and short-latency afferent inhibition (SAI).


METHODS
MEPs and SAI were recorded from the first dorsal interosseous (FDI) muscle of the right hand following 30Hz cTBS over left-hemisphere SI and M1 delivered to the same participants in separate sessions. Measurements were taken before and up to 60min following cTBS.


RESULTS
CTBS over M1 suppressed MEPs and did not alter SAI. In contrast cTBS over SI facilitated MEPs and decreased median and digital nerve evoked SAI.


CONCLUSIONS
These findings indicate that SAI amplitude is influenced by cTBS over SI but not M1, suggesting an important role for SI in the modulation of this circuit. These data provide further evidence that cTBS over SI versus M1 has opposite effects on corticospinal excitability.


CONCLUSIONS
To date, plasticity-inducing TMS protocols delivered over M1 have failed to modulate SAI, and the present research continues to support these findings. However, in young adults, cTBS over SI acts to reduce SAI and simultaneously increase corticospinal excitability. Future studies may investigate the potential to modulate SAI via targeting neural activity within SI.
Department of Kinesiology, McMaster University, Hamilton, Canada. Electronic address: tsangp@mcmaster.ca.
Philemon
P
Tsang
Department of Kinesiology, McMaster University, Hamilton, Canada. Electronic address: jacobsmf@mcmaster.ca.
Mark F
MF
Jacobs
Department of Kinesiology, McMaster University, Hamilton, Canada. Electronic address: leekgh@mcmaster.ca.
Kevin G H
KGH
Lee
Department of Kinesiology, McMaster University, Hamilton, Canada. Electronic address: asmussmj@mcmaster.ca.
Michael J
MJ
Asmussen
Department of Kinesiology, McMaster University, Hamilton, Canada. Electronic address: zapallcm@mcmaster.ca.
Christopher M
CM
Zapallow
Department of Kinesiology, McMaster University, Hamilton, Canada. Electronic address: nelsonaj@mcmaster.ca.
Aimee J
AJ
Nelson
D000328:Adult; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006225:Hand / Q000502:physiology; D006801:Humans; D007858:Learning; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D013003:Somatosensory Cortex / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult
Afferent input; Corticospinal excitability; MEP; SI; cTBS