Fig. 1.

A: experimental setup of the first dorsal interosseous (FDI) experiments. EMG, electromyography. B: mean motor evoked potential (MEP) amplitudes of 10 stimulations at each stimulator intensity [% active motor threshold (AMT)] to obtain a stimulus-response curve for a young male participant. The stimulus-response curve was fitted with a 4-parameter sigmoidal function to generate an estimate of the minimum MEP (eMEP_min), maximum MEP (eMEP_max) and the stimulator intensity that elicited an MEP response midway between the eMEP_min and eMEP_max (S₅₀). M_max, maximum compound muscle action potential amplitude.