Modulation of intracortical excitability for different muscles in the upper extremity: Paired magnetic stimulation study with focal versus non- focal coils

T. Shimizu, M. M. Filippi, M. G. Palmieri, M. Oliveri, F. Vernieri, P. Pasqualetti, P. M. Rossini

Research output: Contribution to journalArticle

Abstract

Objective: Intracortical excitability was studied for 4 muscles in the upper extremity by paired transcranial magnetic stimulation on the motor cortex, using focal and non-focal coils. Methods: Surface EMG responses of two hand and two forearm muscles were simultaneously recorded in 13 healthy subjects, after delivering paired stimuli at interstimulus intervals (ISIs) of 1-50 ms using circular and figure-of-8 (focal) coils. The intensities of conditioning and test stimuli were submotor and supramotor thresholds, respectively. Results: Paired stimulation using a circular coil showed constant inhibition at 2 ms ISI for all muscles, but not at 5 ms ISI, and induced facilitation at 10 ms ISI. The results using a focal coil were similar to those with a circular coil at all ISIs except at 5 ms ISI, where the former showed inhibition. At 20 and 30 ms ISIs, there was interindividual variability for both coils, some subjects showing inhibition and others facilitation. Conclusions: The difference of the inhibition at 5 ms ISI between using circular and focal coils could be attributed to the cortical mechanism. The inhibitory effect at 2 ms ISI, consistently observed for the 4 muscles with both types of coil, could be easily applied to assess the inhibitory intracortical function in patients with neurological diseases.

Original languageEnglish
Pages (from-to)575-581
Number of pages7
JournalClinical Neurophysiology
Volume110
Issue number3
DOIs
Publication statusPublished - Mar 1 1999

Keywords

  • Human motor cortex
  • Intracortical facilitation
  • Intracortical inhibition
  • Paired transcranial magnetic stimulation
  • Pyramidal tract neurons

ASJC Scopus subject areas

  • Clinical Neurology
  • Radiology Nuclear Medicine and imaging
  • Neurology
  • Sensory Systems
  • Physiology (medical)

Fingerprint Dive into the research topics of 'Modulation of intracortical excitability for different muscles in the upper extremity: Paired magnetic stimulation study with focal versus non- focal coils'. Together they form a unique fingerprint.

Cite this