Intracortical inhibitory circuits and sensory input: a study with transcranial magnetic stimulation in humans

Neurosci Lett. 2001 Jan 5;297(1):17-20. doi: 10.1016/s0304-3940(00)01648-7.

Abstract

We compared intracortical inhibition (ICI) following paired transcranial magnetic stimulation (TMS) (interstimulus interval, ISI: 3 ms) and the inhibition of motor evoked potentials (MEPs) to TMS induced by stimulation of the median nerve (ISI: 200 ms) in six normal subjects. MEPs evoked by focal TMS were recorded in the relaxed opponens pollicis muscle and the size of the conditioned responses was expressed as a percentage of the size of the non-conditioned responses. Maximal ICI, ranging from 4 to 40%, and inhibition after median nerve stimulation, ranging from 11 to 68%, were significantly correlated. The results suggest that both phenomena are possibly mediated by the same gamma aminobutyric acid-ergic (GABAergic) inhibitory circuits and that afferent inputs to the cortex may contribute to their physiological activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Electric Stimulation
  • Electromagnetic Phenomena
  • Electromyography
  • Evoked Potentials, Motor / physiology*
  • Female
  • Humans
  • Male
  • Median Nerve / physiology
  • Middle Aged
  • Motor Cortex / physiology*
  • Neural Inhibition / physiology*