Fig 1.
Experimental setup (A), simulation of the electrical field by cerebellar TMS (B), and general procedure (C). (A) Experimental setup: EMG, electromyography; FDI, first dorsal interosseous; MVC, maximum voluntary contraction of muscle. (B) Visual Representation of Transcranial Magnetic Stimulation (TMS) Electrical Field in the Cerebellum: Horizontal Perspective. In this illustrative depiction, the double-cone coil, denoted by a composite of small circles in blue, symbolizes the apparatus employed for TMS. The magnitude of the electrical field is graphically represented by the labeled unit MagnE (V/m). The region characterized by a robust electrical field is highlighted in red. This visual simulation provides insight into the spatial distribution and strength of the electrical field generated by the TMS application in the cerebellum when viewed horizontally. (C) General experimental procedure: The resting motor threshold (rMT), cortical silent period (cSP), and motor-evoked potential (MEP) during rest/contraction (to calculate contraction-induced facilitation [CIF]) with/without conditioning cerebellar TMS (to calculate cerebellar brain inhibition [CBI]) are evaluated before and after repetitive transcranial magnetic stimulation over the right cerebellum.
Fig 2.
(A) Resting motor threshold (rMT), (B) Cerebellar brain inhibition (CBI), (C) Contraction-induced facilitation (CIF), and (D) Cortical silent period (cSP). (A) rMT before and after repetitive transcranial magnetic stimulation (rTMS): The vertical scale indicates rMT (percentage of maximum output: %MO). The red circles and blue triangles indicate participants’ mean rMT. Error bars indicate 95% confidence intervals in groups. (B) CBI in the Sham-rTMS and Active-rTMS groups before and after rTMS: The vertical scale indicates CBI (conditioned/unconditioned). The red circles and blue triangles indicate the participant mean CBI under the rest and contraction conditions, and error bars indicate 95% confidence intervals. Asterisks indicate significant inhibition. (C) CIF before and after rTMS: The vertical scale indicates CIF (contraction/rest). The red circles and blue triangles indicate the mean CIF of the participants in the sham rTMS and active rTMS conditions, and error bars indicate 95% confidence intervals. The asterisks indicate significant facilitation. (D) cSP in the Sham-rTMS and Active-rTMS groups before and after rTMS: The vertical scale indicates cSP (ms, ms). The red, green, blue, and purple crosses indicate the mean cSP in the Active- and Sham-rTMS groups under conditioned and non-conditioned states, respectively, by cerebellar single-pulse TMS for cerebellar brain inhibition. Error bars indicate 95% confidence intervals. Asterisk indicates a significant difference between pre- and post-stimulation.
Table 1.
Result of rMT for motor cortex stimulation.
Table 2.
Result of rMT for cerebellar stimulation.
Fig 3.
Typical waveform of motor evoked potentials in one participant in active-repetitive transcranial magnetic stimulation (rTMS) condition.
Upper lines indicate in rest conditions, and lower lines indicate in contraction conditions. The left and right sides indicate pre- and post-rTMS conditions, respectively. The respective left lines show MEPs elicited by test stimulation of the motor cortex alone (no-Conditioned), whereas the respective right lines show MEPs elicited by single-pulse cerebellar TMS (C-TMS) preceding the motor cortex stimulation (conditioned).
Table 3.
One-sample t-test of CBI.
Table 4.
Linear mixed-effect model of CBI.
Table 5.
One-sample t-test of CIF.
Table 6.
Linear mixed-effect model of cSP.