Stimulus–response curves (SRCs) of the relaxed left APB muscle using a stimulus intensity referenced to maximal stimulator output. Experiment 2; n=9). The SRCs reflect changes in mean MEP amplitude (panel A) or mean MEP latency (panel B) with increasing intensity of half-sine wave TMS. Twelve stimulus intensities were used, ranging from 50 to 100% of MSO. Filled circles refer to MEP evoked by a half-sine wave stimulus producing a PA current, whereas open circles refer to MEP evoked by a half-sine wave stimulus inducing an AP current in right M1-HAND. In six participants, MEP latencies were not reliably measurable at stimulus intensities between 50 to 65% of MSO. Therefore, changes in MEP latencies are only displayed from 70-100% of MSO upwards. Error bars represent standard error of the mean. % of MSO: percentage of maximum stimulator output. Asterisks indicate significant differences (paired t-test, Bonferroni corrected).