Input-Output Characteristics of Late Corticospinal Silent Period Induced by Transcranial Magnetic Stimulation

Elisa Kallioniemi, Laura Säisänen, Minna Pitkänen, Mervi Könönen, Jari Karhu, Petro Julkunen

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Purpose: Corticospinal silent period (SP) may be interrupted by a burst of muscle activity followed by a second (late) SP, generally assumed to be a continuation from the primary SP. Our objective was to characterize the input-output behavior of the late SP. Methods: Transcranial magnetic stimulation was applied on the cortical representation area of the right-hand muscles of 12 healthy subjects. Single-pulse transcranial magnetic stimulation was given with varying stimulation intensities normalized to the individual resting motor threshold (60% to 130% of the resting motor threshold) during voluntary muscle contraction. Electromyogram was recorded from first dorsal interosseous and abductor pollicis brevis muscles. Primary and late SPs were analyzed as absolute SPs, and input-output characteristics were assessed. Results: The late SP exhibited fundamentally different input-output characteristics from that of the primary SP. The late SP most likely presented itself at stimulation intensities of 90% to 100% of the resting motor threshold. Conclusions: Different input-output characteristics of the late SP compared with the primary SP indicate that the late SP possess mechanisms different from the primary SP. The exact origin of the late SP remains unclear. Understanding the origins of the late SP could provide valuable insight on corticospinal inhibitory processes.

Original languageEnglish (US)
Pages (from-to)346-351
Number of pages6
JournalJournal of Clinical Neurophysiology
Volume32
Issue number4
DOIs
StatePublished - Aug 5 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physiology
  • Neurology
  • Clinical Neurology
  • Physiology (medical)

Keywords

  • Inhibition
  • Late silent period
  • Motor cortex
  • Silent period
  • Transcranial magnetic stimulation

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