A method to measure the distribution of latencies of motor evoked potentials in man

Clinical Neurophysiology : Official Journal of the International Federation of Clinical Neurophysiology
Lea FirminK M Rösler

Abstract

To measure the intra-individual distribution of the latencies of motor evoked potentials (MepL) using transcranial magnetic stimulation. We used the triple stimulation technique (TST) to quantify the proportion of excited spinal motor neurons supplying the abductor digiti minimi muscle in response to a maximal magnetic brain stimulus (Magistris et al., 1998). By systematically manipulating the TST delay, we could quantify the contribution of slow-conducting motor tract portions to the TST amplitude. Our method allowed the establishment of a MepL distribution for each of the 29 examined healthy subjects. MepLs of 50% of the motor tract contributing to the motor evoked potential laid between the intra-individually minimal MepL (MepL(min)) and MepL(min)+4.9 ms (range 1.6-9.2). The individual MepL distributions showed two peaks in most subjects. The first peak appeared at a MepL that was 3.0 ms longer on average (range 0.7-6.0) than MepL(min); the second peak appeared at MepL(min)+8.1 ms on average (range 3.7-13.0). Slow-conducting parts of the motor pathway contribute notably to the motor evoked potential. Our data suggest a bimodal distribution of central conduction times, which might possibly relate to different fibre types with...Continue Reading

References

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May 24, 2005·Clinical Neurophysiology : Official Journal of the International Federation of Clinical Neurophysiology·W J Z'GraggenK M Rösler
Jun 19, 2008·Annual Review of Neuroscience·Roger N Lemon
Apr 17, 2009·The Journal of Neuroscience : the Official Journal of the Society for Neuroscience·C Nicholas RiddleStuart N Baker

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Citations

Jul 14, 2010·Clinical Neurophysiology : Official Journal of the International Federation of Clinical Neurophysiology·Shahram Attarian

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