Figure 4. Effects of ICF on IHI10 and IHI40 data from nine subjects.

IHI_1mV represents IHI with a CCS of 1 mV (IHI10: condition 2B/2A, IHI40: condition 2G/2A). IHI_1mVCS10 represents IHI with intensity of the CCS adjusted to produce a 1 mV MEP in the left FDI if preceded by a CS10 pulse (IHI10: condition 2E/2A, IHI40: condition 2J/2A). ICF-IHI_1mVCS10 is IHI in the presence of ICF (IHI10: condition 2F/2A, IHI40: condition 2K/2A). Both IHI10 and IHI40 were significantly reduced by ICF when matched for MEP amplitude (IHI_1mV versus ICF-IHI_1mVCS10), but not when matched for stimulus intensity (IHI_1mVCS10 versus ICF-IHI_1mVCS10). Inhibition or facilitation is expressed as a ratio of the conditioned to unconditioned MEPs. Ratios above 1 represent facilitation and ratios below 1 represent inhibition. Error bars represent s.e.m. *Significant difference (P < 0.05).