Figure 6. Effects of different conditioning stimulus intensities for interaction between short interval intracortical inhibition and short interval intracortical facilitation (Experiment 4).

Data from 6 subjects. A, the effects of different conditioning stimulus (CS) intensities for short interval intracortical inhibition (SICI) on short interval intracortical facilitation (SICF) in the presence of SICI, and for SICI and SICF alone. The abscissa indicates CS intensities expressed as a fraction of active motor threshold (AMT). The ordinate indicates conditioned MEP, including SICF in the presence of SICI (SICF_SICI, filled circles), SICF alone (SICF_Alone, open circles) and SICI alone (filled triangles). They are normalized as ratios of conditioned MEP to the test MEP. *P < 0.05, **P < 0.01, comparing SICF_SICI to SICF_Alone. B, relationship between SICF_SICI and SICI. The abscissa indicates the strength of SICI, with one being no inhibition. Ordinate indicates SICF in the presence of SICI. SICI and SICF were normalized as ratios of conditioned MEP to the test MEP. Each point represents the averaged value of six subjects at a given CS intensity.