Increased motor cortical excitability after whole-hand electrical stimulation: a TMS study

Area of Science:

• Neuroscience
• Motor Control
• Neurorehabilitation

Background:

• Motor cortical pathways play a crucial role in voluntary movement.
• Understanding neuromodulatory effects on motor cortex is key for neurorehabilitation strategies.

Purpose of the Study:

• To investigate the neuromodulatory effects of whole-hand mesh-glove (MG) stimulation on motor cortical excitability.
• To assess changes in motor cortical pathways using transcranial magnetic stimulation (TMS) before and after MG stimulation.

Main Methods:

• Twenty-eight healthy volunteers (14 controls) underwent 30 minutes of whole-hand MG stimulation.
• Evaluated motor thresholds (MTs), motor evoked potentials (MEPs) recruitment curve, short intracortical inhibition (SICI), and intracortical facilitation (ICF) at baseline, immediately post, and 1 hour post-stimulation.
• A sham stimulation group was used as a control.

Main Results:

• MG stimulation significantly reduced MTs and increased the slope of the MEP recruitment curve.
• Sustained decrease in SICI and increase in ICF were observed in the contralateral motor cortex for at least 60 minutes.
• Effects were more pronounced 1 hour post-stimulation compared to immediately after; no significant changes were seen in the sham group.

Conclusions:

• Whole-hand MG stimulation increases motor cortical excitability for at least 1 hour, involving corticospinal and intracortical mechanisms.
• Synaptic modifications, potentially long-term potentiation, may underlie these observed cortical plasticity changes.
• MG stimulation is a promising tool for neurorehabilitation applications.