Figure 3. Effects of different levels of masseter contraction (A and B), TS intensities (C) and coil orientation (D) on SICI assessed in the contralateral masseter muscle of 5 subjects.

Two CS intensities (A = 90% AMT; B = 70% AMT) and three levels of contraction (10% MVC, black column; 25% MVC, light grey column; 50% MVC, dark grey column) were evaluated. No significant inhibition at any level of contraction was seen using a CS of 90% AMT; on the contrary a CS of 70% AMT was effective in inducing a significant inhibition, but only at a contraction level of 10% MVC. SICI was significantly larger at all ISIs tested when the TS intensity was higher, while it was unaffected by changes of coil orientation. The ordinate indicates mean conditioned MEP amplitude expressed as a percentage of the test MEP amplitude, taken as 100% (dotted horizontal line) and abscissa reports interstimulus intervals (ISIs). Error bars represent standard error of the mean. Asterisks indicate significant differences (*P < 0.05;**P < 0.01).