Modulation of excitability of human motor cortex (M1) by 1 Hz transcranial magnetic stimulation of the contralateral M1

Clin Neurophysiol. 2003 Jan;114(1):130-3. doi: 10.1016/s1388-2457(02)00342-5.


Objective: Previous studies demonstrated that single-pulse transcranial magnetic stimulation (TMS) of one motor cortex (M1) exerts a brief inhibitory effect on the contralateral M1. The purpose of this study was to test the hypothesis that 30min of 1Hz TMS of M1 will result in a lasting increase in excitability in the contralateral M1.

Methods: Healthy volunteers were tested on 2 separate days, before (baseline) and after one of two interventions: (a) stimulation of M1 with 1Hz TMS for 30min at 115% of resting motor threshold, and (b) sham stimulation. Recruitment curves to TMS, pinch force, and simple reaction time were assessed in the hand contralateral to the unstimulated motor cortex.

Results: The main finding of this study was that 30min of 1Hz significantly increased recruitment curves in the contralateral motor cortex in the real stimulation condition relative to sham (P<0.005, factorial analysis of variance (ANOVA)). This change outlasted the stimulation period for at least 15min and occurred in the absence of changes in pinch force or reaction time.

Conclusions: These results raise the potential for inducing lasting modulation of excitability in M1 by 1Hz TMS of the other M1, a phenomenon possibly reflecting modulation of interhemispheric interactions.

Significance: It is conceivable that 1Hz TMS applied to M1 may be used to modulate excitability in the opposite motor cortex for therapeutic purposes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Electric Stimulation*
  • Electromagnetic Phenomena*
  • Evoked Potentials, Motor*
  • Female
  • Humans
  • Learning
  • Male
  • Middle Aged
  • Motor Cortex / physiology*
  • Reaction Time
  • Reference Values