. Author manuscript; available in PMC: 2022 Apr 18.

Published in final edited form as: J Clin Neurophysiol. 2020 Mar;37(2):170–180. doi: 10.1097/WNP.0000000000000662

Table 1:

TMS Measures of Excitability and Plasticity

TMS Parameter	TMS Protocol	Definition	Likely Mechanism
Motor Threshold	Single pulses of TMS applied at varying intensities until individual threshold is defined.	Strength of TMS stimulus necessary to achieve a MEP (muscle twitch) >50μV in 50% of trials. Measured as a % MSO. If a MEP cannot be elicited, than rMT=100% MSO	Motor neuron membrane excitability
N100 Peak	Single pulses of TMS applied at 120% rMT.	Amplitude of the maximal negative peak seen on EEG at approximately 100msec after spTMS pulse	GABA_A&B mediated intracortical and network inhibition
MEP Plasticity	Single pulses of TMS applied at 120% rMT followed by 1000 pulses of rTMS administered at 1 Hz at 85% rMT. Then single pulses TMS at 120% rMT applied a second time.	Amplitude of MEP/N100 Peak After rTMS Amplitude of MEP/N100 Peak Prior to rTMS	Long-term synaptic potentiation or depression.
TEP Plasticity			Long-term synaptic potentiation or depression.

MEP = Motor evoked potential; rMT=resting Motor Threshold; TEP = TMS-EEG Evoked Potential