Voluntary contraction shortens peripheral conduction time in response to transcranial magnetic stimulation of the brain

Shin Ichi Izumi, Thomas W. Findley, John F. Andrews, Miriam C. Daum, Naoichi Chino

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

We investigated the effects of voluntary contraction on peripheral conduction time in response to transcranial magnetic stimulation (TMS) of the brain in 10 normal subjects. We obtained surface recordings of compound muscle action potentials (CMAP) from the abductor digiti minimi muscle (AI)M) and nerve action potentials (NAP) from the ulnar nerve, at rest and during contraction (10% of maximal voluntary contraction) in response to TMS delivered at 100% output using a coil shaped like a figure 8. The distance between the two recording electrodes was 10 cm. The distal latency in response to TMS was calculated by subtracting the NAP latency from the CMAP latency, Distal latency was also measured by recording ADM responses to supramaximal electrical stimulation (ES) 10 cm proximal to the recording electrode, TMS-induced distal latency was significantly shorter during voluntary contraction than at rest (P < 0.00001). There was no significant difference between TMS-induced distal latency during contraction and ES-induced distal latency. TMS-induced distal latencies at rest and during contraction were correlated with the ES-induced distal latencies (r2 = 0.468, P = 0.028 and r2 = 0.769, P = 0.0009, respectively). Our results showed that the peripheral conduction time in response to TMS was related to the activity of the target muscle and to the fastest conduction velocity of the target nerve. Voluntary contraction reduced the peripheral conduction time in response to TMS.

Original languageEnglish
Pages (from-to)329-333
Number of pages5
JournalElectroencephalography and Clinical Neurophysiology - Electromyography and Motor Control
Volume101
Issue number4
DOIs
Publication statusPublished - 1996 Aug
Externally publishedYes

Keywords

  • Facilitation
  • Motor evoked potential
  • Nerve action potential
  • Nerve conduction velocity
  • Transcranial magnetic brain stimulation

ASJC Scopus subject areas

  • Neuroscience(all)
  • Clinical Neurology

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