Table 1 Description of TMS protocols assessing M1 activity
From: Non-invasive brain stimulation as a tool to study cerebellar-M1 interactions in humans
Measures | Protocol | Outcome |
|---|---|---|
RMT | Smallest intensity of the SMO required to elicit MEPS of ≥ 50 μV | Synaptic excitability in M1 Excitability of axons in M1 activated by TMS |
MEP | Average amplitude of MEPs using a fixed SMO (1 mV intensity, or percentage of RMT) or multiple intensities (recruitment curve: e.g. 100 to 150 % of RMT) | Global corticospinal excitability |
CBI | Dual-coil: suprathreshold CS to the cerebellar cortex 5–7 ms before a suprathreshold TS over the contralateral M1 | Excitability of the DTC pathway |
SICI | Paired-pulse: subthreshold CS 2–3 ms before a suprathreshold TS over M1 | Short duration GABAa-ergic inhibition |
LICI | Paired-pulse: suprathreshold CS 100–200 ms before a suprathreshold TS over M1 | Long duration GABAb-ergic inhibition |
CSP | Suprathreshold TS applied during slight tonic contraction of target muscle | Long duration GABAb-ergic inhibition |
SICF | Paired-pulse: suprathreshold CS 1.1–1.5, 2.3–2.9 and 4.1–4.4 ms before a subthreshold TS over M1 | Excitability of cortical interneurons and I-waves generation |
ICF | Paired-pulse: subthreshold CS 7–20 ms before a suprathreshold TS over M1 | Cortical net facilitation involving glutamate |
SAI | Pairing of a median nerve electrical stimulation 20–25 ms before a suprathreshold TS over M1 | Sensory afferent inhibition mediated by Ach and GABAa-ergic inhibition |
LAI | Pairing of a median nerve electrical stimulation 200 ms before a TS over M1 | Sensory afferent inhibition (pathway unknown) |