Enhancing the effect of repetitive I-wave paired-pulse TMS (iTMS) by adjusting for the individual I-wave periodicity
Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neurology, D-04103 Leipzig, Germany
BMC Neuroscience 2011, 12:45 doi:10.1186/1471-2202-12-45Published: 18 May 2011
Repeated application of paired-pulse TMS over the primary motor cortex (M1) in human subjects with an inter-pulse interval (IPI) of 1.5 ms (iTMS1.5 ms) has been shown to significantly increase paired-pulse MEP (ppMEP) amplitudes during the stimulation period and increased single-pulse MEP amplitudes for up to 10 minutes after termination of iTMS.
Here we show in a cross-over design that a modified version of the iTMS1.5 ms protocol with an I-wave periodicity adjusted to the individual I1-peak wave latency (iTMSadj) resulted in a stronger effect on ppMEPs relative to iTMS1.5 ms.
Based on these findings, our results indicate that the efficiency of iTMS strongly depends on the individual choice of the IPI and that parameter optimization of the conventional iTMS1.5 ms protocol might improve the outcome of this novel non-invasive brain stimulation technique.