A comparison of two methods in acquiring stimulus-response curves with transcranial magnetic stimulation

<b>Background</b><br />The stimulus–response (S–R) curve is a well accepted constituent in transcranial magnetic stimulation (TMS) studies. However, it has been suggested that parameters of the S–R curve differ when stimuli are provided in a “ramped” (measured steps from low to high intensity), or “random” fashion.<br /><br /><b>Hypothesis</b><br />We hypothesized that there would be no difference in the parameters of the S–R curve between either methodologies.<br /><br /><b>Methods</b><br />Using a randomised cross-over design, 10 healthy participants (29.6 ± 6.4 yrs, 3 f) completed “ramped” or “random” curves in biceps brachii (BB) and first dorsal interosseous (FDI) muscles of both limbs. Curves were compared using mixed-factor ANOVA and correlated between limbs and methodologies.<br /><br /><b>Results</b><br />No differences (P > 0.05) and high correlations (range 0.71–0.97; P < 0.001) were observed in BB and FDI data between curves.<br /><br /><b>Conclusions</b><br />This study demonstrated that either methodology provides similar parameters of the S–R curve in healthy participants.