Multiple EMG Activity and Intracortical Inhibition and Facilitation During a Fine Finger Movement Under Pressure

ABSTRACT

The 1st purpose of this study was to examine multiple electromyography (EMG) during voluntary hand movements. A secondary purpose was to investigate possible effects of pressure on intracortical inhibition (ICI) and intracortical facilitation (ICF) functions of the motor cortex, using paired-pulse transcranial magnetic stimulation. Twelve participants traced a 15-cm diameter target circle using a small laser pointer attached to the right index finger. After 5 acquisition trials, they performed 3 nonpressure trials followed by 3 pressure trials. The results showed that pressure had effects not only on agonist EMG activity but also on multiple muscles, such as synergist. In addition, a decrease in ICI and an increase in ICF were both observed under pressure for muscles other than the agonist.

Keywords:

• electromyography
• motor evoked potential
• stress
• transcranial magnetic stimulation

ACKNOWLEDGMENTS

Financial support for this study was provided by the Mizuno Sports Foundation and the Tezukayama University Research Institute for Economics & Business.