Short-term adaptations in spinal cord circuits evoked by repetitive transcranial magnetic stimulation: Possible underlying mechanisms

Monica A. Perez, Bjarke K.S. Lungholt, Jens B. Nielsen

Research output: Contribution to journalArticle

47 Scopus citations

Abstract

Repetitive transcranial magnetic stimulation (rTMS) has been shown to induce adaptations in cortical neuronal circuitries. In the present study we investigated whether rTMS, through its effect on corticospinal pathways, also produces adaptations at the spinal level, and what the neuronal mechanisms involved in such changes are. rTMS (15 trains of 20 pulses at 5 Hz) was applied over the leg motor cortical area in ten healthy human subjects. At rest motor evoked potentials (MEPs) in the soleus and tibialis anterior muscles were facilitated by rTMS (at 1.2×MEP threshold). In contrast, the soleus H-reflex was depressed for 1 s at stimulus intensities from 0.92 to 1.2×MEP threshold. rTMS increased the size of the long-latency depression of the soleus H-reflex evoked by common peroneal nerve stimulation and decreased the femoral nerve facilitation of the soleus H-reflex. These observations suggest that the depression of the H-reflex by rTMS can be explained, at least partly, by an increased presynaptic inhibition of soleus Ia afferents. In contrast, rTMS had no effect on disynaptic reciprocal Ia inhibition from ankle dorsiflexors to plantarflexors. We conclude that a train of rTMS may modulate transmission in specific spinal circuitries through changes in corticospinal drive. This may be of relevance for future therapeutic strategies in patients with spasticity.

Original languageEnglish (US)
Pages (from-to)202-212
Number of pages11
JournalExperimental Brain Research
Volume162
Issue number2
DOIs
StatePublished - Apr 2005

Keywords

  • H-reflex
  • Presynaptic inhibition
  • Primary motor cortex
  • Reciprocal inhibition
  • Transcranial magnetic stimulation

ASJC Scopus subject areas

  • Neuroscience(all)

Fingerprint Dive into the research topics of 'Short-term adaptations in spinal cord circuits evoked by repetitive transcranial magnetic stimulation: Possible underlying mechanisms'. Together they form a unique fingerprint.

  • Cite this